AB100 Amplifier - Micro Article by Nelson Pass

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

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do in fact have a 13 year old piece laying around unpublished,

I Hereby Present the AB100 Class AB Bipolar power amplifier.

Salient Specifications:

Rails: +/-50V or so

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

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

Damping Factor: about 500

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

Slew Rate: 30 V/uS

Bias Current: about 0.08 A per channel

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

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

😎

Orders now are open for Quad PCM58 Iout boards, ready built and tested or as a bare-board kit of parts. This board is not a complete DAC, it requires an external I/V stage. PM me while not forgetting to include your chosen payment method and location so I can quote you inclusive of fees and shipping.

When developing the 'Dark LED' I/V stage I prototyped a number of DAC chips to feed it and it was the PCM58 that won out in our listening. According to its datasheet, the PCM58 is the lowest noise multibit DAC chip available - later generations (including PCM63, PCM1702 and PCM1704) haven't been able to improve on its idle channel noise.

The quad PCM58 current out design has discrete regulators fed from IR LEDs for the DAC chip power rails and accepts I2S input. To create a complete DAC you'll need an interface board on the input (S/PDIF, Toslink or USB) and for generating the output, an I/V converter. The intended use case is with the 'Dark LED' module - the power rails are the same for the two PCBs, +/-18V. Using 0R resistor options the PCM58s may be configured in single-ended mode or alternatively, balanced with an on-board phase splitter. Multiturn pots are included so you can trim the 4 most-significant bit weights of the DACs assuming you have suitable measurement kit. If you don't have that kit, I'll leave those trimmers off the board by default so as not to disturb the factory trimming of the DACs.

Physical dimensions: 100mm * 100mm, max height 20mm. Fixing centres : 95mm * 95mm, M3 holes.




Price for a quad PCM58 built and tested unit is : 780RMB (~USD108) to include 4 recycled PCM58 DAC chips which are fitted in turned-pin IC sockets.
for a bare-board kit, including 4 DAC chips the price is 640rmb. We'll be putting up the stuffing guide shortly.

If you already have your own PCM58s the price for the board without DAC chips is 500RMB and I'll supply the sockets unsoldered unless requested otherwise. This is because many recycled PCM58s have disfigured legs which are rather tricky to fit into sockets when they're soldered down due to the nearby components.

Our preferred payment method is via Wise which typically adds a 2% fee. Our receiving currency is CNY, alternatively USD or Euro. PayPal may also be used, in USD but will attract higher fees, 5.5%.

Shipping is in addition and depends on your location and speed of service. Courier (FedEx, TNT, DHL) typically takes 8 - 10 days and e-packet four to eight weeks. Not all locations can be serviced by e-packet though.



What else is needed to turn the Quad PCM58 into a fully operational DAC?

You'll need an input interface board to feed an I2S input to the Quad PCM58 over 3 wires (no MCLK is required). The popular gold-standard USB interface chip CM6631A though is typically not compatible with this board as in stock form it outputs a BCLK of 128fs at 44k1 sample rate whereas we require a 64fs BCLK. If you buy the CM6631A card through us we can perform the firmware upgrade needed to make it compatible. Your output stage (I/V stage) could be as simple as a couple of opamps, configured in transimpedance mode. A low-noise, high speed one is preferred. The ideal I/V from the SQ perspective would be a discrete one like 'Dark LED' customized slightly to run from a unipolar input current. Seeing as the PCM58's DAC internals are unipolar, it generates a bipolar output current through the provision of a secondary fixed current source which adds half the full-scale peak-to-peak output current (1mA). This is the function of the BPO pin on the DAC (pin5). Seeing as this additional current source adds noise it is best to avoid using it if the I/V stage can handle a unipolar input current, which the Dark LED can, given a change to two resistors (R1 & R2). When the BPO pin isn't being used the 0R resistors R7,R30,31 & 32 are not fitted, nor are C7,C14,C20 & C27 which decouple the BPO current source.

You'll also need a well regulated low noise power supply of dual rail +/-18V rated at at least 150mA An LM317 and LM337-based board will be sufficient as the PCM58s have their own regulators. If you already have a single winding AC supply (an AC wall-wart) then 18VAC at 10-20VA would be in the right ballpark. Use a half-wave rectifier so you get both rails from a single winding or alternatively, a centre-tapped trafo. I don't recommend using switching supplies due to issues with common-mode noise, its very hard to filter out unless you're using balanced connections to your amp or pre.

Speaking of balanced mode, the board may be configured into being a 4 channel (L+,L-,R+ & R-) system at 1mA peak per channel or a 2 channel, 2mA peak per channel solution with the four DACs configured in two paralleled pairs. In balanced mode you'll need 4 channels of I/V. The configuration is handled by 0R resistor on the jumper 0R resistor locations U16-U18 and R33,R34.

