Looking for some help trying to identify this amplifier. Not sure of the brand. LP! ???? there are no other identifiers on the amp anywhere. I have googled my brains out and came up with nothing. Anyone familiar?? anyone seen this brand before??

The customer is absolutely in love with it and wants it repaired. trying to figure out what in the heck it is.

Hi All -- I'm a long-time reader who is finally getting ready to design my first build. I studied music technology in grad school but have been working for decades on the software side, and just now buying my first soldering iron 🙂

I am working on a Marantz PM7000 with many issues, most of them are already solved. But I have a problem that it is literally driving me nuts. One of the amp channel, RIGHT CHANNEL, has a very low gain.
I first focused on the input differential amp, prior to measure, I checked transistors and fixed many cold soldering. The problem remained and I began to do some measures. As I have the other channel working I did, as usual, some comparative readings and on DC I can't find any difference from the good one to the failing other. Applying a 1 Khz signal I see the signal reaching R3316 and R3314 is very low if we compare it to the 3315 and 3313 on the Left Channel. And I am a bit lost, this are the challenges I like but, at this point, I think I need some fresh ideas as mines are on a loop. I have tested voltages, as mentioned, transistors (not with a cheap transistor tester but with a wonderful LEADER LTC-906A and a modern PEAK DCA75), diodes and resistors, even some capacitors that, to my surprise, were encapsulated as a resistor. First time I see this. The feedback is OK, power supply and limiting-protection resistors, everything is just fine.
Also, I didn't say it earlier, the signal reaching both channel inputs has the same level. I want to say this in case some may think I have any issues on tone or volume control, this is already fixed (there were some problems before)
I look forward for your experience and ideas because mine are exhausted. Thanks in advance

Hey people,

a not soo much relevant question as "warm up": Two identical 8ohm chassis, same signal. Would you take two separate TDA7293 amps and drive each chassis at 8ohm, independently, or take a dual master/slave amp and wire the chassis parallel to 4ohm?
Or asked this way, may i have any disadvantages if i do the two chips one pcb/ 4ohm thing (i used such a config as (12", 50l, sealed) subwoofer-amp for about 18 month and was pretty satisfied with it's performance) ?
Each box has 4 amps, 300W toroid with 2x 25V and some buckets of µfarads.

best regards
Jochen

hello,

it's Andrea here, long time lurker and appreciating a lot this community. this is my first post, just registered to signal a China board i've not seen described here.

of course, i've not any economic interest in the vendor. i've just ordered one sample to check the quality because it looks like a compelling price! 🙂 i don't' know what to expect..

i tried to find schematic info and demo project but nothing to be seen.. have you ever heard about this stuff?

bests

andrea

Has anybody here ever cloned or bought the cloning kit of the Meitner’s DAC?

It’s very difficult to find a Meitner’s in my location. But, I used to listen to it, the Meitner Idac-44, once and I cannot forget its sound.

Could anyone suggest ways to sourcing it, the Idat-44, either the original or a kit, please?

For a while I've played with the idea of creating a speaker that is not a multiple entry speaker per se, but keeps the woofers outside the horn but fed through slots to ensure proper summing and directivity without the complexity involved with synergy-style speakers.

I recently read Scott Hinson's thorough document outlining his multiple entry horn (MEH). He uses the B&C coaxial compression driver and heavy duty 10 inch woofers to create what seems to be a fantastic speaker.

I thought i could use his general outline (driver selection, dimensions, tuning) but to see if it would work with the woofers outside the horn. The idea being that if the speaker would work well without the taps (quite large) it could improve the sound since the compression driver won't see the taps until the frequency is low enough for it not to matter. Since the horn won't load woofers at the crossover frequency (300hz), it seems it could be possible to build the horn this way:




At the throat is a expansion based Hughes' quadratic throat waveguide. The overall dimensions of the horn is otherwise similar to Hinson's design, around 580mm wide, 90x65 degrees expansion


To check effect of the slot loading on the frequency response, i created a model of the woofer chamber entry and exit and has a go at simulating this. I didn't model the driver (fixed driving) just to see the effect of the geometry:



The results on-axis show a few 3b reduction at 200hz, and the first cancellation dip at 430hz.




I was thinking that if the cancellation here is too low in frequency, this project is dead on arrival. So my question is:

Does this frequency response make sense in your experience, or did I do some serious modelling mistake? Intuitively, if we assume all the input comes from the center of the driver, that there should be a large at the half the wavelength of the center to edge and back (in this case the same as the driver diameter, around 10 inches). So i would expect the first cancellation to be at 340/0.25 which is 1360hz.

This is the normalized simulated responses if we assume the opening of the slots are driven (ideal source) and the compression driver (ideal source). Ideally i would like the slot to not affect the frequency response until much higher in frequency, so that i don't compound the directivity effects of the horizontally separated woofer sources and the cancellation effect of the slot itself (unless the slot itself can be seen as an acoustic filter that matches the crossover frequency).



So i really have two questions: 1) Is the idea sound at all? 2) Is my Akabak modelling or intuition way off? If so, what can i do to improve it?

Hi, want to buy the Elekit TU-8900 with the Lundahl OPT(must). Shipping to New Jersey- USA.

Hello everybody!

I'm renovating my per-amplifier Hitachi HCA 7500 MK2 and are in need of a replacement or NOS part for the old volume potentiometer that is the following:

ALPS 164B Quad Log Stereo potentiometer 2x65K 2x3K

Can I have the luck that one of you in the forum have a NOS-part for sale or good tips on a replacement for my pre-amplifier.

Thank you in advance!

Best regards,
Richard N (Sweden)

Hi everyone, Recently I've been able to find some 3LF4 DHTs around. I wonder if anyone traced this tube's curves in triode mode?

Thanks in advance.
Sajad

I stumbled on this photo of our cat enjoying audio...sort of...and thought I'd post it. If you have a photo, post it. I'd love to see it. Mama Katz resting among RCA and speaker cables I'd put aside while we rearranged the living room for the Christmas tree.

Hello.
I am a owner of 2 similar CD Transport/Player – C.E.C. CD3100 and Parasound CBD2000.
One time, the CD3100 is broken with damage of microcontroller. I took microcontroller board from Parasound and place it to CD3100
During repairing process, I build full new CD transport – new controller (ATMEGA32), new software on ARDUINO IDE, new servo board, new power supply. I only took the box and laser pickup from original device.
The work started at june 2020 and finished only now.
I post the result here.
The new and old mainboard


The complete device

hello vintage audio friend
I would like to ask if anyone at home has a service manual for your Vincent SV 233, one channel stopped playing and I want to save the amplifier
thanks in advance for your answer
my email is
rene.smekal/at/seznam.cz

Hello all,

I am working on my DIY Preamplifier new project based on the Elektor Preamplifier 2012 (Douglas Self) schematic.

I don't need the TONE and BALANCE control sections in my design, painted in Red in the picture below. I will directly connect the output of IC2A pin 1 into the input of IC9B pin 5 (Green traces).

Still I have this question regarding the filters in the input of IC2A pin 2 and 3, painted in Yellow. Do I need them or they are part of the BALANCE section only?

And if needed, should I replicated the R11-R12-C6 filter with R8-R9-C5 connected to ground?

Thank in advance 🙂

Hi All,

I have a stock of new transistores for sale:

0 x KSA1381E (Fairchild/On Semi)

118 x KSC3503D (Fairchild/On Semi)

0 x KSC3503E (Fairchild/On Semi)

300 V / 0.1 A / 7 W / TO-126 / (grades D and E, hFE = 60-120 and 100-200).

Price: 1 Euros/piece + Shipping.

For matching please PM.

Regards,
VS

Hi All,

Here is a stock of new BJTs for sale in pairs. They where bought from Mouser and Farnell some years ago:

50 V, 150 mA, 250 mW (Onsemi):

KSC945 G (10) + KSA733 G (10)
KSC945 Y (10) + KSA733 Y (10)

80 V, 500 mA, 625 mW (Onsemi):

MPSA06 (G, 10) + MPSA56 (G, 10)

120 V, 800 mA, 900 mW (Onsemi):

KSC2316Y (10) + KSA916Y (10)

160 V, 600 mA, 625 mW (Onsemi):

2N5551 (G, 10, TA 10)+ 2N5401 (G, 10)

300 V, 500 mA, 635 mW (Onsemi):

MPSA42 (G, 0) + MPSA92 (G, 0)

350-400 V, 500 mA, 625 mW (Onsemi):

2N6517 (TA, 20) + 2N6520 (TA, 20)

400 V 300 mA, 625 mW (Onsemi):

KSP44 (TA, 20; BU, 10) + KSP94 (TA, 18; BU, 10)

Offers accepted.

Regards,
VS

This speaker started as a spinoff from this thread where I was studying the effects of different levels of stuffing/damping in a TL:
http://www.diyaudio.com/forums/multi-way/281281-pmc-tl-stuffing.html
The speaker that inspired this was the PMC TB-1:

Which has a 48in long internal path TL with the following damping scheme, which I think provides a borderline critically-damped aperiodic TL based on the measurements I have seen on-line:


There was a rather lengthy debate in that thread about whether or not the TB1 follows Bailey's TL approach and whether or not a proper TL should have single or double impedance peak. Rather than debate it, I decided to model it.

