For sale a pair of Jensen Trafo JT-11-DMCF

https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-11-dmcf.pdf

price 107 euro

only sale for EU

So I'm quite liking my Telefunken RE074 neutro DC1938.

The tone is very good, with a more 'colourful' presentation, (not ugly ) than the CX301-A , with slightly more compression ...however it has this Nazi Swaastika printed on the tube.
.
Is it ok to use such a tube?

Hello everyone,

I am a music and audio equipment enthusiast, I enjoy building tube equipment and modifying, repairing, improving audio equipment. I own a modified Teac P700, which transport, using various DACs I built, as well as a Conrad Jhonson Premier Nine, (magnificent devices the Premiers). The transport employs a Sony CXD1125Q DSP, which also has three connections for Sony's “2's complement signal 16bit” format. I would like to be able to take advantage of this output to connect it to one or two AD1865 DACs in NOS configuration. Unfortunately, I cannot find an interface, perhaps even a simple one, to bring the Sony format, 16bit to 18bit, compliant with what is needed for the DACs.

Is anyone aware of or has experienced such logic? Perhaps for 20bit or 24bit DACs to be derived........
I welcome advice and guidance of any kind.

Thanks in advance
ICHINO

CamillaDSP need no introduction and what is it not to love? An Open Source DSP written in Rust by a fellow Swede! I have read about different uses cases like active XO and room correction but why try to use it as a preamp?

My first experience with a DSP was the ADAU1701 based one by 3e Audio. It started out as an active XO but ended up as a preamp. The background and build is documented on my blog. The Linkwitz Transform worked really great with my current speakers but relying on an old laptop with proprietary SigmaStudio and a shady USB-interface for maintenance never feel right. That is why I got quite excited when I discovered CamillaDSP, here was an opportunity to replace proprietary tech with Open Source hardware and software! I just need a proof of concept and that is why I started my latest project - DSPreamp.

The code took me just hours to write but integrating hardware and software into something resembling a preamp took weeks. I have now bench tested everything I set out to do and the result exceeded my expectations. It will probably take some time until I get the time to build the final product but I want to take the opportunity to share my findings if anyone is planning to go down the same route.

Putting together a complex system is always a matter of tradeoffs. I have made a set of choices, your mileage may vary but know that I made them deliberately based on my specific needs. First of all, I decided to go with all analog controls. It would almost have been easier to go with rotary encoders and a display (easily enable remote control etc.) but that is not how I envision the final product. Another deliberate design decision was to run CamillaDSP and the ADC @ 88.2 kHz but more about that and sound quality in a future post.

I decided to run CamillaDSP on a Raspberry Pi and build around good but cheap and available hardware. I stayed away from USB based capture and output devices and opted for a HiFiBerry DAC+ ADC instead, it is one of the few ADC available as a HAT for the RPi. I initially planned to route input through a switch but I basically only got one analog source these days, my turntable. I use AirPlay a lot for casual listening and I therefor wanted to integrate it as a separate transport.

It might be tempting to add a web based music player managing my collection of ripped CD albums (all in FLAC format) but I don’t want a kitchen sink kind of mess without separation of concerns. I want the preamp to be a preamp and keep the music player on another device (RPi, NAS or whatever). What I would need is a lossless CD-quality transport over IP, preferable Open Source (and not proprietary like AirPlay). Looking for a solution led me to ROC Toolkit.

Another problem with the RPi is the lack of ADC for analog controls like potentiometers and power management. Overlays like gpio-shutdown and gpio-poweroff is great but HiFiBerry is hogging some crucial GPIO pins. Re-configuring the overlays and soldering a couple of pin headers on the HiFiBerry DAC+ ADC card solves the problem and makes it possible to manage power with an external Micro Controller.

I discovered the Raspberry Pi Pico while shopping for an 8 channel ADC for the RPi. The cost was more or less the same so I grabbed a Pico. It has 3 ADC and a bunch of GPIO pins. I decided to make it into a standalone front-end for my analog controls and to use it as the power controller for my RPi. It ended up as another project, meet rpi-sidekick. I tried to keep it generic enough for future reuse in other projects.

I now got pretty much all the bits and pieces needed for my bench tests. CamillaDSP, Shairport Sync and ROC was all configured to run as systemd services and I started to put together a minimal Linux image for the RPi. To get everything going with buildroot felt like too much work so I started out with pi-gen but even stage1 ended up too bloated with NetworkManager, Avahi, D-Bus etc. I therefor turned to Arch Linux ARM and ended up pretty bare metal systemd. I wanted to start-out with just ALSA and no sound server like Pulse of Pipewire to keep boot times fast and things not too complex. I ended up compiling Shairport Sync and ROC without support for Avahi or Pulse. Still a lot of work to be done to optimize it but it was enough proof of concept for me to call it a success.

The functionallity of the preamp was modeled after some of my favorite vintage amps (especially Yamaha CA-800 and Kenwood Model 600) and are:

• A log volume control ranging from -80 to 0 dB attenuation with 12 o'clock @ -20 dB.
• Baxandall tone controls, bass and treble ranging from -10 to 10 dB with individual defeat and two different turnover fq.
• High and low cut filters with individual defeat and two different turnover fq.
• Selectable digital RIAA filters and amplification on analog input (None, Moving Magnet (MM) or Moving Coil (MC))
• Mono filter
• Automatic Adaptive Loudness filter (on or off)
• Mute filter (-20 dB)
• 3 x input transports (ADC, hw:Loopback,1,0 and hw:Loopback,1,1)
• Linkwitz Transform filter (parameters provided as command line arguments to dspreamp)

I have made all my source code available through Codeberg (I left GitHub after the Copilot incident). There are still a lot of information to add in future posts and snippets to be added to the git repository. Especially about ROC streaming from an external music player like MPD. Stay tuned…

DSPreamp @ Codeberg
RPi-Sidekick @ Codeberg

I would also like to take the opportunity to thank Henrik Enquist for sharing CamillaDSP and for patiently answering my questions about its inner workings...

There are some really useful youtube videos out there and I was wondering if anyone here has a channel?

Hello,

This is fully isolated DSC2 DAC project, I'm finished this dac and here is project files for their build. Curently I'm not tested this but my hope somebody from you do it. Note that main buck regulator accept maximum 100V and minimum 5V at the DC imput, and I have set fixed 4.4Vout from the buck. You no need clean DC on DC input since push pull and LT3042 will make clean supply DC voltage for DSC2. Main care must be done to iso push pull reglators because it not accept more than 5.5V!!! You need to wire ferite to 1.2mH on primary and on secondary you need to have 7V, so please do the things carefully right before you put the rest of components on board! Take a look to schematic!

PCB dimension: 90 x 81.5 mm

Ferite is: FEPTN10/6-3E25
dimension: 10,6x5,2x4,4 mm
AL 2250nH
Primary: 1.2mH + 1.2mH, with center tap! Secondary - do it yourself for 7 Vout.

DSC diff current: my choice was 8mA diff, if you need less calculate your resistor values for dsc! My choice was 10k resistors since my i/v frontend accept this value. This is also I think good enought for an transformer based i/v, and I used those 10k values in original dsc2.5.2 with this audio transformer -> https://it.aliexpress.com/item/32810421236.html

Resitor value calculation formula for IdiffMax=+-8mA :
5V / ((0.008A / 32) + (0.008A / 32)) = Rvalue

C_NP and R_NP components if need! Its connected to one of the mount hole pad which will be connected to the case trought metal spacer, and in case you have some noise on iso side you can put resistor and capacior there e.g. 1M + 10nF .

Let see your build, thanks! Enjoy!

Here I will publish a Headphone Amplifier with 6N1P and 6AS7
based on the optimized Morgan Jones circuit with OTL output.
Here is that circuit https://headwizememorial.wordpress.com/wp-content/uploads/2018/03/cmoy5_1a.gif

There will be one circuit for 300 Ohm headphones and one for 32 Ohm.
You are all welcome to follow and discuss 🙂

Here is the 300 Ohm version. It has lower distortion.

Hello everyone, I am a new member of DIYAudio. I like home theater and I want to learn about it. Thank you.

I have a pair of gold cone colored Mark Audio 7.3En drivers for sale. I bought these for a project that I never started. I attached several photos. One of the drivers has a very small crease in the cone. I do not believe this will affect their performance. I tried to take a close up photo to show this. Asking $150 for the pair plus shipping cost.