Hello everyone,
I hope you’re all doing well! I’m reaching out to this wonderful community because I’m in a bit of a pickle with my beloved Lavry DA11 DAC.
The headphone output has stopped working, and upon inspection, I found several burnt components (transistors, resistors, and capacitors) in the headphone section. Unfortunately, the markings on these components are now completely unreadable.
I’ve tried contacting Lavry support several times for component identification, but haven’t had any luck getting a response. As a former Lavry dealer in France (2007-2010), I really love this DAC and would hate to see it end up in a landfill over something potentially fixable.
What I’m looking for:
• If anyone owns a working Lavry DA11 and wouldn’t mind taking clear photos of the headphone circuit components
• Any repair technician who has worked on these units and might recognize the components
• Someone who might have schematics or component list for this section
I’ve attached photos of my unit showing the damaged parts. Any help in identifying these components would be greatly appreciated!
This community has always been amazingly helpful, and I’m grateful for any assistance you can provide.
Thank you in advance,

Hello everyone! I'm new to this, so apologies if my questions are a bit basic.

I'm working on a small project to "re-factor" an old Samsung HW-D570 soundbar into a compact 2.1 audio system. My plan is to move the amplifier section into a standalone box, connect two wired speakers to it, and keep the wireless subwoofer as it is.

According to the specs, the original soundbar uses two speakers described as "2-way, 80 Watt, 4 Ohm, wired". Each speaker actually contains two small woofers and one tweeter. The woofers are labeled "HUSNF-00900, 8 ohms." When I measure the impedance from the wires going to each speaker (which includes both woofers and the tweeter) with a multimeter, I get about 4.5 ohms.



I have a couple of questions:

• Is this a 2-way or 2.5-way speaker system? And are the two woofers in each speaker likely wired in series or parallel? I can't see the internal wiring clearly.
• Main question: Can I replace the current speakers with some spare Monitor Audio Radius 45 speakers I have? These are 8-ohm, compact satellite speakers rated for 15–50W, with a 3" woofer and a rear-firing tweeter. (Or should I rather use 4-ohm speakers? Or only keep the original speakers?)

My main goal isn't necessarily to improve the sound quality, but to change the format and case of the system to better suit my needs.

Thanks in advance for any advice or insights!

I'm thinking about upgrading my surround system to Atmos so have a need for in-ceiling speakers. In my search I came across these:

https://www.crutchfield.com/S-bYgFC...c2IpAbYCHpZzlSha3oc8dEza696tvhZYaAhdoEALw_wcB

This got me to thinking... these use a single full range driver shoved in a can which seems doable with a 3d printer and a few hours in Fusion 360. Can anyone think why this wouldn't be a good idea? If this isn't a completely dumb idea what drivers should make my short list? I think my starting qualifier would be that they have to get loud enough to be used at reference volume without notable distortion.

Hi
the base of this amp is the huge thread about :

100W Ultimate Fidelity Amplifier​

these is the thread for all fans of the Vertical brother of APEX FX8 done by XRK and prasi:
the amp was modified by XRK and others and use no Lateral MOSFET --> therefore well known IRFP240 and IRF9240 are used.

here are some examples and comments:
here
here:

I have for sale 2 sets of components for building the Miro AD1862 DAC. Each set consists of 1 x AD1862 SMD DAC board, 1 x Miro PSU1 board, and 1 pair of AD1862 IC's. AD1862 IC are genuine (from Paddy & zoom777) Each set is priced at 40 usd plus shipping. Please see the attached pic.

Regards,
MM

It has been a Long time after the DDDAC1543 saw the light and the world moved on, especially if we look at available sound track material. So much great soundtracks with high Resolution. Red book is not dead of course, but if I spend money on sound tracks, I look for 96/24 or even better 192/24, or the SACD equivalents 88.2 and 176.4...

In the past year I have been working on my new project: designing a DAC which will play up to 192kHz / 24bit material from a PC (or Mac...) There are many DACs who can do this, but I wanted to design a NOS version, as so far, every listening test I did, this led to a more open, natural and detailed sound.

I found this to be possible by using the well-known PCM1794 and avoiding the digital filtering built into the chip. This proved to be quite tricky, but I managed to find the key to do it. It has been a great adventure with much to learn and a fantastic result at the end....

To feed the DAC, I kind of integrated the WaveIO USB Receiver from Lucian. Great design and better sounding than all others I tried (see my website for this as well); I give a very detailed report on www.dddac.com

You can download the circuits here: dddac1794_nos_ver30.pdf



The Images below show:
The Mainboard with I/O and I2S to right justified conversion
The actual dual mono DAC Module (can be stacked parallel)
Built up with 4 modules and two power supplies (5 and 12 Volt)
Wired up in Chassis (Mundorf Gold silver oil output and optional Sowter 1:2
The DAC in my Audio rack
Another view inside
Block diagram


I opened this thread to share my design and experience and give a platform for questions, feedback, remarks and/or discussion...

Hi all,

Talk me out of this? I'm just enamored with the idea of a small foot print "tower" that is taller with lots of 8" drivers in it. Instead of a big box, a tall skinny tower. The small foot print is just easier to place in various rooms. Visually it's fun to see. It allows the use of lots of inexpensive drivers. And generally doesn't need much power to get loud. But would it need to be a sealed enclosure? Or ported? All the subs sharing one volume? Or make groups of 2 in their own cubbies in the enclosure? 4 to 8 drivers so that wiring loads is easier?

I tried modeling some options in WinISD but I'm not sure if it handles real world what happens with multiple drivers in one volume or not? Any other options that are more realistic?

Overall bad idea? Better to just build two 10's and stack them instead?

Purpose would be music mostly.