I then went on to model and design my own little TL box to study the effect of damping but using drivers I had on-hand: a Dayton Classic Series DC130A-8 5.25in midwoofer and a Dayton DC28F-8 silk dome tweeter. Both of these drivers actually have quite nice published and measured performance specs and are great sounding high-value drivers. You might be hard pressed to find another 5.25in class midwoofer with the same performance for $20. Similarly, the DC28F is an extremely smooth sounding soft dome with low distortion and flat frequency response.

Anyhow, my design constraints were to use approximately the same 48in long TL that the PMC TB-1 has, and about the same physical format. I put the vent in an up-firing position at first, but eventually went with forward firing to gain a few dB of sensitivity in the bass. I also wanted a tuning frequency fb of about 60Hz - 80Hz depending on the damping scheme used.

The design of the TL was as follows with a 6.0in wide internal dimension:



The predicted frequency response for this TL depended heavily on the amount of stuffing inside. Here are 3 cases of light, moderate, and dense stuffing. As expected, each case is a tradeoff in bass extension and SPL for light damping with lower group delay and improved transient response with dense stuffing. The predicted impedance curves go from double peak for light stuffing, to single peak for dense stuffing. The dense case tends to an aperiodic TL.

Light stuffing:



Moderate stuffing:



Dense stuffing:



Here are the corresponding Group Delays for the light to dense stuffing, the GD goes from 16ms down to under 5ms at 50Hz which is about the same as a sealed cabinet, but with deeper bass extension.

Light:


Dense:


Here is the predicted impedance for light stuffing:


Moderate stuffing:


Dense stuffing:


The predicted speaker cone excursion goes from a classic double peak 4th order:


To what you would see in an aperiodic TL or a sealed cabinet:


So these plots intrigued me and I decided to go with a prototype build in foam core. I was aiming for the moderate to dense case somewhere in between. I thought it important to get at least a -3dB point at 80Hz to get a sense of some bass output. I redid the model with front exit vent and the stuffing plan closer to how I will implement it using loosely teased out polyfill. Here is the predicted frequency response with a 2kHz XO and baffle step loses included:



And here is the predicted GD:


If stuffing is added to the final leg, here is the predicted response - about 80Hz f3:


With about 7ms GD at 50Hz:


With a semi-bordering on aperiodic TL impedance peak with a mild double bump:


Anyhow that was the goal and here is the build process:





Stuffing plan (adding stuffing in final leg transforms to aperiodic TL):


Here is the completed speaker:



And here are the measurements using a miniDSP and TPA3116D2 amps for an active 2-way. I am using 1st order electrical HPF at 2kHz on the DC28F and a 4th order BW low pass at 1kHz on the DC130A to get an acoustic XO of about 1350Hz. The slopes are quasi-Harsch and allow somewhat of a time-coherent output. I will refine the XO later but these are just to get started.

Raw measurement of the woofer in the TL running full range:


Frequency response showing XO profiles:


Harmonic Distortion:


Phase:


Impulse Response (there is a slight rise and wiggle before the main pulse due to the time delay on the tweeter to get it to be quasi transient perfect with the woofer):


Group Delay (with 1/2oct smoothing for clarity) is about 6.7ms at 50Hz:


I did take impedance sweeps and they look a lot like the mild double bump prediction above.

The TL sounds very nice - the transients are well aligned in time between the two drivers, the bass is clear and precise without the muddiness of a reflex, the mids are articulate and pleasing, and the highs of the DC28F are excellent - very smooth, transparent, engaging, with no sibillance or harshness. I still need to do more work to refine the XO with careful measurements and simulation in PCD, then transfer to miniDSP rather than doing the XO "by eye". I think I might move the XO up towards the 2kHz point but see that there is additional HD from the woofer there to avoid. If I have time, I may even try to design my first passive XO to see how that looks. Of course it won't be transient perfect given the flush baffle.

I am quite happy with how these turned out and am considering a thin 3/16in Sureply wood baffle to permit the drivers a better mount.

Edit 10/31/15: Polar data shown has tweeter rebated and brillo pad diffraction reducers installed



Edit 10/31/15 - latest Measurements with 2kHz XO and rebated tweeter with brillo pad diffraction control - sounds great and settings are now"locked down" for enjoyment (and to build stereo pair):

XO plot:



Phase - +/-23deg over 150Hz to 15kHz :



Harmonic Distortion - about 1.4% at 50Hz at normal listening levels:



Impulse Response/Step Response - very nice:



Group Delay (8.6ms at 50Hz - increased 2ms due to BW1 HPF at 32Hz):

Hi everybody,

this is a special request, as the gallery section of the passdiy is no longer available for the moment, if you have build an Nelson Pass amplifier can you post pictures of it. It will help me and others to get inspiration for designing our amplifiers. I develop a kind of interest lately in looking for different amplifier aesthetic design and layout. It don't matter if your design is orthodox or unorthodox, just share your realization. No need for words, only pictures will be enough.

Thanks in advance

Hi...
I have made a pcb based on the Blame ST MKII schematic V1, everyone can find i the internet. For the first test i used 100 ohm 3 watt resistors with a voltage of +-35 volts.
I could adjust the same voltage drop over the resistors of about 4,7 volts. No bad smoke, not heat.

Today i tried to adjust the bias to 13 mv with a railvoltage of +-55 volts, delivered from a Connex SMPS. But it isnt possible to adjust the bias right. If i try and the bias reaches 10 mV suddenly the bias rises up to 34 mV.
There is no difference if i trimm the pot or make a adjustment in ohm and power up later...10 mV through warming up and the the bias suddenly jumps up to 34 mV.
If i trimm down it is not possible too to reach the 13 mV. Reaching a certain point the bias voltage jumps down to 4,9 mV.

I have compared my kicad schematic with the original schematic and can not find a mistake in the moment. I had built the BLAME ST and all was fine. It has the same components for bias adjusting on board.

The only difference between the older Blame ST and the now newer MKII is using a starpoint and a connection from the starpoint to the groundlift resistor GNDA. Also using a loop breaker.
But i think that is not the reason of the strange behavior.

Perhaps someone has an idea to search for or a solution for this problem.

Thanks
Peter

As already mentioned earlier in the F5Pi thread, we have all the ingredients that will also make a nice Preamp.

It has taken much longer than we wanted, but it is finally playing music since yesterday.
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7524606
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7538379
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7741027

As always, I don't comment on subjective sonic impressions.
I'll leave it to Fran to tell you what he thinks, when he has enough hours on it.





Happy reading,
Patrick

.

I just finished building a pair of Pensil 12s with Alpair 12P drivers and today I installed the drivers after running them in for about 100 hours playing a classical music radio station at low volume. I stuffed the cabinets and closed the backs and hooked them up to my 300B amp and one cabinet sounded excellent (if a bit toppy) and the other sounded just horrible, as though the driver is damaged. It sounds badly distorted, as though the cone is ripped or coming apart. I opened the back to see if some of the stuffing was contacting the back of the speaker cone, but it looks fine.

This is my first real speaker building project (I've built a few open baffle speakers, but nothing like this), and I don't know how to diagnose the problem. I built the cabinets using the Pensil 12 plans on the Planet10 site and I made holey braces for them. When I installed it, the magnet of the driver in question wasn't quite touching the brace behind it, and I added a couple of strips of sandpaper to fill the gap, so I don't think the driver is being deformed by the brace.

I glued 1/4" thick wool felt to the walls around the driver, but not on the front wall itself.

I built both cabinets as identically as I could. There's nothing about the bad sounding cabinet that makes it different from the other one.

Here are some photos:

The wool felt


The driver installed



The stuffing


The cone of the unhappy driver, which looks fine to my (untrained) eye


I have so little experience building speakers that I don't know what the problem might be. Of course, I'm wondering if I simply got a defective driver (bought them from Madisound), but I thought I'd ask here before deciding I didn't inadvertently cause the problem.

looking for

• 
  
• KGSS
• KGSSHV
• KGSSHV Carbon
• Stax mafia portable
• CFAE
• or any other ES amp

I really don't like having to reach around the back of my amps to turn them on, this was a big incentive to design this.

A 256 step relay attenuator with 0.5dB steps controlled by a touchscreen and IR remote. A Teensy 4.1 micro control unit is used to control everything, I have been playing about with this for a couple years trying to develop a really good intuitive user interface. The board was going to use a PGA2310 to do the attenuating but last week decided to use a stepped relay attenuator. The PCB ended up at 200mm x 130mm, I managed to fit 2 PSU's, 2 buffers, 2 Amyalice filters for the buffers, 230vac 15A relay for a power amp, and a relay for speaker grounding (anti-thump). It has 5 inputs, 2 outputs that will accept SE or DIFF in or out.

The ILI9342 is a 2.8" touchscreen display and it is really hard to take photos of it. You can change the colour of all the different elements on the screen and uses BrunoSans font. For the large gain numbers I had to edit it the font to make it work, the numbers were different widths which look good if they are static but when changing looked weird. You can also rotate the screen, adjust the brightness, adjust the backlight and calibrate the touchscreen.

