I have a DAC, pre-amp, and headphone/pre-amp which use an Arduino, specifically the LCDuino, to control them. The power/config switch is a capacitive touch style with configurable RGB LEDs. I wanted to build a board to make hooking this up easier, then had the idea to modify the LCDuino firmware to use an extra pin to indicate when mute is enabled. Between the SSR trigger pin and this extra mute pin I can use that to turn the switch's LED on when the device is powered on, and change it's color when mute is enabled.

What I've come up with is a dip switch to configure the colors, and a couple logic gates to determine which transistor/dip switch combo should be active. On my breadboard this is working fine but now I want to turn it into a board I can plug in to the LCDuino. I've built a bunch of things over the years, but never designed anything, so before I go buying parts or having PCBs made I was hoping to get some feedback on what I have so far.

I think the circuit itself is ok, but maybe there's a way to simplify it a bit that I'm overlooking? When the device is powered off the SSR trigger goes low, but the mute pin stays high, so in this scenario I need to make sure the mute indicator also goes off. I can certainly work around that in code which would remove the need for the logic gates, but there's very little memory left and I don't want to add more code than I need to. This is especially true in the event of a firmware update where I could lose some of the currently available free space.

I went SMT because of space constraints on the board and in my pre-amp where there's very little extra space to add this in. I've worked with components of these sizes so soldering them won't be an issue. I also added some jumpers so I don't need to populate all of the components depending on how this is used. If I know what colors I want I don't need a dip switch, and if I don't want the mute function I can use JP1 and skip populating most of the circuit. Not all of the headers will be used either, so some of them will be left off depending on where it's used.

The ICs are the same series used in the DAC this will be going in so I don't see why there'd be any issues with those. The resistors and capacitors all seem like ok versions of the through hole parts I've been using. The diodes I picked are what I'm really not sure about. With my breadboard version I'm using 1N4148 because that's what I had extra of but I'm not sure if I picked a good alternative for the PCB version.

The switch is a Schurter 3-101-412 and each LED control line draws 0.05mA when shorted to ground to turn on it's corresponding LED. These are the parts I've picked out so far:

• SN74LVC1G08DBVR
• SN74LVC1G86DBVR
• MMBT3904LT3G
• SD103ATW-7-F
• C0603C104J5RACTU
• RC0603FR-1310KL

I've gone through more PCB iterations than I can count. The current version should have the pin headers in all the right locations which is what dictated the rest of the layout. I also need to be mindful of components on the board this is plugging into which is why there's nothing on the back aside from the headers. It's a 4 layer board with the back side facing the LCDuino when plugged into it. It's setup as as follows:

Front: LED control circuit
Inner 1: power
Inner 2: ground
Back: connector passthrough

Here's a quick demo of the breadboard version in action.

Login to view embedded media

I have some spare parts if someone has a whammy board and they need a good deal on some parts to get them going. This has MOST of what you need to get the power supply completed.

What is included:
- brand new Talema 18VACx2 25VA transformer

- all the heat sinks (low profile)

- 6 Panasonic 3300uf 35V caps

- 4 IN4004 diodes

- 4 5.1 ohm resistors (for the CRC psu)

- red LEDs

- 2 pairs of different 220uf caps

- a pair of Nichicon UEH bipolar 22uf caps

- opa2134 opamp

- a pair of 1uf poly caps

- assortment of Vishay/Dale RN55 1/8th watt resistors.

I am asking $60 shipped and will throw in some Mogami wire.

When I decided last year to explore some Stax electrostatic headphones, I discovered that even their older-model headphone amps are jaw-droppingly expensive. So I got an SRD-7 Adaptor and converted it to power high- and normal-bias Stax 'phones. Unfortunately, the sound quality left much to be desired.

The good news is, it's most glaring problems are fairly easily addressed. I just completed these detailed mods for the SRD-7 adaptor:

Transforming the Stax SRD-7

Comments/questions welcome. (This is my first crack at creating web content of this ilk outside of a forum, so be gentle... 🙂 )

"Tweeterectomy", InDIYana 2025 dates are set, and website is updated.
The theme/challenge portion surrounds the DIY build of a 1.5way, something not as commonly seen, called Tweeterectomy.

Dates are May 9/10, 2025 a Friday/Saturday set as usual. Details are at the event website on the front page under the drop down menu at the top here:
https://sites.google.com/site/indiyanaevent/

There has been a lot of discussion about the details for the theme already here:
https://diy.midwestaudio.club/discu...erectomy-but-build-look-alikes-if-you-want/p1

April was just too congested this year with everything else.
If you plan to attend, and are not listed on the attendees list, please PM me at the event website email addy listed on the front page.
If I have included you and you do not plan to attend, please also let me know of this change.

Hope to see you!
Wolf

A few months ago, I inquired about a capacitor/inductor filter I wasnt familiar with, on a post about Dynaudio speakers.

I now understand that this is an All Pass filter used for a time delay/ phase alignment of the tweeter.

On my current build, the tweeter is about 75deg phase shifted from the woofers between 1k-3k Hz. Moving the tweeter back 1cm solves this.
So does one of these All Pass filters with 1uF caps and 0.2mH inductors. It perfectly lines up the phase, and results in a deep null when the tweeter phase is flipped.

Any reason these filters are not more widely used on DIY builds here?

Who's ordered @Gabster 2000 's TD1 board? I ordered two so I'm curious who else is building this one?

https://gabster.ca/Gabster-TD1/

Hello !

This thread is dedicated for discussion of methods of generating stereo sound in a small room acoustic space by using a single DIY loudspeaker !

Encouraged by the results achieved in the Stereolith thread I explored the concept of single speaker stereo further:

http://elias.altervista.org/html/SingleSpeakerStereo.html

The general principle I'm using is this:


Interesting is the selection of parameter x !
When x = 0, the speaker is bipolar sideways projection (Stereolith).
When x = 1, the speaker is MS stereo.

I think the optimal value is about x = 0.5, which I'm using at the moment.


The Cardboard is back, but now totally different since enhanced with psychoacoustic vector steering !

I've been listening to this for about a week now, and results are very positive ! There is a great potential !

Experimenting recommended ! 🙂


*************

EDIT 2017:
Dropbox has deceived their customers and eliminated public folders. Thus the pictures linked herein are not visible any longer.

Go to http://elias.altervista.org/html/SingleSpeakerStereo.html to see the pictures


- Elias

Hi there,
I own a NAD216 amp, it's been playing in my stereo system for almost 13 years now.
about 5 years ago it start making some problems - taking it for service resulted in two things:
1. amp was fixed
2. service guy removed several components / changed several components - making the amp sound way better than stock

three months ago the amp went off again, this time it was due to electrical problem from the AC network.

took it again to service -
this time the service guy (a different one) used the amp original electrical schemes and just went over them and made sure all working properly.

now the situation is simple - i had an improved amp (i do not know exactly by what measuers), i sent it to service and now i got a stock amp again.

i need assistance in reviewing the amp electrical schemes and noting there what places can be "Improved" by manners of:
1. remove / bypass redundant / unnecessary protections
2. remove / bypass circuits that are in no use (bridge channels part / soft clipping)
3. remove filters applied in the amp which are not necessary

i found the schematics of the amp here:
Index of /~jga/nad216thx

link is taken from a thread located here:
http://www.diyaudio.com/forums/solid-state/148986-help-noisy-nad-216-a.html

i could not locate and electrical schemes for any Silverline amps from NAD for comparison, so if any1 has some assistance about that as well, this may also help


would appreciate any kind of help

BR


Ron.

