Please bear with me. I do not have a strong grasp of the complex interactions of my audio equipment. I have never designed or built a new circuit from scratch.

I have been considering adding a tube output to my Philips CD880 for about 10 years now. I have spent a many, many hours trying to learn the technical requirements of I/V conversion and how to build a working tube output. Today, I ran across Regal's thread from 2011 https://www.diyaudio.com/community/threads/new-look-at-tube-analog-for-tda1541.194134/ and a light went on.

Why has everyone focused on building line level outputs instead of MC phono level outputs? I have never seen any discussion of a MC cartridge level output. My Ortofon Cadenza Black cartridge only has an output of 0.3mv and my CAT preamp and ARC D70 MkII have no problem driving my Martin Logan Sequel speakers to good volumes.

It seems to me that there would be more options to build a low level I/V conversion output that outputs 0.3V than 2.0V. What are the technical barriers to converting the TDA1541A's 0.4ma PP to 0.3mv and outputting that to the phono in of my preamp? Is there an insurmountable impedance mismatch problem between the chip and a preamps phono in? Even if I cannot eliminate the tube output, wouldn't I have more options for which tubes I use and which amplification cuirt I use if I am trying to build a phono level output?

I hope someone who has the knowledge will help me with this.

Just an interest,

How old do you want to be when you retire?

Any thoughts about jacking in and getting the "Good Life" or is it looking a bit doggy..

Any pitfalls from those that already have...

Thought it might be fun to see what the thoughts are..😱 or

Victor meldrew always comes to mind....
http://www.youtube.com/watch?v=c1qs_eFRXqs&feature=related


Regards
M. Gregg

Hello. I have a question about modeling the acoustic design for a low-frequency speaker. I am confused by the different final frequency response with and without the "show effect of inductance" function. Which of these options will be closer to the real response?
Blue line with inductance effect. 2 dB differecnce at 55 Hz 😕

I salvaged a pair of mini piezos and was thinking of adding them as super-tweeters.
Do they need a cap? They were originally installed behind 2.2uF?
Do they need a resistor? What does the resistor do?

Here is a PDF of of the Pearl 3 from Burning amp 2023 for those of you whom already have circuit boards.





EDIT: Video presentation on Pearl 3 for BAF '23 can be found here - https://burningampfestival.com/videos/


EDIT: Build documentation "Pearl 3 Phono Build Doc-1.0d" is attached below. Version 1.0d is the most current. Download and print.


EDIT: Interview with Wayne about Pearl 3 - #881

EDIT: Modushop/ HiFi200 Chassis set available here - https://www.diyaudio.com/community/threads/pearl-3-burning-amp-2023.404054/post-7538807 https://modushop.biz/site/index.php?route=product/product&product_id=971

EDIT: Online build guide - https://guides.diyaudio.com/Guide/Pearl+3/28

EDIT: SMD soldering tutorial using Pearl 3 - Login to view embedded media

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I know this forum excludes politics, but I don't consider this a political issue, rather a universal existential threat. This is devastating news and I feel it's important to spread awareness over every avenue I can.

AB100 Amplifier - Micro Article by Nelson Pass

Since villagers armed with pitchforks and torches have begun camping
out my front door demanding a Class AB power amplifier, and

Whereas, I am inclined to demonstrate my goodwill in this manner and
do in fact have a 13 year old piece laying around unpublished,

I Hereby Present the AB100 Class AB Bipolar power amplifier.

Salient Specifications:

Rails: +/-50V or so

Gain: 36 dB (this was the request of the people who commissioned
this but did not want to pay for it)

Bandwidth: 5 Hz to 100 KHz (-3 dB)

Damping Factor: about 500

Maximum power: 100 Watts 8 ohms, 200 Watts 4 ohms

Slew Rate: 30 V/uS

Bias Current: about 0.08 A per channel

Following are several graphics. (Unfortunately I scanned them in the
distant past, so the quality is not up to my usual standards)

Let It Not Be Said: That I never did anything for you....

😎

Does anyone have a schematic for the Foster (also called Fostex) LC300 3 way crossover? I have a pair of Goodman's speakers with the Foster crossover. I want to rewire the speaker and don't know which connections go where.
Thank you

Ian

The most important thing in an EMI filter are the coils, these must have a particularly high permeability and a very low internal resistance, smaller coil values and very large X2 capacitors are best in order to achieve a lower cutoff frequency of the filter, be careful with Y capacitors, too high values can trigger the FI!

The last picture shows a Chinese DC filter and EMI filter board, which sits directly in front of the transformer in a ChipAmp amplifier.

Lot of updates have happened. Version 2.0 PCB has been made and group buy completed. All PCBs sold, but if you want one, PM me.

Latest schematic and build docs
Test PCB Image
Power up procedure
Distortion measurements
Gain calculations
Part I Upgrade to original design
_____________________
Original Post

Introducing the Schade Common Gate (SCG) Preamp. Signal comes in at the bottom source follower (unity voltage gain) and is then amplified by the Schade-enabled top MOSFET operated in a common gate configuration. This gets around the problem of low impedance on the gate of the Schade device.


Note: the schematics and information presented here is for personal and DIY use only and NOT for commercial use. Any other use needs my permission.

Inspiration came from George (tubelab) and Smoking-Amp, who were exploring the source-follower to common gate configuration for tube pentodes. I made a comment here that you could do this with MOSFETs too. Wrenchone and others have explored the Schade idea and Papa himself posted that really elegant Schade-enabled amplifier where the feedback connection is on the primary of the transformer to get around the problem of input impedance. I really like simplicity and elegance this circuit provides.

Here’s some of the pros of this approach:

• Gain device operates in triode mode.
• Low parts count.
• No unobtanium transistors or tubes.
• Low cost.
• No cap on the input.
• High input impedance and low output impedance (though I haven’t measured this yet).
• Preserves the phase: the source follow and common gate stages both preserve phase.

I built the resistor-loaded circuit and also a CCS loaded one (next post). It sounds excellent. It has the negative phase H2 (blue goes down when red goes up and blue goes down when red goes down), which really brings out the magic. Over the past couple of weeks, I’ve compared it to my other preamps, the 801a and the LuminAria, and it is comparable in sound.

Here are some measurements of the resistor-loaded version. I haven’t played with the load line much, but raising the load from 500R to 1k does improve things. The CCS version has almost no distortion. Subjectively though, I prefer the resistor-loaded version, it has much more of that 3D and “live” sound of LuminAria.

The build is a rats nest right now. Used the existing LuminAria setup with the Salas shunt reg. Hope to put it in its own box.

Acoustic Horn Design – The Easy Way (Ath tool)

This is an associated thread for a waveguide generator called Ath (Advanced Transition Horn), version 4.
Ath is a piece of software for designing waveguides and horns. At the same time it makes it possible to easily simulate their acoustic behaviour by means of FEA (BEM) via ABEC/AKABAK tool.

The current Ath release is available at https://at-horns.eu





Thread milestones (last edited 26.12.2020, no longer maintained):

#233 Birth of the OS-SE formula
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#375 Measuring driver's exit wavefront
Acoustic Horn Design – The Easy Way (Ath4)

#666 Some of the practical verifications:
Acoustic Horn Design – The Easy Way (Ath4)

#844 Ath 4.4.1 - Introducing superformula
Acoustic Horn Design – The Easy Way (Ath4)

#922 JBL M2 "How-to"
Acoustic Horn Design – The Easy Way (Ath4)

#933 JBL M2 - Ath clone
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#1003 Comparison of an OS waveguide and a flat piston
Acoustic Horn Design – The Easy Way (Ath4)

#1117 Ath 4.4.3 released (Fusion 360 import)
Acoustic Horn Design – The Easy Way (Ath4)

#1533 Ath 4.5.0 released (scripts not backward compatible)
Acoustic Horn Design – The Easy Way (Ath4)

#1602 General phase-plug discussion
Acoustic Horn Design – The Easy Way (Ath4)

#2389 Joining profiles of different curvatures
Acoustic Horn Design – The Easy Way (Ath4)

#2494 Tritona Waveguide
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)


Spherical-wave phase plug

#1706 Initial ideas
Acoustic Horn Design – The Easy Way (Ath4)

#1824 Kessito's input
Acoustic Horn Design – The Easy Way (Ath4)
Acoustic Horn Design – The Easy Way (Ath4)

#1892 Compression cavity modal analysis
Acoustic Horn Design – The Easy Way (Ath4)

#2016 Diaphragm suspension analysis
Acoustic Horn Design – The Easy Way (Ath4)


Free standing waveguides

#2600
Acoustic Horn Design – The Easy Way (Ath4)

#2936 Rolling back the profile
Acoustic Horn Design – The Easy Way (Ath4)

#3390 Employing axisymmetric BEM (finally)
Acoustic Horn Design – The Easy Way (Ath4)

#3427 Rollback added
Acoustic Horn Design – The Easy Way (Ath4)

#3532 Source amplitude shading
Acoustic Horn Design – The Easy Way (Ath4)

#3549 OS-SE formula extended: k
Acoustic Horn Design – The Easy Way (Ath4)

#3664 Effect of an enclosure and other parameters
Acoustic Horn Design – The Easy Way (Ath4)

#3822 Compression driver throat plug
Acoustic Horn Design – The Easy Way (Ath4)

#4186 Preferred in-room response and DI target (discussion)
Acoustic Horn Design – The Easy Way (Ath4)

#4503 Incorporating compression driver model
Acoustic Horn Design – The Easy Way (Ath4)

Hi all, I am installing some more powerful sub amps in my home set up and I have an interesting 'problem'
To cut a long story short when I earth the chassis I have a GND loop sound the signal GND is NOT connected to the chassis earth and I have double checked. So the chassis each is only a safety earth and not related to 0V signal in any way directly as far as I can measure. The chassis has no connection to the board. Apart from the heat sink and this houses the output transistors in the normal way, no short as far as I can see or any leakeage

Any ideas, it has a relay for soft start but this is only on the Signal out. The transformer has L, N only connections and I have rewired the unit for mains as I have added a 12V fan with power supply (thermally operated) so very clear on all of the mains connections. It works its just the 'GND loop' sound that I want to remove but still want to keep it safe and have the chassis earth

Any ideas ?

I don't know if this guy's speaker will ever be marketable but he's got a playing prototype, and I've not seen anything like it before.

If I'm understanding the concept correctly; a typical digital audio setup recreates a music signal as a mixture of pure sine waves that mix and interact via the Fourier transform principle, and the mixing occurs within a digital processor, upstream of the power amp(s) and speakers.

In contrast; in this guy's setup the mixing of the component sine waves occurs at the speaker itself. That is; driving each speaker are twenty separate signal processors feeding pure component sine waves into twenty amp channels-- discretely driving twenty drivers in each speaker. As such, the Fourier transform occurs at the speaker itself, as the separate driver outputs blend together in front of the speaker.

That's a lot of digital processors and amp channels so even if this guy succeeds in taming all the gremlins, it's a complicated and expensive setup.

Enjoy!

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ELEKIT TU-8888 Monoblock (available now)​

Another wonderful products from Mr Fujita...
PCB type DIY KIT...


















Here below are the spec of the monoblock amp.
Tube usable : KT series from 88 to 170 (for output tubes) KT170 recommended
EF86 x 1 and ECC82 x 1 (driver tubes)
Max. output : Over 50W/unit (with KT170)
Manual bias adjustment - A meter at the top panel
No headphone feature
SP impedance : 4ohm and 8ohm
Input x 1
Balance adjustment volume (with 41-point click) on the rear side
Coupling capacitors : 3pcs (100n 450V x 1, 470n 630V x 2)
Max size for the coupling cap :
100n 450V ... D22 x L44 mm
470n 630V ... D20xL57 mm
* as of now and could change the spec a bit.
Tubes are not included.
*The amp is designed to use custom made Lundahl LL3733"
PCB for OPT and harnesses are included in the kit.