The input names can be changed, I have a list of over 20 to choose from. An inputs gain can be fixed so it will work well with an input with its own volume control like a TV or computer. Another thing I added is a gain offset for low power inputs, this allows you to set the apparent gain so it matches your other inputs.


The gain can be displayed in dB or as an ascending number. The gain speed can be changed and will do 3 slow 0.5dB steps when the button is pressed before faster 1dB steps.

My schematic is a mess, I haven't had time to sort it out and I have not finished the layout. I tried to keep parts count low and used SMDs to keep the PCB as small as possible. The buffers are OPA1632 opamps with the input buffer having 3dB of gain, I will add some pads so they can be bypassed. The 8 relay attenuator has 256 0.5dB steps, I chose 5k but you could do what you want. There is a mute relay that grounds the inputs. I added 2 Amyalice filters for the analogue power, not sure if I should add one for the +5v. The analogue power is from a +-12v DC-DC converter that gets its input from the +5v psu. The +5v is from a small AC-DC converter which is mounted on the board. The Teensy 4.1 is a really powerful MCU, I thought I needed the power to update the screen at up 50fps but after optimising my code I did not need it but I am leaving it in. I have 14 UN2-5NJ non-latching relays so I decided to use them.

The IR remote works really well, they are not very responsive but with a few little tricks it is good enough. Im using the Apple Remote, it is one button short so I have programmed for the menu button when held for a second to change outputs. Left and right change inputs, play/pause does the mute, up/down does gain, menu does menu and select button does standby.

The touchscreen is supposed to be intuative and clutter free. Touching above or below the gain changes it up or down. Touching left or right of the input text changes the input. Touching a symbol or MENU will mute, change output, enter the menu or standby.

When standby is selected, mute is activated, speaker ground (NC) relay is de-energised, then all other relays are de-energised. When turning on mute is activated, the power amp relay is energised, then 2 seconds later speaker ground is energised and mute is switched off. When turned on at the mains it will enter standby. Hopefully this will be quiet and safe. In standby the standby LED is on, the display part of the touchscreen is off but the touch is active and used turn it back on.

When muted the gain numbers on the display are dimmed and the speaker symbol loses its sound waves

My breadboard is simulating the relays as you can't connect the relays easily. I have used optocouplers and LEDs to check the MCU is controlling the relays correctly (they use more power than the relays would). Apart from the relays the breadboard has the touchscreen, a standby LED, IR receiver and the Backlight control for the touchscreen. The backlight control is done with a PWM signal from the MCU and a simple analogue filter. The other components I have not tested are the 3 ULN2003LVDR, these are low voltage relay drivers that contain flyback diodes and the transistors need to operate the relays. I am happy the MCU is working as it should, not sure about my buffers and need to quadruple check my schematic and layout.

Not sure if I will use this in a preamp or as part of an integrated amp. Sorry about the dodgy schematic and bad photos.

Looking for advice on Hypex amp for repair or upgrades

Hi everyone,
First of all, I would like to thank the community for the great dissemination done in this forum, I appreciate it for helping me with many aspects involved in the audio processing.
Basically, I am writing to you about my last project regarding the active sub filter. Many years ago, when I was 20 yo, I built a TL subwoofer with the same enclosure and size of the AWCS (BOSE) and the corresponding active filter. Besides my knowledge at that time, I had managed to solve many issues involved in its design (L and R separation,L and R mixing, grounding loops, noise etc). Lately, I decided to improve the mid and high range, thus I need to recalibrate the bass level, consequently the past design is no longer suitable for me, because it was not adjustable.
Looking for this forum I came across in two different posts, as usual I take the interesting part of several schematics, then I modify them in order to fit my needs. In these case, to build an active sub crossover, I decided to consider these two schematics:
https://www.diyaudio.com/community/threads/my-balanced-line-receiver.398440/
https://www.diyaudio.com/community/threads/active-subwoofer-filter.299230/
my design is made up of the following stages:

1. two balanced line receivers to get the max CMRR and to separate the ground between the external DAC and the main amplifier;
2. an arithmetic mixed which does the averaging of the both signals (no amplification is needed at this step;
3. signal amplification/attenuation + - 4.5 dB
4. second order high pass filter (15 Hz cut-off freq.)
5. two second order bessel low pass filters in series (the last one can have an adjustable cut-off, both have a cut off freq. of 80 Hz, (the TL sub resonates a lot around 100 Hz thus I need to get a plain response, also a 4th order is the minimum).
6. Lastly, a phase control in order to accord it with the TL midwoofer I’m designing now, the bessel type of the LP-filter should in theory help to have a plane and effective control of the phase.

Attached to this post there are the corresponding images of the circuit, besides I’ve added a simulation of the final band pass to show the difference between my config and the forum version adjusting the two resistors available in the schematic to get the same cut off freq. in the LP filter (the Sims are carried out in LTSpice). As you can see the Bessel configuration provides a greater attenuation in the proximity of the cut off freq. and a more linearity in the phase variation.

After this preamble, I would like to know if this design is fine or it requires some mods, in few words, what do you think about it? Did I do some mistakes?…
At the end of the project I am going to share the final schematic, gerber etc. using SMD components on EasyEDA platform.
Thanks in advance.

Roberto

Hello.
I chose to do MTM for my room
To 2x Satori MW16P-8 .8 ohm
1x Satori TW29RN-B 4ohm.
I started looking at virtuix sim. I don't have the measurements of the drivers and I downloaded their Spl and impedance curves from the manufacturer's graphs.
I know this is not accurate, but it is more for reference and familiarization with the program.
I know this is not accurate, but it is more for reference and familiarization with the program.
My microphone is broken and for now it's just a practice session.
The crossover cutoff is around 1.7khz as Torrels did in his project.

What do you think of the crossover's graphics and values?

Thorels has connected the tweeter with straight polarity. In the simulation connected in this way, a large drop in the cutoff frequency occurs. If their polarity is inverted, the graph straightens out.
How should these XYZ driver offsets be entered for each driver? Is there anything else I need to enter into the software and set up?
The easiest thing is to buy the crossover ready, but I want to learn the program and how to work with it. How do I enter the position of the drivers relative to each other in the box so that they affect the result? After all, the tweeter will be between the midbass and will be shifted from the center.

I would be grateful for your help and advice.

I have recently acquired a used Rotel RB 1572 power amp (yet to receive it though). It is born with two Icepower 500A modules. The unit was in production from 2009-2016 so it is safe to assume that the unit does not have the latest generation of Icepower's 500a module.

I was therefor wondering whether it would be feasible to replace the amp's old 500A modules with the latest gen 500A module? And would this be a relatively "easy" task for a novice (like me)? As I understand it, the newer modules of 500A series (and other Icepower series) are made to be "similar" to the original module so amp manufacturer's wouldn't need to do a complete redesign of their amp's if integrating a newer generation module.

For reference, you can see a picture of the Rotel RB 1572's internals on Rotel's website here: https://www.rotel.com/product/rb-1572 .

Any help and guidance would be much appreciated.

I have a 8 channel active setup. When I want to take a sweep in Rew I only have the option to playback one channel at a time. output is 1 to 8 but I want to measure the response on all of them.

I use Audiolense to create correction files. Playback in Roon.

I accidentally bought this transformer and it was too big for my project. I am selling it along with 4x 15000uf 50V caps and a CRC psu board.

The transformer new costs $65 and the capacitors are a little less than $5 a piece.

Looking to sell it all for $65 shipped Conus.

This thread is intended to be a place to discuss the balanced and unbalanced output versions of the stereo phono preamps as well as the Devinyliser designed by Doug Self and sold as boards only via The Signal Transfer Company website.
Website description: “The Signal Transfer Stereo Phono Preamplifier is a stand-alone version of the phono system used in the Precision Preamplifier. It offers both moving-magnet and moving-coil inputs, the latter with two gain options for optimal performance. It gives extremely accurate RIAA equalisation, a noise performance that approaches the theoretical limits, and superb linearity.”
No parts kits are currently available, according to recent correspondence with Mr Self.
Balanced output version: http://www.signaltransfer.freeuk.com/RIAAbal.htm
Unbalanced output version: http://www.signaltransfer.freeuk.com/RIAAunbal.htm
Devinyliser: http://www.signaltransfer.freeuk.com/devinyl.htm
Mr Self has taken over managing the website and fulfilling orders. He has been very responsive and the boards were received quickly.
I’m impressed with the build quality of the boards. Most of the parts are easily sourced using the BOM provided in printed documentation (or perhaps you will get a pdf) with the boards by searching for the values needed at your preferred supplier and verifying the part you choose has the correct lead spacing to match the board.
He does have a supply of the 2SB737 low noise transistors that he sells, tests each first and ships.
It took some digging and help from other diyaudio members to source a few of the parts.

Pending:
BOM with parts numbers from Digikey, Mouser, etc
Instructions to bypass Phono Preamplifier onboard subsonic filtering to leave that for Devinyliser to handle
Suggestions for some hard to source parts or their alternatives

Five pieces of protoboard for sale.
...................................................
FR4 1.6mm, identical traces on both sides,
Through-hole 1mm diameter.
Hole Pitch: 2.54mm
...........................................
OFFER!!!
8.5 Euro five pcb , shipping included inside EU !!!!