Hi,
I am selling my Relaixed2 preamp. It is in a case I made with Koa wood for the face. I've downsized and clearing out the closet. Great balanced preamp that can use both RCA and XLR inputs and a XLR for output. I don't have a remote but they are easy to find. $300 plus shipping.

https://www.vaneijndhoven.net/jos/relaixed2/

Hi - Does anyone know what the power consumption of the Amp Camp Amp 1.6 is in watts? In Nelson Pass's notes notes on the F5 he says it consumes 180 watts but I can't find any figure for the Amp Camp Amp. Thanks.

Hey there, I'm Antonio, from Paris, France.

Got into hi-fi a couple years now, and getting into modifying amps and speakers.

Learned a lot on this website!
So I guess is time to share more from my side.

Cheers

I have a Yamaha R8, works fine except for volume and left channel not working.
Turning volume knob has no effect, except for maybe a pop here and there.
Pressing the "Simulated Stereo" button introduces normal behaviour.

Does anyone have an R8 schematic?

"rolibark" mentioned he had an R7 schematic, but the link is broken.

so i would say i became a audio head after purchasing a phillips cd 104 ,my first Cd was Marillion ,script for a jester tears, sure i also had both vinyl and dire straits brothers in arms on cd ,but there was amazing music around so i thought i would post it for some old time memories,
i will also post some of the music that got me into DIY as i needed a subwoofer which happened between 82 & *#,there is more music but these were some favorites
Login to view embedded media Login to view embedded media Login to view embedded media Login to view embedded media Login to view embedded media https://www.youtube.com/watch?v=EZXNr4aa2wk
https://www.youtube.com/watch?v=NbVHiGDMVRI
https://www.youtube.com/watch?v=PedUiJ2TBEg
https://www.youtube.com/watch?v=LnoGts-zT0A
https://www.youtube.com/watch?v=5owM5EitjhQ
https://www.youtube.com/watch?v=wrarS7mLlB0
https://www.youtube.com/watch?v=gE7FK33e0pY
https://www.youtube.com/watch?v=eJ5O6O9jl48
https://www.youtube.com/watch?v=Xl19WyZKCE0
https://www.youtube.com/watch?v=NJA9nQQPqZA
https://www.youtube.com/watch?v=F1RR6vEE7-c
https://www.youtube.com/watch?v=E0uMTJu0ML8
https://www.youtube.com/watch?v=d9Z2CIUjh_0

Happy holidays! Unloading some gear from the archive (aka my storage room).

Audio Note AN-E speakers, mid needs a redone, built up from the official kit

Bastanis dipoles, two pair, includes active subs

Lots of other stuff that isn’t quite free, but come visit and we’ll make a deal. Studio is in Catskill. See what we make here: www.aforara.com

Pickup only (that’s the rub!).

Mouser has a suitable Form A relay, but the amplifier uses both Form A and Form B relays. The Form B is non-stocked with a ridiculous minimum order quantity, so I need to find an alternate supplier. Tried Newark and Digi-Key, but neither had them or their search system was so bad I couldn't find what I needed.
Looking for the appropriate relay in Form B. This is the electrical pinout of the original relays. Both are welded closed and need replacing.

There's a 2016 topic about some people that designed a pcb to use an LT3062 regulator which I found very interesting.

Can anyone update the results over time of those regulators? Are they still working? Were there any problems later on?

Are the regulators reliable and provide all they promise, or they are not?

Thank you for any answers.

Hi guys, working on a vintage MTX Thunder 2300 that came in DOA. Found several bulged caps that apparently shorted out and burned the circuit board pretty badly.
Does anyone have pictures of the underside of the board to see how the traces ran prior to the board burning? If not, a schematic might be helpful. Thanks in advance

Starting a thread to evaluate various op-amps in the output of mainly DIY or legacy DACs.

Here are my recent findings, in case they may be of interest. I've just done listening tests on a bunch of op-amps in the output of my V-DAC, which originally comes with a NE5532. It has a replacement DIP8 socket and also has the 47uF output cap removed. Input is SPDIF via a V-Link, and a V-PSU was used. The V-DAC directly feeds a 2 stage SE tube amp into Mission 761 speakers. Test tracks were Bill Evans album "I Will Say Goodbye" and some Keith Jarrett for piano, Dee Dee Bridgewater "Keeping Tradition" for vocals and Solti Meistersinger (most recent) plus some Steely Dan and modern gospel. Tonality of acoustic instruments was in this case the main consideration.

Top group - judged to have all-round good natural tone including the most realistic piano and vocals
OPA1612
OPA1642
AD8022
AD8066
LT1361
LT1364

Eliminated for various issues
LT1469 - rather thin, very clean
AD8599 - too thin, very clean, excellent high treble
LM6172 - wooden piano sound
LT1057 - bit meh overall

Previously eliminated in a AK4490 DAC
LM4562 - clean but thin
OPA2134 - quite good
OPA2132 - quite good
NE5532 - OK but not special
OPA2228 - nothing special

The top group would need to be re-tested for a winner, but maybe there isn't an overall winner since I enjoyed them all in different ways. For DIP8 you'd need LT1361 or LT1364, the rest needed adapters. They all sounded stable in the V-DAC though they weren't tested with a scope.

Subjective results which apply to directly replacing a NE5532 in a V-DAC output stage, so may not be the same in other contexts. Still, I hope this might be of some use.

Hello everyone,

I've been working on a schematic for a preamp designed specifically for my piezo contact mics, based on the Altoids piezo preamp by Stompville. My goal is to create a compact preamp powered by phantom power, utilizing basic SMD components to minimize soldering and keep costs down. I’ve settled on the TL072 as the op-amp for both buffering and amplification.



I would appreciate any feedback you might have on my design. Here are some specific questions I have:

1) Does the TL072 work well with the used supply and bias voltage?
2) Are the voltage ratings of the capacitors sufficient, particularly for C15 and C18?
3) Are the 100µF capacitors in the power supply section necessary, or can they be omitted? I couldn't find SMD 50V 100µF capacitors in the basic parts category. Or are there other viable replacements?
4) I want to replace the Zener diode D3 with an SMD part. What characteristics should I look for in a replacement?
5) What is the needed wattage rating for the resistors R4 and R5? Is 1/8 W enough or should it be 1/4 W?

Thank you for your help! I’m looking forward to your insights and suggestions.

Best regards,

Benni

Recently, I bought a couple of small cheap Chinese DAC board, with CS8416/CS4344; the boards are intended for a simple low-cost system.

The output pins of the CS4344 are connected to the analog output of the board trough a first order low pass filter, similar to the one proposed in the IC datasheet; beyond this filter, there is a couple of transistor (Q1 and Q2) connected between each signal line (collector) and ground (emitter); I was not able to find where the transistor base is connected.

I can only suppose that this couple of transistors is used as a muting circuit, but I don’t understand the utility.

I tested each board feeding its optical port with the TOSLINK coming out from my CD player, playing Denon Audio Test CD; in the pictures, you can see the DAC board output waveform when reproducing a 0 dBFS sine wave at 315Hz and at 9999Hz.

There are two problems: the distortion in the lower part of the sine and a lot of “dirt” in the 9999Hz sine.

The distortion is caused by the external load of the CS4344 output (probably by the useless output transistor, maybe in inverse conduction?); the waveform at the IC pins is perfect (harmonics level is more than 70dB below the fundamental) when they are isolated from the filter.

The “dirt” on the waveform (I can’t find a better definition) has an amplitude that increases with the frequency of the reproduced sine wave and is completely absent without signal (trace “silence” of the Denon CD); the “dirt” has no components in the audible band (20Hz – 20KHz)

The 3.3V power supply looks clean; the second DAC board I bought behaves in the same way.

The only hypothesis I can do is that the CS4344 internal filters don’t work as they should and the “dirt” I see is the effect of the image frequencies.

Any suggestion regarding the cause of this behaviour and how to eliminate it will be appreciated.