Hi Everyone,

I'm in the process of knocking out holes in a chassis for some small Chinese analog panel meters.
Unfortunately every drawing online seems to be conflicting. I must be getting old but these drawings
make zero sense to me. Does anyone have a physical meter they wouldn't mind measuring for me?
Just need the usual...

• Hole Size needed to slide the thing in from the front. I won't be rear mounting with the face protruding through the front panel
• Physical edge to edge dimensions
• Mounting hole to mounting hole dimension

Thanks so much!

Ron

Hello,

I've started sketching on a new speaker project and looking for some initial guidance. This will be the first time I design, design a crossover, etc as I dont plan on following any set design for this project.

The design requirements I've been following:

• 2x 8" woofers
• 1 tweeter
• I want a big box, so around 100-140L (picture below)

I've been looking at these woofers:
HiVi M8N-1B 8" Damped Aluminum/Magnesium Cone Woofer 45 euro (if buying 4)
Maybe the HiVi-M8N-1 version though 🙂
https://www.soundimports.eu/en/hivi-m8n-1b.html
https://doc.soundimports.nl/pdf/brands/HiVi/M8N-B/M8N-B-manual.pdf

or

Dayton Audio DS215-8 8" Designer Series Woofer Speaker - 72 Euro (if buying 4)
https://www.soundimports.eu/en/dayton-audio-ds215-8.html

And I'm leaning towards the HiVi M8N, they look nicer to me and are a bit cheaper.

For tweeter I'm looking at:

SB acoustics SB26STWGC-4 85 Euro
https://www.soundimports.eu/en/sb-acoustics-sb26stwgc-4.html

Looking at the crossover, based on the very little experience of designing this myself, I'd assume it would be somewhere around ~1500Hz. I have bought a calibrated mic, so I will measure and simulate before I actually buy components for crossover.

I don't have a hard budget, but aiming for like 350-400 tops. This current setup would be 350 euro. I was also considering building a 2.5 or 3way, but seeing how it's my first time doing crossovers and things myself maybe its better to limit myself to a 2-way?

But I have a few questions:

• Does anything stick out as unreasonable?
• I get the feeling that 100-140L is big for WinISD, but since I have two woofers maybe that is ok? WinISD didn't seem to change that much depending if I selected 1-2 drivers.
• Comparing the two drivers in WinISD, HiVi seems to perform better with lower freqs despite being 50% cheaper. Does this make sense? How much should I trust WinISD?
• Should I do some optimizations to make front baffle more narrow? Currently I have it maybe 1-2 cm wider than the woofer element so it has some "breathing room" inside.
• Any issues with the design of enclosure other than it will be more difficult building than a normal box due to angles?

Picture is of inner dimensions of the enclosure. Will add 15-18mm of material.



Just pic of how the two different drivers look in WinISD. HiVi 140L, RS225-P around 120L.



Thanks 🙂

Hi to all,
I have been a lurker here since around Covid, making use of the knowledge so freely shared, as i took my first steps towards extending my lifelong hobby and love for music to encompass experimenting with making my own, and recently, to my surprise, replacing kit with components i made myself, initially with cables, then to a tonearm, and most recently, a rubenoid speaker

As I said above, this journey has been advised, from the outset, by posts from this amazing community, and its way past time that I modestly request to be a more active part of it, and return the favour by sharing my own DIY, as well as continuing to benefit from the wealth of experience it makes available

respectfully
Simon

AI, for or against?
I'm one of those who thinks AI should be reserved for important things, like research, basic research, medicine, etc.
Any other use, often futile and out of laziness, drives me crazy!
And what about "images" generated by AI? It's unbearable. For me, who loves photography in general (as someone who looks at things, not takes them), everything in an AI photo is disgusting and disgusting.

I see more and more people using AI to try to troubleshoot or modify one of their devices. I think it's even worse than anything. It's literally separating the head and the hands, and generally, when you separate these two, it doesn't go very well (referring to the headless chicken running around).

This is a DIY forum, I mean, the answer is in the title... and also a place for mutual support and LEARNING, and I'd rather not see this AI thing here. Even for fun, it's an insult to human intelligence and its hundreds of thousands of years of evolution.

I also think that human beings are lazy by nature and will always take the easy way out rather than the hard work, even if the latter allows us to grow and learn.
As proof, relatively speaking, I have people who no longer know how to park their car without assistance, and worse, those who don't know how to park it with assistance.

The "Method" and the "gesture" are things that have been lost for years. AI is accelerating this phenomenon, and I would like it to be banned from this place.
I would like to know what you think.

I’m looking for a socket that will allow me to easily switch out to-126 transistors for matching.

I'm looking for a magnifier to use for soldering and repairing equipment. From what I see on Amazon, they mainly come in two types: head-mounted ones with lights, and desktop lamp-style ones. Which do you recommend? Also, do you have any advice on what magnification level would be ideal?

https://www.amazon.com/s?k=magnifying+lamp

I've been on a quest to build my own own reference monitor. In that journey I've come to know the JBL m2. Maybe its highly prized for its flat response but all I see is another 2-way. There are already flat two ways on the market. So not sure what the hype would be around this speaker, beyond having accuracy and spl, making useful for far field as well as near field.
As a full-range solution if a 2 way that took care of sub bass, gets rid of another cross and thats cool. I've found a driver that could be used for the top

FaitalPRO HF146 - 1.4" Compression Driver

A woofer for the bottom can be found. The question is, how is a woofer that is going to be easily responsible from 30hz to ~1000hz going to behave? Lets say we are auditioning rap, edm, or some other deep bass reproduction that causes high woofer excursion, how is the top range of that speaker going to sound? It seems to me a 3 way is almost always better, but I'm not the finally say, the results are, anyone have a strong opinion on this?

Hello DIY Peeps,

I am excited to share my first amp build in over 10 years.
It is the standard / original RH84 circuit.

I made the box from salvaged Urban Lumber (city tree that would have ended up in the landfill) and it is European Walnut.
The Aluminum Plates are 4mm thick and were made by Proto Panel. I was happy with PP's pricing and fast service. 1/2 the price of their competitor.

Playing around with aesthetics, I decided to hang the iron under the top plate, and hide all components except the tubes.
Room inside filled up much quicker than I expected.
I ended up having to mount a tag board directly over the heater wires, which I was worried about, but fortunately the amp is dead quiet.

This is my amp at work and replaces a mini watt EL84, which ironically got me interested in building again. Amazing little amp for $200.
The dynamics and extended frequency response (low and high) are greatly improved however I perceive a strange phase character in the sound. Literally like the speakers are connected out of phase, however they are connected in phase and the imaging is still quite good. Not really 3D like a DHT amp but still good. It is subtle but still quite apparent and a BIG distraction and very annoying! I guess you could also describe it like a reverb or delay effect pedal for a guitar.
Is this a function of the feedback in the circuit? Could it be a bad tube? I have swapped the 6bq5's without change in sound but only have one new production ecc81 at the moment.
Not sure if I am hearing the character of the amp that I don't like, or if it could be a build or component problem?
B+ is a little high at 324V with the specified 5U4 and 318V with the tube store 274b replacement (which sounds better).
I am assuming it's ok to run the EL84's a little hot? Or is a pair of 7189's worth the $?
I don't want to waste any more time or money on this amp if it is a characteristic of the feedback in the circuit that I don't care for. But I really have no idea...
I am surprised that so much of the mini watt magic has disappeared in exchange for better frequency response and dynamics.