9.5 Euro five pcb , shipping included inside EU !!!!


Payment via PayPal.

Hi,

There are plenty of TPA3255 BTL amps available but 4 channel amps are almost non-existent.
As per the app note, the schematic of both 2 channel BTL and 4 channel single ended are different, but the BTL amp is completely differential, it looks like if we separate the differential input to single ended stereo input then we may get two separate outputs instead of 1 BTL output. If, this is the case, its easy to convert stereo BTL boards to 4 channel ones. I mean, INPUT_A goes to OUT_A and INPUT_B goes to OUT_B. Can somebody please tell me why its not a good idea?


Thanks,
Warm Regards,
WondefulAudio

By a timerelated fluke (no pun) I got stuck with 150 pcs of this wonderful transistor. As any symmetry ridden person knows it needs its sibling, one that I haven’t got.

My loss is your gain.

$2/pcs, min 50.

Shipping at cost.

R

I'm using 4" full-range whizzer cone speakers: Boston Acoustics 704. They operate normally. No lack of treble. However, one day, I found the NOS tweeters of the same series with these full-range; Boston Acoustics 700, are being sold. I think what if I buy and add them to the 4" full-ranges.

Of course, the HPF for the tweeter is required. But, how about LPF for the full-range, isn't it required?

If so, the x-over point might be set at around 4-5kHz (no problem). But, if not, which means running the full-range (closed) to 20kHz as usual and assigning somewhere upper frequency for the tweeters to handle, then, what frequency should be set for HPF of tweeters?

PS. I have a DSP in my system so I can actively control x-over.



As can be seen in the diagram, there are green labeled (X)Hz. They are meant that there's still no information about crossover frequencies on them.

The cone drive units will be used are full-range 4" Boston Acoustics 704 speakers, see pictures attached for specifications. Here is the question: what frequency should be applied to the 4" full-range driver as a high-pass crossover and the 6" mid-bass drivers for a low-pass crossover?

Love to hear everyone's thoughts. Happy weekend!

Hi all,

Before I go cut some baffles just to measure and find out, was curious if someone already did this and knows how bad it would be to basically mask the surround on a full range driver, not the cone, just the surround. Or if the surround has to be exposed and has a contribution to the output and shape of response. Vs, if the surround were masked. I imagine since it moves it makes sound too, so masking it would be weird and likely bad. I'm willing to cut wood and find out. But I'm curious if someone already has done this and was it really bad or not. Let's assume the driver doesn't need to go lower than 200hz so it would just be for upper bass, mids and treble as a wide band.

Point in case, this Fast-8. The image when I ordered showed a bone white color for the entire cone and surround. The surround is yellow though on this production unit.



So on my test baffle, I installed it just to see how it looks and listen to it a while. Sounds great. I like the look. But, my wife doesn't like the yellow surround. So now I'm wondering if I can just mask that yellow surround (smaller diameter hole, rear mounted, masked). Or if it would be a horrible response result by doing it. I've never masked a surround. I'm willing to cut a new baffle just to test it. But, maybe someone can save me the heart ache of how bad it is if they already tried it. Or maybe its fine?



Very best,

Hi y'all! New here but not entirely new to DIY audio projects.

My friends and I are looking for replacements for Toshiba 2SC3381 and 2SA1349 BJTs. There are forum posts with single package replacements over the years, but even those replacements are out of production. I'd like to avoid eBay or sketchy transistors if possible. If I'm not mistaken, the parameter we are having difficultly with is the DC current gain (hfe) classification we're looking for a minimum of 350.

Any help is appreciated, thank y'all!

By a friend occurs an issue at the display on this device:
Naim | All-in-one-Player | Uniti-Serie | SuperUniti

Obviously there are several other models with the same technology and the same basic deficiency.

You can find a lot about this on the web, but no helpful information:
Naim Audio Forum Archive
NaimUniti Mk.1 display panel fading - Hi-Fi Corner - Naim Audio - Community
Naim Unitiqute -- repair or cut my losses? | Audiogon Discussion Forum
Naim gebraucht, Geräte mit Display - Langzeiterfahrungen, Kaufberatung Stereo - HIFI-FORUM (in German)
http://www.hifi-forum.de/viewthread-33-1036-678.html#34185 (in German, #34185-#34213)

The actually question is, what is the exact reason therefore and whether sustainable self-repair is possible by replacing the associated parts (Naim Audio unfortunately recommends - like many others - always urgently not to lend a hand and invest the 300 to 400 € costs for genuine repair service).
Thank you for your advice

Hello Friends

Geneva Audio Classic/XL great simple looking speaker and config. 2 tweeters 2 5.25woofers and 2 - 8" woofers ported​

Wanting to build a powerful All in one box for parties and moe around the house. I want more bass pressure I dont get from Marshall Woburn or Bose S1 speakers at home.

Can you suggest the combination Thinking of using the Dayton KAB 4x100 bluetooth amps that also have DSP. Unfortunately they Dont have AirPlay 2
I was also wishing if TPA 3255 based amps had some DSP built in

In Drivers please suggest Peerless or SB or last option Dayton

regards
anand

Hello everyone!

I'm starting a new project - a "simple" DSP assisted 2-way, ported, boombox speaker.
I already figured out which woofer I want to use, it's a salvaged 3.5" woofer from a single Monacor EUL-30 PA speaker with a dead mylar tweeter.
I have already measured the tsp parameters, haven't measured the frequency response yet but it sounds almost like a wideband speaker. I suppose it can cross over with pretty much any tweeter also thanks to its small diameter.
For amplification, I am using a dual channel TPA3118+BP1048B2 bluetooth amplifier+DSP unit which will take care of the crossover and straighten out the frequency response for the single drivers, woofer and tweeter(s) separately. The speaker will work in mono. I can use very steep filters on it, if needed.
The speaker's enclosure will be 3D printed, therefore all of the design is done inside FreeCAD.

I need help with the tweeter configuration. Since this is a bluetooth speaker (which will be likely used to play some music outside with friends) I would like to achieve some decent sound coverage, within the limits of what I already have.
I do understand that a narrow, monopole directivity pattern is good for indoor, on-axis listening, however, I'm very willing to sacrifice that to achieve a wider coverage.

As far as I know, there are mainly two ways of doing that. I could either use a rear firing tweeter (which, I guess, would have to be padded down by quite a significant amount) or two "splayed" tweeters with a ≈15deg angle between them (this might cause some issues with clearance, unless I angle them inward).
I will be using a pair of simple, cheap and old 2" cone tweeters I already have lying around the house. I also have some 1/2" Mylar tweeters (the cheap kind) I could use.
The front baffle measures 252x130mm.

I had some trouble finding the theory behind that so I wanted to ask if someone has had a similar experience.
Thank you very much!

Some left over boards from my NAP clone project.
PCBs for speaker protection, they sound much better than the relay protection I had before.
PCBs with and without an extra footprint for an output inductor.
High quality PCB with 2oz copper thickness.
For information please see here.
Please PM me with a sensible offer.

Some left over boards from my NAP clone project.
PCBs for the amplifier, the power regulators and the front end regulators.
High quality PCB with 2oz copper thickness.
For information please see here.
Please PM me with a sensible offer.

Based on the pmd100-to-tda1541-in-smultaneous-mode thread I made a small PCB that can be used to replace the SA7220 and provide a better clock.
Tested and working, very good sound.
I can provide schematics and code for the mcu.
High quality PCB with 1oz copper thickness.
Some information can be found here.
Please PM me with a sensible offer.

Based on the discrete diamond non-feedback I/V stage by Pedja Rogic.
Works well and sounds excellent.
High quality PCB with gold plated pads.
For information please see here and here.
Please PM me with a sensible offer.

This is a thread to make announcements and highlight new products that will be coming out in my shop on Etsy.

Here is the link to the store:
https://www.etsy.com/shop/XRKAudio

Products to highlight as of May 3, 2023 are:

RTR BTSB with Tube Buffer - HypeSET (preorder):
https://www.etsy.com/listing/147415...499&click_sum=cca02e94&ref=shop_home_active_1

RTR BTSB Panel Mount buffer:
https://www.etsy.com/listing/137689...619&click_sum=dd1364a2&ref=shop_home_active_2

RTR SSR Speaker Protection:
https://www.etsy.com/listing/932716...41&click_sum=483bacd9&ref=shop_home_active_15

RTR TPA3255 Class D amplifier:
https://www.etsy.com/listing/755264...34&click_sum=c1251dcf&ref=shop_home_active_24

And I will soon add pre-orders for the HyperSET - a BTSB with a SE triode tube buffer and volume control - please stay tuned.

Hi all,

Newbie member here looking for help with constructing an outdoor speaker solution using horn loaded compression drivers.

Long time audio fiend. I know small angles create big changes. I have made car audio sound 2 feet bigger than the car, and the rearview was high, but it could still go higher! Thanks image Dynamics 6.5 coaxs! Set them in rings on flexible metal, then fiberglass in place!