Very best,

Some pics of a prototype general purpose DAC Clock board, for which I plan to post the Kicad project. First pic is driving a Andrea Mori FIFO Buffer board; second pic is driving a @MarcelvdG RTZ FIRDAC with asynchronous USB, and reclocking before the dac board (clock board prototype is outlined in red).





The original premise was that the clock board would use 45/49MHz clock modules (or external clocks, including sine wave oscillators using suitable squaring adapters). The 45/49MHz frequencies can be used to externally clock an I2SoverUSB board. The clock frequencies are then divided by two to produce 22/24MHz clocks for driving dacs. Both continuous and switched 22/24MHz outputs are available (USB board usually controls the switching). All outputs are buffered with high performance buffers. Very clean +3.3 power distribution and bypassing is also used. That's the short story.

The board design evolved to also support 22/24MHz clocks (or even 11/12MHz), then use a frequency multiplier to drive the USB board (as an option).


So far with the prototype and some pretty good clocks, it does raise the DACs in the pics into what I would consider to be a higher sound quality performance league as compared to what they would sound like with off the shelf NDK SDA, Accusilicon, and or Crystek (although the clock board can make those clocks sound better too), and or especially better if compared to having the master clocks internal to the USB board.

Of course, all the above having been said, there are commercial solutions out there too. Some may be essentially SOA, but they may be more costly and possibly less adaptable than the clock board of this project.

----------------------------------------------------------------------------------------
Clock board v2.1 files attached below.

Interconnect Board open source project for connecting I2SoverUSB and PCM2DSD to the clock board and reclocker board is at (#68):
https://www.diyaudio.com/community/threads/general-purpose-dac-clock-board.413001/post-7702293

Reclocker Board open source project files available at (#157):
https://www.diyaudio.com/community/threads/general-purpose-dac-clock-board.413001/post-7729422

Some comments on using the clock board with very high performance dacs in #144:
https://www.diyaudio.com/community/threads/general-purpose-dac-clock-board.413001/post-7729060
----------------------------------------------------------------------------------------


NOTE: Clock board schematic was found to have wrong part number (now removed) for the Omron relays. Please see the clock board notes document for more information on part numbers.

8/11/24 - Clock Board Notes document updated to v1.1 (some changes to recommendations for regulator load resistors)

I originally made a similar post in the Room Acoustics forum; however, there appears to be a lot more discussion of CLD in this forum. (Pretend the room is a big speaker enclosure – just kidding.)

I am remodeling my family room and want to make it a better “listening” environment for stereo and future multichannel. About ten years ago I read Earl Geddes excellent book “Premium Home Theater” and one of my big takeaways was his recommendation to use CLD in a listening room to absorb bass while preserving midrange and treble liveliness. Although Geddes also recommends CLD for sound isolation - that is not my objective, since one corner of the room has an open ½ flight of stairs up to the middle level of our home with no good way to enclose it.

Tentative plan is to incorporate CLD into the ceiling, the front wall and one sidewall of the 8 x 14 x 24ft room. Sound isolation clips would be attached to studs/ joists with 7/8” steel hat channel attached a maximum 4’oc and spaced a maximum 2’ apart. Two layers of lightweight ½” drywall separated by a suitable damping compound (Green Glue?) would be attached to the hat channel.

Is this a worthwhile endeavor to hopefully preclude the need for standalone bass absorbers, multiple subwoofers, room correction software, trial & error measurements, etc?
Is this a good design? Am I on the right track with the following design assumptions?

Increase the flexing of the constraining layers (and thus energy absorption via CLD) by decreasing the stiffness and mass of the constraining layers.

Reduce the strength of reflections into the “listening” room by decreasing the stiffness and mass of the constraining layers.

The damping compound that is used between the constraining layers should have very good adhesion and be more viscous than elastic so that energy is absorbed rather than returned to layers.

Minimize the Resonance Frequency of constraining layers by increasing mass and decreasing stiffness.

I'm really looking forward to this -

Designing Audio Power Amplifiers: Amazon.co.uk: Bob Cordell: Books

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

Premium Drivers information sheet​

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

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

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

Premium diaphragms: Key points - Changes / Improvements

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

Click to expand...

Hello, I'm a new member from the USA. I'm currently building a 2 way speaker. I have interest in building a power amp.

Hey Guys, I have found this forum invaluable in helping me evaluate which sub I want to build to start my mini rig. In particular the Xoc1 TH18 thread has me sold thats the way i want to go. Thanks for having me!

Hi guys, new to the "business" and trying to build a wifi speaker 😀 will be fun

I've been trying to find a reliable formula to calculate the total group sensitivity of a relatively odd configuration and number of LF drivers. They would be arranged as close as possible to each other.

In my own personal scenario ->

- 3 identical 12" LF drivers, wired in parallel, individual base sensitivity of 87 dB/2.8V/1M per driver, arranged in a triangle.

- what would the total sensitivity be of all 3 drivers playing together at frequencies lower than the equivalent of 1/2 WL?

With an even number of 4 drivers connected 2 in series, then the 2 groups paralleled, we'd theoretically observe a 3dB gain from doubling the driver count and another 3dB from doubling the cone area, but lose 3dB from cutting the drive voltage to each woofer of the series connections. That leaves us with a total net gain of only 3 dB if we only count the frequency range that falls in the 1/2 WL CTC driver spacing.