Also, This amp is a warm up for some future builds so would appreciate any comments, suggestions on rookie mistakes or areas for improvement on basic layout or any other glaring build mistakes.

Next two amp builds will be a 45 and 6CB5A, both IT coupled Thomas Mayer designs.

Thank You for taking the time to read and for your comments!!!

Hi , I own a Dynavox 307 VR , it´s a chip amp with tube preamplification 6n2 tubes. If i connect the left input only it plays fine on left channel . same with right input on right channel , if i connect both inputs it goes mono and volume drops many db´s . Anyone seen this before ?

I'm focused on speaker design and construction and I'm here to learn from you experts! I've built several pairs but want to simulate on my PC to end up with a better XO. My current project is replacing the woofers in a pair of Infinity RS2000s and re-doing the XO. I found a helpful video as a good starting point and just purchased a pair of Dayton Audio RS180-4 woofers. 4 ohm with what looks like a good match with the RS2k cabinets (from what I can glean of Vance Dickason's book). I'd appreciate any feedback - especially if someone has already been down this road. Thanks, John

$170 shipped USA​

I also have the JBL 2425J drivers themselves, many of them, and horns.

2 of the drivers need these diagraphs.

Complete working amp, toroidal 600va trafo
Someone interested? 800 euro
Nelson Pass sorted Vfet’s closely matched, 4x2sk82, 4x2sj28, I build too many amps…

Hi,
I have got a Chinese PCB board and its called a super regulator by Jung, not sure if it is one of W.Jung's designs but it works quite well, I tried it with a NOS DAC chip, not a but result but it sounds very forceful, a bit too much of a good thing I would say.
I have drawn the schematics of it and it would be great if the design can be improved if can to be improved obviously 🙂.
...please have a look at it and add your comments.
best regards
K

I picked up a Zapco AG150 that someone else started working on. When testing it on a 2.2A current limiting supply it will try to draw the full 2.2A but in pulses. I removed the rectifiers and it only draws .25A with no pulses. The power supply transistors have a sine wave input and output. All of the output and power supply transistors have been replaced and I am not confident that they are correct as I had another amp from the same person with the incorrect fets installed. A schematic or part identification would be great. Any thoughts on the repair would be great also.

Have three of these white spacers not sure where they are meant to be located , dismantled the player and then worked on another project and forgot where they should be positioned.

hello. im a long time user, donovas being my old handle, and this is my second account I'm making for the purpose of promoting via social media my audio brand that is in the works. The brand is called Sonocus, sound tree in latin, and the goal of our products are to offer the highest quality circuit design at any price point in a packaging that is highly affordable. In other words, another giant killer hopeful.

I'm comfortable with the outlook of the project though. I have been working on this single design for 3 years and it was already received favorably in Seoul where the sales were my partial income.

the project is a dual mono preamp, now modified into a headphone amp that I'd like to post on kickstarter very soon.

Anyways, thanks for letting me ramble and hello.

mods: could you please change my name to SonocusEric if possible? thank you

2 x Precision EF3-3 boards (V 4.2) which includes 2 x wolverine IPS boards. (Color -Black, )
$40.00 USD.
EF3-3 IPS, Pre-Driver & Driver: $20 USD (6 Heatsinks Total)
Total 60 USD , + shipping (worldwide). Paypal for friends

Hey there DIY-Audio-community

I’m a total beginner when it comes to Hifi-Projects but since my current setup is in desperate needs of some upgrades and I’m traditionally on the DIY-approach when it comes to “new” things, I thought about constructing my own speakers… how hard can it be? During my research with a lot of detours, the World Wide Web finally lead me to Charlie’s infamous jazzman design and I’m in quite in awe about the community surrounding the project, that is mainly based on this board. So into the rabbit-hole I went…

In a first instance, I was simply impressed by the aesthetics of this ESL, which is why I got completely lost in the project. After a first attempt to simply copy the design and therefor understand the design-choices made, I had a bit of an idea while researching for appropriate wires...

Since this is a one of a kind and my workshop is quite limited in size, I want to avoid the tensioning-jig that is usually necessary for the elongation of the single-stranded wire, by tensioning the wires within the actual Speaker.

So, in short this is the attempt to have a segmented wire-ESL with tensioned stranded wires.

By putting tension on the wires, one could also avoid a lot of the horizontal segmentation. The wire tensioning would be achieved by simple harp-pegs, that are screwed in the top of the speaker. This of course results in an odd number of wires per electrical segment. In my case 5 instead of 6 in the Jazzman-design, so my active diaphragm width is actually a bit smaller than the Jazzman-design. Nevertheless, I hope to be able to copy as much as possible from the original design, especially when it comes to electronics… Really not my expertise yet 🙁

This will be a hybrid design with open-baffle speakers. I do have four Peerless SLS 8 (830667) left, which I hope to be able to use. One idea is to use two dual speakers per speaker, the other idea is to integrate 1 per speaker and build a sub out of the remaining two. But I haven’t checked if the spl would be sufficient for an open-baffle design. Since this is really in the early stages of research, feedback is very welcome!

I’m probably in way over my head with this as a first project but maaaaaaaybe there is a chance for me to actually get these things running 🙂 And even if this is a dead end, it was quite a fun journey so far.

I have some drawings of the project attached.



Where I am at the moment:

I started a first prototype based on some leftover 22mm wood, some FLRY-A 0,5mm2, 1,55mm OD cables and some harp pegs. I build a quick router jig and milled one vertical segment. constant wire distance as well as looping of the cables is achieved by some 3D-printed parts.











After having tensioned a first loop, things look promising, after 3 days under tension the wires are still as straight as they can be. I had some problems with the wire snapping at the top in the beginning, which is in my opinion mainly due to friction in the 3D-printed parts and the loops around the nails. I’ll have to redesign this part in order to allow the wire to distribute its tension over the whole length. But I’m optimistic that I’ll achieve this in the next try.

Many years ago I bought a BYOB (Build Your Own Buitar) from Hobby Lobby and got it together a few years ago. As a non-musician I have since decided that maybe I could eventually learn to play a frew notes on a bass guitar so I bought a Harley David ... Bentley P-bass kit from the German shop Thomann.
Whilst making work on the body (I will borrow a jig saw for the headstock - my design), I have started looking for a amp/speaker combo. Luckily, with workers replacing the old roofs, and throwing away plywood offcuts, I have enough material for a box to hold that one. It's not furniture grade, but still 15mm pretty acceptable plywood (often referred to as "plyfa" in Swedish). (All dimension in normal units (centigrade).

The guitar is the Harley Benton P-bass as it looks nicer and I just found a heavy coaxial speaker from Master Audio (Italy), an CSX08, an 8", 4.5kg piece with what looks like a small horn tweeter. Stated freqency range 63Hz - 20kHz (could be lower) and recommended crossover frequency of 1.7kHz. 6dB/12dB crossover.
I had an idea to go for a speaker box of approx 400 x 500 x 250mm (16" x 20" x 10") or slightly smaller, using a sort of Onken design or maybe just a single slit, but nothing decided yet.