My name is Roy and I'm based in LA. I'm interested in digital crossovers, new/old 3way projects, Purifi and Bliesma drivers. Just getting my toes wet so I have lots to learn from everyone. Thank you in advance for your advice and patience for my noob questions.
Roy

Hello, while trying to take quasi-anechoic for some of my test speakers for a variety of drivers, I noticed that non of them exhibit, the usual behavior, of sharp SPL drop from the woofer around the port tuning frequency. Also, when measuring the impedance with REW and a DIY jig, there aren't two separate and define spikes of impedance (the middle of which is usually the port tuning frequency). The measurements show relative agreement with models made with WinISD show I suspect it's something with my designs.

How should I utilize drivers like this in vented enclosures? The ND90 supposedly should be able to provide good and linear results, but the other two either give a huge output spike if the tuning frequency is near the Fs or the response ripples near the roll off.

Driver's I've used:
ND90 8ohm
TEBM35C10-4
Aliexperss 3inch T/S parameters acquired with manual measurements.

(measurements not baffle diffraction corrected)

Hi guy newbie here, I have some sony deep bass speakers that I fitted with a fenton intigrated amp from a spb8 400w, thinking that it would be enough for family karaoke parties, but sadly it doesnt preform well, the interphase is great it can read mp3 on both sd or usb, it has bluetooth to connect a phone or laptop, has seperate volume and echo for twin mics a simple tone control with seperate volume for music, but not a master volume control.
I also have a compact ish samson 260 w servo studio amp which runs the speakers beautifully, my plan is to steal a signal from the small amp to feed the samson input.
The fenton amp uses 4x tip41c transistors npn on 4 tiny HS. I'm guessing they use 1for music and number 2 for the mic feeding the left speaker and similar to feed right speaker, even though the heatsinks are small they do interfere with the tweeter horns and would be better shortened to be 'nice'. My question is should I pull the signal from the 5551 and 5401 driver transistors or reduce the collector voltage of the tip41c down to an acceptable level to feed the samson preamp. Sorry for the essay hope you are still awake !!
Thanks guys.

Good day guys, I have an Hifonic Brutus Class-D to rebuild Power supply…I was thinking to use the 3205 Mosfets but my local supplier is out of those, what are the next best mosfet and gate resistor I can use comfortable drop in?

As a quick distraction from the everyday I decided to jump down the guitar amp rabbit hole again. I've been looking into "intentional" distortion, and something doesn't make sense to me. In higher end amplifiers, distortion is usually created by cascading multiple gain stages, cumulatively driving the last tube of the preamp, and then into the power section. Couldn't that same effect be created by using an op amp circuit with sufficient gain pumped into that last tube stage? For that matter, couldn't some of that distortion also be supplanted by diodes in the same circuit in order to account for the lack of it in prior gain stages? Or would that not matter since you would be driving that tube with so much gain anyway?... Or is this another case of "you missed this..."?

These days I found a seemingly flawless Phillips subwoofer (from a HTD5000 home theater) on the street, in a spot meant for trash, its only issue was that someone ripped off its wires.

I took it home and soldered new wires, it works, but sounded lame, despite the fact it looks perfectly intact.

It's speaker is an 8 inch Eastech sub, FSB52A680-8300, a driver that exists for sale only here in Brazil (used ones only) and that doesn't exist even on Eastech's site itself, nor any other database.

This is it:



It's visually similar to this other 8 inch sub from Eastech, same design, basket shape etc, except for the magnet, mine looks like is has only 60% of the diameter of this one here: https://www.eastech.com/standard/asdsd4026-0301. Plus, according to the site, its surround is supposed to be rubber, mine is foam (a good quality one, but foam).

Even its Fs and Re are similar.

The only problem is that, after I measured its TS parameters using a setup I already used before, I've found its BL to be only 4.67 N/A, causing it to have a large Qts of 0.896.

I've used this setup several times, and it never seemed to give nonsense results, I rechecked my calculations and everything thrice, everything seemed correct, but decided to do a second test:

I've put a thin copper wire attached on the frame of the speaker, coming up above the cone and making a hook shape above the surround, in such a way its tip lightly touched the cone, when it's at rest, to mark its resting position (when lying on a surface, with its cone pointed up).

Then I fed it a DC current and checked how much weight I needed to pile over it (only non-magnetic materials, of course) until it returned to its resting position. When that happens, the coil force and the weight force are canceling each other out, and the surround and spider are keeping it at the resting position again.

My measurement came to the result of 4.79 N/A, strikingly close to one calculated based on its max impedance, Re and side frequencies.

So I've accepted that, whatever the reason, it has a very low BL.

My question is: why? How?

Honestly I don't think this could be the result of aging or demagnetization.

Perhaps, has it always been like that?

The smaller magnet would make sense with this idea. Eastech itself has a few subs with similar Qts, but much higher Fs. None has an Fs similar to 40 Hz and such a high Qts.

But that would mean this sub was never properly tuned.

With the TS parameters I'm seeing now it's completely improper for any vented design, leave alone its original enclosure, which is why it was sounding horrible.

The TS parameters I got were:

Vas=35.896129906 L
Cms=0.547857247922 mm/N
Mms=33.7729816147 g
Qes=1.04372168889
Qms=6.35603786481
Qts=0.896506775221
Re=2.9 Ohm
Fs=37 Hz

on an Onkyo Dx-1400, and I am sure others, there are two connectors for wires to the CD mechanism (actually 4) that are 8 and 9 pins and go from the board to the laser assembly. Does anyone know exactly what these connectors are so that I can order a new plug. single row, 2mm pitch, pins on the board and crimped sockets on the wire end.

Hi gang.
A guy in the German Visaton Forum did a mod to the Visaton BG20 that is worth sharing here.
Maybe it has been covered but I did not find it with the search engine.
The basic mods like additional magnet on the back, basket damping and felt rings in the center of the voice coil suppose to benefit the BG20 allot but
this mod seems to make the biggest upgrade to the unit:
Applying Dekalin a visco elastic sticky sealing paste onto the ridges of the surround exhibit the following measured results.
First photo is the stock unit
Second with only the inner ridge treated
Third with two ridges treated

Hello all. Can some H2 units be modded to a 3-way active tone control with gain and without losing the H2 flavour?

PCB (1) will be less than 10$ US each + envelope +shipping (to be confirmed based on quantity). Price will decrease if the numbers of pcb increases. Therefore this is not commercial Diy...

Please write your name here and the quantity from the latest list in the thread.
1)
...

Hundreds of pcbs have been already delivered to Diy builders.

See more details about the USSA-5 here:

USSA-5 Build with Review


------------- added information ---------

USSA is a family of 20-25 Wrms (8 ohms) class A amplifiers depending on PSU and bias current.
For 4 ohms load it will give still about close to 20Wrms in class A (Square law effect) and up to 45-50 Wrms in class AB.

Design philosophy:

• Current feedback type thus almost constant feedback factor amongst all the audio band.
• only 2 stages (also with buffer stage for versions 3 to 5)
• low/medium feedback factor (< 35db)
• medium damping factor (25 to 70 for 8 ohms load at 100 Hz), depending on version
• Square law effect maximizing class A for mosfet output versions (very low source resistor)
• push-pull that allows to switch into class AB if maximum of class A is reached
• THD is dominant 2nd and 3rd harmonics
• Audio grade transistors only and operated in their more linear region
• Soft clipping behaviour
• main target is big soundstage, sound big (not thin) even at lower level, articulated bass, natural tonal balance (not artificially over bright), no extra sibilance and overall smoothness while being lively.

Pcb features:

• output transistors optimally positioned for better heat distribution on heatsink;
• carefull layout using ground plane, ground return scheme, reduced cross coupling of signals and proper feedback point
• 2oz density copper trace
• 2mm pcb thickness
• gold immersion exposed traces
• pcb compatible with either USSA-3, 3.1, 3.2 or USSA-5 , 5.1 , 5.2
• pcb almost compatible with USSA3B or 3.xB and USSA5B or 5.xB (reverse output transistors pin out)
• LATERAL fet ouputs for initial versions (except versions 7 and 8)
• BJT ouput for B versions

See post # 346 for schematics of USSA5, USSA5.1 and USSA5B: USSA-5 PCB GB

For USSA3B and USSA3.1 see this thread:
USSA-3B new Version based on USSA-3
USSA3.2B: jfet input, using quad matched available mosfet drivers. Using power bjt as output.