There are only 30 pairs or 60 pieces for USA/Canada in December​

​

Price after Dec 15, 2024 $1,475.00 (will ship from Vancouver Canada)​

I am back again with the same amplifier, my lovely Xtant X604.
Last time I was able to recover the functionality with your help (water leak). Now I discovered that my front left tweeter is not working and making strange sound (I am bi-amping the front end). So I popped the cover off, inspected for water leaks - didn't find any but found 2 burned resistors. One is R111, the other one has no reference designator but since it sits between R108 and R110 it is likely R109. Also did a search before making this post and found the schematic for X603 posted by Perry Barin. Wonder if Perry or someone else has the same schematic without additional markings written over it. Perry was wonderful helping me fix the amp last time I had a short due to water leak that formed crater in pcb (2021). Will try to dig into this tomorrow.

Hello everyone.🙂

This is the first thread I have opened here with the aim to share my experiences with you and to broaden my knowledge about electronics from possible replies.

Over the 2020/2021 winter I have built an amplifier based on A60+ boards from eBay and was quite satisfied with the result: an amplifier sounds great, is relatively easy to build and involves everything what is needed to complete the project: power supply and effective speaker protection.

Below is a photo of one channel of the amplifier.

The amplifier comes in two different versions:
A60, smaller, with 3 output pairs of transistors
A60+, larger, with 8 pairs of output transistors.

There are variety of possible versions: with different output transistors
MJL3281A/MJL1302A
2SA1943/2SC5200

It is also possible to purchase bare boards, partially stuffed boards, complete boards and also amplifiers in chassis.

In addition to this the board incorporates a solid power supply and effective speaker protection. You only have to add your heat sinks large enough, transformers, transistors and capacitors.

I have decided initially for a A60+ version without output transistors and without power supply capacitors.

I also have tested A60+ and it sounds splendid indeed. Someone else on internet said its sound is "golden" and has gone that far to state that it has "euphoric tone". He is right it really sounds extraordinary. Just read this review.

I have also done extensive measurements: it measures great. It is done right across the whole audio spectrum and beyond. I will repeat the measurements and make them soon public.

The sound was great so I have decided to spend a bit more of time and money on this project.

I have purchased two A60+ and three smaller A60. This will be my spring 2021 project.

Finally, some hints for these who decide to build this amplifier:

Only capacitors with diameter 35mm and 10mm lead spacing will fit into this board. Initially I was afraid that just 4X10.000uF per channel wouldn't be enough, but it works indeed very well.

Carefully with biasing – this is a wild beast and can quickly go incredibly hot.

Chose heat sinks large enough to have freedom to set higher bias.

Just got them delivered from the UK. Doing up a Lowther Acousta Enclosure for them pretty soon

Premium Drivers information sheet​

Standard specifications: Many misleading terms have been used to describe the paper preparation of the Lowther diaphragms, doping, age-conditioning, curing, varnishing, etc., leading to discussions & myths around old preparations, similar to the legend of Stradivari’s varnish. There is no magic formula. The standard process, used for many years, is to apply freshly prepared 'special pale' French polish to the made-up cone/voice coil sub-assembly prior to fitting to the motor. This soaks through the paper leaving pure shellac distributed through the paper fibres as the spirits dry. Sugar-like crystals can be seen on the surface of a freshly treated cone. A few months sees a uniform yellowing of the diaphragm due to the reaction of light & air with the shellac. The paper fibres are locked with the shellac to be stiff yet flexible; It is generally accepted that the driver performs optimally after this point, though the foam suspensions co-incidentally loosen up over this period, and this has more of an influence at the early 'break-in' period. Older drivers (pre-Thornton) mostly exhibit a dirty, patchy yellow appearance due to poorly prepared lower grade shellac, which does not cure well over time. Controlling the quality & preparation of the shellac is an all-round long-term improvement, but due to the cleaner appearance, some still think we do not shellac the cones. Standard spec. drivers will continue to be available as usual.

Premium Specifications: The main difference over the standard range is the treatment of the paper. In this process the paper is impregnated with our own in-house formular before cutting, forming & assembling. The 'curing' process is mostly complete by the time the unit is tested & packed, though improvements will still be noticed over the 'break-in' period. The new treatment reacts with the paper fibres differently to the shellac process, resulting in a more stable, consistent & dimensionally accurate cone. The impregnation formular, however, can only be made in small batches in our own workshop and will not scale up to industrial preparation. This limits production to the ‘premium-hand-made' scale,
with the inevitable expense involved. The premium diaphragms are also fitted with the new back centre, replacing the foam standard. The entire set of components is laser-cut, enabling greater control of consistency & accuracy over the die-cut standards. Laser cutting also allows us to make small detail modifications like rounding the points of the 'pips' that hold the voice coil to the inner cone, cut elliptical 'pressure-relief' holes to control the dual cone phase errors, adapt the turned edge of the inner cone to a more suitable paper weight & composition and re-design the assembly relationship of the inner / outer cone / back centre / voice coil - most of which
would have been adopted before, but not possible because of the limitations of the old die cutting. The result of all these adaptations is a diaphragm which excels in all areas, including appearance, with the Lowther logos, radial embossing, and consistency of paper surface & colour. The legendary hand-crafted double-wound speech coil and overall <>10.5g moving mass of the assembly are retained. Foam surround suspension is the same as standard.

Sound: Initially developed for use in the Edilia, testing in all driver models & cabinets showed a marked improvement in all areas. Diaphragms prepared straight-out-of-the box for our most critical 'test bed' - the Lowther-Hegeman with field coils - were received by everyone with amazement; described by various judges as 'game-changer', 'most significant positive step for Lowther in years', 'improvement in all areas of presentation of natural sound'. We are confident that the premium 'upgrade' easily justifies the enhanced price, and all customers are encouraged to hear the difference at our studio showroom. All of our top range handmade cabinets (TP2, Almira/Edilia, LHSR, Audiovector) will be fitted premium regardless of driver type. The premium diaphragms can be fitted to almost all existing Lowthers as an enhanced Re-cone, or LFL trade in.

Premium diaphragms: Key points - Changes / Improvements

Paper gsm weight & fibre type
Laser cutting & CAD design.
Lowther's own paper treatment impregnation process
Inner Cone improved, so:
Enhanced choice of phase plug /centre pole treatment
Aluminum or Silver voice coil
Radial embossing
Logos printed onto cones.
New back centre & assembly
Improvements in quality consistency, appearance, longevity.
Significant improvement in all aspects of sound presentation.​

Click to expand...

I would like to have something that can increase (I already know how to decrease) the damping factor without adjusting the amplifier feedback, such as filtering, preamp, DSP algorithm, or similar... I have seen a DSP algorithm that can increase DP but don't have access to it. I would be grateful if someone could provide even a little information

I'm doing some playing around with active filter designs, and I'd like to get swept filter responses, showing the frequency response of the filters. I'm used to using a vector network analyzer for looking at RF filters, and I'd like to do the same at audio frequencies.

I've got a Focusrite Scarlet 2i2 3rd gen that should be able to do this, but I'm having trouble figuring out what software to use. I've spent some time poking at REW, and it doesn't look like it supports measurements like that. Are there other packages that will do that?

Here's an idea......

• to add a return send / pre out power in.
• to feed the first channel back through the second channel to create higher gain distortion or tube Drive.

will it work or fry


Has anybody here had experience with this kind of stuff

I would like some input on this.
I am repairing a build of this amp where it is humming badly as the regulator transistor is blown. The particular device is hard to obtain so I tried something similar npn of 120v rating and it worked for a while but then blew as well, I imagine due to over voltage as the B+ is 350v in operation and about 400v at switch on.
The build had worked ok for six months or so but I wonder if the design is a bit vulnerable and could be improved.

Are there any similar amp designs I should consider for inspiration on improving this?

Many thanks

Click this for the scientific paper.

This is the Abstract:
Quark movement is almost by the speed of light. Due to this speed their inertial mass-effect increases profoundly. That inertial effect is an accelerating force. Within the nucleon the force is the strong force. As quarks movements are back and forth movements, called zigzag or oscillating movements, there is movement in opposite directions. So the oppositely acting forces annihilate each other. However the force acting on objects receding from each other is a trifle stronger than that acting on objects approaching each other. This small difference between these forces is a “left over” force and “leaks” out of the nucleon. In previous manuscripts, formulae were presented to calculate these forces. In the present paper the “left over”, “leaking” force is estimated, and this force is gravity.

I've got a couple crates just sitting on the floor that I'm already outgrowing. So I needed something with a bit more capacity, and getting the vinyl up off the floor would be nice too...

I used the design here as inspiration. I don't anticipate needing that much capacity anytime soon, and I didn't want something that bulky sticking out into the room. Stacking single rows left-right simplified the design, omitting the center divider.



Lumber was sourced from Menards. I can give more details if needed.

The width of the lumber I used for the side panels and bottoms allowed for a small ledge out front to display the "on deck" sleeves. I ended up routing out a flute along the top edge to create a lip that keeps the sleeve from sliding onto the floor.



I decided to give the side panels some shape. I made a template/profile board and used a flushing bit on the router to transfer the shape to either side.



Simple dowel pin and pocket screw construction.





To prevent the bottom panels from sagging from the vinyl weight, and stiffen up the structure: I added some screws from underneath the bottom panels up into the front and back boards (not shown). It just wasn't needed for mockup purposes so I drilled the holes later.

A new thread to discuss DIY guitar pickups.

I recently built one using six electret microphones. Every other one is wired out of phase with the adjacent mic. The set of six therefore cancel, for far field sounds. Each is arranged to be below the corresponding string, which is near field to the mic. It works pretty well - I've had it out on stage at an open mic more than half a dozen times. Other players say it sounds good. Different sound than you'd get from a piezo bridge pickup or stick-on puck.

Why microphones? I normally play classical nylon, which of course doesnt work with the magnet based embodiment shown below. I melted the hot glue and ripped out the coil, to use the plastic shell as a pre-made holder for the electret mics to start. The three low strings on this guitar are from a nylon set.

I've been working on a bass 8k (power supply seems identical to MD8000.1 so I've been browsing repair posts for those as well). I've replaced IC9, IC3, and IC1 and any accompanying SMDs that needed replaced. I replaced both power supply, output fets, and gate resistors. With the rectifiers pulled to isolate the power supply I can't get it to build a square wave on powerup. IC1 builds a perfect 40khz square wave, IC3 not so much, it tries to build a very odd signal initially and then goes flat once the amp goes through it's power up cycle. While testing R150 went up in smoke. I'm running out of ideas and looking for some guidance. I will be buying Perrys book as soon as I have the funds as well

Any help is greatly appreciated, I have a lot to learn and am very appreciative of any guidance and tips. Thank you!

Hi,

To make a long story short, I'm working on a SET design with a slightly complex PSU design (200, 270 and 380Vdc from three separate transformer windings).
I plan to use 2x 6AU4GTA in a hybrid bridge for the 380V rail (@140mA) and I also wish to use vacuum diodes for the other two (20mA and 100mA respectively).
To keep the costs down I've been looking at russian dampers (6D14P and 6D20P) for the input and driver tube supply rails but I can't quite figure out how to interpret the heater-cathode insulation ratings in the datasheets:


Would it be safe (in long terms) to use these tubes as rectifiers up to less than 300Vdc with the heaters referenced to ground?
I could connect the heaters to the cathodes but would prefer not to if possible, no other tubes will be powered by the same heater windings though.

The Synopsis:

"My thesis is that music written for the ensemble of two violins, one viola, and one cello constitutes the musical art form that most nearly approaches perfection, both in its past achievements and its present possibilities. The greatest minds and most perceptive dispositions find in the literature and performance of string-quartet music an endlessly self-renewing source of wonder and delight. The string quartet is a most felicitous meeting of potential and realization."

There are several YouTube embeds, and a link to a Qobuz playlist.

The pull quote above is the Subtitle of my Tracking Angle Review of the Philharmonic Audio BMR Monitor. BTW, the ArgentPur GaN-FET monobloc amps are AMAZING. Perhaps they are even "The Poor Man's darTZeel." That is, if Poor Men can afford $5,900/pr. SOTA power amps!!!

John Atkinson's measurements and Robert Schryer's review in Stereophile are required reading.