But now ... I am trying to make a quite loud, but not too cumbersome "bluetooth" speaker. I will use it under a LOUD bridge skatepark in Jacksonville FL! It needs to also be listenable as you skate by! I have made many sketches, thought of so many ideas ... I find that the best image is a basic triangliated set of speakers, but then again i have not seen everything ... It would be cool to make this thing MYSTIFYING. I will post some sketches . YES I AM MAD INDEED. Lol. So how do i do this??? I want a stereo image, enough bass, and wide dispersion so you can skate by and still listen! And oh yeah ... Its on batteries... And i have to carry it around! And it has to be loud enough to defeat a highway above!!!

Pleased to meet you all, i literally dream about speakers, and am too broke to buy and experiment!

Halp!

I have recently found out THE TRUTH about low end extension! Just turn up your EQ .... Whatever bumps is REALLY what low end you got ...

Hi all,


I'm looking for a schematic for the Mark Levinson No. 36S DAC, or any information on where I might obtain a replacement transformer. It seems the unit has developed an internal short—specifically, the transformer that supplies power to the analogue boards appears to be affected. There may also be damage to one of the analogue boards.


If anyone has voltage specs for the transformer secondaries or a source for a compatible replacement, I’d greatly appreciate your help.


Thanks in advance!

Hello.

I have too many projects with too little time.

1- Two PCB for Kevin Gilmore's Dynalo MK2 "through hole", populated and in working condition.
It has to be adjusted with the final PSU.
Mix of Takman REY and Dale resistor. THAT340 input stage, genuine MPSA06/56.
80 € with EU shipping

2- Two Kevin Gilmore's UBAL/BAL boards, "through hole"
Same parts flavor as above, with Silmic caps.
50 €with EU shipping

3- One toroid 230v, two 25v secondaries, electrostatic screen. Hand manufactured on the UK, new never used, just tested.
50 euros + shipping

4- A pair of USSA amp, suitable for both USSA3 and USSA5 buildings. Populated for an avorted USSA3.2 project. Uses mainly Dale resistor, and features matched genuine NOS Toshiba Jfets. Does not incluse the heatsink-mounted transistor. 140 for the pair, shipped in EU.
Will provide Fab's documentation with the boards.
Ready to be used if you go the USSA3 route: just solder the second stage transistor and output LatFet, no other parts missing.

5- Four RIFA New old stock PSU capacitor, 33000 uF 70v. Huge! 15 euros per piece without shipping

6- Krell KSA-5 "clone", Class A headphone amplifier, Kevin Gilmore PCB, original parts and fully working.
Cased in black Modushop, with Schaeffer panel work (same company as frontpanelexpress in the USA).
Toroid with linear PSU (original style with TO3 transistors), and Alps volume pot. A pair of RCA input, output is 6.35 Jack and 4 point XLR to suit every cable termination.
Was one of my first DIY project, volume shaft could be aligned more finely.
Original circuit, without the recent proposed revision to improve bandwith detailed here.
Kevin Gilmore's CNC wood knob featured.
300 euros, shipping to be discussed (about 10 Kg).

Hello, I posted this topic as part of an active thread but I feel that it deserves its own.

I built crossovers for a system using both series and parallel topology. These tests were done in a semi- anachoic room so off axis / power response was not a thing, overall frequency response between crossovers was .5dB or less. There was virtually no difference in the frequency response but the stage presentation of the two was very different, the changes were enough where untrained listeners could easily hear differences.

Parallel topology:
This gave a very strong center lock on vocals, very topical of what you hear in a good system

Series topology:
The center lock was much less noticeable but the depth and width of the stage were much more defined. Low level detail was also more pronounced. There was more space between instruments.

Both topologies sounded good and, I can't say that one was better in absolute terms and it comes down to system synergy and personal preference. Some people love the strong center lock , some love the more 3D ambient sound , speakers and amplifier choice play a large role in what subjectively sounds better .

Why do they sound different.... I don't know but we suspect that if may have do do with back EFM that the amp sees and reactive loading on the amplifier is different between topologies. I Would be interested to hear people's experience with series Xos and a possible explanation for the Sonic differences.

G.

Original Naim phono boards for MM and MC:

NA322: for MM
NA323: for MC

in perfect working order, nice condition, very good sound.

Fits NAC32, NAC32.5, NAC42, NAC42.5, NAC62 and NAC72.

You can have one pair or both pairs.

Please PM me with a sensible offer.

Anybody got one for sale UK/EU ?

GAYA2P, the purifi-cation completed

Sounds are propagating air pressure variations in a time continuum, recorded and processed by our complex audiology system and subsequently ‘heard and understood’ in our brain. Based on this fundament it implies for reproduction that a correct amplitude and time reproduction is needed.

This is a new thread, as successor to my rather long thread in DIYAUDIO: GAYA2-Final, finishing the unfinished after 15 years

The Goal: The Purifi-cation & Active filtering completed, a very fine connection to the soul of musicians as result.
The main triggers are: the progress in active filtering and of course the arrival of the PURIFI tweeter. Especially the upgrade to the PURIFI tweeter will imply some serious effort in measuring, comparison, publications, and perhaps some enclosure adaptation.

As shown in the previous thread, and basically most of that interesting Alice in Wonderland journey is done, already very happy with results, as is my wife!
So this final round is to complete the purifi-cation, the active filtering and remaining JDI’s in the entire system.

Next post will be a 'short' walk-through of the period from 2005 to June 2025.

Hallo everyone, I'm Hein from Namibia and looking into repairing a Mark Levinson 36S DAC for a friend of mine. I'm into DIY repairs as hobby. I joined this forum to learn more and hopefully find a schematic or service manual in regards.

Hey!

A few questions from me because I'm already lost completely.

MiniDSP:

I have no idea how to connect it:
1. should I skip the original crossovers that are already in the speaker and connect the drivers to the mini DSP?
2. the original crossovers are to remain in the speaker and I am to connect only the Mini DSP to the speaker terminals?

System:

300B SE AMP--> Tannoy Gold 15

Check pics.

您好：我正在寻求帮助，以查找由日本雅马哈公司于 9 年制造的型号为 A979 的音乐放大器。我在网上只找到了几张电路图，我正在寻找一张完整的图片。此外，https://audiocircuit.dk网站上的维护图纸被标记为“YAMAHA A-9”，但内容实际上与 Pioneer 型号 A-9 有关。感谢您的帮助！

A stepwise volume control is implemented with a set of tiny relays and resistors. In a high-end audio system, a noticable sound improvement over potentiomeneters is obtained, also compared to 'audio grade' potentiometers. Its IR remote control provides convenience over solutions with stepped attenuator rotary switches. The sealed relays will maintain contact quality over a practically endless lifetime. The design represents a audio 'preamplifier' of top-class sonic quality, in a compact and affordable implementation.
The design uses high quality Fujitsu FTR-B4CB4.5Z bistable relays, as well as mil-grade audio grade resistors RN55D, RLR07, CMF55 from Vishay-Dale, which have an excellent reputation in the audio field. The circuit is designed for high-quality audio applications.
The input impedance is constant 10K, 22K, 50K, 100K.
The 1.5 dB adjustment step covers a sound attenuation range of 94.7 dB, 63 steps. By eliminating any active electronics, a very clear and open sound is maintained. There are no clicks when adjusting the volume in the speakers. Encoder for control from the panel.
The IR receiver allows remote control. When the power is turned off, the last volume position is remembered.
The circuit operates from a stabilized voltage source of 5 V.

The input impedance is constant 10K, 22K, 50K, 100K.

Payment is possible via Payoneer or to a bank card. It is also possible to buy on Ebay.

Stereo controller kit (2 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver

https://www.ebay.com/itm/267166457170
https://sgaudioua.etsy.com/listing/1798144856
https://sgaudioua.etsy.com/listing/1871270901
Stereo controller kit (2 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver
Input selector for 4 stereo channels
https://sgaudioua.etsy.com/listing/1825237975

https://www.ebay.com/itm/267166457170

https://www.ebay.com/itm/266863103276
https://www.ebay.com/itm/266932731942
https://www.ebay.com/itm/267151831175

Stereo controller kit XLR (2 channels XLR), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver
Input selector for 4 stereo XLR channels
https://www.ebay.com/itm/267197617946
https://sgaudioua.etsy.com/listing/1824028825
https://sgaudioua.etsy.com/listing/1825237975
https://www.ebay.com/itm/266918250389
https://www.ebay.com/itm/266936692441

Stereo controller kit (8 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver
https://www.ebay.com/itm/266863035366

Stereo controller kit (6 channels), includes: the controller itself, IR remote control, encoder, indication on two segments with IR receiver

I need schematic diagram of Unison Research Unico to take pre-out amp.
Please help me?

I think about some comparative testing of different materials for the ESL63 dust protection purpose.

Background: Quite many posts in different threads are related to the dust protection film and it's potential impact on the impulse response of the assembled ESL63 speaker. Some advocate to omit this dust protection altogether, some claim no influence of the two film sheets, some fit them hands down for practical reasons while trading in a potential slight sonic drawback. I therefore would like to perform some comparative, more theoretical, yet systematic testing of some standard and also of some non-standard materials for dust protection. If the test succeeds, then a more precise weighting/compromizing might become possible for every of the tested materials.