Summary comparison table of USSA-X variations:

notes:
1) versions 7 and 8 are twin turbo class AB versions : +-/ 42VDC and double output. They are prototypes using a pcb meant for single output device thus needs wires to connect two pairs. There is no build manual and not supported for Diy. Special request can be submitted by personal message for USSA-8 for more experienced builders.
2) as a general note, for about the same damping factor, bass is tighter and snappy for mosfet output and less tight but maybe stronger for bjt output
3) damping factor may vary based on input stage current.
4) obviously, more details can be less forviving for bad recordings or low grade input source.
5) all class A designs have a more relaxed sound than the class AB in the table above. If high power is not mandatory, I personally recommend class A for better sound.

Documentation:
detailed manual including pictures at different steps and intermediate testing procedure at different phases of assembly to ensure fully working board at end of assembly.

Test equipment needed:

• 2 x standard multimeters (precision 1mv) ( mandatory)
• intelligent phone/pad sound generator application (optional)
• 8-10 ohms 20W power resistor (optional)

Warnings:

• If you are looking for a high power very bright sound this amp is not for you.
• If you are listening mainly hard rock/metal music at high sound level this amp may not be for you. However, I mainly listen progressive rock at medium/high level and it sounds fine to me. Still my main amplifier.
• if you want very tight /dry bass ( as opposed to articulated emotional big bass ) than this amp is not for you.
• if you are not ready to manage the heat generated by class A than this amp is not for you.

Group buy conditions:
1) partial manual including BOM is provided (only adjustment instructions are missing) since from my estimation roughly only 10-15% of pcb sold are really used for a real build within one year...
2) once pcb are paid, I provide the complete manual including adjustment instructions.
3) once all payments received, I order the pcb from manufacturer.
4) I ship the pcb to your provided address.

Update on 2021/08/17:
Unfortunately the darlington bjt drivers used on USSA-5.1, 5B, 3.1 and 3B are now obsolete. For that reason. An alternate part for the driver is used. Thus this is a new version 5.2. Great sounding ! See post #701 and 702 for more details.

Fab

I made a batch of MIC5156 based LDO supplies, parts cost is 15 euro selling these for €27.50 for my troubles in assembly and testing, ex shipping. Will ship worldwide at cost.

I have 6 available that arent spoken for, Reichelt will deliver the coolers sometime this week, and then its an afternoon of soldering to get them ready to ship.

Photo attached of my previous batch.

Fully tested and assembled, €27.50 or about 30USD.

Boards are good for 2.5A provided the winding can deliver that much current as the 2x 15mF 10VDC has quite an ugly current waveform.

Once these run out, i will do another batch either as a parts kit or assembled of Revision 2. its the same board but more through hole components.

Hoping for some repair help.

I have recently obtained an Ashdown Rootmaster MAG420 1x15 bass combo for free, as a repair project. The combo is in excellent condition for being probably 10 years old, very clean, and with no missing knobs or exterior damage. But the guy I got it from told me that his bass player had plugged it in one day to play and got a bang and blue flash. He obviously hadn't plugged it in since.

Taking a look inside, I see that the amp uses an Anaview ALC0300-1300 power supply and amp module, datasheet attached. From what I can see online, these were once well-regarded, but Anaview and its successors have been swallowed up by acquisitions, and no support or replacements are available.

I inspected the interior of the amp very closely for signs of damage from the flash and bang that was mentioned, he had indicated it was near the mains input, but other than the main fuse being blown I could see no damage. I am not an electronics engineer, but I have done some basic repairs, soldering etc. although not on amps and power supplies like this. But I tested for short circuits on the main inputs and outputs of the PCB, and even PAT tested the whole amp, it passed no problem. The fuse on the amp/power supply PCB was not blown. So I wondered if the flash had just been a bit of an extra surge blowing the main fuse.

So I bit the bullet, put a new fuse in, plugged it in and flipped the switch. Sure enough, huge bang and flash, the main fuse blew, the breaker of the socket blew, and then I saw damage! It was at the corner of the PCB where the flash had been. in addition to some pics of the amp interior generally, and some closeups of the damaged area, I put a pic of this damage below, after I had cleaned it a little with a brass brush. I'm not 100% sure but fairly positive it did not arc from this point to the ground connection point which is surprisingly close, as you can see in some of the pics. But I still can't see any clearly damaged components, just the area of the board. I noticed that the one solder point of the large capacitor nearest the damaged area looks a little stressed. Could it be that this cap is bad? How would I test for this? I did test and it is not shorted.

Can anyone give me some tips on what the issue may be, or what to test next? Or does someone have a working ALC0300-1300 module in the UK that they are looking to sell? I would really really love to get this combo going, as it's in great nick otherwise, and has all the features I am looking for. I am really hoping to repair this myself, although I suppose I could ship it to a repair house, but that could cost more than the amp is worth...

Currently i'm a lowly Spotify premium user streaming via MiniDSP flex 8 bluetooth through my Android phone. In an effort to possibly improve things, I'm waiting on a WiiM mini streamer to test out the limits of Apple Music, which i understand can stream lossless over Airplay 2? In order to achieve lossless streaming may I control Apple music through an Android phone or must I have an apple device to actually receive/control (mac mini /ipad/iphone) Lossless?

I question if any of this makes a difference vs. my current stream via LDAC bluetooth? Is a cheap PC tethered via USB to the MiniDSP Flex 8 streaming Spotify premium inferior vs. Apple Music Lossless via a WiiM streamer? I don't know, but hoping someone with more experience can share their experience. mahalo.

Hi guys 70 yr old newby here, I'm a rock music lover and have always been into audio stuff I love making and modding stuff and like to learn cheers !

Got a tougher one. I have a Nikko Alpha III that I cant set the idle current on. I just installed some used Exicon mosfets. A bit of history. I bought this off ebay along with a Nikko Beta 30. The beta 30 was completely recapped along with some new transistors in the power supply and installed some LM4562 opamps and it sounds great. The Alpha III was doing very well and had bought all the hardware needed for a complete recap. Bad storm hits and pulled my power lines loose enough I had a lost neutral condition and my power protector got a 160v surge, uh yeah. Alpha III smoked and the J49 mosfets took a dive. The 134's survived. I started working on it with another fellow tech and I replaced the trannys on the complimentary differential board which were 2sa872 and 2sc1775. I did hfe matching of the transistors on the left channel only. Once completed it came out of protection but I can not adjust the offset or idling. Following the manual when adjusting the offset and using a shorting pin on the direct input jacks the lowest I can get is 1.62 vdc, left channel and the right side I can adjust right on the nose. Idling adjust ment is stuck on .2mv and no adjusment no matter how much I turn the pot both sides. Funny thing is if I connect the DMM to the pins it reads .2mv with no power.
I know its alot but it helps give you some insight. I have attached the manual. Any suggestions would be greatly appreciated
Phil

Hello not sure if this is the right forum I do apologize, I know the title is a bit weird but I will try my best to explain it. I have been using this tone control from Aiyima ( I know tone control is not very popular here) and I happen to like the sound of it very much, I swapped out the ne5532 op amps for some OPA2134's and it sounds very good. The issue is that this preamp is mounted in the chassis of an amp I built and I made some extensions (roughly max length is 12in) for the potentiometers like this for example so I could mount the pots to the front plate. In doing so I encounter a lot of buzzing noise that is audible when ears are very close to the tweeters on my speakers. I used this 6 conductor twisted pair shieled wire to extend the pots and tied the shield to common which did decrease the amount of noise greatly but wondering what else I can do to get rid of the rest of the buzzing noise. The does also persist when the preamp board is not in the chassis aswell. Any help would be greatly appreciated.

I am a real noob when it comes to electronics. I have successfully recapped an amp and unsuccessfully recapped a cd player. I guess I am batting .500. I would like to resurrect some vintage equipment, and hope to gain knowledge here.
Kevin

I need 1psc of AD1865 DIP from fiable source
Regards
ZlotanChivay

I had a dodgy connection on an amp last Friday that left me worried. My speaker was okay but could have seen a 30vdc offset, it was a Q Acoustics 3030i and not one of my Celestions luckily. So I looked at a lot of speaker protection circuits, read a few articles on here and Elliott Sounds and then decided I would give it a go myself.
I am crap at electronics but came up with a protection idea. First I messed about with one that works with a PIC controller, I had a simplified circuit from Elliott Sounds to work from but could not work it out. I changed a few components and come up with this, it is just the DC detection part at the moment. The circuit will produce a voltage that is proportional to the DC detected.