When it comes to an amp, there's an "issue". I am not going to play at Stockwood ... errr ... Woodstock, but at home and, if I learn more that one note at local events in our old folks club and I think 50W amperage will be enuff.
I've gotten a pair of simple 50W transistor amps built from cheap Chian kits and I guess one of these would be perfect. Else a similar kit from EliExpress is considered: THIS ONE.
For testing I have gotten a D-class chipamp, which had been nice as it doesn't requires a lot of space heatsinks and whatnot. A simple SMPS will do fine (it it works).

I love to fiddle with things and make things a bit diffrunt. I've got 50 shades of pink .. 2 actually for the bass and I will try to mix them in some "odd way". Also gotten a green pickguard that will match the pink body perfectly .
The speaker/amp combo will be covered in vinyl (black-ish) and apart from thinking of power amplifier, I must look up a decent preamp.

This is my plan and I am open for suggestions ... open for REASONABLE suggestions , remember that this is a mid- to lowfi project. For fun. Low cost.

Some recent measurements, show me a 2-3 triodes phase inverter with less than 0.0x% distortion, with more than 50Vrms on both outputs, with no feedback 🙂

Hello DIY-Audio lovers!

I started planning a new FreeDSP project named "FreeDSP OCTAVIA".
An ADAU1452/1466-based Octal(8ch) output board that has various input interfaces.
The attached current idea block diagram feels too much for ordinary use cases...
So I'd like to reduce interfaces after hearing your opinions, suggestions, and ideas.

One more application for USB-DAC, which has 4 differential DAC processing. An additional board will be required for this application.


I also attached a similarly designed board picture I made a few years ago. The New board will be a little bit expanded design from this...

CyberPit

Partially built ACA Mini includes the heatsinks.
Requires the transistors and few other parts.

£30 plus shipping

I have one last pair of PCBs (shown in Photo) for the construction of a Moving Coil RIAA preamplifier as was presented in my article for Audioxpress (March 2014).
The price for both PCBs (two PCBs are needed for a stereo preamplifier) is 55 Euros plus shipping.
If you are interested, send me an e-mail at gntanavaras@gmail.com

Hi all! not really a new member but never posted an introduction! I’m nicoló, i love building audio stuff and do some repairs whenever I can just for fun!
Cheers all!

Hello, I have an old 80s model jvc amplifier/ receiver and the only outputs it has on it are group one and two speaker wire outputs. The issue is, i just fixed an old klipsch subwoofer that i found on marketplace and the only input it has is RCA or Sub in. How do i go about connecting these two items together? Would connecting wire that has up to 60w running through it to an RCA input on a sub be harmful or would it even do anything?

Hello everyone.

I've been lurking on these forums for years. Currently in the process of designing no-compromise studio monitor system. It will be a 4-way looking something like this:

20-60Hz - 15" woofer (still deciding on the woofer)
60-600Hz TAD TL-1601b
600Hz - 8,000Hz TAD TD-4001
8,000Hz and up - RAAL ribbon

Looking for the best horn to make the most of the TD-4001 in those frequency ranges. Was recommended the Yuichi A-290, and can also get the TH-4001 clones made. Looking for the most transparent setup, and it will be driven with a high quality Linea Research DSP (gasp) and Benchmark / Bryston amps, so we have a lot of tools at our disposal, such as time alignment, FIR, linear phase EQ, etc.

Are there any other horn designs we should be looking at for this? Anything we may have overlooked?

Your help is much appreciated.

Hola. Soy nuevo en la comunidad y estoy muy contento de tener la oportunidad de estar aquí. Mi principal interés es la electrónica de potencia y el audio en general. Gracias.

Проект RM-6.
Начало

I want to simulate the circuit of a TAA621 IC in LTSpice.
However, there's a transistor with two collectors (T10, see datasheet linked below).
Any suggestions on how to substitute it?

TAA621 Datasheet: https://ve6aqo.com/Datasheets/German/TAA621_DATASHEET.pdf

I have owned a set of 2CeSignatures for several years; six months ago I purchased a Vandersteen Model 2W subwoofer on eBay. (Presumably, these two components should work well together.) There were no crossovers devices with the shipment (my mistake). A high-pass filter must be injected between the signal source (preamp) and the amplifier. The specifications of that filter are subject to a set of variables including the input impedance of the amplifier. At sale, Van supplied an adjustable crossover component (W-X2) that could be used to ear-test and determine the correct crossover device; once determined, the user could purchase a set of permanent filters form a Van distributor; and the W-X2 would no longer be necessary.

Lacking the W-2X, and using an online filter calculator, I built a few simple. cap/resistor filters using 50Hz cut-off, and random capacitance and resistance values (C/R values were set based on what I had sitting around; notice no input impedance is contained in that calculation.) Nothing worked, so I gave up and bought a W-X2 from a long time Van dealer ($140). Following instructions, I set the only adjustable (dip switch) value which was to be one level below the amp impedance; in my case, with a 50K Hz amp, the next lower value was 33Hz. Works fine, sounds good.

Assuming that 33Hz stays as the most pleasing level, I will have to find a dealer that carries a set of 30-40 year old filters marked "33." Why don't I just keep using the W-X2 and forget finding permanent filters? Per a short conversation with Richard Vandersteen, he told me to be sure to get permanent high-pass filters because the components in the W-X2 were crap and sounded like it. But, what would he know?

Anyway, this is a long lead up to this question: could anyone provide a schematic so I could build my own high-pass filters?

This driver has weak bass and treble, but the vocal extension is excellent.
It would be difficult to achieve this kind of vocal reproduction with a multi-way speaker using a network or a filtered full-range speaker.

Internal wiring was supplied with the speakers, 6mm MDF and PVC sheets were made by Daiso.
Material cost is less than 1000 yen (6.5 USD) per pair.





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I have an HDMI ProII Transport, and a reclock Pi, if anyone is interested. The HDMI Pro was sent by mistake, and Ian said I can keep it if I paid for shipping for the correct part...I don't need the HDMI Pro. It basically hasn't been out of the package except by accident, until I realized it was the wrong part!

I've been asking questions about tubes and capacitors and performance, where the answer always seems to involve "Does it meet specifications?". So, I figured I'd better check.

Tests were performed with a Scarlett Solo into a Mac Mini running Room EQ Wizard. Input voltage for all tests was ~1.76V

The high-frequency rolloff appears to be in the interface, as it appears in loopback measurements.

Frequency response
Manual States: +/- 0.25dB, 5Hz-30kHz
Result: 0.23dB total deviation, maximum to minimum (excluding high-frequency rolloff)

Distortion
Manual States: Less than 0.01% at 2V RMS output, 20Hz to 20kHz
Result: 0.007% THD maximum between 20Hz to 20kHz

Intermodulation Distortion
Manual States: Less than 0.002% at 2V RMS output
Result: 0.02% at 2V RMS output*
Note: Measurement was obtained using 7kHz and 13kHz twin-tone
--

I've included slides for the frequency and 2V distortion measurements. I've also included a 5v output static distortion slide for interest, although it is not relevant to any of the measurements discussed.

Thoughts: The frequency and distortion numbers seem to be inline with specifications. The IMD is high, but I don't understand the potential causes or ramifications of this enough to discuss it. For all measurements, I consider both my tools and techniques suspect, although I am making ever effort to be accurate, with the equipment I have. I allowed the amp to warm up for approximately 15 minutes before taking these measurements.