I have built more than a dozen loudspeakers of my own design (with help from outside experts!), and I can't grok (dating myself to the 1970s) how Philharmonic Audio can sell these for $2000/pair.

I noticed that Amazon UK had some In Phase Car Audio XTC17.2 woven glass fibre coned drivers for £ 21.11p, so I decided to order them and make some omnidirectional speakers with them

The driver is mounted on a small chamber that is connected to another, larger chamber by an aperiodic vent. My initial plan was to support the top chamber on coil springs with a foam seal, however the cast iron weights that became available ( the scrap bin at work ) are to heavy, and the temporary foam spacers that I used for initial testing work quite well

I asked the question some months back: How do our loudspeakers compare to expensive, high end, HIFI brand loudspeakers?"

I have answers.

The Short of it:
For those of you who do not want to read this entire write up I will be kind and put my summary up top in a bullet list. There was 3 of us who went. One musician, one loudspeaker builder, and one wife who only ever listens to the system the former two have and doesn't know how any of it works. We listened to 60 systems in one day. Back to back to back. We then came home and listened to my systems.

The BAD

• Most of them do not sound good
• Most of them have a roughness to the upper mids that just sounds terrible. They use these great drivers but drive them straight into their cone resonances. This was the #1 thing we all found wrong with about 80% of the systems
• I swear they pick their crossover points at random. Their crossover networks are pretty goofy
• A lot of them have phase issues. You stand up and it just sucks. You move to the left and it sucks. You have to sit directly center
• Some of them were amazing. These were generally ones where the loudspeaker designer was right there in the room and you could ask him questions. I will get to these units in a bit
• Anything with DSP had a roughness to it. Every single one of us, by the 3rd floor, could walk into a room blind folded and tell you if it was a DSP system or a passive system. Passive ALWAYS sounded better. We listened to about 60 systems back to back throughout the course of a day. DSP to the 3 of us = no good. Was not really subjective. It was objective.
• A lot of them beam really badly. The ones that don't, have a harsh upper mid range
• Do more expensive drivers sound better? Yes, if you use them properly. Saw some $400 drivers implemented horrendously and some implemented properly. And everything inbetween. But mostly the former.

The good

• A couple of systems were just incredible. All of these except two had the loudspeaker designer in the room.
• The better systems used either bespoke of expensive drivers.
• There were a couple mid tier systems that sounded really good.

You can skip the individual review and go to my comparisons with my own loudspeakers at the very bottom
Lets go through one by one now (I am not going to include most of the bad ones. They sounded so bad I had to just get out of there. If it isn't listed below here and it was at the show, it sounded like crap):


This 4 way was great. It had dynamics and a lightness. Lows were washed out but it was still good



This was ATC. I hear people praise their old mid dome here so I checked them out.

This two way was horrendous. One of the worst speakers at the show. The driver on the table is what they were showing off. Do not buy this thing. It was sticky, like someone covered it in honey. I would guess in your house it'd be covered in dust within a couple weeks. Bad, just all bad.


Morel

These were great. The mid is the one up top and is ported. The woofers down below are also ported. These were REALLY good. I spoke with the engineer about how they don't measure or simulate well. He explained their motor design in detail. It will not simulate right because their design is so different. They have special software they have to use for their motor designs. The price point of morels now looks very attractive to me.



This one wasn't playing. I just thought it was a fun design with the dual AMTs in front of the woofer


MTM Illuminator design. What's not to like? Horrendous upper mid range. So sharp and attacking. Not good. Lows were good, not very dynamic. No idea what they cost but its too much. Feel like the designer dropped the ball here.


I will now never build a line array. This thing just sounded odd. Like a blade of people singing on the left and then a blade of instruments on the right. It was all washed out vertically. Hard to explain. Not a fan. None of us liked this, all of us thought it was just strange sounding. And not strange in a good way.

Full range driver build by Songer. Second best sounding full rang behind a Voight pipe Alpair 11 build. This thing was great. Good dynamics, good upper mid range, very nuetral, good dyanmics. It had it all. It is a giant full range so it beamed like crazy. Move your head left or right and the tone changes. But still very good.


I think these are called frugal horns? Big woofer and a compression driver. Engineer was in the room. Not my cup of tea but the BEST compression driver I have ever heard. He crosses these to the woofer at 700 hz. Pretty impressive and fluid, natural sound out of these. The big woofer lacked dynamics to say the least.




Triangle Art

These were bad. Like just plain bad. Maybe they would sound good if you were 60 feet back in a big room? Crazy directional. Everything sounded muddy. All looks, no beauty.


AudioVideo Artistry

******* AMAZING. What do the Accuton driver's sound like? ******* AWESOME. End game design right here. Nothing topped these except their big brother which will be on this list somwhere. These Accuton drivers are insane. I think he has at least $7k, at LEAST, worth of drivers and crossover components in each of these.

Do expensive drivers sound better? In this case, YES YES YES, they ******* do. I had to shake this man's hand. Can't stop gushing over these.



Alright, we need to chat about these domes. This dome was, BY FAR, the best mid at the entire show. Everything else pales in comparison to these. I asked him if I could buy a set of the mids and he said I could. I just have to call Playback Distribution and ask for a replacement pair. I will be buying a set. Maybe we can get a group buy together? I'm telling you, you haven't heard ANYTHING like this before. These are like sorcery. I will be making a second post where I try to buy these. This is a game changing driver.

As a speaker in totallity these were AWESOME. They are small, but they blow out of the water almost everything else at the show. Another one where the engineer was in the room. I spoke with him 3 times today. Kept coming back.


These were ok. Harsh upper mid. Tweeter were good but they ran them too low. A lot of expensive stuff to sound like garbage. Crazy.


26" dual opposed woofer. It shakes the building. Sounds no different from my coffee table subwoofer in my office. This doesn't hit as low as my coffee table. Impressive...... if you don't have a coffee table that hits to 11 hz.




Tannoy

You like jazz? These are for you. Grainy, poor imaging, you are hyper aware that the sound is coming from the speaker. No low end dynamics. Great for trumpets and a saxophone. Pretty sure they were made for that.


My first taste of open baffle. My buddy liked them. I did not. Sounds all washed out. Someone moved a table and the guy had to jump on the dsp to correct the room again. Not for me. Zero bass


More open baffle. More of the same, washed out and not defined. These had bass because of the horn. That was even a little washed out.



Harsh upper mid. Looks cool, doesn't sound very good.


PS Audio

These are some of the best at the show. If you can tame a mid planar, nothing really compares for silky smooth vocals. Paul did it right. I have half a mind to use a planar mid for every mid I do even though I just gushed over those mid domes.

Use this link for more details:
https://electrodac.blogspot.com/p/dac-ad1862-almost-tht-i2s-input-nos-r.html
Note: 8th pin on the I2S input header is missing connection with the GND (on some of my PCBs this pin is unconnected, if you are going to use it, solder it with the nearest GND pin on the header)


People who are selling brand new unused AD1862 or AD1865 chips:

• Paddy Garcia new group buy
• https://www.diyaudio.com/community/threads/ad1862n-j-dac-chips-for-sale.405922/
• https://www.diyaudio.com/community/threads/ad1862n-d.417897/

I want to thank @Paddy Garcia for the whole happy DIY community. He did very honorable work: Group Buy #92



Special tested DACs:
DAC702BH/CH (Glue logic - I2S data input) (result: audible digital noise on the output, not good for audio use)
DAC8811 (CPLD data input) (result: audible digital noise on the output, sound far away from very good audio, don't waste time and money on such DACs)
...

I bought these amplifiers from an old man at work.
He brought them in because he heard i love tubes and he wanted to be rid of the heavy turds at 80 something years old...
I offered him $500 for these and the preamp which was also a diy effort.

The workmanship was poor and the amps didn't work. The boards were a rats nest and the builder used 5 different types of green wire.
I bought them for half of what I figured the iron was worth because I knew i could do something with them eventually.
(The preamp has SUTs)

I drew out the schematic and it did not make sense and it also didn't work, so I knew I'd need to overhaul the whole thing in order to make something worthwhile.
Luckily the A-340 dynaco is an extremely easy to use transformer. I could copy the dynaco mk2/3 but I already had 2x small tube sockets.
Instead I went full Williamson.
I am in fact William's son...
I put 6cg7 in the front sockets for va/pi
And driver.
I built a fr4 circuit board with a bias/balance adjustment pot.
I rewired everything using cloth wrapped wire to Retma color codes.
Now they both fire up and bias in and it's time to put signal through them and start fine tuning them.

Hi to all,

I just want to make a album for 15 songs time over 16 minutes. It's simple. Each user has to copy and paste adding only one song to the album so in the end it's 12 songs, one per user, and each album has to have a different theme.

Whoever adds the last song of the album gets to say what the the theme for the next album will be and it starts all over again.

Songs over 16 minutes:

1. Pink Floyd - Echoes (23:31)
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.

Just to introduce myself, have been modifying and playing with electronics, mainly audio, for years, in the early days often fixing them after I'd broken them ! Work in IT, networking, virtualisation etc and electronics is a hobby, for fun. Have a number of classic (old, British) transistor amplifiers all modified in some form or another.

Latest is Lehmann Audio BCL which needs fixing after somebody tried upgrading it and just went too far.

Looking to build more and fix less, I'd like to try building a tube amp.

Hey Guys
I am trying to come up with a 1 inch
Compression Driver on a budget here
Trying to stay around $100 per driver.
Is there anything that you would say is on the Warmer Smoother side of the spectrum ?
Trying to stay away from ear fatigue here.
I will be using it with
The B&C me45 horn.
Thanks

Happy New Year !

to Papa - ( I don't wanna bug ya on personal e-mail ) :

I wish ya many more .....

to all spoiled kids - good Health ....... and mucho active brain cells in next year 😉


(I'm going now , and dunno when I'll be able to post again ; I have plans to drink good Rakija ..... without net )

Stumbled upon this interesting board on aliexpress, comparing the prices with other ADSP21489 sharc boards this is peanuts, and already with 2 ADC and 3 PCM1798 DAC boards for a 4in/6out system. Anyone have this?

Lusya ADSP21489 development board ADC PCM1804 Input board+DAC PCM1798 output board 4 in 6 out processor B4 007-in Replacement Parts & Accessories from Consumer Electronics on Aliexpress.com | Alibaba Group

The schematic I downloaded from the internet differs substantially from the amplifier I have on my bench. It shows MPSA42 devices and a different number of diodes, as well as different capacitors. The unit I'm working on has MPSL01 devices, so I suspect it's an older model than depicted on schematic I have.

Problem in brief>

Right channel clipping positive peaks at 80 watts output (observed on bench). Customer complains it's sometimes making loud static/noise.

This far, I have checked voltage drop across all .33-ohm emitter resistors. Also did an ohmmeter check of same parts. It looks like all the output devices are functioning, based on seeing about 300mV across all resistors. This draws my attention to a possible problem on the driver PCB piggyback. Unfortunately, my schematic is the wrong version.

If someone (Nelson?) has the right one for s/n 770811, I would appreciate a copy, Thank you!

By popular demand, here is a new thread devoted to PETTaLS flat panel speaker simulation software, developed by Dr. David Anderson. Flat panel speakers may also be referred to as bending wave speakers, or DML speakers.
Let's use this thread to discuss topics specific to the use of and improvement of this great new tool. Topics could include, but are not limited to:

• new release announcements
• questions about how to use it
• features you'd like to see
• possible bugs
• interpretation of results
• other....

The free version of the software is available here:

PETTaLSFree

Some videos about the software are here:

PETTaLS Videos

Eric

Over the past few months I have been sorting out my measurement techniques using the loopback scheme and have built a REW impedance rig.

Apologies this may be a long post.

Drivers - SB WO24P-4 woofer, Morel EM1308 Dome Mid, Morel ET448 Tweeter.
Box - Approx 40L sealed and medium stuffed with polyester toy stuffing. (re-purposed Akai SW125 box)

I finally got round to making a set of measurement the other day and have tweaked my active crossover to a point where I like the sound and theoretically it models well. The caveat here is that the room I have done the measurements in is not very large and has furniture in so quite a few reflections sothey are not perfect and have been smoothed. Measurement were taken at 1m at tweeter height and around 85dB loudness (roughly calibrated against mobile phone dB meter).