I also learnt how to use the basic functions of LTspice. Here a 4vdc offset is detected and 16mV is between the optocoupler and R6. It is 79mV with a 10vdc offset.


Here is 1.24v between the optocoupler and R6 with a -75vdc offset. Positive dc offsets will produce a result within a few mV of the negative offset.


This is the result for a 20hz 75vac sine wave. I had to play with the resistor values, if R1 and R2 are too low the result would be a lot higher than the DC offset I am trying to detect.


As I stated earlier, I am not great at electronics. I do not know what diodes I should be using. I am assuming the PC817 optocouplers will be ok in this circuit as they are not fully closing. At 75vdc the MCUs ADC will not see more the 1.3vdc so should be safe, I think it can take 3.3v. The ADC has a 100mOhm input impedance, I don't know how to represent this in LTspice and all my results could be wrong LOL. It would be great if someone could help me improve this circuit.
I plan to use a Teensy4.1 MCU to monitor the DC offset, it is what I normally use for my projects. The MCU has an ADC that can receive 0 to 3.3v and can have a 12bit resolution so would be perfect (except they are £30). If a high offset is detected it would ground the speaker outputs, also ground them for anti thump when turning the amp on/off. The teensy needs a 5vdc psu but itself operates at 3.3v. The Teensy is a very powerful MCU, controlling a relay attenuator, touchscreen and remote control it would cycle through the program between 2 and 4 million times a second. Below are pictures of aTeensy, it is simulating controlling a relay attenuator, input relays, power relays and speaker grounding relays with LEDs (I am also terrible at taking pictures of small displays, make it 2.4" and it looks better).

Hello,

I'm looking for your help, what would be a good MC preamp in my case.

For decades I'm using my heavily modified Rega TT (with acryl platter, DDS based motor control ...) with MM pickup.

Now I've acquired a Systemdek IIX 900 and looking to buy a Goldring Eroica (or similar) into it. Low output MC (do not have good experience with high output MC).
The problem is, I do not have a transformer and with the pickup I will spend my budget for a year, can not buy a 1000 EUR transformer now.

In the 90s, I've used to have MC preamp. I had an Ortofon MC10 with preamp first, than with T5. The T5 was different, but not necessarily better to me, on the other hand, more simple to use. I've planned to get a better transformer, but never had.

Now, in the last decades I've used DAC as main source, but LP in parallel also. Lately, LP is used more and that is why I bought the Systemdek.

I'm not sure yet about the Eroica, so I'm not sure about the transformer either and that is the point when I've decided, I build a decent solid state preamp.

The chain after that is a tube riaa and preamp, similar to Audio Note M7 on circuit, than a 2A3 PSE amp.
On LP I'm listening mostly classical and jazz.

Do you have a suggestion for me for a good MC preamp circuit?
What do you think, what is the best diy MC preamp? (I mean, of course it depends on the building more, but anyway, with similar component and build quality, which is the best you would recommend?)

Thanks!

JG

Hi all,

After some great help I was able to measure my WAW open baffle 2 way speakers that I recently build so that I could generate my own FRD and ZMA from my drivers in the baffle to be able to then work on crossovers in simulation software with all the baffle and stuff included in the measurements. I've made some progress and figured I'd share where I am currently and see what else can be done from this point or if I'm going in the right direction.

I measured the speaker outside on a ladder with a heavy blanket so that it was over 6 feet (1.8 meters) off the ground and nothing near by and measured from 1 meter away. I measured each driver individually at 1 meter farfield at the same input signal level. I then measured each driver individually nearfield at the same input signal level. I used the distance to the ground to guide my impulse response time gating for reflections. I corrected for the near field half space to full space response with script I wrote in libreoffice with some great help from some very friendly folk recently. And I summed the farfield and nearfield responses together to make my FRD files for each driver. I used a DATS to measure the impedance of each driver on the baffle and made ZMA files.
















Here are the resulting corrected measurements from the process with 1/24 smoothing.

BG20 full range:



8PT-8 woofer:



These measurements have all the issues from diffraction and step from the baffle, waveguides, etc, that I built already and mounted into. From here, it's just working with the metric data to build a passive crossover. I've already done an active crossover with DSP and listened to them and liked them. I liked how they were from 700~1000hz crossover. I figure I would start working on a passive crossover now in VituixCad with these measurements.

Here is my first current draft from these measurements in VituixCad.

I'm attaching my VituixCad file in case anyone would like to play with it or help in any way, just rename it from *.txt to without that.











When I invert a driver, to see the resulting null at the crossover:




At this point, I like the basic curve. However, I see that for some reason I don't see all the individual spikes I should see from the BG20. It's overly smoothed in VituixCad so I cannot get a good idea of where to place notch filters and see the response here. I can use my measurements to place these filters, but it would be nicer to see it in the CAD software here.

Any ideas on how to remove the over-smoothing in VituixCad? I'm looking for options to turn that off or reduce it.

I know I want to target notch filters around 750hz on the woofer, 2400hz on the full range, 3200hz on the full range and 8800hz on the full range. I've already designed notches for this to address those peaks. I just would like to see it in the simulation. Currently its so smooth it just looks like I'm dropping nulls into the response.

This may be too much really, I'm not sure. This is where I need some guidance I bet.



Notches to target those spikes in the measurements from the baffle and waveguides. It would be nice to see the peaks in Vituix and then apply notches to drop them. I'm not sure why its so smoothed out. Can't seem to find a setting in the preferences to unsmooth it.




Any help appreciated!

Very best,

Preface

To keep prices low and since production in Italy at competitive price is no more an option PCBs will be produced in China.

There will be, for whom is afraid of SMD soldering, the option for boards with SMD parts already hand-soldered with ROHS silver solder, thoroughly cleaned and visually inspected for 50€ more per kit, including SMD parts (a 20€ value).

If interested please PM me your PayPal associated email address and fill your nickname, country (2 letter code), number of kits and smd option on the OneDrive Spreadsheet (please leave blank the 'PP account sent' column, I'll fill it so you have a feedback that I've received your data)

February 2022, 20 price will be fixed and I'll start sending PayPal Invoices, all payments are due by February 2022, 27.

Until PCB order from manifacturer is done it will be possible to partecipate to the GB

Boards will be ordered by February 2022, 28 and should be in my hands in 7-10 days, then packaged and shipped in a week or so.
Now the usual (updated) opener:

The My_Ref Fremen Edition is a variation of Mauro Penasa's My_Ref with this goals:

• a more stable and performing amp using SMD parts
• raise LM318's PS voltage thanks to a voltage limiter
• better PS for LM318

I've designed a brand new PCB with these features:

• bigger caps (16mm diameter with both 7 and 5 mm pads) for C1, C2, C9
• large use of SMD components
• quite all small caps and some critical resistors are still through-hole
• very small paths thanks to SMD
• ground planes design
• zener limiter based on schematic 5b from this link (which seems pretty similar to My_Evo one)
• CCS shunt PS for the LM318
• An alternate C9/R10 arrangement
• Different grounding
• Different compensation
• a double diode bridge like in most gainclones
• support TO247 resistors for R3
• support feedback resistor for fet-opamps compensation

Both PCB and schematic have been tested organizing beta and release candidate mini group buys

I've been authorized by Mauro Penasa to proceed with this My_Ref derivate amp.



You can find references on development, beta and release candidate here:

My_Ref Fremen Edition - need help on PCB evaluation - diyAudio
My_Ref Fremen Edition - Beta build/Fine tuning - diyAudio
My_Ref Fremen Edition RC - Build thread - diyAudio
My_Ref Fremen Edition - Build Thread

KSTR's measurements on beta boards (final boards measured a tiny bit better but almost the same performance):



7th run boards measures even better (Measure by JosephK):


Distortion goes down ten times Vs. Beta (and previous) Boards.

Also Tomchr did a complete set of measurements.

On my OneDrive you'll find:

• Schematic
• BOM
• Build Tutorial

And a YouTube video on SMD soldering of FE modules.