With an abnormal quantity of drivers, CTC spacing and adding in series.resistance from a thinner awg, it becomes a bit more complicated to figure all this out. Short of putting it in a software sim, which isn't always accurate, there has to be a better way to get a closer answer.

V-FET lottery amp #038 P-channel from first lottery
Original, unmodified, perfect condition
In addition: 2 Bulwark FE and 1 Tuba filter
Asking price: 700CHF + Paypal Fees and Shipping

Do i need to worry about baffel step correction if i measure all my drivers in the finished speaker cabinet or will that measurement already account for it? Thanks! Travis

Hello everyone,
I have for sale pair of DIY finished boards of B&K st 140 amplifier built on the original exactly schematics.
Construction with components of absolute audio quality and definitely superior to the original:

• Nichicon Fine Gold audio capacitors
• Nichicon MUSE audio on the signal path (green)
• MKP bypass capacitors (Polypropylene)
• Cornell Dubilier silver mica capacitors
• ORIGINAL HITACHI K135 and J50 final MOSFETS
• Construction with Cardas tin.

Calibration as service manual 200ma @ 20kHz and zero DC offset (see photo) and absolutely perfect measurements in terms of bias, DC offset and THD (see measurements).
Power supply required dual 60V DC to have the nominal power of 105Watt/channel on 8 ohms.
Sound very well and powerful with NO hum and perfectly stable in temperature and elecrtical parameters.
Big heat sinks is not included.
Price request 80 Euro plus shipping (From ITALY).
Consider that the Hitachi mosfets alone are worth the asking price.
Some pics:

The TDA7293 series are underrated gems in the DIY world. This chipamp, with its modular structure, clip detector, mute-stby functions, low noise and low distortion, produced with DMOS technology, actually has the potential to compete perfectly with National/TI's LM3886. On the other hand, it is common practice to use chipamps with a buffer due to low source impedance demands and relatively high input bias currents. Likewise, with composite feedback applications, both the noise and distortion efficiency of chipamps can increase significantly. In our implementation, two matched N-channel JFETs, together with the PNP transistor, operate as a complementary feedback pair as a high-impedance, high-CMRR differential input buffer for the TDA7293. The JFE2140 / LSK389 LSK489 dual JFET combination used provides significant improvement in THD and noise compared to the use of the chipamp alone, thanks to its extremely low noise. The composite feedback rate is 26dB (20x). In this way, ~1.25v RMS input signal is sufficient for full power. On the other hand, thanks to the DC servo circuit established with TI's low-noise, low-offset opamp OPA277, the DC offset remains below 1mv.

Our inspiration for our design was Bob Cordell's LSK489 application notes and JFE2145 datasheet.
https://www.cordellaudio.com/JFETs/LSK489appnote.pdf
https://www.ti.com/lit/ds/symlink/jfe2140.pdf?ts=1717672324923&ref_url=https%3A%2F%2Fwww.ti.com%2Fproduct%2FJFE2140
https://www.st.com/resource/en/datasheet/tda7293.pdf
https://www.ti.com/lit/ds/symlink/tps7a49.pdf?ts=1717660447218&ref_url=https%3A%2F%2Fwww.google.com%2F
https://www.ti.com/lit/ds/symlink/tps7a3001-ep.pdf?ts=1717738722969&ref_url=https%3A%2F%2Fwww.google.com%2F


The ancient 78xx 79xx series regulators, which are well known in the electronics community, have been used in audio circuits for years thanks to their stable structure, high PSRR rates and relatively low noise(?).
Measurements of 78xx-79xx ICs (even though noise values such as "0.003% Vo" are given in their datasheets) have been found to reach noise values of 500uV - 1mV in the audio band, which may disturb sensitive ears, regardless of the input noise. Of course, such a supply noise is meaningless for modern audio opamps whose PSRR is around 120dB.
However, especially in discrete applications (since PSRR efficiencies are quite low), this level of noise will be disturbing.
Although complex, discrete, parallel-hybrid low-noise solutions have been produced to solve this problem, these applications remain a troublesome alternative due to application difficulties, additional noise due to the area covered by the regulator, and the necessity of matching components in some applications.
Our application provides a good and affordable alternative to all these difficulties. TI's low-noise regulators TPS7A4901 for + rail and TPS7A3001 for – rail form the heart of our application. The effective noise amounts of these regulators in the audio band are below 15uV (RMS) level. In addition, while PSRR rates are 60dB in the 78/79 series for 100-120Hz, they are around 70dB in the TPS7As. On the other hand, load and line regulation rates and transition responses are significantly higher than the 78/79 series.
Although the input voltage of these regulators is limited to a maximum of +/-36v, input up to +/-60v can be applied thanks to the input voltage limiter used in our application.
Since the pinout of the 78/79 series is used directly, they can be used as a one-to-one replacement in applications where these regulators are used.