I took measurement from -90 to +90 degs for each of the drivers without moving the mic (note the Tweeter and Mid are both domes and so have protection capacitors, measurements taken with and with out these in place). I took nearfield for the woofer 1cm from the centre dust cap (sealed enclosure) and then impedance of each of the drivers in the box (with and without protection caps just for interest).



The results for the woofer seemed to suggest I am on the right track. The nearfield looks to be close to a Max Flat alignment which is what I was after. The 1m measurement aligns Ok with the manufacturer data and shows the baffle step below around 350hz (360mm wide baffle). Also the Impedance curve matches the Winisd output almost identically (peak : 32ohms at 47hz). So the box look pretty good for the WO24P-4 woofer.



I have been running a Minidsp Nanodigi crossover for a while and have had great fun playing with different slope filters and arrangements and also comparing it to crossover designs in VituixCad that seem to align quite well.

A quick check on the step/impulse response delays between the tweeter and the mid./woofer seem plausible at approx 5mm for tweeter to mid and 75mm for tweeter to woofer. So reference feedback seems to be working and has now embedded the acoustic offset into the phase measurements.

I then loaded up the +cap tweeter/mid and woofer measurements into VituixCad and played around with a few different designs with different slopes for an active crossover, these ranged from BW6 to LR24 in various combinations. The aim was to get a fairly flat on axis frequency response, align phase of each driver as close as I could (min 1 octave either side of the crossover point) and then have an in-room response that tried to follow a slope of 0.9dB/octave (or 6dB form 100hz to 10khz). Note, I did not merge the nearfield so it has room bass reflections under around 300hz.

Without documenting all of the various trials and errors, I settled on the following scheme that seems to meet most of the requirements quite well. To me this sounded the best subjectively, it has a fairly large soundstage with decent separation between the instruments and has a natural and lifelike presentation. I could stand the vocals being a little more forward but this is the only minor criticism. Bass is plentiful in my 10ft x 10ft x 8.5ft [ceiling] room with the speakers pushed a little into the corners.



So, having got a sound I liked I then tried to replicate this with a passive crossover (using the -cap measurements and measured impedances)........and this is what I came up with.

and with mid Inverted

This is basically a simple LR12 electrical topology which ends up being an acoustic LR24 on the woofer/mid crossover and LR12 on the Mid/Tweeter. There is a damping resistor on the mid with a shaping resistor in the low pass parallel leg. There is an L-pad on the tweeter. The resulting impedence curve looks manageable for most modern amps with a low of 3.2ohms at 110hz but is definitely a 4ohm design.

Now the bit where I would like a bit of critique of what I have done to tame the rising frequency response of the tweeter that is seen in many Morel units. I added a small inductor in series to tip over the curve at around 8Khz and then added a notch at around 10khz. This seems to flatten things off nicely but is having and inductor in series in a tweeter circuit a good idea and will it affect the sound negatively?

In general think the p[assive version matches the design aims and the active system fairly well.

Finally, before I splash some cash on crossover components to see if this scheme sounds as good as the active version (would be happy if it did), for the woofer inductor is it Ok to use a 1mm/18awg iron core coil or do I need to go 14awg Air coil and also for the 100uF capacitor is something like a Jantzen eLeCap 5% Electrolytic Bipolar Capacitor Ok to use or again do I need to go for a Jantzen CrossCap? Just trying to keep the cost sensible at the moment until I know it is Ok. The rest of the Caps are affordable using Jantzen Standard and the coils will be 18AWG Air Coils.

Anyway, congratulations for getting to the end, and thanks in advance for any comments left. Everyday is a school day for me!

As the title states, this is a thread dedicated to dome midrange drivers, specifically any larger dome driver at least 50mm or 2" in diameter intended to be used in a 3 way or larger speaker design.

Being there isn't a good collection of data on this rather rare type of driver and its use, it would be nice to have it all in one thread. My goal was to give anyone interested in the successful design of a speaker using a dome midrange a solid starting place to gather or share the info necessary to design a new speaker or to modify an existing design to use them ie. xover, baffle modifications, etc.

If you have any specific or technical info (measurements, graphs, data, xover design, pictures, links etc) regarding your favorite dome midrange or a specific technical question, please feel free to share it in this thread.

Please keep your post to the point and avoid any strong subjective opinions. I was hoping this thread could accumulate as much relevant info as possible. Thanks in advance for any productive shared info.

Here is my latest Tokin SIT amplifier. It is a DEFISIT amp (Depletion Enhancement Follower SIT) output stage based on Nelson's First Watt SIT-5 output stage. Diyers more knowledgeable than me picked apart what information Nelson provided in his SIT-5 owners' manual (https://www.diyaudio.com/community/threads/first-watt-sit5.418023/), and I rode on their coattails and came up with this version.

My build is only the output stage, and it incorporates the duo output capacitor arrangement which can be tweaked to adjust the amount of current amplification that the mosfet part of the DEFISIT push-pull output contributes to the total current amplification. This is a departure from the regular DEFISIT amplifier, where the SIT and mosfet both fully contribute to the total current amplification.

Here are a couple of LTSpice simulations. I did many simulations, but these two are what I based my design on. I chose -47VDC for one sim since I intended to build it using one of my existing amplifier chassis and power supply. I chose the -63VDC for the other since that is a reasonable voltage that will take advantage of the power capability of the THF-51S and still keep the power supply voltage reasonable for capacitor voltage and heat sink heat dissipation.

As shown in the simulation results (47VDC power supply and 2.0A Iq), the measured current through C4 connected to the SIT drain was 361mA peak, the measured current through C7 connected to the mosfet drain was 150mA, for a total of 511mA. As a check the current measured through the speaker, R8, was 509mA - close enough. So the contribution of the mosfet was 150mA/511mA = 29%.

I have not included the LTSpice screen shots of power output but the 8 Ohm power output was nearly 23W at 1% THD and 4 Ohm power output was nearly 40W at 1% THD.


63VDC PS 2A 8R 1Watt:



63VDC PS 2A AC signal current through C4, C7, and 8R Speaker:



47VDC PS 2A 8R 1Watt:



47VDC PS 2A AC signal current through C4, C7, and 8R Speaker:





As mentioned I decided to build the 47VDC version. The chassis and power supply is from my BAF2015 Amplifier - A SIT Mu Follower Revisited With Feedback (https://www.diyaudio.com/community/...t-mu-follower-revisited-with-feedback.408193/). The power supply is CLC, comprising 2x22mF - Hammond 156B - 2x22mF, and an Antek AS-3218 transformer per channel for full dual mono construction.

I put together a PCB design and sent it off to JLCPCB for fabrication. In addition to stuffing the PCB once I received it, I also changed the CLC filter from V+ supply to V- supply.



Initial power-up and subsequent Iq and SIT Vds adjustments went smoothly, and Iq and SIT Vds were stable.

Next up was testing with an 1kHz signal and distortion measurements. Unfortunately when powered up with an AC line powered 1kHz oscillator connected, the amp immediately blew the powerline fuse. So it was trouble shooting time. After checking the schematic and pcb, checking that the input capacitor was not faulty, and not finding any visible ground shorts with the meter, I was baffled.

I knew that the issue was mostly likely a grounding problem and that it only manifested itelf when an input device was connected to the amplifier. Luckily a thought came to me fairly quickly - when I changed the CLC filter from V+ to V- supply, I forgot to move the power supply connection to safety ground on the CLC filter board. The correction was made and success. Only one fuse was permanently damaged.

The dim bulb tester came in handy here as once the fuse blew, the dim bulb tester went in and I was able to probe around with power and not blow anything. In addition to using it during trouble shooting, I always use it for first power-up testing of power supplies during various stages of construction and first power-up testing of audio circuits.

As for the amplifier supply not shorting with no input device connected but shorting with an input device connected, I gave it some thought. The power supply was for V-, with V- from the supply connected as power to the amplifier circuit. V+ from the supply was connected to the amplifier circuit board as ground. The V- from the supply was ground in the previous amplifier but I forgot to change it so it was now incorrectly connected to chassis safety ground. With no input device connected to the amplifier circuit, the power to the amplifier board was floating. Although the V- was also connected to the chassis safety ground and to the powerline/IEC ground, there was no other direct connection to V+, so no short. The live from the powerline/IEC was connected to the transformer primary, which was isolated from the transformer secondary. Also the speaker and input jacks were isolated from the chassis. So with no complete direct connection of V- to V+, the current can only flow through the audio circuit. The chassis was connected to V- but there was no path for the current to flow from the chassis to power supply V+.

When the oscillator was connected to the amplifier input, the circuit was completed, current flowed, and the fuse blew. That was because the oscillator was AC powered and had a safety ground connection. So the oscillator line safety ground connected to the oscillator power supply ground, then connected to the oscillator signal ground, then connected to the amplifier signal ground, then connected to the amplifier V+. The oscillator safety ground is also connected to the amplifier safety ground through the line ground, and the amplifier safety ground is connected to amplifier V-. The net result was amplifier V+ and amplifier V- were connected together - a short circuit. There was a CL60 thermistor at the amplifier power supply ground connection. That would have limited the short circuit current: 47V/10R = 4.7A. Fuse was 2.5A slow blow.

I have swapped power supply polarity before but had always remembered to switch the safety ground connected, until this time.

So always be careful. Electricity can kill.

Hi.

I thought that all compression drivers used the same thread? When trying to mate Eminence Asd1001 with an mrh-80 horn from Monacor it works fine for the first 5-6 turns, but then it jams up. Data sheets for the parts have the same thread. Comparing with a Noname driver the asd1001 thread is slightly off.

Anyone else tried something like this? I'm tempted to cut of some of the internal thread in horn, but it seems wrong. It should fit?

Kind regards TroelsM

A thread to discuss how well a compression driver matches the profile of a particular horn, and how to determine that match - or mismatch.
When choosing a compression driver to go with a particular horn, what is important to know so that the two work well together? Can any driver be used with any horn? Or do some compression drivers work well certain horns and not well with others?

EDIT: April 19, 2023
Attached to this post you will find a spreadsheet, kindly provided by @marco_gea, that allows you to calculate and see the match between a given horn and driver. The spreadsheet takes the parameters of the compression driver throat and calculates an exponential horn that has an equivalent flare rate to the driver throat. With that information you can calculate and see how well a certain expo or hypex horn will match the driver's initial flare rate.
Instructions are included in the spreadsheet.

Obviously the first thing we would look at when choosing a compression driver for a horn is "are they the same size?" In other words, is it a 1", 1.4", 1.4" or 2" entrance to the horn? We normally choose a driver of the exit size as the horn throat. Also to be considered would be the mounting style, such as screw or bolts and the bolt pattern. Adapters can be used for different mount styles and even sizes. For example a common adapter is to use a 1.4" exit driver on a 2" entrance horn. PRV even make a 1" to 2" adapter. But beyond those obvious mechanical matching issues, will a certain driver work well or poorly with a different horn? And how can we determine that for a good match? How do we know the internal geometry of a particular driver?



Horns come in many shapes, sizes and profiles. We might look at a Smith horn that has no vertical expansion at all, but a wide horizontal expansion, to a Kilpsch horn with a long narrow vertical expansion and somewhat wide horizontal expansion - to a long horn that looks somewhat like a trumpet, to the Yuichi and others with mixed expansion.



I'll cite a recent example. Forum moderator @kevinkr recently went thru a good deal of trouble and expense to learn what driver works best for his new Yuichi horns. The Yuichi is a wide horn, but not very tall. In fact the horn very quickly goes to over 90° flare in the horizontal axis, while remaining with zero expansion along the vertical axis for about half its length. The horn is very much axi-asymetric, as opposed to a round horn where the expansion is axi-semetric. Is the horn a rapid expansion, narrow, or somewhere in between? What driver geometry would work best on this horn?
This is what the Yuichi looks like inside.