Mouser shared projects (order 2, each project is for a SINGLE board):
Industrial BOM
Industrial BOM without SMD parts
Industrial BOM + Evo A Mod
Industrial BOM + Evo A Mod without SMD parts


Actual price will depend on number of partecipants/kits, the Group Buy is about PCBs only, with an option for SMD populated ones.

Approximate price is 25-27€/Kit (one kit = 2 PCBs, PayPal fees and 1€/kit donation to DIY audio included):

Actual price will be calculated and fixed before ordering boards and it will lower as kits numbers goes up.

Shipping prices will be about (up to 2 kits, more than 2 will be calculated, final shipping prices will be indicated in February):

Italy 10€
Europe 14,50€
Rest of the world apart Oceania 18,50€
Oceania 20€

PCBs (circa 12 x 10.5 cm) will be blue, 2mm tick, 2 Oz/70um copper, gold plated, made in Italy (from 25 kits) or in China (up to 24 kits).

One transformer 160VA-300VA will be needed for each board (monoblock design)

BOM cost is around 67€ per board (premium industrial BOM) which can be lowered to 53€ (On a budget BOM).

Build a complete amp (premium industrial BOM with case, connectors, cabling, transformers etc.) will cost around 400€ and up.

Greetings:
Mauro Penasa (R.I.P.) for his great design and kind permission
LinuxGuru for his help on new compensation
Luka for the LM318 PS initial design
KSTR for the new C9, R10 arrangement.
Soongsc, Marce, Sebaastian, KSTR and Metal for help on PCB design
BMCBob for all support, tests and reviews
JosephK for his measurements and advice on further reducing distortion.

Images of boards from the 7th GB:


__________________

Hello there, I'm Tracy from the US. I'm an engineer by trade and currently build amps and pedals for guitar players. Most of my amps are tube driven, but I also play around with solid state amps. Thanks!

I know it is only assembly of the parts so limited Diy work and it costs a fortune but anyone has heard, assembled or seen detailed reviews of this speakers kit designed by SB Acoustics?

https://sbacoustics.com/product/sasandu/
Fab

Hi,

AP are discontinuing support of the 2700-series at end of 2024 (I found this out when they posted a cartoon on their social media, showing dinosaurs next to 2700 machines, with flaming asteroids approaching...ha ha..ha...).

They are offering a 20% discount on new AAs if you trade the 2700 in, but it goes to 10% next year.

On a 555B, a 2722 = $8,750 discount (~£7K GBP), which is likely more than the 2722 will fetch on Ebay.

If the 2722 goes kaput after 2024, who will fix it? Duke is based in the USA, but to my knowledge he doesn't handle 2722s.

I am a relatively happy UPV user. My concern is that the 2722 will become an actual boat anchor in 2025. Let's say I get 20% off the 555B. Were I to sell the 555B after a year, I am likely to get well below the cost price - 20% (I've never seen a 555 for sale, but very much doubt they fetch anything like advertised Ebay prices, which seem to have gone crazy for everything now), so the 555B will be a costly experiment. I could get a good Pick+Place machine for the business instead...

The 2722 is currently sitting in the rack. I feel it's saying 'do ya feel lucky, punk? I could go for another 5 years...or a cap could flame out and burn through 12 layers of tracks...'.

Is the 555 really the only game in town now?

(cap flaming out is an extreme example, I admit).

edit - come to think of it, the 2722 is more boat-anchory than I thought. If I sent it for servicing now due to an issue, what are the odds it would be economical? The UPV cost £3,700 to service last time (ex sales tax). £3,700 to service a 2722 would pretty much render it unviable financially. And I doubt AP are cheaper than R+S...

My Technics se-a900s power amp, had a temperature of 60c on the heatsink, I have replaced the fan with a temperature controlled pc fan and got the temperature down to 43c but is it still too hot for a Technics class AA? I am thinking about lifespan since I want it to last for a long time?

I have been into music since I was 1 or so, I am now 49. I have played with car audio forever and have always had a nice system in my house. I recently bought 11 Mono Amps from a company that claimed they produce 240Ws each into a 4 Ohm load and having a .006 percent distortion level. I must say they are pretty close, my Onkio is not nearly as clean and lacks the power. At this point I kinda wished I had just bought two for the LR channels and then 4 for my subwoofers as I am finding I like true stereo more than anything. The surround for movies I think would have been just fine from my Onkio.

Anyways, I am here cause I want to learn about crossovers and how to calculate them and see about making my own custom-built speakers that will fit my listening needs. I have built many subwoofer enclosures from basic builds to 5th order bandpass enclosures. I am itching to build a sealed 4way enclosure with a 10" two 6' then two tweeters, one from 3.5K to 12K or so then a super from 12K on up. Hopfully I am not biting off more than I can chew but I am sure going to try.

See you in the forum,
Ross

Hi fellow DIY audio enthusiasts,

My name is Mattias, and I’m based in Sweden. I’ve been building both home and car audio systems for many years. However, I have to admit that I’ve often "cheated" a bit when it comes to the technical theory. That’s why I’ve decided to join this forum—to learn from all of you experts and deepen my understanding.

I’m excited about having meaningful discussions, exchanging ideas, and expanding my knowledge with the help of this amazing community.

Looking forward to connecting and learning from you all!

Regards Mattias

Hello! I am a German lover for music and currently trying to build a louder and more powerful boombox 2.1 version for parties. I am relatively new to this hobby and trying to explore it further.

Forum experts,

This is my first post on the forum, so please excuse any misunderstandings or mistakes—I’m still learning the ropes here!

I’ve been searching for an answer to what I believe is a relatively simple question, but so far, I’ve only found bits and pieces of information. I’m hoping someone here can provide some clarity.

My Question:
How can I calculate the required power handling for my tweeter? In this case, it’s a compression horn tweeter. I’ve read on the forum that a rule of thumb is to use a power rating of around 1/5th of the woofer’s power rating, but I’d like to know if there’s a straightforward way to calculate this. Additionally, how can I calculate the actual power delivered to the tweeter when using an L-pad?

I’ve attached a simple diagram to explain my setup, and I’m always open to suggestions and advice.

Now, I should mention that this is going to be a “scream as loud as you can” type of speaker. Yes, I know this might hurt the hearts of some audiophiles (it hurts mine, too!). But for those of you with teenage sons who task you with building a car speaker setup that can blast sound across a McDonald’s parking lot, you’ll know exactly what I’m talking about.

So, my idea is: why not build some PA-style horns and toss them in the back of the car? It’s simple, it’s loud, and it gets the job done.

Looking forward to your insights and suggestions!

Enclosure size or volume isn't a concern so just considering overall performance............sealed F3 is too high at 120hz for this application but i can get it to 80hz by porting it and power handling in this application isn't a problem......they'll be 32 of em per channel.

Graphs dont look right, I have been back and forth with the help section and cant get a graph to look anything like my previous measurements.
I also get the warning that signal to noise is too low.
I have not changed anything in my system since the last time and wanted to measure before testing some different woofers
Any recommendation of what REW setting I have changed?
Top two graphs are from last session about 3 weeks ago

I've got an ML9 with one channel distorting substantially that needs repairs. Does anyone have a service manual for this beast?

Thanks

I am trying to design a discrete headphone amp with BJT differential input, but it's hard to find matched pair transistors models which are still in production, I find that Nexperia is still producing quite a few models like BCM856BS, BCM62B, but their Vce-Ic curve isn't that flat, SSM2212 is an expensive choice which seems to perform really well, but I cannot find its Vce-Ic curve in the datasheet.

SO actually my question is: Is a flat Vce-Ic curve needed for matched pair transistors used in differential input stage? My guess is that since Ic is fixed in a BJT differential input stage with constant current-source on the emitter side, Vce-Ic curve doesn't matter that much. Or did I miss anything?

So I've been working on my 3 way setup outlined in my other thread The Debutante's. I realized a tablesaw would be necessary to build the cab with the precision I want and ordered a sawstop to my parent's house. I started assembling the cabinets the weekend before Thanksgiving and they mused if I could finish before guess arrived during the week. My father was impressed by the sound quality of the basic initial design, despite it being leaky and powered by cheap chi-fi amps. He was so impressed he would stay up until morning listening to music.