EPIC S

EPIC S


Positive Regulator Schematic


Negative Regulator Schematic


Final prototype measurement of EPIC S.
1K-1NF input filter
47K-4.7K NFB Resistors
4.7mA Input bias
Power: 78W 8ohm (2x42V)
Input sensivity: 1.25V
Slew Rate: 8V/uS 8ohm/1nf (JFE2140)
Slew Rate: 9V/uS 8ohm/1nf (LSK489)
Bandwidth: 5-75khz -3db
DC Offset: <500uV



EPIC S Output Noise

Hello,
I'm building a P3A amp that will be paired with the ESP tone control preamp. The pre already has an output cap so I'm wondering if there is any reason to keep the input cap on the P3A, and if not, could I also eliminate R1, R2, & C2?

Only looking for the SuperCables Cookbook now. The Vacuum State site is no longer available, so hoping to find someone who wants to part with their book.

Well, origin thread is here : Iron Pumpkin(s) and other smaller vegetable animals

If nothing else, read at least first several posts on linked page , to grasp enough info about concept itself.

This one having two purposes :

-placing all necessary info about final iteration,

-trying to layout clearer picture of what's fuss about,

-with edits of this first post - making comprehensive list of tips and tricks and funny fine details , and answering on any clever or dumb question you'll possibly have ......either here or further in thread

(3 purposes then , not two )

edit at 22.05.2020. short how-to-do for Iron Pumpkin SE, referencing to post #2:

do not connect buffer output to Turtle

maximize trimpot R36 (measure across R39 to confirm max value)

R37 position is irrelevant for now

if you're sure that you connected everything properly, just power it on

set positive and negative rails to +/-12Vdc , with trimpots R9 and R10

power off, place DVMdc crocs across R34, power On then fiddle with R36 to set 20mV across R34, then fiddle with R37 to set 0mV DC offset at output


do everything the same with other channel, connect outputs of buffers to Turtle, enjoy

Earlier in the Le Monstre Preamp thread, we posted schematics and spice files for 3 different line level buffers.
www.diyaudio.com/community/threads/preamp-for-hiraga-le-monstr-2024.421562/

They all have JFET inputs and use 4 complementary transistors in total.
We have now built and measured them all, as shown in the pdf attached.


Patrick

.

Hi

The big thread of "100W Ultimate Fidelity Amplifier" is a chaos.
i need time to search through all the page and mark all i can find.
pcb is done in yellow by jlcpcb.

Gerber and all other documents are in post 13908: here
input BJT i use the recommended KSC1845, driver are 1381 and 3503, power mosfets are the renesas 1058/J162
as C4 it is written 220µF, and XRK use a polymer elco with 330µF. I use a orange 1000/16VµF by epcos
for C9,C16, C12, C15 i use Panasonic 680µF/50V
input cap is a red polymer panasonic 2,2µF/400V instead of 10µF
i use the lower gain setting R11, R12--> 550R and 20k
i did my first output coil...its not nice done but it has about 0,9µH the resistor is under the pcb

bias setting:
post 6686 bias at 100ma-170mA, wrote about goldmund amps--> bias 200-300mA
my bias is set according to the hint of post 7753 by bimo to 400mA. the amp is working fine.
post 6971 test by XRK as an Class A amp with 1,3A works fine...big heat sink is needed!

i used for the first test a 0,65K heat sink.
i plan to use a 4U/300 case by modushop with a 300VA 2x24V sec. transformer

i will just check the other channel.
psu voltage is 31 per rail and bias is after 2 hours 420mA stable. no heat problems, no smoke..

Gain is about 31dB, at 8ohm load about 29WATT.

if you have any hints , let me know.

edit:
Apex directory - done by XRK ..thx:
here:

edit: 26.8.2024: set bias current back to 400mA #post 104
edit: 25.03.2025: post 123 latest PCB Gerber by Peter(Kleinhorn) - thank you!
post 123

kr
chris

I have a distortion in one of my tweeters on my 3-way. The distortion occurs only at certain frequencies and above a certain volume. The distortion is pretty deterministic, I can reproduce it. They are old 3 ways energy speakers from the 2000. I managed to isolate the distortion problem : it is only one side, and because I can bi-wire it, I can confirm that the distortion is coming from the tweeter and not from the mid or bass (because mid and bass share the connector).

I also swapped sides of the amplifier, so I know it is the tweeter on the speaker and not the amplifier that is problematic.

The screw to remove the drivers are not accessible (see: https://rvb-img.reverb.com/image/up...,t_large/v1639605839/olidljagmyhg8zmbkcx4.jpg), so I would like do the debugging and part sourcing before taking them apart.

Is there something I can do to pinpoint where the problems, i.e. crossover, dome, magnet, voice coil? And the potential solution?

Thanks

I don't really post up here as often as I should, but I have been posting as tarior on AudioKarma for over 20 years now.
At any rate I have a ton of obsolete chip amplifiers and some excess small signal transistors. I would like to trade them for parts I can use, or, I can sell them outright.
All of the transistors were sourced from Digi-Key, Arrow, or Mouser. I'll start with parts I don't have enough of:
KSA1381, 2SC2240/A970, 2SA1370/C3467, KSC1845/A992 with a gain range higher than F, KSA1220A, through hole versions of 2SC4207/A1552, 2SC1904/A899, 2SC1885/A912, 2SB568, 2SB718, and TDA7109P. If you have interest in any of the parts, and have some of the ones listed, I'll let you determine the trade ratio, within reason. If you would like to buy any outright, we can also talk about that.
First up, we have a few transistor part numbers.