ELEKIT 2A3/300B SET AMP
Price US$1945.00 (Ll2785C amorphous core OPT)

Stereophile Reveiw : July 2023 Edition ​

https://www.stereophile.com/category/gramophone-dreams​

Stereophile Class A Components​

https://www.stereophile.com/content/recommended-components-fall-2023-edition-integrated-amplifiers




This is our first time to offer Amorphous core OPT. I want to make sure the Lundahl amorphous core is superior than the regular C Core.
This is the sample of Amorphous Core for TU-8900.. Amorphous core requires a longer burn in time..
Is it better??



No Takman for this model - Takman is running out of material to make 2% carbon resistors.

TUBE SET OPTIONS:
COSSOR/Linlai Delux 2A3 + Sylvania 12BH7A $380
COSSOR/Linlai Blackplate 300B +Sylvania 12BH7A $345
COSSOR/Linlai WE300B +Brimar 12AU7 $$695
Western Electric WE300B (5 Years Warranty) + Sylvania 12BH7A


COSSOR/LINLAI Delux metal base 2A3 $285
COSSOR/LINLAI WE2A3 $385
COSSOR/LIMLAI E-2A3 $495
Sylvania 12BH7 $95 (pair)
Brimar 6067/12AU7 $159 (pair)

If you buy TU-8900 with LL2785C and Western Electric 300B, the Cossor/Linlai Delux 2A3 is free

COUPLING CAPS 100nF 450V x 2 (VCAP CuTF $195
Cossor/Linlai WE2A3

46 x Audio Note Tantalum Resistors $5.25 each
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap









LEFT - TU-8600S (Metal Tube Cover and metal knob), RIGHT - TU-8900 (Plastic Tube Cover, plastic knob) https://www.flickr.com/photos/64593884@N08/ https://www.flickr.com/photos/64593884@ https://www.flickr.com/photos/64593884@N08/


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Matching headphone impedance/volume levels.

You can change the headphone impedance/volume levels by
simply removing the front panel and change the position of a
short pin.



Directly-heated triode tubes like the 300B and 2A3 enjoy an enduring popularity among audiophiles. The 300B with its rich midrange and extended bass- and 2A3 with its delicate expression and gentle tone offer a very special sonic experience. These 2 tubes are similar in appearance but very different in characteristics and can both be used in TU-8900 without any special changes in amplifier settings. Many manufacturers are producing 300B and 2A3 tubes so users can enjoy trying the various versions available from different vendors. *
*NOTE- TUBES ARE NOT INCLUDED WITH THE TU-8900!



■ Automatic detection of 300B and 2A3 tubes
“300B” and “2A3” tubes look similar but their respective filament voltage and operating parameters are totally different. Their supply voltages need to be adjusted depending on which of these tubes are used in the same amp. In TU-8900, the tubes that are installed are detected automatically and the correct filament voltage and voltage of B-power are automatically set. When 300B tubes are installed- the LEDs on the sides of the volume knob will light up in blue. If 2A3 tubes are installed- the volume knob LEDs will light up in green. Additionally- these LEDs on the right and left side of the volume knob will turn red when there is excessive current due to defective tubes, etc., and the current is shut down to protect the amp. The red LEDs will also diagnose the problematic tube- the right side of the volume knob turns red when excess current occurs in the right channel, and vice versa.




■ Tube-friendly design
Warm-up time for directly-heated tubes and indirectly-heated tubes are different. In most designs, directly-heated tubes warm up faster than indirectly-heated tubes- so often directly heated tubes are often overloaded. With TU-8900, the voltage is gradually raised and reduces the level of overload to the directly-heated tubes.


■ 12BH7A instead of 12AU7
TU-8900 is designed to use 12AU7 as voltage amplifying tubes. However, 12BH7A, with high driving ability, can also be used instead of 12AU7.


■ Ample space for larger coupling capacitors
Coupling capacitors can have a big effect on the sound quality. For the TU-8900, high quality conductive polymer electrolytic caps and polypropylene film caps are provided. However, exchanging for other coupling capacitors is also possible. The maximum size of the caps that can fit in the space is 22mm in diameter x 44mm in length.

■ Matching headphone impedance/volume levels
You can change the headphone impedance/volume levels by simply removing the front panel and change the position of a short pin.


■ Newly designed circuitry
The power transformer has independent windings for the right and left channel to minimize the interference between channels as much as possible. The filament power uses the latest DC-DC converter for extremely low noise and high efficiency. Schottky barrier diodes and fast recovery diodes are used as rectifying diodes that reduces even the most negligible noise spikes. Listeners can enjoy music free from noise even when using a pair of high efficiency headphones. The main circuit of the power unit is unitized per channel as a module.

■Easily change the feedback setting to NON-NFB
Many triode tube amps use negative feedback in their design. The TU-8900 has an option for listeners to hear the triode tube sound without negative feedback. In TU-8900, changing the position of a short plug on the PCB can change the setting to NON-NFB. The gain level increases by approx. 8dB when NON-NFB setting.

■ Updated more reliable tube sockets
After brainstorming with our vendor, we have come up with a more reliable 4-pin sockets for 300B/2A3. Tubes are mounted safely and securely when installed in these sockets.


■ High heat-resistant polycarbonate tube cage
The IEC (International Electrotechnical Commission) sets guidelines on thermal limits on materials and parts, such as a chassis and the tube cage. The TU-8900 tube cage top can heat up to 100 degrees C due to the heat from the output tubes. A robust polycarbonate tube cage with high heat resistance is used to meet the IEC standard.

Specifications of TU-8900

●Stock tubes 　：　300B (or 2A3) x 2pcs, 12AU7 (or 12BH7A) x 2pcs *Tubes not included
* specifications below are with the 300B+12AU7, with NFB, 8Ω loaded
●Rated output ：　8W+8W (300B) / 3.5W+3.5W (2A3) <THD 10％>
●Rated input ：　1Vrms (300B) / 650ｍVrms (2A3)
●Residual noise：　15μV (IHF-A)
●Frequency response： 7Hz-90kHz (with NFB) / 12Hz-45kHz (Without NFB)
●Input impedance ： 50kΩ
●Output impedance ： 4-6.3Ω, 8-16Ω (SW on backside)
●Input terminal ： LINE x 1
●Output terminal ： Speaker output terminals (L/R channel)：Gold-plated screw type terminal (Banana plug usable)
Headphone terminal ：6.3mm headphone jack
●Power voltage ： AC110-120V or AC220-240V 50/60Hz (3P inlet)
●Power consumption： 95W (300B) / 65W (2A3)
●Measurement　： W356xH214xD320mm (including projections)
●Weight ： Approx. 11.4kg (excluding a power cable)
●JAN code : 4952682107941

After 200 hours listening, I am confident to offer the Audio Note upgrade option:​

46 x Audio Note Tantalum Resistors $5.25 each
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap









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MUSES02 is currently $44 each plus shipping at Mouser. Anybody know where to get genuine MUSES02 instead of fakes at a lower price? 4 x 44 + 8 shipping = $184 for four op amps plus tax so ~$200. Not willing to pay that.

I have a 5v regulator with a 2 wave rectifier.
The secondaries powering it are from 12.6vac heater secondaries. (tube amp)
The heaters have been elevated with DC so now I am trying to connect the reg board.
I have been told that I should float the ground of the regulator and relays but not sure how that is done.
Do I ground the the relays to the ground on the regulator board and nothing ground to the chassis?
Do I make the ground reference the junction point of the two 100ohm resistors from the heaters where they connect to the DC?

JohnAudioTech JAT501 Class AB Amplifier PCBs from JLCPCB

4 of 5 pairs sold. Last final set remaining.

Made from JohnAudioTech's publicly available JAT501 gerber files.
No modifications to John's design were made.
Inline layout, board revision 1.1, two layer, double sided, and blue solder mask.

$10 Canadian plus shipping.
This sale is not for profit. It is being offered as a service to the community. And to help promote John's channel.

These are just the bare PCB boards. You have to source your own components, assemble, and test.
Bill of Materials (BOM) including part numbers is also provided.

Includes two hand made and tested Thiele network coils (labeled L1)

Shipping within Canada is $3.00 using Canada Post oversized letter mail (sorry no tracking).

Shipping to USA is $10.00 using Canada Post Tracked Packet - USA. Includes a tracking number.

Known issue, the board stencil has some typos.
Transistors labeled 2N5551C should read 2N5551.
Transistors labeled 2N5401C should read 2N5401.

The "C" variant has a different pinout.
2N5551 / 2N5401 (1. Emitter 2. Base 3. Collector)
2N5551C / 2N5401C (1. Emitter 2. Collector 3. Base)

One board has scratched solder mask that happened at the factory. The exposed copper was tinned. The traces are ok. See attached photos.

Hi everyone,
I'm trying to build this amplifier based on the Sanyo STK465 amplifying module (I attached the originals down below).

And this is my version:


I simulated this circuit using LTspice and everything works as I expected. I attached the simulation down below.

The problem is that when I build it in real life the DC bias point of the output stage is not going to 0V DC. It sits close to the positive rail and I can't figure out the reason. I can't proceed further until I get the DC bias point right, so I'm stuck here.

I'm currently using a 10K resistor as the load so i don't fry the output transistors, but the problem persists even with a 10 ohm load. R6 and R7 are there to protect the output transistors as well.

What I tried:

• I checked the supply rails and they are fine. They come from a dual power supply I built which uses L7812CV and L7912CV linear regulator.
• I checked the connections a thousand times.
• Tried to remove all capacitors (excluding the decoupling ones and the compensation capacitor C4) in order to focus on the DC response only.
• The circuit was originally built on a breadboard. I've now soldered the amplifier on a perf board, while the rest of the circuit (the input section, the output filter, the feedback) is still on the breadboard.
• I put a 10K potentiometer on the emitter of Q5 and tried to trim it (therefore decreasing the gain of the VAS stage) until I got 0V DC at the output. I couldn't get it to work: as I got closer and closer to zero, the output flipped to the negative rail; I then trimmed the pot on the opposite direction, and the output flipped back to the positive rail. I think this happens because Q5 gets shut completely off, causing the output to swing to the negative rail.

I'm at a loss. Why doesn't the VAS stage bias the Sziklai pairs in the output stage correctly? Do you have any suggestions? Thank you very much for your time and for your help.

Working on a Kicker KXA2400.1, there doesn't seem to be much info out there on these. Found schematics of the KX (not "A") series, radically different. Powers on, everything looks reasonable, protect light comes on then goes off, draws about an amp once it's stable, no output.

Opening it, found a nice flash mark where a little lockwasher came from somewhere and wandered over to short the positive rail busbar (near the green LED & USB port) to the grounded pressure plate for the rectifiers. The washer was mostly vaporized and the rail is no longer shorted -- the positive rail comes up to voltage fine, but the negative rail is dead.

Also found a blown capacitor in between the two output coils, replaced that, still doesn't work. No other obviously failed components or flash marks from said washer shorting other things before meeting its demise.

Weird power supply architecture, using two non-isolating boost converters instead of the usual transformer. Seems to be asymmetric as well, the positive rail having more transistors and higher voltage rated caps than the negative. And here I thought Rockford was the king of trying to find new ways to patent a switching power supply.

Anyone worked on one of these yet and have any pointers, or perhaps a schematic of it?

Thanks!

Welcome to SylphAudio thread!

Our New Product Release Roadmap for 2024



****

SE800 PFFB High Power Class-D Amplifier
Supply Voltage: dual ± 25V min, ± 85V DC max
Unclipped Power (<1% THD+N, ± 85V): 350W-8Ω, 700W-4Ω
Input configuration: Single Ended
Output configuration: Single Ended
Input sensitivity (PFFB): 2.6V RMS
Voltage gain (PFFB): ~25dB
PCB area: 140mm x 70mm
Overvoltage Protect: ±88V to ±91V DC
Undervoltage Protect: none, UVLO @ ±12V DC
Speaker Protect: none, requires external SP

Can be used with a 2Ω load if powered with a lower power supply voltage around ± 60V DC, can reach 800W output (< 10s burst signal).
Designed with PFFB to reduce load dependency and improve noise and distortion. 5W at 4Ω THD+N is around -82dB, with THD at -94dB.
Rugged and super-stable PFFB design based on TI, implementation by SylphAudio.