He said he wanted a pair as well. I stressed that the current design is simply a preliminary design and not something that I felt comfortable making for someone else yet. He relented that he is fine with something that looks rough as long as he enjoys the sound. He also was saying how he wanted more low-end which was tough given that I had already boosted the WO24P by 10db in my design. I told him he could benefit from another woofer to get the low end he wants instead. I the remembered I picked up a pair of Bliesma M74S for testing, but decided against using. This would make the basis of my design.

Dual satori WO24P with bliesma m74 mid and an undecided tweeter.

Then the Madisound BF sale happened, and I realized that the SB34NRXL75 was cheaper than the Satoris. Naturally, I bought 4 🙂.

So now it's: Dual satori WO24P SBA SB34 with bliesma m74 mid and an undecided tweeter.


I picked up 10 SB26ADCs to play around with in the meantime, but I'm still undecided on the tweeter. I considered Audax TW034XO to match silk with silk, but the cost of importing Jantzen waveguides made me hesitate. I then realized Viawave is an option again and I'm heavily considering buying a pair of SRT-7. Even if they don't work for this build I'm sure I could find a use for them...

Unfortunately, my dad decided to "claim" my speakers until his appear, so time is of the essence.

I'm still not sure what I want to do for bass alignment, but I'm wondering if ported is the way to go. Similarly, I haven't decided active or passive, but given that he has HT ambitions I'm leading toward passive 3.5 way. I also have a spare Wiim Amp that should be fine given the high sensitivity the speaker will have. The onboard PEQ should help with tweaks over time as well. I'm hoping to get away with passive first order butterworth XO at 600hz and perhaps LR2 at 3khz. I am open to suggestions though! Curious if anyone has done anything similar.

SLE

Wouldn't adding negative feedback increase bandwidth just like emitter degeneration, without necessarily adding noise?

This is an amplifier I made a long time ago
But due to the parts at that time not meeting the specifications. I made it around 2012.
But the test results were very poor. So I have been improving it.
I have recently obtained some very good transistors. The test results in the new version make me feel very good.
It has almost the same performance indicators as the machines produced by QUAD's original factory.
So I'm going to take the time to assemble it and listen to it myself. I will update the assembly steps.
of course. I am also an amateur businessman. I will provide it to others. But the condition is.
This product needs my approval. Otherwise, I will throw it away. For example, the QUAD707-2012 version. I have never had anyone sell it before.

hi, I have a pair of JBL L100 Classics and they definitely needed a sub ( since they roll at about 70 hertz).
That 12" is more of a low mid driver than a real low frequency driver.
My 4312SE sounds much lower like 30hz and warmer.
I wonder what I can do to get to 30-40hz?

Hi mates,

i'm interested in Hi-Fi since my early youth. Started with Dual, changed to Denon and bought a Michaelson & Austin M100 + TVP-X combo in the early nineties, because they where the best sounding amps i've ever heard, but always broke. So the friend didn't wanted to keep them.
First i changed parts, fixed connections, changed the burnt, broken pcbs in the M100s and had a good working pair for some years. Then one audio transformer blew up and i had the chance to buy a new pair from the manufacturer of the originals. Now the second one blew up and took the pcb with it.

Another permanent project is a Sherwood S-5500 III and a tuner of that age. Worked like a charm even with nearly non functioning tubes and capacitors. Changed some of the capacitors and used it for some time to drive a pair of Martin Logan CLS, but suddenly it stopped working. Found a bad tube and changed it. Had one channel back, but the other was dead and some deadly current on the chassis. Found a broken heater connection with a cable loose, fixed that and had the voltage on the rca inputs after that.

So there are two projects to work on.

I am from Germany and just tried to answer to a thread as someone did search for a schematics and give him some tips for repair. But I have learned that I have first to provide some introduction of myself.

Hello,
I was listening to a headphone amp today, which was quite good. The maker says it is an IC amplifier, DSL differential line driver like TPA6120, but not the TPA6120, something better.
I was told the output impedance is very low too.
I could not compare it to any other amp, but I know it was good to listen to.
Regards,
JG

I have built the prototype transformer for a 1.2 kW LLC converter. I use an ETD49 core of 3C94 material. The primary is 35 turns. The secondary is 70 turns. My input voltage is 400V from PFC stage. The output is 400V.

My math shows I need about 11.5 uH of leakage inductance and 50 uH of magnetizing inductance. I have attained the required leakage inductance by using overlapping and offset windings. Currently I have 14uH of leakage inductance in my design. My transformer is margin wound with about a 5mm margin.

In my transformer, it takes a large gap in the core to attain the required magnetizing inductance. The gap is on the order of 0.25 inches to get 50 uH of magnetizing inductance. The leakage inductance is not affected much by varying the core gap.

My question is this: Is using such a large gap likely to cause a problem? Is it common to use a large gap in these designs?

What effect does changing the value of Ln (the ratio of magnetizing inductance to leakage inductance) have? My current design value of Ln is 5. Is this a decent place to start? For smaller values of Ln, I will require a larger and larger core gap.

I have a ZRT build with two Scanspeak Revelators bass elements on each side. Last time I went to use them there was no bass. Initially I thought there was something wrong with my NAD D3020, but tried with a different amp and realised the problem were the speakers. They are about ten years old, from Madisound Speaker store.

When taken out and measures with a multimeter, they all show open circuit. They have, to my knowledge, not been playing loud and I can see absolutely no damage on any of them (except two of them which has some unrelated cat scratch cone damage). I read somewhere that these might have issues with absorbing moisture, causing rust? I'm just very confused about why they would all fail at the approximate same time. We're in Australia, and the weather here changes from humid part of the year to quite dry and hot.

There's some discolouration on the labels, am wondering if that can indicate moisture? Any ideas?

Hi everyone, Thanh (pronounced Tawn, like wonton) here. I'm new to this board and was brought here by Wayne's BA2018. I'm hoping to get some advice to complete the build and look forward to discussions for future projects as well.

Hi all!

Been into audio/stereo/radio, etc since I was a little kid and now getting deeper into the DIY aspect. I have built a couple of tube amp kits (incl. a Parks Audio ST-35 clone), just finished a pair of GR Research LGK 2.4 speakers and am currently rat-rodding an ADCOM GFA-535, with the assistance of Chris Hoppe.

Looking forward to getting into it, with the group.

Cheers, chrx

Hello,

I'm looking for a DAM 1021 SK Lite for my Soekris project. I know I'm late to the game, but maybe someone has one they never used or has an extra they want to sell.

Thx!

I have been completely rebuilding a pair of dbx 234XL analog crossovers.

I swapped all the TL074 types for OPA1644, & LM353 for OPA1642 dual - all worked very well in that position.

The output opamp drivers were more hassle - replacing NE5532 using a mix of OPA828 for the high end/ upper mid, OPA627 for the bass and Burson v7 Vivid discrete for the sub - all these opamps are working at their peak in these frequency ranges.

I had to make up some custom boards (white/ gold) for the OPA828's with the heat transfer pads, and a transfer plate for the 1644 SMD taking it back down to fit the 14 pin DIL sockets.

Caps were changed to WIMA FKP, and the decouple caps to Nichicon UKZ. Bridging/ bypassing the UKZ decoupling caps are Mundorf EVO Silver/ Gold caps 0.47uF for the high frequency channel.

External dual R-core PSU replaces the standard onboard transformer - the R-core has 14,000uF capacitance per +15/-15v side and is dead silent.

The speed and pin sharp detail and clarity of the OPA 2828 's is on a completely different level from other opamps/ discretes.
Possibly because of its ultra-fast slew rate of 150v/uS & 45Mhz bandwidth gain, but its bass is almost non-existent, so can't be used full bandwidth.

Quite a story all told, but sounds a real WoW - at the end you couldn't believe its the same circuit.
The crossover drives 16Kw of Alcons amps and the speakers are a modified Alcons Pro-ribbons.

* if anyone wants to buy either of the 2 PCB types or mounted OPA2828 you can message me.

Some of you know I'm making some monitors for my office. I've been playing with mostly 6" drivers with plans to vent them. Well, Madisound put the 8" version of SB Acoustics Ceramic on sale and it looks like it will work.

Question is if I can get away with this for nearfield listening? I'll be crossing at 800 hz. I can cross a bit lower at 650-700 if needed. I know there is some calculation for how close drivers need to be to meld for nearfield. Does anyone know it well and can explain to me how that works, if this would work, and why?