KSC3503D 200-300 available.
KSC1815GR 2000 available
KSA1015GR 500 available, maybe more in the future.
KSD1616A(L) 2000 available
KSB1116A(L) 2000 available.
MJ2901 NOS 9 available.
SGSD00034 6 pieces
SGSD00032 2 pieces
SK3009 3 new, one used. I'll throw in any used ones for free.
SK3014 1 new, two used. ""
Tektronix 151-0337 One piece
SK3113 Germanium damper diode One
2SC3976 3
2SC3982 2
2SD1441 1
2SD1453 1
SGSD00042 3
SGSP321 2
SGSP579 2

Next is the long list of obsolete chip amps.

(Rohm) BA511 9 pieces BA511A 3 pieces BA521 1 piece BA532 4 pieces

Sanyo LA4430 7 pieces LA4420 9 pieces LA4400 3 pieces LA4422 2 pieces LA4100 4 pieces LA4032 2 pieces LA4122 4 pieces LA4220 8 pieces
LA4140 4pieces LA4102 1 piece LA4182 1 piece

Hitachi HA1338 3 pieces HA1308 7 pieces HA1339A 5 pieces HA1306W 10 pieces HA1306P 2 pieces FA6013 2 pieces HA1366W 2 pieces
HA1366WR 2 pieces HA1368 1 piece HA1377 4 pieces

Panasonic AN7120 6 pieces AN315 6 pieces AN214Q 2 pieces AN7147N 1 piece AN630 1 piece MN2114 2 pieces M5115P 1 piece M5115PR 1 piece
M5109P 1 piece

Delco DA101 2 pieces DM31 1 piece DM11 1 piece DM44 1 piece DM32 4 pieces

Dolby NE545B 2 pieces

NEC upc1230H2 8 pieces upc1182H 4 pieces upc1181H 3 pieces upc1181H (board pulls) 4 pieces upc1025H 6 pieces upc1185H 4 pieces
upc575C2 11 pieces upc577H1 1 piece upc555H 1 piece upc554C 1 piece

ST Micro TDA1170N
TFK TDA1170N

Toshiba TA7205P 10 pieces TA7209P 2 pieces TA7201P 2 pieces TA7203P 1 piece

Fujitsu MB3731 1 piece

Mitsubishi M51513BL 3 pieces MB51514AL 7 pieces MB51515BL 3 pieces M51102L 1 piece

Few years ago I build Seas based speakers. (T25-001 and W17E-002). Speakers was my own design, even filter.

I was quite satisfied speakers sound to the moment when I get chance to listen original Jamo Concert 8 speakers. After that I was not satisfied anymore


So my question is that, does anybody have Jamo Concert 8 (Jamo D830) crossover schematic?

I have seen some pictures taken from that crossover board, but component values are not clear to me.

Picture shows how components are placed to board.
Red are capacitors, white are resistor and black circles are coils.

I got the proto of the s.e. trafo with multi tap
5 kohm, 43% and 20% UL
5 ohm single secondary
around 20H
primary wire 0,28 mm diam - Rdc 140 ohm
max Ia around 200mA
Pmax around 10 watt, column 40x45,
M3 - 0,3 mm. o.g.
4,4 kg




This is not available.

To play in the real world not in virtual
Testing some circuit.
Unfortunately I have to service now my Sofia ( some hard problem) then I can test the tube that will play in the circuit
proposed


Walter

The Iron Pre is now listed in the diyAudio store for anyone to purchase.

Until the 'Build Guide / Build Thread' is created, this post will contain all current schematics and notes for the Iron Pre sold through the diyAudio store. Check back frequently to ensure you have the latest files.

Sep 14 2023 - Below is what you're waiting for! See some awesome information and help from 6L6 on the SE build. A new thread and the guide using the web interface will be posted ... soon. Post #2291

Background

Hello Happy DIYers / Greedy Boyz!

I am thrilled to announce that Zen Mod's Iron Pre essentials kits will be offered in the DIYAudio store. This is not a group buy. You can learn more about the project in the thread linked below.

https://www.diyaudio.com/community/threads/whats-wrong-with-the-kiss-boy.293169/

Highlights include matched Toshiba JFETs from Nelson Pass and high-nickel CineMag transformers. 6L6 has volunteered to post one of his incredible build guides also.

If you're a Smiths fan, you may ask, How Soon Is Now? They should be available for order before the end of the year. At this time, we have enough parts sourced for 100 SE and 50 balanced kits.

The next obvious question is, how much? Costing is not final yet, but the goal is $100 for the SE kits and $125 for the balanced kits; a tremendous bargain. We have contingencies for all the parts, and we hope that this will be a permanent addition to the store. However, for now, we can only promise what we've got. Get 'em while you can.

Click the link below to see what will be included in the kit, answer a few questions about what you might like to see in the future, and get on the list.

Note - The n-channel JFETs will be 2SK370.

Quick and Dirty Startup Process

This happens after: the boards are stuffed, the AC supply is verified and connected properly, and I/O has been connected. Nothing needs to be shorted. Note the additional step for the V4 SMD version.

1. Set V+ and V-
   
   Adjust P1 and P2 for each board until V+ is +15V0 and V- is -15V0
   
   GND, V+ and V- pads are clearly marked on PCBs.
   Do not move forward if you cannot adjust the voltages to within 0V1 or if the voltage seems unstable.
   