ETA: Jan 2024

Sample pictures



FB100 and FB360
We've applied the largest feedback factor possible without reducing the output power capability. Which results to exceptional performance.

FBUltra
Under development, composite OPA1612 and LM3886 design.

I have some questions (to this always greatly helpfull community!):

1. How do I overcome the nasty impedance peak of the Tang Band W3-881SJF Full range unit? I was hoping to use this as a mid driver from 400Hz to 4000Hz in a 3 way design. But I am worried about the huge impedance peak this driver has.

2. A lot of people are writing or talking online about complex crossovers sucking the life out of the sound.. (am I thinking about impedance correction networks and notch filters here?)

I would like to pair a 10" sealed or 8" ported woofer to this driver, and have a tweeter take over on top where the 3" driver starts loosing on dispersion of energy.
but I am very uncertain how to go about this.. Any thoughts are welcome! (By the way, the speaker is to be used in a domestic situation for stereo music listening in a livingroom. My main goal here is to have as wide a range of frequencies come from a very small point, to obtain fantastic stereo imagery.

Over the years Ive built many indirectly and directly heated amplifiers, and always if some dht was in the system, it sounded better in a way I cant quite explain. A lot of people build amps with them, they even started to be made again for new amplifiers etc. From the builders standpoint it has only disadvantages - you need separate filament supply for each tube, well filtered, current regulated in the best case, everything that happens on the cathode, every small hum or noise gets amplified. They are more microphonic than indirectly heated tubes. Now I have DAC output stage with the 45 tube used as a preamp tube. (if anyone wants more details, its choke loaded with output capacitors). And the same thing happened.
Like I said I can not even properly describe the sound. It never is boring every track is interesting, I actually enjoy music now. I stopped thinking about how to better the schematic, I just dont know what to play next. The sound is big, like even at lower listening values. Like it comes from nothing in the air. The voices and treble are heavenly. Music is now actually touching me emotionally way more than before. Like the simplest description that Im always saying is magical emotional sound. That just is not quite there with other tubes.

My big question is WHY, what electrical factors are different than from indirectly heated amplifiers? I really want to find out why this happens. I wondered the same thing in electrolytic vs foil caps in the power supply, but the explanation here was quite simple, being way lower losses in the dielectric, vibration not being a problem cause the foil caps are sinked in oil. The tangens delta difference between electrolytic and foil cap is like 0.3 vs 0.001. Plus the foil caps are way better at filtering higher frequency noise etc. But with DHTs I still dont know. Why nobody measured this?
Its the exceptional linearity (the curves are perfectly spaced and also as flat as a ruler).
Or its some microphonic feedback from the speaker vibrations getting to input tubes?
Or its the special care that you must take while building a DHT amp compared to indirectly heated amp?
Or its a different cause? I still dont know, does anybody has any ideas?

Hello everyone,

and I would like to discuss a topic that is often mistakenly associated with the dynamic range of loudspeakers in my opinion. It is about the subjectively perceived by the listener decay time of instruments. In some loudspeakers, for example, a hi-hat decays for a very long time, and in others, although the strike itself is not less loud, the reverberation disappears very quickly and a clean, empty background appears. I thought that these loudspeakers might differ in the SPL characteristic as a function of the supplied electrical power - a loudspeaker that produces a long reverberation would have this characteristic more linear, and the one that produces less reverberation, falling more abruptly towards the muting of the sound level.

Since I could not find such graphs on the Internet, only a typical SPL graph in the frequency domain, I decided to make simple measurements myself. I connected the amplifier to a computer that played white and then pink noise, and I measured the sound intensity from the near field to eliminate the influence of the room. I increased the volume from zero to a specific level, then repeated one of the measurements with reduced amplifier gain, i.e. the volume intervals were smaller. And what?

These graphs show that the faster decay of instrument reverberation in some loudspeakers and slower in others does not result from the slope of their measured SPL characteristics vs. the supplied electrical power. So it is not any dynamic range of the loudspeakers or their SPL given in catalogs that decides the phase of the instruments' decay, because even if some loudspeakers play louder overall, the reverberation is received relatively to the impact and also decays relatively to the level of the impact (attack phase).

And my question: what, in your opinion, can decide that some loudspeakers beautifully convey the nuances of sound with a long phase of instrument decay, while others leave this information "to themselves"? PS. I used the Revox BX-350 and Wega Direct 200 speakers for the measurements. Both have dome tweeters, with the Wega being 3-way and the Revox being 2-way. The midrange measurement in the Revox speakers concerned one of the 4 parallel mid-woofers, while in the Wega - one midrange dome. The Revox BX-350 have 4 paper speakers and one tweeter, and the crossover frequency is 3200 Hz. As you can see in the graphs, the course of the SPL curves is almost identical, apart from the difference in levels for the midrange, resulting from the measurement of only one of the four speakers in the Revox speakers.

The question returns: what does the length of the instrument decay phase depend on? Is it about, for example, the damping of the speaker membrane? I almost forgot: out of the tested speakers, the Revox are the ones that "eat" the details of the sound. In addition, they have their own character, which is always audible, and the Wega speakers "disappear", they are almost transparent to the sound, they do not add a strong signature to it. Both play very pleasantly, but the difference in sound detail is huge in Wega's favor. And this despite the fact that the Revox-s have undergone recapping to MKP capacitors, and the Wega still have factory-fitted Wego electrolytic capacitors in the entire crossover. Any hint will be valuable - besides, this is a topic for an interesting discussion 🙂 And now I will try to paste photos 😉

For tweeters (X axis - PC volume sent to DAC and amp):



For the midrange:



And now midrange with reduced volume increments and reduced room noise floor.



...and well, above graph says that Revox is a speaker that should transmit more silent details to the listener as the difference between quiet and very quiet sounds is lower than in Wega. The reality shows the other way 😉 And what could I do to encourage Revox four tiny cones to show more silent nuances of the sound - no idea as this is not about sensitivity of a speaker. That must be something else - more sensitive speaker of course would play the decay phase louder but that is all relative to the attack phase which would be also louder played.

Regards,
Mike

I have spent several hours over the past two days searching for size/shape compatible surrounds. The most likely candidate so far are surrounds from Simply Speakers.

The surrounds attach to the underside of the SBX500 woofer discs which is a shiny metal surface - presumably aluminum.

Two years ago I attempted surround replacement to the undrside of 5" woofers with a poly cone and those surrounds coincidently came from Simply Speakers. That attempt was not successful due to the awkwardess of accessing the underside of the cone and the clear, fast setting adhesive provided by Simply Speakers. I think that clear glue was rubber based. There was not enough time for me to position the surround on the cone before the glue got too stickey to work with. They then sent me some conventional slower setting white glue.

I expect that gluing a surround to the underside of these Technics SBX500 woofer discs will be fiddly and somewhat time consuming. My question is will the conventional white' slower setting glue bond properly with the metal surface of the disc's inderside?

The attached photos are as they are now. The residual old surround material on the disc's underside is still in place. I am debating on attempted removal by blade & scraping or trying some type of solvent.

Rod's instructions say "a 0.5°C/W heatsink for normal hi-fi use if the quiescent current is maintained at the minimum recommended of 20mA."
I don't know what to do with that.
This is the heatsink I was considering and I found this calculator, but I'm not sure what value to use for Ts (max).

One of my early projects: the Objective 2 (or O2) headphone amplifier, built as a preamp. 4 RCA inputs with rotary selector, one stereo RCA output. Includes 15 volt AC adapter (this is an important detail, don't use a 12v DC adapter!).

Asking $40 obo, local pickup in San Francisco preferred. Will ship ConUS at cost.

The purpose of this thread is aimed for people who (or recently completed) are currently undergoing construction of the Elektor Preamplifier 2012 that was published in April, May and June 2012.
See these links.
https://www.elektormagazine.com/labs/preamplifier-2012-1-introduction-and-line-intonevolume-board-110650

http://https://www.elektormagazine.com/magazine/elektor-201204/19844

Your constructions, ideas, problems, images etc would be valuable for other constructors to view.

Although, most readers will be familiar with the Elektor project, below i have list some basic details below.
Printed Circuits Boards for this project are available direct from Elektor: -

LLLL BOARD (110650-6V120) £14.95
POWER SUPPLY BOARD (110650-5V110) £16.95
FRONT PANEL BOARD (110650-4V110) £11.95
INPUT BOARD (110650-3) £22.95
Preamplifier 2012 (2) (110650-2) £22.95
LINE-IN/TONE/VOLUME BOARD (110650-1) £22.95

It's probably easiest if I start this off by explaining what I am aiming for. The speaker I'm designing is going to cover the range 80 - 18 kHz and ideally have a directivity of 90x40 (HxV). At the low end of the range I'm am willing to accept the speaker becoming a mono pole but I would like the directivity to extend as low as possible in frequency, however I would also like broad horizontal directivty even at low frequency. The speaker also needs to be able to output 125dB/1M peak AES SPL. The speaker is to be used at home where I will be listening 17 degrees off axis vertically (hence a speaker with nominal 50 degree directivity would be preferred over 40 degree) due to positioning constraints and also as a PA top where it will not have to array. I will be running different crossover settings depending on application, ideally I would like to get down to ~600 Hz if possible.

What I'm having trouble with is the lack of good quality data on horn/waveguide combinations. I'm aware of the following issues:
1. Large diaphragms only having high frequency output by operating beyond the pistonic mode but manufacturer data is very smoothed and as such I can't see if this is well damped or not.
2. Often I read about some wonder wave guide from a few years ago but the manufacturer doesn't exist anymore or has moved out of the market. Or the manufacturer dosen't sell to the public. (E.G the K402 waveguide looked very interesting).
3. The expected exit angle isn't listed for the waveguides and most manufacturers are not giving the compresion driver exit angle so matching a waveguide with a driver seems to involve expensive trial and error.
4. Many waveguides are not constant directivity at all and yet are listed as such by the manufacturer! (I.E I can see from the shape that its exponential)
5. The high frequency dispersion of a waveguide can be limited by the dispersion of the compression driver but no data is supplied on this.
6. Vast differences in price between various options with no clear data on why.

So taking on this difficult landscape I have come up with a few combinations and I wonder what you think of them and if you know of any more information I have missed:
1. P-AUDIO PH-4525 This is the largest P-Audio wave guide and is only £25 and has a mouth width of 425 mm with a throat of 2". I have read that a lot of P-Audio products are clones of JBL, if so does anyone know what model this would be? In terms of driver pairings they measure it with this P-Audio BM-D750 (£85) or there is the huge P-Audio BM-D950 (not sure where to buy) a 4" diaphragm seems to be pushing it in terms of possible breakup problems! P-Audio claim it can go lower than the D750 though...

There are some measurements of the D750 combo here seems that at least one person likes it.

2. The same horn but assuming the dispersion of these large diaphragm drivers is poor using the very expensive (for me) BMS 4592 ND (£430). This is a coaxial and carry's a number of risks that make me uncomfortable. Firstly I'm not sure if it will work well with this horn and secondly if using it I would like to have a passive crossover between the 1" and 2" driver which will add a lot of development time. Ideally as this driver can go super low (300Hz) I would like to mate it with a much larger horn but I don't know where to get one for sane cost. I would be willing to try and extend the mouth of an existing flare but building the throat area I'm not very confident I could do well. This is also more money than I would like to spend considering I will also need to add woofers, electronics, box etc.

3. An in-between driver not as expensive as the BMS but with better data than the P-Audio such as the HF200. This seems to be quite well damped as the frequency response isn't as smoothed (£187).

3. 1.4" exit drivers. As my SPL requirements aren't crazy this may actually make a lot of sense, as the horns will be smaller and dispersion better? and result in lower cost. For this the RCF HF950 looked quite attractive (especially as it has 50 degree vertical dispersion and claims 'perfect' constant directivity) (£55). For a matching driver the RCF ND840 ooked quite interesting and as its from the same manufacturer it may match up with the horn well? (£145)

*Yes I am aware that I should build a synergy horn type thing and I will but this will take a while and in the meantime I need better speakers...