For my refitted ESL63, I used Vliesseline stich n tear, which showed some quite pleasing results while measuring. I do not claim that it is the best compromize, and I don't know how it performs against other options. So I would like to test this product against some experimantal 100% PET felt sheets/panels and of course also against different brands and strengths of standard film ("standard" == routinely used as dust protection). It would also be interesting to test some, say 3 different brands and strengths of standardly fitted films one against the other.

To perform these tests, I need some samples. So my question/request to the pro ESL63 rebuilders here in this forum is: Are some of you experts willing to send me 1.5m of yours preferred and routinely fitted dust protection film? Of course I would pay for the material and shipping. Please contact me per PM for my shipping address and for the mode of payment. I will perform this test if I can get 2 or 3 samples.

Test setup would include the absorbtive and the reflective property of each dust protector candidate (DPC) under test. I imagine to place everything into a line:
Sound source - Mic - DPC - Flat/plane surface as near-perfect acoustic reflector. The mic would therefore catch first the wavefront of the direct sound, then the wavefront reflected by the DPC, then the reflected and twice partly absorbed wavefront. Reflected by the acoustic reflecting plane, absorbed by the DPC.

Any comments welcome.

I decided to experiment with stainless steel enclosures... This was pretty hard to achieve, but it turned out very well. Because of bipolar bass/middle placement, they "disappear" and those ribbon tweeters are wonderful in this configuration. Crossovers are second order Butterworth @5KHz, internal damping is dense foam. Front and rear sides are some sort of dense board used for wall insulation and is glued to the steel with construction contact cement glue. Very thick and dense wood based stuff that's nice to work with and it has fake wood grain. Finding the right drivers for these enclosures was really hard, if you look closely, there's no space between the walls and the driver's basket edge. The enclosures are 5mm stainless steel thats used in food industry and are finished in automotive valve cover wrinkle paint. Size of the speakers is 100 X 150 X 150mm, internal volume is about 1.5 liter, and each speaker weights 3.8kg! 😂 The sound is open, clear and punchy, they go down to about 200Hz. I love them! 💪

Hello,

Edit: only amp modules and os devices left for sale.


So I had this Adcom 5802 from which I got the enclosure, the transformer, the big caps in the ps filter(which were recently replaced and measure 4miliohm and 22000u) and the small power supply that controls the big toroid.

So I decided to use the enclosure to build a nice 20w/8r and 27w/4r.
The amp uses the Stasis Fe as a front end, accepts rca and xlr inputs and has a voltage gain of 10x.
The output stage is similar to the one in Sit 5 and uses same working principle.

Here how the pcbs look. There is the main pcb with the output stage and a slave pcb with the front end.


The amp looks like this
From outside(good shape cosmetically, can send more photos using direct messaging)


And here the inside


A few more photos with the amp





You will notice that I used the small 12v power supply to control the big toroid from the front switch.
I installed some temperature sensors connected directly to each sit capsule to monitor the temp meanwhile testing. If needed I can leave these in place else they can be removed though it won’t change a thing soundwise.
The sensors will help if you use the amp with improper cooling because once the capsule reaches 75C they will turn off the main trafo.

Here are a few thd graphs
1w/4r


1w/8r


27w/4r


20w/8r


The power supply is dual mono, each channel is powered from its own winding from the trafo.
Initially the Adcom trafo gave too much output voltage which I had to lower a bit so I took the trafo at a trafo winding factory near my town so they rewinded completely the secondaries. When I got the transformer back it made a bit of noise so I have to return it back for a 2nd attempt. Now the noise got lower but there still is some. I will askthem to make another attempt.
I didn`t get a new trafo because I wanted to be able to use the amp at 120/240v like it iniatially was designed and still can be used.
In the meantime that the trafo was at the factory I used smps power supplies with great success and practically no noise and very low cost(320w meanwell)

Because I want to go ahead with my projects I need to pull some funds from somewhere and this amp will save me this time. So don`t have other funds to put a new trafo inside.

I was thinking at the following..
I was planning to ask 1300e for the amp it the trafo would have worked as expected.
A trafo for this amp is around 250e at Toroidiy so what about 1000e for the amp as it is?
I will send it with the actual trafo.
The amp weights a bit more than 25kg. I can ship it in the UK and some countries in the EU(Austria, Italy, Germany, Belgium and probably others) at 1.2 pounds/euros. For the UK no custom taxes will be implied. So in these cases the shipping will be quite cheap.

If you have a pair of field coil drivers that that you want to trade I am all eyes and ears 🙂

As for the sound.. what I can tell is that it`s explosive! I built a few sit amps but none sounded so powerful like this one.


Edit:
Somebody asked how h2 looks so here we go
10w/8r


10w/4r

I am able to pick up a very rare Phase Linear A60, it was under the pro series.

there is not much info out there, around $1000 in 1981

Can someone comment on the design ?
Speaker protection for a pro amp, very rare I guess

Hi everyone.

I've always been interested in audio (and vision), and I'm lucky enough to be quite involved in the vision side of things for my work. As kids have gotten older I've started to have a little more time to spend on other interests and one such project was a desktop near-field listening setup in my home office.

That project is kind of complete, but as with any hobby... is it every really 'done'?

The desktop setup allowed me to dip my toe in to DIY Audio, because I ended up finding a pair of Pioneer SP-BS22-LR speakers with blown tweeters. This was fine by me because I was planning to do the Denis Murphy tweeter and crossover modification anyway. The cabinets were also a bit tatty, but that was also OK because I planned to strip the vinyl and veneer them.



In case anyone is interested I'm running these with a Mac and Apple Music as the source, through an SMSL RAW MDA-1 DAC and a Topping PA5 II Amplifier. I also have an ELAC Debut S10.2 subwoofer handling the low bass, but to be honest, the modified Pioneers punch way lower than a 4" driver should!

The tweeters were a little tough to get hold of, but by trying my luck from a few locations I ended up with 3 pairs of tweeters, so I've decided to build another pair, and this time try a more complex cabinet finish... and that's the reason I'm here... for advice on an issue I'm having with veneer prep and finish.

This has been a consistent issue I've faced. It appears as if everyone I watch building speakers can make boxes near recommended and fairly flat, but whenever I do it the excursion is through the roof. Here are some examples:

1. Driver at 0.2ft3 to not go into over excursion can only handle 4w of power.
2. Parts express recommends 0.2ft3 for sealed enclosure and 0.3ft3 for vented. If I use the same 4w for vented, it has pretty bad over excursion.
3. These drivers should be able to handle 30w, but no enclosure seems like it will work because if you get big for any type of response, even as recommended, it will get no where close. There is no amplifier in the world small enough, so therefore I must be doing something wrong here.

Can anybody assist? Let me know where I'm going wrong?

https://www.parts-express.com/pedocs/specs/294-2760--prv-audio-4mr60-4-specifications.pdf

Escaping the heat while recovering from a 200km bike ride yesterday and I got some audio work done.

• Assembled the first prototype of Bog on a Plate, a 200W plate amplifier based on my Bog Standard concept (which in turn is based on Blameless).
• Finished the breadboard prototype and code for my digital sub filter
• Added a mono low-level output to my main amplifier (also a Bog Standard, of course)
• Hooked it all up, Frankenstein-style and... it works!!!

And yes, it's currently missing an output pair. They're ordered and should be here in a couple of days.

I have a long way to go to reach the level of some of you, but I'm sort of getting the hang of this! 🙂

As usual, all schematics, layouts and code will be published on Github on the off chance that anyone cares.

Now I just need to build an enclosure.

Any audio enthusiast in West palm beach, fort lauderdale, miami area?

Martin

We discussed previously whether or not EnABL would improve a MAOP driver, and I volunteered my MAOP-7 to try it. Sorry, couldn't do it earlier. Preparations for winter occupied most of my time - I live in a countryside.

First, I tried to do tap test to determine optimal positions of the patterns. It didn't work - at any distance on the cone radius tap sound was the same. Tapping worked on a 4" Sony speaker with a paper cone, I could find positions where tap produced the loudest sound. I guess the MAOP cone is pretty well-damped as-is. Without tap test guidance, I decided to apply patterns 1) close to surround; 2) on former close to cone boundary, and 3) on top of the dome. See pictures for details.

The patterns were applied free-hand using extra fine Utilto acrylic paint markers, black and white. Surround pattern was applied to back side of the cone to conceal my ugly handiwork. To build up thickness (pens lay paint pretty thin), three layers were applied: black-white-black. On the cap, a single layer of white.

The difference showed on the first test record, Beatrice Rana Chopin Preludes. This is a very well recorded piano album. The second prelude is played between piano and pianissimo. Control untreated driver played soft, but with the EnABLed driver I could hear string buzz that wasn't apparent before. Those familiar with the sound of top level instruments like Steinway or Fazioli will understand what I am talking about.

Further testing is unnecessary. It worked.

I have had the edge to get what I would call a good bench meter. I have plenty of digital handhelds, Fluke 289, Fluke 87V, Fluke 27FM, Agilent U1252A and then a Klein with an amp clamp of some kind that I generally use for auto stuff and where it will get dirty. I do have one bench meter, a really old Fluke 45. Not the highest resolution, but still dead on accurate. Kind of boring and it’s getting old, wait it is old.