   
2. For V4 SMD Only- Set current through JFETs
   • Set DMM to DCmV.
   • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
   • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
3. Null DC offset
   • SE
     • No jumper caps in place for JP1 or JP2
     • Measure at center pin of JP1 and JP2 NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers for your choice of gain.
   • Balanced
     • No jumper caps on JP+ or JP-
     • Measure at pin 1 of JP+ and JP- NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers.​

Updates

4-May 2023

Edited 7-Aug 2023. All in-line photos have been removed. Please see attached files for all documentation.

5-May 2023

Updated Single-Ended BoM to correct 330R part notations in the gain stage to R28 and R29.

Attached are the Bill of Materials / Parts Lists - Note File Names for Balanced and SE

26 - May 2023

Updated SE and Balanced Bill of Materials to indicate that snubber components should not be installed.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v5.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v5.pdf

27 - May 2023

Updated SE and Balanced Bill of Materials to correct and clearly note which diodes should be installed for input switching.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v6.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v6.pdf

1 - June 2023

Note - No changes required. However, the packing lists some of you will receive may note LM336-5.0. That was a typo; apologies. The correct parts (as supplied and noted in the BoM) are LM336-2.5.

Removed the link to sign up indicating interest in kits. Those currently on the list will get first priority for the next round of kits. After that, they will be sold through the normal process through the store.

6 - June 2023

There are two gorgeous prototype chassis available; one designed specifically for SE, and one for Balanced. You can find some details in post #431. The depth for both chassis is 280mm. There is additional information sprinkled throughout the thread re: acceptable sizes and some potential part numbers for IECs, input / outputs etc. along with pictures of some examples. Please search first before asking chassis questions, and I'd recommend using the latest posts' information. Again, they are prototype chassis, and anything could change at any time until the design is finalized. The best source of information re: the chassis is directly from Modushop until they are sold in the diyAudio store. Timing TBD.

8 - June 2023

Added parts placement and pcb layouts for those interested.

30 - June 2023

V7 - Minor Updates to BoMs. QTY added. Ensure to check quantity per board against the quantity you need for your project. Added links to a popular online website to show examples of parts that will work for the connection between the main boards and the twister boards for input selection / LED power etc. Added generic descriptions for those that would prefer to select their own parts.

1 - July 2023

V8 - Minor Updates to BoMs. Added heatsinks for M3 if 12V relays are used.

7 - Aug 2023

I'm excited to say that more kits will be available very soon for 'round 2'. Continue checking this post (as always) and the thread overall for up to the minute updates.

In his graciousness, ZM has made some minor running changes. Changes are:

• Updated transformer snubber circuit.
• Easier positioning / mounting of the CineMag transformers in some situations.
• Changes to allow easier use of some logic circuits for input switching.

Boards that include the changes will note "2023" vs. "2021" on the silkscreen. The Twister board accompanying the 2023 boards notes V.3. Both 2021 and 2023 boards are included with 'round 2'. You cannot choose which you will receive, and you will not know which you will receive until they arrive. Do not fret if you get a kit with 2021 boards. If you need to use a particular type logic solution, there is a very easy modification previously noted in the thread, and the snubber is not necessary. The changes made were a kindness from ZM, but all 2021 boards can be made to function just like 2023 boards with a few user-tweaks described in the thread.

Note - The attachments have been packaged and note which files to choose for the respective boards. Previous attachments and in-line thumbnails / photos have been removed for clarity. The BoMs have been updated slightly for clarity.

9 - Aug 2023

There is a minor error on the silkscreen for the boards marked Iron Pre SE Zen Mod Labs 2023. The polarity notation for C11 visible when the cap is installed is incorrect. Ignore it.



13 - Aug 2023

His Mightiness created two graphics for how to wire standard pots for both SE and Balanced. Attached.

29 - Aug 2023

Minor updates to balanced BoMs. Removed reference to D15.

31 - Aug 2023

Added wiring diagram for AVC for SE. See post #2113 for context.

21 - June 2024

All testing for the Super Mega Deluxe version is complete. Kits will be back in the store 'soon'.

25 - September 2024

"Soon" is relative. 🙂. SMD kits are on sale. The schematics and files for the Super Mega Deluxe (SMD) have been attached in their appropriately named .zip files. Enjoy your builds.

26 - September 2024

A few people purchased the "completion" kits for the V3 and earlier boards and were wondering if they could be used for the V4 SMD kits. A lot of the parts are identical, but below is what you'll need in addition and to swap a few parts.

For balanced you will need:
4x additional 825R or 820R resistors - I like these Vishay BC 825R
8x 58R or 62R resistors - I like these Vishay BC 62R
4x 1R resistors - I like these Vishay BC 1R
8x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
4x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

For SE you will need:
2x additional 825R or 820R resistors - I like these Vishay BC 825R
4x 58R or 62R resistors - I like these Vishay BC 62R
2x 1R resistors - I like these Vishay BC 1R
4x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
2x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

27 - September 2024

Some potentially helpful additional parts in post #3784. If people have more helpful suggestions, I can add them.

3 - February 2025

Added diagrams for setting buffer current in V4 builds.