I got lucky last weekend, & found a pair of KEF C40s on the side of the road. Someone had stuck a piece of veneered chipboard on the top of each, presumably so they could put a nice pot plant there, and they had obviously been stored somewhere damp, given the light coating of mould.

I didn’t want them in the workshop in this condition, so when I got home immediately wiped them down with vinegar to kill the mould (fortunately no moisture damage), cleaned them with detergent, and the hot day made it easy to remove the ‘pot plant stands’. I removed the components, and then attacked the sticky residue left on the vinyl with solvent.
The boxes ended up in usable condition, with some nicks & chips, and obligatory spatter of white paint droplets. There was a convenient date stamp inside showing them to be from Apr 1987. Someone must have told KEF to get stuffed, these were sealed and absolutely chocka with polyfill.

The components: the crossover were clean, although with 38 years under their belt it’s time for a recap of the five electrolytics. The woofers cleaned up nicely and are in good condition; the tweeter coatings were bad, almost completely gone from one, seriously cracked on the other.

The plan: take measurements, re-cap the x-over, and re-coat the tweeters, Re-assemble to see how speakers from the ‘Golden Age’ sound, keep them if I like them, otherwise flog them on Gumtree (I need more speakers like a hole in the head).

Hello DiyAudio community,

TL;DR: This is a USB transport for audio output (up to 8ch) and input (2ch for now) and user device control (e.g., DSP management) from PC (MacOS/Linux/Windows) thru I2C/GPIO. Including bootloader for remote firmware update, flexible device configuration, HID interface, multiple audio output options, integration with SigmaStudio (simultanious audio playback and ADAU DSP configuration). Compact module available in USB-C and USB-B versions, isolated or non-isolated.

Latest docs, config tool, link to buy:
http://york.eclipsevl.org/

So, the story started when I needed a USB transport for audio output and another channel for device control, such as for managing DSP.

Last time, I solved this problem using a USB hub and a USB to Serial converter. This way, I assembled the required interface from 4 chips:
https://www.diyaudio.com/community/threads/audio-transport-module-york.406025/
(first post)

I tried to combine everything into one XMOS chip. This was also a working solution, but there was a big problem with the availability of the chips, especially in the desired package.

Thus, developing the transport on the pic32mz seemed the most logical to me. The first prototype module was based on Dortonyan’s project from Vegalab: in terms of circuitry, it almost completely repeated the original project and was designed for two-channel audio output, plus a serial interface. During testing of the firmware based on the original source code, several problems were identified when working in different OSs. The serial port was also not fully implemented.
I posted my version of the firmware with fixes in the original thread and on GitHub: https://github.com/eclipsevl/york_pic32mz_uac2_osfw/

After that, I continued working on the functions I needed. The following features were implemented:

1. Bootloader. Necessary for firmware updates via USB, without a programmer.
2. Flexible device configuration using a PC utility (which is also used for firmware updates).
3. HID interface for transmitting service information and device configuration. Initially, I planned to use the serial port, but HID is much more suitable.
4. Serial interface, which can be optionally enabled.
5. Various additional audio output options: s/pdif, 8-channel TDM, dual i2s (for using some DACs channel-by-channel in mono mode). Recently I also added support for old dacs with clock/data/latch interface. I.e. direct connection to dac ICs such as AD1862/PCM1702 etc is also possible without glue logic.
6. Various clocking options: module oscillators, external clock (slave mode), internal PLL clocking.
7. I2C port and library for integration with SigmaStudio: for simultaneous audio input/output and DSP ADAU programming.
This last feature is currently a unique combination and fits well into DSP projects: https://www.diyaudio.com/community/threads/freedsp-octavia.393804/page-18#post-7625685

The configuration and firmware update utility looks like this:

Device name and PID/VID settings


Audio interface settings:


Input of up to 2 PCM channels, up to 192kHz (384kHz with external clocking at 1024fs)
Output of 2 PCM channels, up to 192kHz
(384kHz with external clocking)
Output of 8 channels in TDM8 mode (up to 96kHz, clocked by PLL)
Output of 8 channels in 2xI2S mode
Output of 2 S/PDIF channels, up to 192kHz clocked by PLL



And of course, in the simplest version, this module can work similarly to any USB interface, in slave or master mode.
DSD has not been tested yet.


Photo of the module, second version.

The additional 4-pin connector can be configured as i2c/uart/gpio, and is also used for forced entry into the bootloader (in case of unsuccessful software update).



Available in two versions: USB-C and USB-B. The transport itself is quite compact: it fits into an area of about 2x2 cm - which is important for integration into other devices.
So I'm working on a smaller PCB with same functionality.

Later I'm going to release a software library to basically enable anyone to create their own app for PC to control custom devices: toggle GPIO of USB module/send I2C transactions.


The module is available with USB-B or USB-C, the price is 49 Euro.
For purchase PM me. Also available on Tindie:
Multichannel USB UAC2+HID+CDC interface York

I'm open for requests for additional features but whether it is going to be added to the firmware depends on hardware limitations and time required to implement it.

Latest version of config tool:
https://york.eclipsevl.org/york_config_tool.zip

P.S. Huge thanks to:
1. Alexey (Dortonyan) for publishing the project. His work laid the foundation, and without it, this project would never happen.
2. Beta testers of the first version: @CyberPit, @Ludilu

UPD Oct 28th 2024:
Documentation draft attached

UPD Feb 17th 2025:
Latest docs, config tool, link to buy:
http://york.eclipsevl.org/

Hello, I recently acquired a pair of these in great condition. They have a couple issues, but hopefully not a major problem.

I have the full build and owners manual along with schematics

1. The LED's that turn from red to green on the preamp board are out and will need to be replaced. The part number listed in the manual HZ-MNT LED with a 895000 designation. I am having trouble finding this at mouser with this number, although there is a 895006 that comes up as a led that hey stock.Any help sourcing these would be much appreciated

2. I have a minor hum coming from one of them I have not moved tubes around to see it they are causing it. This leads me to my next question. Does this need to be recapped? It was produced somewhere around 1995.

3. If there tubes in it are original, should I just buy new ones?

4. How can I ensure that there is no residual energy in the amplifer so that I can open them up and look around, I wants to listen to them, not have them take me out haha.

5. Thanks for any help along the way on these

Does anyone have a schematic, (or sell a PCB), for a circuit that can monitor the voltage drop across a 1 ohm sense resistor and output a latched high output if the voltage goes over the pre determined set point? Whereby if the voltage rises over a set point it will output a latched high that can then be used to energize a relay that cuts mains power via its NC contacts. For example your amplifier loses its bias for some reason, your four 300B tubes worth $1,000 start to melt down and you want the whole amp to simply turn itself off. I see that the INA300 chip does exactly what I need, but I don't want to start from scratch on that.

Hello all
I have fallen in love with the Pearl Acoustic Sibelius but can't afford it.
Is it possible to clone it or build something similar? Please advice

Just ordered the PFA10K from ShennDare, a very new design it seems.

REEEEEAAAALLY hoping it's useable, feeling a bit apprehensive.
If all else fails I hope it is possible to delegate it to subs only...

Edit:
Link

Edit Nov 5, 2022: nice analysis and summary of DML materials and response with python script by @homeswinghome

https://www.diyaudio.com/community/...s-as-a-full-range-speaker.272576/post-7159983

Edit oct 27, 2021: a nice Google drive library of DML publications by vdljev:

DML - Google Drive

Edit April 1, 2020: nice summary of DML patents by Burntcoil

A Study of DML's as a Full Range Speaker

Edit Aug 12, 2019: Nice summary here by BurntCoil on how to maximize performance.



I had some cheap exciters that I got from PE a while back and tested them out a while ago with a full 20x30in FC panel here:

Foam Core Board Speaker Enclosures? - Page 225 - diyAudio

I found that a large 20in x 30in panel can sound quite good with nice bass extension and a snappy transient response:



Impedance:



Frequency Response & Harmonic Distortion:



Impulse Response:



The results were interesting in that it sounded nice - with surprising bass and good midrange. I thought nothing more about it until recently prodded by the master of DML, CLS. He has worked on this extensively and is a treasure trove of good info. I since have discovered that you can really do some cool things with them by playing with driver placement, cutouts, adding mass, adding felt, adding ribs, making them huge, making them multi-way FAST, etc. the options seemed almost limitless. Take for example, a large center channel and a super 40Hz capable multiway that CLS built here: PIEZO NXT type panel - Page 60 - diyAudio and PIEZO NXT type panel - Page 61 - diyAudio

I feel like this technology just isn't getting enough attention. There are several very large threads on this on the web. It might be tough for a newbie to comb through. I am a newbie at this so thought I would document my journey for the Full Range forum to follow. I think it really could be a great full range speaker with some careful experiments. This will be really useful with some modeling using CAD and FEA modal analysis - such as available in many CAD packages like SolidWorks. One can play with shapes, cutouts, mass loading, variation in thickness and materials, boundary clamping conditions, etc. The idea is to spread the modes evenly with not any one mode dominating and causing a spike.

First thing is to play with it to get a feel of what we are dealing with. What is nice is that it is relatively cheap to play with. Exciters cost $3 to $20 ea and can be made by removing or cutting out large holes in the cone from an old driver and leaving the spider and VC to attach to the panel. Foam core or corrugated cardboard doped with shellac or PVA seems to be the materials of choice.

Some interesting facts:

1. Although it has no baffle, it is not an open baffle (OB) dipole in behavior - that is, there is no huge bass rolloff and it hits surprisingly low (40 to 50Hz is easy) for a zero baffle driver.

2. It is not a dipole but behaves more like a bipole or an omni.

3. It has very quick snappy transient response - nice drum sounds.

4. It is sensitive to how you mount it or frame it or hold it.

5. You are building a driver in reality - a driver and zero enclosure.

6. You want to avoid symmetric shapes and symmetric exciter placement in order to reduce the effects of the main symmetric transverse drum head eignmodes. Think reflection anti-symmetric shapes like uneven trapezoids, pentagons, blobs, etc.

7. It operates more by having high velocities and large areas for good efficiency vs large displacements - thus small drivers and large panels can be surprisingly loud.

8. The impedance is essentially "flat" relative to normal drivers in that there are modal peaks (many of them) but they range from nominal Re value (say 6 ohms to maybe 8 or 9 ohms throughout the 40Hz to 20kHz range - this presents a very flat load to an amplifier.

Here is a photo of a basic panel I was testing (right before I cut off some edges to form a trapezoid) - panels is about 1 square ft in size and made of standard dollar store foam core board. I suspended it with two pieces of twine from the top corners between a ladder to reduce the effects of edge boundary clamping:



Then I started to play with mass loading by adding blobs of modeling clay (8, 5, 4, 2, 1, 0) so you can see the effect on the resonance modes and the harmonic distortion. What is neat with this test is you can do it live while playing music and immediately hear what sounds more pleasing to the ear. Note the 50Hz bass extension. It is also surprisingly efficient with 85dB and a puny little voice coil. These are 0.5m and 0.71v for equivalent SPL at 2.83v and 1m.

Frequency Response and Harmonic Distortion for...

No added mass:



8 pieces of added mass:



5 pieces of added mass:



4 pieces of added mass:



2 pieces of added mass:



1 piece of added mass:



Impulse Response of 1 piece of added mass, note the sharp transient capability with relatively low after pulse or ringing:



I liked the sound of the 5 and 1 mass the best and for a FAST with a 200Hz XO, the 5 mass might actually do fairly well. Of course, sound clips to follow once I have more time to work on this. Just to demonstrate how quick and easy this is, I did all these experiments in less than an hour including making the DML.

Greetings to all of you.
After lurking in the shadows of the DIY community I decided to get socially involved in my next project, and present you the building process of THE LOUDSPEAKER 1 of Troels Gravesen.