I’m wondering if getting a bench meter is wise since I have so many other meters, but I guess I could sell some.

I really would like to get at least a 6-1/2 digit meter. I’d consider myself an extreme hobbyist. I love repairing and restoring old pieces and enjoy building diy amplifiers and preamps. I am guessing I really don’t need that resolution, but I would really like to have it.

The models I have been looking at are the Siglent SDM3065X ($745 USD), Keithley DMM6500 ($1600ish USD though it looks like directly from South Korea I could snag it for $1450), and lastly the Keysight 34465A. I also looked at a couple of used units, like on eBay there is a Tektronix DMM4050 that won’t boot for $385, but not sure I want to chance a repair on a unit that will have future screen issues.

So, the Siglent. It’s half the cost of the other two. That’s a pretty big savings. On the other hand it also looks like it’s lacking compared to the other two, there is a reason it’s so much cheaper. A huge plus for me is that I can purchase it on Amazon and pay interest free payments over the course of 5 months, $149 a month. That is incredibly helpful and may be the decision maker.

The Keithley DMM6500, personally I love this meter. I own a couple of Tek scopes so why not. I have done a ton of reading and it looks like the DMM6500 is fairly equal to the 34465A, but is less expensive and more people recommend. Plus I like the fact that the DMM6500 has a low ohm function, will be very useful for short finding on a circuit board. Honestly this is the one I truly desire.

The Keysight 34465A looks like a fantastic meter. It looks like it has a couple of shortcomings compared to the Keithley, but at the same time is better in a couple of ways. I highly sought I’ll be doing any data logging or anything like that. If I happen to find one that is used in good condition for a price that makes sense then I would pick up this unit over the Keithley.

I found one place at looks like I could pick up the Keithley and make payments through Klarna interest free over 4 payments, but it looks like the auto draw every two weeks, so $800 each month. If someone knows of a longer payment term please let me know. I could pay all at once, but spending that kind of money all at once, I’d get the side eye from my wife. Over several months, less of a big deal.

Anyways, looking for opinions on these units, maybe people that have used a couple of these have an opinion? What would you do in my situation? Financially it seem the Siglent would be the way to go, but it seems less “wow” and I’d hate to have buyers remorse wishing I had bought better.

Thank you,
Dan

Hi everyone,

I’m in the early planning phase of a DIY speaker project inspired by the Avantgarde Acoustic Zero 1 XD and Zero iTron. While I don’t intend to clone them directly, I’m fascinated by their compact, active horn design and how they blend traditional horn acoustics with modern electronics.

My goal is to design a 3-way horn loudspeaker that reflects this idea — but with my own twist: a focus on analog signal integrity in the mids and highs, and digitally controlled, active bass using Hypex DSP.

Concept Overview​

• 3-way loudspeaker with horn-loaded mid and high
• Passive mid/high crossover
• Active DSP-based bass section
• Frontend:
  
  • Turntable and external DAC
  • Pass Aleph P1.7 preamp
  • Aleph J Class A amplifier for mid/high
• Bass amp: Hypex FusionAmp FA251 or FA501

No built-in DAC or streamer — I want to keep things analog-first with the option for future upgrades, such as fully active signal paths or streaming integration.

Tools & Research (So Far)​

I'm currently researching and evaluating tools to simulate and design the horn sections:

• Hornresp – for estimating horn behavior and cutoff frequency (F12)
• ATH4 – for modeling OS-SE or Tractrix waveguides and exporting STL for 3D printing
• AkAbak – potentially for system-level simulation (once I’m deeper in)
• Also collecting Excel sheets and online calculators for basic flare geometry and alignment

No simulations done yet — I’m still learning the tools and comparing approaches.

Tentative Driver Selection​

Midrange Horn​

• B&C 5MDN38

Tweeter Horn​

• BMS 4524 compression driver

Bass​

• Considering FaitalPRO 12PR320, B&C 12PS76, or Beyma 12P80Nd
• Enclosure: sealed or reflex
• Powered by Hypex FA251/FA501, using built-in DSP for:
  
  • Low-pass XO (~250 Hz)
  • EQ and delay alignment with mid/high section

Since I’m at the very beginning, I’d love your thoughts on:

• Which tools are best for horn simulation at the mid and high frequencies?
• Tips for integrating a hybrid analog/DSP setup without phase or delay issues

Thanks for reading! I’m happy to document the process as it develops, and share test files or results as I move from research into prototyping.

Cheers,
Friedrich

Does anyone think it would be possible to replace the vintage drivers in the EV xb manifold sub with a modern B&C driver and get better low end extension out of them?

I recently got an pair of JBL Studio 530 monitors on sale for $250 direct from JBL. I was curious what an entry level horn loaded CD 2-way monitor could sound like. They actually sound quite decent and measure well when the tweeter is padded down a notch. The reviews of these are generally very good and for $250, no DIY project will come close really given the nice cabinet (no parallel walls in sight), a horn, passive XO, and decent bi-wire/bi-amp 5 way binding posts.

What intrigues me about these is that the horn has lots of opportunities for cutting slots and holes for mid range injection to make a bookshelf Synergy. Has anybody thought about doing something similar? My one reservation is that this speaker sounds very good as is and I would hate to cut into it.

Here it is next to my 10F/RS225 TL speaker for size comparison. It works well with either my Class AB or class D amps. It needs so e power though, probably at least 40w to really come alive.


This is how I padded the tweeter but adding a resistor between the woofer binding post and tweeter binding post.


Here is how it measures with the tweeter padding in place. Without it, the response is a bit bright for my taste. The JBL 530 is the yellow trace and the blue is a new speaker I just developed with a typical “Harman house curve” voicing for comparison.


Here is what is interesting, Ron from New Record Day, did a tear down and you can see the inside of the horn. Lots of open surface area for mounting small 3in midrange cones for a mid injection a la Synergy.

Anyhow, I thought I would just throw this idea out there to see if anyone else has wondered the same thing.


Here is the XO schematic from The manual:


Here is the horizontal directivity from the ASR review:

Power Buffer with ECX10N20/ECX10P20.
Delivers more than 20 Watt at THD 1% into 8 Ohm.
Here I feed the buffer with opamp OPA552.
Distortion at 1 Watt is only 0.008%

The Fourier shows an interesting spectrum.
H2 and H3 is way above the rest of the harmonies.

Hello everybody,

This is my first post in this forum 🙂

I am starting planning my next DIY subwoofer build project.

The background: I am fascinated about the sound the REL line array which consist of 6* REL S510 subwoofers. I am considering if I can build something similar (or even better!) myself. The REL S510 subwoofers are with a 10" woofer and a 12" passive radiator.

My subwoofers will only be used for music listening on my Naim+Focal system. All focus on SQ, musicality, control, speed & attack.

What I have come up with until now:



The system has 1* 12" woofer in the bottom and 2* 10" woofers at middle/top (4x 10" & 2* 12" total). The subwoofers aesthetics are designed to match my Focal Sopra 2 main speakers.

The enclosures outside dimensions are all identical, but the inner volume will be made to match the selected woofers. Maximum volume is arround 50L for each enclosure. But if the enclosure for the 12" woofer needs to be bigger I can extend the depth of that enclosure.

I am only focusing on sealed enclosures, as my experience teels me this is best for critical music listening.

I am considering using the the Dayton Ultimax II woofers:
10" UMII10-22
12" UMII12-22

I am considering using 6* ICEpower 1000ASP Amplifier modules:
Rated power output:
1x 1100 watts at 4 ohms
1x 525 watts at 8 ohms
Minimum load: 2 Ohm
Efficiency: 83%
Distortion: 0.007 % THD+N
Gain: 26.7 dB

For crossover + DSP i will be using a miniDSP Flex Eight with MSO software.

My first questions are:

1) Which are the best woofers for this kind of project? My main focus is SQ - price is not so important (but I really like the aesthetics of the Dayton woofers!! 🙂 )
2) Are there better choices for the amp ? is the ICEpower powerful enough ?
3) Theoretically, could this kind of system compete with a REL S510 line array ? (6* S510)

Any input would be much appreciated! Thanks!

Best regards,
Rune

Quick question, as I have gone through this problematic amp channel at least three times now.

Bought a basket-case MM7055 that I wanted to try and refurbish for a friend. Opened it up and the outputs, a couple Caps, a diode and some resistors were bad. No problem, put in some MJL4281/4302 for outputs and replaced the other parts per the schematic. Went through and checked every resistor, diode, capacitor and transistor in the circuit and also compared to the channel right next to it on the PCB (it works fine and bias' up without any issues). I also checked the variable resistors and they go from ~700r to 0.3r range, and consistent with the adjacent channel.

Strange part is that I get music and it sounds fine. the issue is I can only get it to bias to 0.65mV, when the service manual spec is 1.5mV. this is across 0.1r emitter resistors, so I should have ~15mA and I'm only able to get ~6.5mA. As I mentioned it plays music fine, no issues and I can't really "hear" any difference in my HT room playing music through the repaired channel and any of the other 4 channels.