Also, my baffle will be tiny. And I mean TINY. This whole thing I want to fit in the 350mm cubed print bed of my new 3d printer. Its probably a good restriction since it will force me to keep all the drivers very close together.

Here is the driver in question:
https://www.madisoundspeakerstore.c...oustics-sb23cacs45-8-8-ceramic-woofer-8-ohms/

Here is Joseph Explaining that it will work well within the range I plan to use it. I do plan to use it sealed. My enclosure will only be 0.5 cubic foot. That should be enough I think
https://josephcrowe.com/blogs/news/sb-acoustics-sb23nbacs45-8-8-woofer-review

Hey everyone! I’m wanting to swap my speakers out in my car with some Dayton audios

I have currently swapped out focals for JBL GTO components as one had a blown tweeter anyways

I’m running a PPi 900.4

Channels	4 ch. Class D
RMS Power 4Ω	145 x 4
RMS Power 2Ω	225 x 4
RMS Power 4Ω Bridged	450 x 2

and I run deck power for my rear speakers which is 50 watts peak

I’d like to get some Dayton audios and a tweeter problem is
I need a passive crossover, I understand by using DSP I’ll get better fidelity but I also am using my rear bridged Channals of the amp to bridge for a sub

So I’m limited on inputs and outputs and want to stay passive

Can anyone help me with designing a passive crossover ? Or teach me and explain how I can create a butterworth filter (at least I believe what it is)

Please suggest part number of this NPN with small voltage like this in amp.

Thx

I’ve had the LS50 meta’s now for a few months and feel these are my endgame speakers (Better than what I’ve owned, BMR, Revel, Focal, Kef R3, PSBs and many more). They’re absolutely perfect in every way except for the bass. So, I want to build a 3-way woofer module of some kind. My space for SUBS is limited therefore a subwoofer stand is ideal. Also, I want it to cross around 200hz with 1st order filter to avoid changing the overall character of the LS50s as the tonal balance is spot on, but want to cross higher than a typical sub to improve max spl and reduce IMD. These are my options and I wanted to see what you guys think. Since nothing is commercially available DIY is my only option.

LS50 measurements (sensitivity ~83.5dB @200hz): https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/

• Kits – all have passive crossovers
• Jeff Bagby - https://meniscus.lightningbasehoste...he-Kairos-and-Continuum-Three-Way-Writeup.pdf
• 1.78 cu ft or 50-liter cabinet
• Continuum 3 way module by Jeff Bagby – CSS SDX10 - Might match well with the 83.5dB sensitivity of the LS50M. (Can do ported, sealed or PR.
• Kairos 3 way module by Jeff Bagby – Seems to similar in sensitivity in the crossover regions but a bit more bass below 150z (I can always use DSP to fix boominess etc, and it’s free SPL.
• Troels (SBA10) or CSS bass modules – both of these have sensitivities above 85 dB, so a passive crossover is unlikely to work with the LS50M.
• Design my own
• Crossover - I don’t really have time to tinker for family reasons, so I have to try and get this right on the first try. If I did my own crossover, I would have to do it in the digital domain with a Minidsp 2x4HD.
• I was hoping to make my box taller than the 3 way modules listed above. This means I would end up with a larger internal volume. I could port it or run it sealed or run a PR, but again I have to get this right on the first try. Alternatively, I could use Jeff bagby’s design, increase the height but reduce the depth to keep the same internal volume.
• 12x14x32” = 2.3cu ft or 65 liter cabinet

OPTIONS:

• Build a passive kit as is
• Can the passive crossover have a detrimental affect on the LS50M impedence?
• Use JBs cabinet design but use a minidsp (someone on another forum said that the minidsp would add delay vs a passive crossover… but from what I’ve read it’s not too different than delay added by a passive crossover)
• Design my own box using a simulator to get the dimensions I want, and use the minidsp for crossover. I have read that the simulations are not accurate re port length etc. So I don’t want to mess this up. (Port noise scares the **** out of me, but I could always stuff the port and use dsp to boost the lows 😊)

Please help!

I've got a custom build project on my to do list, which involves an output stage with quad 6L6-GC output tubes.

I want the amplifier to have a full power bandwidth of 7Hz-50KHz, like the old UTC True Fidelity output transformers could provide.

Primary: 3300 ohms
40% screen taps
Sec: 4/8/16 ohms
Power handling: 100W
Budget: <$1,000 each

All of the generic transformers made today seem to be limited to 30-15,000 cps and suffer notch distortion at the low end and slew rate limiting with signals above 4Kc.

I know there are maybe one or two companies (perhaps in Japan?) that know how to make quality transformers on the level of the old UTC parts, but I don't know the names or where to contact them.

Prefer potted to match the existing power transformers.

Any leads on a high end manufacturer that can make us custom transformers within the modest budget outlined, would be appreciated.

Hi! I'm working on a small but time-accurate speaker project, and the problem with small speakers is bass. However a speaker brand called Devialet ( Mania, Phantom, Dione are all very small without passive radiators) has small speakers but impressive bass, can someone tell me how they did it? I've tried every DSP algorithm I have ( maxxbass, Rbass, BBE phase, TruBass, dynamic bass, Dolby) it seems that TruBass works but not as expected, I tried playing a recorded track through the phantom and it worked great, (I tried it on a devialet mania subwoofer driver). I would be very grateful if someone could tell me what Devialet did with the DSP

Hi,

I was digging through some junk the other day and found a pair of interesting chokes that I bought some time ago and then more or less forgot about. Signal Transformer CL-2-4, a rather small piece of airgapped iron with two 10mH windings that can be wired in parallel for 10mH 4A or in series for 40mH 2A.
40mH 2A sounded close enough to the specs of the Triad choke used in the Zenductor amp and those dual windings struck me as interesting.

Over at the tube forum, we would call this a "Parafeed output stage with 50% cathode feedback" or perhaps "a single ended version of the Macintosh Unity Gain output stage" or maybe even "What the hell is that, and why doesn't it glow?":


Fortunately, I had a pair of old 2SK133 mosfets with bias circuits and everything already attached to heatsinks after my attempts to duplicate Hiragas Nemesis amp a couple of years ago so wiring up a prototype was easy:



No measurements yet but I've been listening for an hour and it sounds surprisingly good, running at 12V 900mA, which should be good for around 3 watts into 8 ohms.
The point here was to build something that is essentially a simple follower but with ~6dBs of gain. The experiment is successful so far, we'll see what the oscilloscope says...

JH Reproducers Synchronous Turntable with Formula 4 Arm; Australia’s Linn Sondek. Uprated model with springs.

Excellent reviews, especially the Uni-pivot arm. Motor runs, plater runs, belt OK missing a screw for the cartridge, anti-skating bucket is there just needing attachment.

Photos from part of the description. No warranties, no guarantees, no returns.

I am no expert. What you see is what you get.

Dirt cheap at AUD465, plus shipping/insurance/box. Bank Deposit or PayPal Family & Friend for Overseas people.

Negotiable. But if not sold by 16th December, it goes to the charity shop with the other things.

After a bit of work by some tuning with Nichicon UKW Caps and a great new Bourns Trimpod (that makes the Power-drive sense. adjust. now and fixed a diode problem in the Amp everything worked fine and i was pretty happy and couldnt wait to listen...

Till...
...I wanted to dial in the idlecurrent before and by that I shorted the Amp at the TP Points.

I kind of feel I damaged the Amp seriousely and would appreciate if its possible to help me out a bit to determin which parts got probably damaged by the cuircuit I've created, by showing you what happens, because my shematic reading abilitys are kind of limited.

I marked the short with the black line in the following pictures [the DMM clamps, I surely think touched TP2 and than the 0.1 Cap in front of it - TP1, was not hooked up at that point]




So as the short happened the blew was pretty heavy and I shut down the Amp immediately. After turning it on again, I saw smoke coming from R243[marked it with the red cross(the resistor is surely burned)] and then instantly the main Fuse at the PS burned trough also.

So by looking at the Images can someone determine what will be surely damaged especially? (maybe the following Transistors? Output Transistors?)

So I have the 0.1uf cap and the resistor here and about to change them, but im too afraid and don't have the courage to try turn it on yet as I don't know if following parts in thr cuircuit are pretty surely dead.

Thanks!