For full specifications: https://www.arcdb.ws/model/SP8

*Note: Slide for this measurement was lost

I have been reading here, there, and everywhere about the different Pass amps that have been made. I have many questions which is evidenced by my random scatter-brained post. MY question for this thread concerns the possibilty of substituting the Semisouth power J-Fet's in the Aleph J layout. THis uninformed question is based on the firstwatt articles including specifically the Sweet Spot. I am a newb, but have plenty of time to ask questions while simultaneously trying to figure out what the hell i am talking about. If this is doable, i will probably go ahead and buy the pcb's from Peter if they are still available. MY thinking is that this amp would be similar to the J2. I would just do the F5, which is a much easier build according to most, but i have limited funds and think, at least for now, this is what i want.

I know several V-FET / SIT data sheets have been posted over the years across many different threads, but I thought it'd be nice to have them all in one place.

Here's one fresh off the scanner - more to come when I have time to spare. Meanwhile, feel free to attach or link to whatever you have.

(Note to Mods: I hope posting these doesn't violate rule #9 - please delete the thread if you think otherwise. Thanks!)

Edit: I realize my file naming convention is not immediately obvious ==> the attached PDF contains 2SJ18, 2SK60, 2SK63 and 2SK79.

I haven't made a decision as of this time but I am planning on replacing my JBL 2380A horns with clones of either the Yuichi A-290 or TH-4001. The drivers in use are Radian Neo 950 FB / 16. (Recent upgrade from JBL2440)

Athos for either A-290 or TH-4001:

AthosAudio - Passionate about wood and sound

They also sell on eBay and have a good buyers rating. Located in Hungary shipping is a bit pricey, but manageable.

MAKA for Yuichi A-290:

Homepage - MAKA Precision Horns

Located in Holland, likely a bit quicker and a little less expensive to ship.

I've heard of both, have no direct experience with either.

I'm currently trying my hand at a USSA5 amplifier and need a few more exotic capacitors. Does anyone have at least four of each of these in his drawer and want some space for new parts and some cash?
What I'm looking for:
2200uF 16v United Chemicon Polymer APSG160ELL222MJ or RNL1C222MDS1 and
4700UF 35V United Chemicon EGPD350ELL472MK30H or EKYB350ELL472MM or UKW1V472MHD
-min. four pieces each

And yes, I know that some of these types are still available from some retailers, but ordering a handful of components from them always involves astronomical shipping costs—so I'm asking you first.

Thanks for checking!

I read about this a long time ago. Development in amplification didn't jump from vacuum tube then to the transistor, there was something in the middle......the magnetic amplifier.

WWII Germany perfected the device, and I read that one of their V-2 rockets crashed in England and didn't explode. When it was salvaged and analyzed the scientists there pieced together a magnetic amplifier used in its construction.

I have a couple of books on them, and I heard that it could be used to amplify sound. I did a quick search before making this thread and the subject is a little dead.

Just today I found this awesome site:
Homemade Magnetic Audio Amplifier.

http://sparkbangbuzz.com/mag-amp/mag-amp.htm

This is a tantalizing bit from the first site I listed site:
"The mag amp is true amplification without the use of tubes, transistors or IC's but it does require the use of an AC power source. While most ac oscillators require the use of transistors, this amp could conceivably run using an AC power signal from a carbon arc or maybe even a zinc oscillator or similar."

I wonder if the experts here could build on this and make something really well performing.

I hope somebody is interested in this stuff as much as I am, it looks neat.

Designing my amps around TPA3118 since the beginning I am always curious to discover these in commercial applications. This one was inside the Bose Soundlink. It can be seen that the bean-counters replaced output inductors by ferrite beads here. Considering the short speaker cables and the metal housing this might comply with EMC regulations anyway.

I'm trying to increase my knowledge of bootstrapping techniques and started experimenting with a simple bootstrapped op amp. It's all done in LTSpice so far. I can get it to work just fine, however... It's extremely finicky on component values. The schematic below works fine, but if I change R3 and R7 from 15k to 12k, the whole thing latches up. I'm suspecting this has to do with SPICE. Maybe it's having trouble finding the OP with all the loops in the circuit?



Here's the performance with 15k resistors. Output in the middle and high and opamp VCC and VEE at top and bottom. Looks great!
Now I nudge the values of R3 and R7 to 12k. As you can see, it latches almost immediately. Is this a legit design problem or SPICE weirdness? BTW, increasing the resistors to 18k has the same effect. I tried replacing them with zeners and voltage sources, but to no avail.

How can 3/4 plus 3/4 make a wholez?

When two quasi single-ended amplifiers rely on a quarter of the partner. Here is my preliminary finale from the unfortunate thread. It should be noted that the input of the "3/4 + 3/4 = quasi 1 amplifier" would like to be driven with a very low impedance.

HBt.

PS
A test setup will follow.

This is going to be the topic where i post Gerber's that you can order yourself. Just don't sell the boards please, allthrough there is nothing i can do to stop you from doing so.

Suggested board house is JLCPCB, those are the cheapest.

Most of what i post here are boards for tube projects. I will try to add some description of what exactly it is.

The fastons i use are 61-1536-11/0031 OSTERRATH. TME.eu symbol: FS1536/NC

However i do not offer warranty on my designs, so order at your own risk.


furthermore all through i have a lot of spare time please i'm no tech support.
If you see something that suits your needs but isn't quite to your taste, pm and i will make changes for a small fee.



If you want to send me something for my efforts, my paypal is on some of the boards.

Here's the first revision of the mini-build guide for installing Zen Mod's Soft Heat circuit for the Korg NuTube B1 preamp. Feel free to post pictures of the modified board here to help others understand how to go about doing it.

Here's Mouser cart link for folks who want to buy the parts themselves.

Note that NO Trace Cutting is required with this approach. Removing the 270 ohm resistor is the "cut" and allows one to revert back to the original design w/o the soft heat circuit easily if one so desired.

A pair of original ESL63 stands. They have been in storage and are not pretty, paint has come off in places.
In 's new' shape they go for up to 300 euro in some places.
If you know what a sand paper is and know how to handle a spray paint can, you can pick these up at my place for 100 euro.
Pick up only, so attractive if you are in southern Netherlands, Belgium or adjacent German area: Aachen/Maastricht/Tongeren.
Let me know.

Jan

I went to AXPONA in Chicago this past week, where I could hear tons of systems, compare and enjoy the best of them, critique them, and not get impressed in some rooms. I found some DIY speakers that were my favorites and searching for them led me here. Cheers!

Hi All,
in the following I would like to describe my way to my first ob construction (and at the same time my first own speaker construction ever). After building two boxes I became aware of a thread here - the Manzanita. I built it and it happened - the OB bug bit me, it is a great speaker!



After that - it always has to be bigger - I also built the Manzanita Ultra.
But we didn't become friends, this speaker didn't fit my space, my music, my listening habits, etc.



In particular I like the open way of playing, the room, the stage, I haven't heard anything like that from conventional speakers, up to the high four-digit price range... I still tried to listen to music with conventional speakers, but something was missing... That was the point where I decided to make my own OB construction. And if possible, it must have a high sensitivity in order to be able to operate it with enough reserve with First Watt amps without any problems.
So, enough of the introduction...

Right from the start it was clear to me that it had to be a woofer-full-range combination, i.e. a 2-way system (the xo is easy there... I thought). At the same time I found a thread about the new SB Acoustics SB20FRPC30-8. Cheap enough so I ordered it straight away and two days later I installed them - in a TL box that was absolutely not designed for this speaker. I just wanted to know how the speaker sounds, approximately. And what I heard made me happy, to put it briefly.