I have gone back in 3 times and even changed the MJL outputs to original TO-200s, because I thought that might be the issue. Same problem, very little to no bias.

Any idea where to start looking, I pulled Q209 out of circuit and tested with the adjacent channel's Q209 - they tested 99% the same. I retested all the resistors in that vicinity and they all test good and any outside tolerance, were compared again to the adjacent channel and the two match ~95% (for resistance or diode voltage drop)

I have attached the schematic and the parts "circled" have been replaced with new parts from Mouser. The outputs were MJL4281/4302, now NOS 2Sa1216/C2922 (known trusted seller). Anyone want to give this a fresh set of eyes and possibly point me in a direction for parts that might be causing the no bias?

Hello everyone,

I've spent some time reading threads on here about restoring an Empire 208 that I have, and looking forward to buying some parts. I bought it from the Frank Zappa Foundation and it's in mediocre shape, but hoping to bring it back to its former glory. Also possibly looking to get into custom speaker cabinet builds but that's down the line!

Hello,
Ive been slowly chipping away at repairing my m1.5t carver with the help of others in this forum in another topic.
I finally got everything installed and began testing using the service manual instructions.
I am very new to testing amps so pretty sure I am doing some stuff wrong, but headroom testing seems pretty straight forward.

• Drive both channels to clipping,
• output should drop 3dB after 5ish seconds.

Mine did not. I drove that thing so hard I was almost putting a 1khz square wave though it, it never protected itself...and then I started to smell something and I killed the input.
I started to look into the headroom protection circuit and explanation and after looking at the schematic and theory of operation, I looked at the amp and found the double diodes from IC1 connected to Q5 and Q6 do not exist on my amp(s). I have two, and they both are missing them.

Was this a design change that was never captured in the service manuals? The holes are there, and the traces on the boards are there, just no diodes feeding Q5 and Q6.
Granted I dont think I will ever be driving these amps to this point under normal operation, so its maybe no big deal. I was just curious if this is a known thing to have these headroom protections seemingly disabled like this.

Thanks.

I am looking for help on the Palette unit in the Cello system. The internal power supply is putting out + and - 25 VDC and I think it should be + and - 15 VDC.
I do not have a schematic and do not know where to get one.
Any help would be appreciated!

I recently acquired an ancient philips dfa888 amplifier with builtin TDA1541A based dac. Disappointingly it didn't contain the S1 TDA1541A as I had read somewhere it would, just the plain TDA1541A. Nonetheless, it's a very nice dac with dc servo to maintain 0 volt at the output. It has an input circuit consisting of a lot of sanyo cmos switches , the LC7821 and LC4966, providing input and output selection and a "source direct" function, bypassing tone control and balance , but not loudness. The part of my query is the power amp section: The audio signal from the inputy selectorcircuit enters at JE51 (from PV01 the selector circuit) with right the loudness circuit and left the 50 kOhm volume pot. The slider of the pot goes through the source-direct/tone-control selector ic lc4966. When source-direct is selected the ac-signal goes straight via the 680Ohm resistor RG02 to J701 input connector and there via C701 10uF cap. and 100Ohm resistor R705 to the inverting input of the NJM2068 opamp. As far as I am able of understanding the circuit the output of the opamp drives the emitters of the first stage of the fully balanced output circuit. The collectors of these drive the Vas , which drives a triple emitter follower power stage. The thus inverted output of the power stage is fed back via a 27kOhm resistor and 15pF cap to the the non-inverting input of the opamp , thus forming a shunt feedback gain factor determined by the 27k resistor divided by the sum of the 150Ohm R703 and the position of the 500Ohm pot RG19-2 (coupled with the the 50kOhm RG19-1 volume pot). The amp is spec'd for 85W in 8Ohm output. This equates 26V and the input sensitivity is spec'd as 150mV. The feedback arrangement has a gain of 27000 divided by 150 max, which is 180. The sensitivity of 150 mV requiers for 26V output a gain of 26 divided by 0.15 which is 173. That seems rather on top. My question is, did I interpret the circuit correctly and/or can someone more knowledgable shed a light on this power amp circuit. The used opamp NJM2068 gives a 35mV offset at the powerstage output. When replaced with a opa1656 the output offset voltage is reduced to less than 1mV and when replaced with an opa2189 the offset is ca. 1.8mV. The offset voltage of the NJM2068 is spec'd as 0.3mV , of the opa1656 it's 0.5mV and of the opa2189 it's 5uV , but the offset voltage at the power output seems more related to the input offset current,which is lowest for the opa1656 and highest for the njm2068. Is this a correct observation ?
Tha amp sounds wonderfull with the opa1656 by the way, as with the njm2068 , but the latter seems a tad less sparkly and spacious, anyway I like 1mV offset better than 35mV offset so the opa1656 is there to stay.
Thanks, systux

What is offered:

4x pieces of a speaker protection module as shown in the thread here:
https://www.diyaudio.com/community/...-universal-speaker-protection-circuit.415149/
enough for 2 stereo amplifiers.

Since the MOSFETs used are tricky to solder effectively at home, the boards will be provided with the MOSFETs already soldered. The rest of the parts will need to be supplied by the subscriber. They are easily available and in stock at Mouser, DK etc. The modules use SMD parts with the smallest at 0603, but most are larger than this - I'm only saying this as some people do not like using SMD parts. Full BoM and build/test instructions will be provided on paper as is usual.


Technical details:

The built units can be used for amps with total voltage from 24V to 100V, either single or dual rails. It must be run from the existing amplifier rails and you do not need an additional auxiliary supply. Current draw is less than 15mA per rail. The boards are designed to be mounted on the amplifier heatsink - one TO-126 transistor is configured to be bolted to the heatsink - it will dissipate up to 1W.

If using BoM values the units provide a start up delay to avoid turn-on thumps of about 3s and will trigger after the DC level exceeds the threshold for around 2s. The trigger voltage is around 1.2-2V depending on components used.

Board dimensions are 30x58mm

The boards are designed so that a mirrored pair can be made using the same PCB, making input and output wiring simpler and neater for each channel in a stereo amp.
By design, the protection is latching - i.e. it does not automatically reset for a long period. You will want to figure out why there is DC on the output before resetting the latch! It is also possible to manually reset the latch for testing etc.

Costs:

€60 for a set of 4x boards, with 2x MOSFETs per board pre-soldered. Tracked and insured postage anywhere in the world is €15. The rest of the parts will cost about €30 per stereo pair without any volume discount, depending on where you shop for them.

If you would like to take part, please add your DIYaudio name below here along with the number of sets you would like to sign up for. 1 set = 4 channel protection PCBs (2x stereo amps).

Example:

woodturner-fran - 1 set

The group buy will require a minimum of 20 participants/sets. When the group buy closes, it is expected that ordering and delivery will take about 3 weeks, and once the units are here and verified, I will send invoices to each participant. As usual, no payment until the boards are here and ready to distribute. Previous experience shows it will take an average of 2 weeks to arrive anywhere else in the world.

Thanks for your interest!

Hello. I am struggling to decide which of these woofers to pick for a 2 way crossed at ~1-1.4KHz. I'm specifically interested in which will handle the midrange better. Thoughts? (Tweeter is Peerless DFM 2535R00)

https://www.parts-express.com/pedocs/specs/264-1110-tymphany-sls-p830668-spec-sheet.pdf

https://www.parts-express.com/pedocs/specs/295-658--dayton-audio-sig270-4-specification-sheet.pdf

Hi everyone,

I’m currently in the planning phase of building high-end floorstanding speakers and would love to get some advice from the community to make the right decision.

My Situation:
I have a relatively large and open living room, roughly 8m x 9m (72m²) which will serve as my main listening room. Due to layout and placement constraints, I can’t pull the speakers more than 1.5 feet (~45cm) from the front wall. So rear-ported designs are not ideal, I’m focusing only on front-ported or sealed floorstanders that can perform well close to the wall.

After extensive research on Troels Gravesen’s site, I’ve shortlisted the following designs that meet the above criteria:

1. Illuminator-5
2. Illuminator-4
3. Jenzen Illuminator
4. Jenzen NEXT T29
5. SBA-10
6. NEXT-4
7. ATS-4

Genres range from jazz, blues, rock, and electronic (occasionally) to vocal-focused recordings. My main listening position is about 3.5–4 meters away.

It doesn’t have to be a Troels design as long as the project is well-documented, uses premium drivers (Scan-Speak, SBA, Accuton, or higher), and the total cost remains under €5,000 for the complete build (minus the cab of course). I'm open to recommendations from other designers or kits, provided there’s enough guidance to ensure a solid build.

Questions:​

• Which of the Troels designs listed (or others) would work best for my room size and placement constraints?
• Any particular models with especially strong imaging, sound staging?
• Thoughts on the differences between the Jenzen designs vs. SBA-10/NEXT-4, especially in a large room?
• Any non-Troels projects I should seriously consider under this budget?

Really appreciate any feedback, comparisons, or personal build experiences that could help guide my decision.

Thanks in advance!
Awni

Attaching a photo of my living room, which is currently under renovation. there’s no door on that wall, it's just being repainted but the speakers will be placed in front of that wall basically.