Objectives:
-Taking the time in design. I truly believe in aesthetics. A nice presented dish is part of the meal, so is with speakers... I enjoy the process of trying and finding a pleasing form etc. Would be great if you could help me with this part of the process. I well know that tastes are different thou there is a common silver lining, I would like to find it with your help!
-going full monty in building process, meaning, giving 110% of my abilitys. I am a young carpenter, so I I have the tools. What I luck is experience...
-making this speaker as if I would make it for a costumer (and a wealthy one as well 🙂 thinking dubai luxury is a good guide line.
-sharing ideas and experiences with you guys, gone are the days of working alone in a basement. This part I am specially excited about!

Inspiration

As for now, the living voice vox project is my inspiration. I foresee disagreement on the aesthetic side but one thing is clear, the vox project is the most perfect, implacable wood working I've seen anywhere! That's exactly what I'm on about.


Disclaimer
So, to summarise, I will take the time with this one so please do not expect quick results.... 🙂 let's make it insane.

Could be cool if you could check other works of mine:
Troels Gravesen DIY loudspeakers - YouTube
And
NEXT4 DIY Loudspeaker Project - YouTube

So, looking forward for you insights. I take all comments as long as it's stays constructive and positive 🙂

Update 8.3.2013- you can now skip the page turning and see the video here:
Login to view embedded media

This thread's purpose is to assist builders with their Aleph Jzm kits.

For general discussion, customization, parts substitutions, or anything unrelated to the kits, The Aleph Jzm thread is perfect.

The goal is to have this thread be a quick source for relevant information for kit builders. It will also be used as a source of information to update the Aleph Jzm Build Guide. At this time, comments are not active in the build guide.

For builders specifically needing help with their power supply, please search for a thread supporting your specific power supply, create a separate thread as needed, or post your question in the The Aleph Jzm thread.
For those needing assistance with their amplifier boards or overall assembly and wiring, please post the following:

1) The current step # from the AJzm build guide.
2) Well-lit, in-focus photos of the build in its current state.
3) A description of the issue or question.

I cannot seem to set the center voltage on my Quad 303, started with replacing R130 as was open, I've changed the adjustment pot but to no avail I still cannot get the voltage to go under 40vdc ( should be 33.5vdc)

Any ideas on where to look next?

Hello there all,
I thought that it might be interesting to 'collect' in one Thread the myriad of amplifier-output Stability Networks.
I would love to see variations of these networks AND a general discussion of the subject 🙂

since i am in a good mood i am starting now also a reggae thread. no matter if roots or dance hall. lets start with dub:
Sly & The Revolutionaries With Jah Thomas - Rizla - YouTube

I have a rather large stock of NOS MOSFETs. New and used.

New are $20/pcs, used $15/pcs.

Ships from Sweden.

Thanks for looking.

R Malmin

Hi to everyone,

I'm looking for the service manual of an old DBX 224 mkI (round buttons, none on/off mains switch).

Thx a lot in advance

I'm finally restoring my inherited Quad 303!

I'm following this guide:

https://www.rs-online.com/designspark/refurbishing-a-classic-quad-303-amplifier

I've replaced all the capacitors and everything went good 😉

Now to the problem:

Adjust RV100 for 33.5 volts between tags 5 and 9

One of the channels gives me an irregular reading of 38-41v with the pot all the way up. With the old pot setup it was reading 60v.
I only had to make minute adjustments to the power supply pot and the other channel.

What do you guys think is the culprit?

I'm a noob with a soldering iron.

The classic tower speaker. We all know it. It is burned into our brains. It stands well off the floor. It has impressive looking multiple woofer in a line going up. It impresses friends. It sells loudspeakers. An absolute staple in the hifi world. If you ask the average person on the street to draw you a picture of a hifi speaker I'll bet my speaker collection that they draw sketch out a tower on that piece of paper.

So lets discuss the dark art of multiple woofers. I am going to ask some questions along the way. For this we will focus on the 500hz and down end of the woofers. Just to simplify things a bit

1. Multiple woofers because the sensitivity of woofers is, in general, lower than the mids and the highs.

We have all padded down a tweeter. We have all experienced the loss of sensitivity because of those resistors. Everyone knows that more speakers equals more louder. I hear it is +3db. I have a question though. Lets take 2 woofers. Specifically, lets take two 8 ohm 6.5" woofers. Dayton RS150-8 for example. I probably wouldn't ever use these but its easy for me to sim this.

Lets look at a single woofer and lets say we are only going to use it from nill up to 500 hz.

We have about 89 db sensitivity there. Lowest impedence is 6.0 ohm.

Cool, we have a baseline. Now, lets add a second woofer. We will wire this one in paralell

Alright, now we have jumped up to about 95 db sensitivity. +6db. We are now down to 3 ohm

Let's now wire that woofer in series.

Alright, we are back where we started. 89 db except now we have a 13 ohm lowest impedence. So, what happened to all of sensitivity increase?

It went out with impedence is my guess. Then was ou6r previous +6db gain from the impedence as well? I do not know.
Do we only gain our +6 db when wire in paralell or are we getting +3db from the dual speakers and +3db from the impedence?

Lucky for us, there is a 4 ohm version of this driver. Lets compare a single 4 ohm and series 4 ohm.
91.7 db, 2.8 ohm lowest impedence Same in series, 91.7, 2.8 ohm


Now, we can decipher that adding another woofer in series doesn't make it play louder. However, two woofers with the same impedence as one woofer gives us a +3db sensitivity.
The two in parallel with a combined impedence of 4 ohm is about +3db louder than a single driver with an impedence of 4 ohm.

Is this how this works then?
2. Crossover values diminish with lower woofers

Lets take a look at inductor values
Lets cross at around 250 with an 8 ohm. 3 mh is needed. 43 uf cap. You see we are crossing 90db at 204 hz with these values

Now, same values with a 4 ohm driver. We see we would need higher values of components to cross as low as the 4 ohm driver. We are crossing 90 at around 300 hz now.


So, from this we need higher values with an 8 ohm driver. So what if we use two 8 ohm drivers in paralell.
95 db at 109 hz. Cool, this looks nicer. Look at all that low end gain and we get to use lower values for components

Alright, one more time but in series.
Booooo, well that stinks. Now we end up with a hump where we don't want it and it looks like we have actually lost high end extension
If we do try to use the low end here we would need huge components and we get no gain. Lose lose situation as far as I can tell.


Ok, so with this, I have concluded that there are senstivity benefits, low end extension benefits, and lower value component values if we use multiple woofer but ONLY if we use them in parallel. Am I on the right track here? I am not seeing why anyone would wire them in series other than to save their amplifier because it has an impedence limitation and all they have lying around are lower impedence drivers.

I am seeing how we get more low end extension with two drivers. At least in theory

3. More Cone area = More Bass
Now this I have heard all my life. However, when I start to run this through the ringer of physics, I am not seeing it play it out the way I would expect.

Lets toss a single 10" woofer, a single 12" woofer, and dual 10" woofers into WinISD.
5' box for the single 10, 6' for the single 12, 10' for the dual 10"

We have wayyyyyy more cone area with the dual 10 yet, basically no more bass extension even though we doubled the box size. Not only this but the single 12 still hits harder. I see this across the board with any driver I have ever tried to sim in whatever combination. It doesn't matter. Never does multiple smaller drivers hit as low as a single large cone. Never. I could sim drivers all night long (and I have) and not see this standard change.

So, is WINISD completely off base? I find that hard to believe because I have used it in conjunction with Hornresp and have had it spit out eerily accurate results in the world I reside.

Does more cone area just mean louder? It doesn't mean lower?

4. Floor Bounce and Diffraction

These two, in my mind, are combined. Far as I can tell, the floor and the diffraction are two metrics that combine to give you a low end response. The baffle step takes away, and, if done right, the floor can give back. Or the floor can take away. Or the floor can take away AND give back. Ahhhh, the wizardry begins.

I understand these the least. Or rather, I have done the least testing with these. I fully understand the physics of what is happening.

I am a visual person so lets do some examples. I just learned how to do this so let me know if I am doing this entirely wrong. Which I think I might be.

6" woofer at 20" heigh on a 10" baffle where you'd normally place a single woofer close to mid.
We lose about 6 db off low end to the baffle.

Then we gain some from the floor at 20".

Then we get the summed response and we end up with that stupid dip at 100 hz that I have experienced in a build and very much annoys me. Though we still gain some bass so thats cool.


Lets slap a second woofer on the floor. Right down below. I have seen some speakers designed like this and honestly do not understand how they get away with the phase issue unless they are crossing very low like 120hz or something.

Doesn't matter! We still get a stupid dip at 100 hz.

Questions:
Do I sum two woofers together in this simulator?
How do you avoid the 100 hz dip? Do you need to go up much higher from the floor? WMTMW style?
Is there any way to apply this to a simulated response just for design purposes and factor this in?

Hi all
some years ago I built a couple of 2 way speakers based on mid-woofer SB17NRXC35-8 and a tweeter SB26STC-C000-4.
The cabinet was sealed with a volume of 15L
I enjoyed a lot them, but I feel that bass are too poor. So I decided to realize a new project 3 way that is an extension of that one.
I'm evaluating 2 sub-woofer: SB26SFCL38-8 or dayton sd270a-88 (the first one to be preferred bcause it is 8 ohm).

I designed the cabninet, all SPL response and the crossover. My only problem is that the final impedence seems too low (about 2 ohm expecially at high freq) and I'm not able to adjust it. I tried with LPAD, but I'm not so familiar and I was not able to reach good result.

Can someone help me?

I bought a pair of these as basis for some experimentation.

I have listened to them a bit 'out of the box', but did not really like the sound. A bit harsh and a bit weak in the LF bass was the impression.
After some simulation, I have drawn the conclusions that the feedback DC cap could be increased (120uF), and so can the input cap (3,3uF). That could improve the bass slightly.
I put a 1000u bipolar for the feedback (to the left of the grey input cap), and soldered another 3,3u in parallel to the input cap on the back of the PCB.

From measurements I found that bias needs to be increased to reduce distortion. I added a 5k trimmer in the position seen on the picture and tuned it to the minimum Iq for lowest distortion at abt 1W. A value of 4,3k seemed to do it on both boards, and that resulted in a emitter to emitter voltage of abt 7mV, which translates to abt 16mA per output pair.
Distortion now stays below -100dB at abt 1W 8ohm. Improvement was abt 10dB with bias adjustment.

Last week TI put a preliminary datasheet online for the OPA1656, a low noise, very low distortion op amp targeting audio applications and fabricated in a CMOS process.

http://www.ti.com/product/OPA1656

I just checked and the sample button for the prototype devices is now active:

http://www.ti.com/product/OPA1656/samplebuy

I started this project in 2017 with the designer of the OPA1622, and although I had a change in my role at TI before the device was released to market, I'm still very proud of what was accomplished. The goals of the project were fairly straightforward:

1. Start with the OPA1688 architecture which gives very good distortion performance, even with low-impedance loads. Beef up the output stage even more.

2. Push the input voltage noise down as much as possible. Ideally below the OPA1652 and OPA1678 levels, which are fabricated in the same process.

3. Don't let power supply current limitations get in the way of performance. OPA2134 and NE5532 both have power supply currents of about 4mA per channel, and have been widely adopted in the market (understatement). That seemed like a reasonable target for the supply current of the OPA1656 as well.

A quick snapshot of the OPA1656 performance specs:

• 2.9nV/rtHz broadband voltage noise
• 6 fa/rtHz broadband current noise
• -131 dB THD+N at 1kHz, 600 ohm load, 3.5Vrms signal, 80-kHz measurement bandwidth
• 53 MHz gain bandwidth product, 24V/us slew rate
• >100mA output current
• 4.0mA typical supply current, 4.5mA max

I'm looking forward to seeing what people think of the device, and hopefully it finds its way into a few projects on here!

Christmas comes a bit early this year! The single channel version of the OPA1656, called the OPA1655, released yesterday and the product page is now live on ti.com: https://www.ti.com/product/OPA1655

It doesn't look like units have been stocked yet for ordering, but they should be in-stock soon.