The next step was to install it in an OB - I used that of the Manzanita Ultra. But since the Manzanita´s woofer is not very sensitive (at least compared to the SB FR with 92 dB), a new woofer was needed. Based on a recommendation, the choice fell on the SB Audience 12" OB, which is intended for OB applications. "Quickly" built an xo - low pass, high pass, 6 dB/octave, done... and it sounded terrible
There was a lack of... everything. And the measurement confirmed it...





To improve the highs I added a tweeter, of course the xo had to be redesigned quite a bit.
At first it sounded good (in the upper range), but the longer I listened, the more unbearable it became...



The lack of bass was also very clear... so I figured a second, larger woofer might help (yes, it can, but not in the way I thought).
After a short search, the Eminence Alpha 15A was delivered - and that's when things really got going. I guess I've built countless baffles out of cardboard and if it sounds bearable, also out of foam... with and without wings, with big and small ones, or even with asymmetrical wings, but it didn't really work out. After a while the bass was okay - far from good, but okay. But there were big problems in the xo, because I treated the 15" and the 12" woofer separately, with different (high) crossing frequencies. And the mids... absolute no go...
There are no pictures from this phase, that was more doggedness than conscious action 😀 Of course I also changed the xo every time... I didn't even get to measure it because I usually didn't like what I heard.

That was the point where I thought "what were you thinking, or even imagining?" But I didn't want to give up.
So - read, read, read was the motto. And most importantly, understand what works and what not. And why. @Pano helped me a lot with his contribution - many thanks

The most important thing was to lower the crossing frequency. Originally I crossed at about 1 kHz - that's incredibly high, even if that seems to be okay according to the specification of the drivers. But it is not. And that was one of the keys. First I decided to switch the two woofers in parallel (gain in output) and then I lowered the crossing frequency to around 120 Hz - and it was like a revelation. There was also the almost endless trial and error with and without wings, different wing shapes, heights, depths, etc... until a certain size and shape proved to be right (better: to be the best for this configuration).

But the revelation was only partial..., the mids didn't want to appear.
I stared at the circuitry of the xo in the SIM - and then inverted the full range. Wow, the fr response became "smooth as glass".
Put into practice quickly.
With two different full range drivers.
The MarkAudio Alpair 12P was added to the SB as an alternative, because I didn't really like the high-frequency range of the SB (on paper). So it started with the full range again. Cardboard baffle with different positions; middle, right, left... I'm still not sure which is the better option, but these are minor things compared to the start...



Currently the 12P is in break-in, the SB is now centrally positioned, and I like it.
And now the speakers sound incredibly good. For real. The best of all wives (she has nothing, zero, niente, nada to do with this hobby or with music) has heard all my speakers so far and yesterday also the "new ones"... and she said - "wow, they are them best of all, but far the best".
The feeling of pride came on 🙂



I took measurements today - I like the fr response 🙂



And finished a version of the baffles with the router. They are made of 18 mm MDF, in this version with decentralized placement for the Alpair 12P.



Yes, three-piece baffle. One of the findings was that - if the gap is not larger than 4-5 mm - the sound is better (for me).
I have no idea why, maybe the resonances of the individual baffles don't influence the other drivers.

Well, of course it's not finished yet. But I'm incredibly happy. I started at the beginning of November and there were phases where things looked bad.
At the end of this contribution, the current status of the xo - not quite finished yet (as you can see, not only the SB and the 12P are taken into account, but also the Sonido SWR250, which I will be ordering shortly).
This is so much fun.




The journey will continue 🙂

I need something with a lot more glowing tubes on it. My current amp, one big hot 6AS7 isn't enough. I feel the need for a big push-pull, 3 stage, regulator tubes, lots of heat. brrrrrrrr !

Audio Amplifier Performance Assessment Program (AAPAP)

(This introduction must be read in conjunction with the accompanying Excel spreadsheet)

General use and objective of AAPAP

The program looks at several important amplifier performance areas and provides an objective method of assessing the design and engineering effort brought to bear in reducing or eliminating shortcomings that will materially affect electrical performance and therefore sound quality negatively. The philosophy behind this approach is that, for example, hum and noise or TIM/SID cannot bring positive benefits to any amplifier either electrically, or when assessed separately, for sound quality. These are problems that require design effort to eliminate, and this is what AAPAP addresses.

The assessment process can be used during the design phase to guide the designer towards improved electrical performance and/or to assess finished designs, be they DIY or commercial.

For assessment and scoring, the amplifier under test (AUT) is treated as a black box except for the protection features scoring where the AUT specification is consulted.

The following areas of electrical performance are covered by AAPAP:-

• Output Power
• Capacitive load drive capability
• Overdrive recovery
• Frequency response into 8 Ohms resistive load and complex load
• Complex load drive capability vs distortion at high power levels
• THD + N at 1 watt into 8 Ohms (0 dBV) and at rated power (dBr measurement)
• IMD 19+20 kHz at 80% of rated power into 8 Ohms
• Noise floor of mains-related noise and hum, including cross-channel ground loop noise
• Speaker and amplifier protection assessment
• $ Cost per stereo watt (not scored, but must be stated in the assessment)

The assessment program explicitly does not address subjective notions of amplifier quality, only those that can objectively assessed using test instrumentation.

The tool distinguishes between different amplifier technologies and assesses performance within the capabilities of the designer's chosen technology. The technologies currently covered are: -

• Linear solid-state amplifiers with global feedback
• Linear solid-state amplifiers without global feedback
• Vacuum tube amplifiers
• Class D amplifiers will be added to the program once agreement is reached on how certain parameters will be scored

Tool outputs

A report card and audio analyser plots against which the parameters listed above are scored with a top-level score that places the amplifier in one of 6 categories as detailed in the Excel spreadsheet attached below.

I have already searched for info on this site and found a very informative thread from a PDX V9 owner but it falls short of explaining now to remove and replace ribbon cable. Recently purchased a used PDX F4 and one channel is not working properly. I suspect it is the preamp ribbon cable but I have not worked on one of these before and I am afraid to force the 15 year old plastic connectors. I have attached pics of the bad channel and a good one on my scope and the connector I am looking for help with. I don’t know how to release the ribbon cable connectors.

This is the Soft as a Feather Pillow Plus (SFPP) circuit that combines the solid state relay SFP soft start with a solid state relay low voltage switch remote on/off capability. There is also provision for remote shutdown logic via closing a contact that’s useful for thermal switches, etc. The SFPP has about a 2 second long soft start period where the in rush current is reduced by going through two NTC resistors in series. After 2 seconds, the NTC’s are bypassed allowing full current to go to the power transformer.

The circuit can handle up to two loads useful for dual trafo monoblocks in the same chassis.



Example of usage in single chassis dual monoblock amp:


Schematic:


Here is a video demonstrating the operation.
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The board has some tricky SMT parts with small pin spacing to solder. I am getting a new version with simpler easy to solder SOIC8 parts in the future but still have not tested that board out yet.

Here ya go guys, a place to share pictures and a brief explanation of your favorite amp or latest project. For discussion or an in-depth writeup, let's post at the Discussion Thread. Hope this will suffice- Who's gonna start things off? (again)

First, I would like to give this one to find a space for discussion.
I first thought of here.
It is the same as the structure of many friends here.
Maybe I didn't do the best.
+ -75V DC

I have been used for a few days in a row, it sounds very good, from the test also and I expect the same.

Although it is still a little hot, I replaced many capacitance, testing,

I hope that any I design an amplifier can steadily work for many years.

In the case of more than 300 w power 4 ohms, can stable operation.

Temperature basically control within 50 degrees, but I think maybe a fan, will be cooler.

So I need to replace 2SC2878 in muting circuits. In the short term I got a couple of (hopefully) NOS at a high price. But I'm curious to know if any current parts have been determined to work well as a drop in replacement?

Thanks...

I'm looking at affordable option to replace the OEM Plate amp in my JBL E250P which is rated at 250W 4 ohms. This is part of my home-theater setup and the sub amp is actually driven by the signal level output from my Denon AVR.
A replacement plate amp (such as a Dayton Audio) is both expensive and physically prohibitive as involves much more rework of the cabinet to accommodate.

In mini amps, what I'm currently considering might be:

Aiyima A3001 - https://www.amazon.com/dp/B08LZFBLDM or

Nobsound G2PRO - https://www.amazon.com/Nobsound-Hi-Fi-Subwoofer-Channel-Amplifier/dp/B07TTMN51V

These look to be pretty much identical inside and utilize the TI 3255 - one difference being the power adapter is 6A for the Aiyima vs 5A for the Nobsound
I'm also wondering whether upgrading to a 48V 5A power adapter is worth the investment for either of these and give a meaningful boost in power?
The benefit of those is they are certainly easy to integrate, just hook up to the speaker.

Then there's this option to go with a Sure/Wondom board:

e.g. https://www.amazon.com/400Watt-Class-Audio-Amplifier-Board/dp/B07HHNWQSK?ref_=ast_sto_dp
Then get an appropriate power supply to drive it - lots of inexpensive options on Amazon.

I'm not sure that the mini amps are enough to drive that sub although I've seen reviews of others doing similar as plate amp replacements. For sure the power number they quote are wildly optimistic though, per dyno tests of similar on YouTube
I don't have any point of reference for the Board type solution but even if those specs are exaggerated, then would still be ahead of the minis. (they have 5 & 600 W boards too, but thinking this one would be adequate) Integration is not really much of an issue, I would just fit the board and PSU in the sub enclosure. And you can even get a volume control for under $10 for those boards. A low pass filter would not be necessary as handled by the main amp.
Board, power supply and volume control would collectively be about $85, very similar to the mini-amps, which would however be a little more if adding a 48V adapter.

So what are your thoughts/opinions?

I have a Pioneer SX-820 that has developed issues while on FM: low volume (about 10% of what it should be), one channel has less volume than the other and loudness switch does not work. Both The FM Stereo/mono switch and loudness switch have been cleaned thoroughly. On all other modes such as AUX, Phono and AM Radio there is no issue. Any suggestions where to look for the problem. Any technicians out there?

Hi,
I have a long history of dabbling with DIY speakers - I dived in with a KEF Concerto kit in 1975 at the tender age of 15, then after a long hiatus starting around 1990 I designed and built some Home Theater subwoofers (1 x sealed, 3 x ported and 3 x IB) and built a set of three DIY Sound Group "Elusive 1099" kit speakers.

I am now retired and just for the fun of it I have decided to have a crack at designing a pair of bookshelf speakers from scratch. I am about a week into it - the drivers have arrived and I have a basic cabinet design. The remaining bits and pieces are on are on the way so now it get's serious - the next step is to build the cabinets and take some measurements so that i can start a crossover design. So much to learn....
Cheers
Bill

I have several ultra-low distortion oscillators from Viktor. This one has both 1kHz and 5kHz oscillators.
It sports both single-ended and balanced outputs as per Viktors recommended connections.
Has internal SilentSwitcher so runs from 5V USB absolutely clean, I routinely got down to -150dB distortion in both frequencies and all outputs.
Yours for 150 euro + shipping at-cost.

Jan

Hello people,

Looking for a half decent small mixer with at least:
4 Mic/instrument inputs
1 stereo input
USB for using as an audio interface
MIDI I/O for use with synths
Good noise figures
Not too expensive

I do not have a huge amount of experience looking for mixers so I was hoping for some advice, basically I want 1 thing that do all these things instead of having lots of boxes with lots of signal routing in between.
So far it seems the Tascam Model 12 may be my best option, but with my limited knowledge in this particular field there might be some other good contenders that I have no idea about.
Been looking at devices with compareable specs like the Yamaha MG12 XU but it has no MIDI, and the Tascam does look much better even though that is not a requirement of mine it is sort of a bonus to have the aesthetics covered.

Thankful for any advice not involving a cluttered mess of 3 different items to fulfill these criteria.

ALL SOLD
I am advised to create a new sale post instead of riding on the old one, which I have sold a couple years back.
I have now additional boards for sale because I am beginning to have the I/V op amp stage on some of my DAC boards.
Sorry for the earlier confusion.
Working AD811 IV board, more details can be found here:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-368#post-7451599
https://www.diyaudio.com/community/...including-burson-audio-op-amps-as-i-v.394295/

Board + shipping to you = Singapore Dollars 210 paypal FF only

Hi, Is anyone successfully connected

Bose PS321 II powered Acoustimass subwoofer with an external amplifier?​

If yes, can you please guide me. Thank you.​

For sale a pair of ATC SB75-314S in very good condition and with fresh new surrounds.
They can be used as well to replace the SB75-314SL because they behave and measure equal to those. Just Some better an more linear roll off in the SL. The SL has not a resonance peak more than 12dB below crossover point at 500/600Hz.


Price for the pair will be 450€ + PP fees + Shipping at cost.

Hi Everyone,
I based in Muscat, Interested in world of Audio. Used few setup as of now. Here I am to learn and gain knowledge about audio. I am sure this community will help to connect with other experts. Thank you

could someine olease help me understand how to use anything that i have got on hornsrep to use in akabak?

i can upload any details needed from hornsrep

Mosfet F6 Illustrated Build Guide

The Firstwatt F6 is a power amplifier from the brilliant mind of our technical, spiritual, and menu advisor, Nelson Pass.

The F6 is unique in that it uses a transformer for phase inversion, and both phases (The ‘push’ and the ‘pull’) of the amplifier are powered by an N-channel device.

This guide uses this PCB set — F-6 clone boards (2 PCBs, makes 2 channels; Rev 2.0) - Circuit Boards
Or here, the PCB with transformer bundled - F-6 Board + Transformer Kit – diyAudio Store



SCHEMATIC

The Schematic can be found here -



CHANGES TO THE SCHEMATIC - Change Z1, Z2 to a value higher than 5.1V if you need more bias. Increase in ~.5v steps until you can bias properly. The 1N4xxx series diodes are used here, 1N4733 is 5.1v, 1N4734 is 5.6v, 1N4735 is 6.3V, etc...

Suggested change, make R11, R12 110ohm. More information can be found in the BOM.

And an example PSU is here -




diyAudio PSU v3 build guide — diyAudio Power Supply Circuit Board v3 illustrated build guide



CHASSIS

The example amp is build into a diyAudio Deluxe 4U chassis — Deluxe 4U "Jack of all Chassis" (All Aluminum) V2 - Full width with 40mm Heatsinks - Chassis

Also utilized was the diyAudio Premium back panel parts kit — Error 404 - Page Missing

ASSEMBLY



Here are the PCB. The production boards are blue, and have some very slight changes to the silkscreen, but are otherwise identical.

Note that the PCB are a matched pair, not 2 of the same PCB. This is to facilitate keeping the input transformer as close to the back wall (and away from the power transformer) as possible.


Stuff resistors first.


After the resistors, stuff the larger components. Jfets, pots, capacitors, etc…


A stuffed PCB, sans transformer and LEDs (Didn’t have any blue ones on hand. 🙂 )


Input transformer. Note that on pair of pins is slightly narrower than the others. There are corresponding pads on the PCB for the narrow pins.


Transformer mounts here.


Both transformer mounted.


Remember, for best heatsink efficency, the mosfet should mount towards the bottom. This heatsink will make the left wall of the case.






You can see all the wiring of the PCB in this photo. (Red Black Green) is from the PSU, (Black White) is to the speaker posts, and the thin coax connects RCA to input.




Black is PSU GND and Speaker negative
White is Speaker positive
Red is V+
Green is V-



Input wiring from RCA




Completed, working amp. Need only to finish assembling the chassis around it.
(The black box on the transformer lead is a clamp-on ferrite clamp. Necessary? No. Might it help? Yes.)







POWER SUPPLY


IEC socket. You must wire the fuse holder to the switch as shown.


The long wires go to the terminal block with CL-60s, line cap and then the transformer primaries. I needed a bit huskier wire for the safety earth, and added the yellow for clarity.


PLEASE NOTE - this shows 120VAC wiring. Please consult your transformer for proper wiring for other voltages.
Into the block you can see the thermistors and cap, the AC mains from the IEC switch (Red Black) and the transformer primaries (Black Brown White Orange)


Safety earth and the CL-60 used to elevate PSU ground.


Two things to note - 1) I didn’t know if the power transformer was going to magnetically couple with the input transformers, so I wanted it as far away as possible. This will be almost touching the front plate. The L bracket was something I had from a salvage broken amp, so I can’t suggest a part number. Sorry. 2) Although I didn’t use the current PSU PCB, you can see that there is sufficient room (barely) for the board you can buy from the store.


I used an older diyAudio PCB that I had on hand, mainly because I really wanted to use it up.


Bridges mounted.


Wiring up the PCB.


More wiring.

For those of you wondering why I choose to have 2 big caps on one side and 4 on the other, it’s simply because I had those caps in my box. There’s no gain nor detriment to doing it in this manner.




The secret to clean wiring? Simple - start with your leads overly long and trim as you need to, and use lots of zipties. 😀


You can see the connections from transformer secondary to bridges and from bridges to PSU board.


PSU lit up.



TESTING AND POWERUP

Test PSU first for proper voltages BEFORE connecting amplifier circuit boards.

Then, connect only one amp PCB at a time.

Power Up

I suggest starting with a meter across the 0.47ohm source resistor, and watching it as it turns on, you want to have less than .5V across it to begin, turn it down with P2. If you start with the pot in it’s default position, it will most likely have too much bias initially. Turn off the power, turn down P2, and try again.



BIAS


P2 is marked BIAS on both PCB. Adjust this pot as necessary to set bias. Please note that as the pots and source resistors have the 1000uF capacitor in-between, the adjustments will happen in slow-motion and take a while to stabilize. Make small adjustments and wait as necessary. Patience is a virtue.


With DC voltmeter across the 0.47 source resistor, start by setting a bias reading of .5V (500mV) This will give a current of 1.05A, (.5V / 0.47ohm = 1.05A) which with a 24V rail gives about 25W of heat. Then zero your DC offset. Once you are satisfied that everything is stable and happy, you may increase the bias if you choose.

Remember the 3 rules of maximum bias… stop when you reach any of these -

Heatsink of 55C and/or Transistor pin 2 65C
Total bias , both channels, (in watts) of no more than 1/2 the power transformer’s VA
1/2 the maximum dissipation (in watts) of the output device. In the case of the IRFP240, it’s a 150W device, so no more than 75W. (Which is really, really hot…)

Generally, you will reach the 65C limit of the transistor before anything else.



OFFSET

P1is marked OFFSET on both PCB. Adjust as necessary to set 0V DC across the speaker terminals. Again, because the capacitor needs to charge and discharge as you make changes to the pot, any input to the pot will take some time to display on the meter, and it will seem as if it’s reacting in slow motion. This is normal.

Lightbulb Mains lead notes -



Please note that it must be an incandescent light bulb, not an LED or Florescent.
If the bulb ever turns on and stays bright, you probably have a short.

Normal operation when turning on a cold amp will have the bulb glow bright for a second or two, then dim, perhaps off. (this is the capacitors charging, then full)

As you increase the bias of the amp the bulb will glow brighter, and this is linear with the bias amount. A fully biased amp can get the bulb to glow very bright.

You cannot set full bias with the bulb in place - as it increases the bulb will glow more, limiting the voltage to the amp and all the readings will be wrong compared to when the bulb lead is out.

You can, however, set the initial bias with the bulb in place. Start the procedure, turn the pots until something happens, and set, at maximum, 0.1V across the source resistors and zero offset. Getting the pots started this way is a good idea. Remember, this is with a reduced voltage, and the pots will make the circuit draw MUCH more bias when the normal mains lead in used. Expect to measure 0.2V or more with a normal cord.

Sell as a full lot or individually various values/type inductors with few hours of use. Price 60%of their new value+ shipping
Lot 1 Intertechnik 2x0,47mH, R0,11 2mm wire
Lot 2 Mundorf L 100 2x0,39mH, R0,29
Lot 3 Solen 2x0,56mH model 16.56
Lot 4 Jantzen 2x 0,33mH R0,22
Lot 5 Jantzen 2x0,47mH R0,25

See pictures

Dear members,

Please take a look at the attached very simple power supply ripple filter.

Key performance figures:
406 V offload voltage
134 mA quiescent current
14 mVpp ripple

These are comparable to a 15H choke (~100R Rdc), yet you can get all parts for the mosfet filter for less than 1€, compared to the price of a decent choke.

Am I missing something, or why are chokes still so popular in our tube amp power supplies?

Cheers

Bought from Radio Antigua and never used as that build project never materialized. Due to shipping costs prefer to sell them both together. Brimar is the black plates,Halo getter with smoked glass. Both I paid 130 Eur. See picture and make your offer. Ideally want to get back same money 130 Eur and will gift the shipping to Europe destibation(not cheap these days) but fair offer will be accepted

Sell new for 70 euro+ shipping. I propose 50 Eur delivered to Europe destination(subject to check from my side of shipping costs, provide destination please)

They have been soldered to a speaker to test freq response and then choose a different mH value

Sell 2 inductors as per object. Used for some time, so tin residual on ends foil. 3 months old. Bought new for 95 Eur, sell for 50eur +shipping.

Hi all you folks, i ask for your competence for the Hiraga amp "the monster" that seems to me to be a interesting and simple amp. As anyone of you ever builded it? I'm interested to study a mosfet version to use it as car amp to economize to PSU. Any comment is welcome.

I just came across this article and I have to say I have never heard of magnetic amplifiers before. Were these types of designs ever used in amplifiers or other high end audio we see today? Considering this was used for military tech at the same time as the vacuum tube I would think there would be some audio maps made this way.

Magnetic Amplifiers

Does anyone have schematics for this technology or ideas on if it's worth salvaging for home audio?