Good morning

I am building a clone of the SUGDEN A21 amp (class A) and want to associate a very good preamp with RIAA, tone control.
That of ELEKTOR 2012 caught my attention. To validate the quality of the PCBs manufactured by JLCPCB, I ordered the tone corrector part from them. Superb quality.

Now that I am sure I can have PCBs, I would like to have feedback from those built or use/used the Elekto Preamp 2012 or want to go in the same adventure than me!
So any feedback from this preampli would be appreciated, going to build it alone with no support is a bit hard.

Please let me/us know

Georges

I have a limited supply of these extremely low distortion NatSem ICs.

Common price, €10/each. + postage. Min 5 pcs, mixed ok.

Ships from Sweden, so no tax in EU.

R

Morning all. I joined in hopes of finding drivers to refresh a Fischer & Fischer SL 1000 speaker built in 2000. I purchased the speakers used. I'm looking for Seas W17EX002 bass woofer preferably in black. Unfortunately, this particular Seas woofer is long out of production. The original speakers are in white, but I'm trying to redo the speakers in all black. If you happen to know the crossover points for these speakers, please let me know. Thanks.

Hi Everyone,
I`m an EE student, loved music since i was born. I`ve been on this forum for a while to gather info and ideas since there`s plenty. Have a great time.
Marco

ONLY 12 PAIRS LEFT. HURRY UP.

€80 FOR THE REST, REGISTERED SHIPPING INCLUDED.

I have a few hundred pairs for sale. As you can see they are quite old, the 2SA is green.

Also unopened plastic bags of 50 each. Not shown here.

Price $6/pair.

R

Onsemi announced that KSA1381ESTU is end of life with a last order date of Jan 5, 2025. Is there any interest in a group buy for these?

My thought is to combine it with a group buy of 2SC3503E which is available from Rochester Electronics (link here), but only in large quantities (1000+). This makes for a good pairing as KSC3503 is currently only available in D grade.

Lot sizes will be 100 pieces of each device.

As this would be a large cash outlay for the initial purchase, we'd probably need to have money up front. We'd have to backorder them as both Mouser and Digikey are currently out of stock, but accepting backorders. Maybe it'll arrive in time for Christmas.

I will keep the first post updated with anyone interested in participating.

PRICING UPDATE:

Pricing factors in the price to order, taxes, shipping and repacking materials with a bit of a bump so I don't hopefully loose money on this.

Round 1: $30/100. For example, 100 x 2SC3503E and 100 x KSA1381E would be $60 + shipping.

Round 2: $30/100 for 2SC3503E and $35/100 for KSA1381E. The higher price in round 2 for KSA1381E is due to a price hike on Mouser's end.

SHIPPING:
For shipping, US will be $5. International will be $20 if the quantity is 100/100. If over this, I'll PM an estimate. This is due to the weight threshold where international shipping prices increase.

VAT: If there is VAT in your country, I understand this will be collected from the recipient, not paid by me.

TIMING UPDATE:
The Mouser order for KSA1381ESTU has been placed. Its backordered at Mouser with a restock date of 11/11/2024 (if Mousers date is accurate).
Domestic orders arrive in the second half of November.
International orders will go out via USPS international which shows shipping times of 1 to 4 weeks.

PAYMENT:
I'll send payment info once I get close to being able to ship. I have PayPal and Venmo.

April 2025 UPDATE:
The Mouser order for KSA1381E failed to come through. Mouser canceled the order despite it being placed months ahead of the final order deadline. It's unclear if this is a Mouser or OnSemi issue. We looked extensively for alternate sources of KSA1381E but could not locate anything that was cost effective. It was determined that KEC KTA1381Y was the next best alternative.

April 20, 2025: Profusion order for KEC KTA1381Y placed.
April 25, 2025: Profusion order received
April 30, 2025: Estimated Ship Date for Round 1 order (for those that have paid)
Early May: Payment instructions to be sent for Round 2 participants

ROUND 1: Closed for new participants (Shipping April 30 ,2025)



ROUND 2: Closed for new participants (Shipping early May 2025)



ROUND 3: Open for new participants (based on available stock)

I have a rather large quantity of these extremely versatile MOSFETs. They are of -85 vintage.

Can be sold in pairs or as sealed bags of 50.

Rated at 160V they can in many instances be used instead of 2SJ79/2SK216.

Perfect as drivers in power amps.

$20/pair. Shipping at cost.

Regards
RM

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

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

Ships from Sweden.

Thanks for looking.

R Malmin

Moving to a new house is a great opportunity to clear the shelves of stuff that’s not needed any more.

I thought I had sold all I had, but apparently I hadn’t.

So I still have several hundred pairs of the highly sought after Toshiba 2SA970BL - 2SC2240BL. They are bandoliered and will be sold in pairs of minimum 50 pairs at $5/pair. Shipping at cost.

Thanks for looking.

R

I have for sale a number of these very low Cob Toshiba TO-126 transistors. They are of course original, NOS, and will only be sold Hfe matched. Y means Hfe 120-240.

€10/set. That is for one 2SA1360Y and one 2SC3423Y.

Shipping at cost.

R

I have been rebuilding a pair of Quad ESL-63s and am getting close to finishing. By rebuild, I mean I have reglued stators, and replaced diaphragms in all eight drivers.

I used Gorilla clear polyurethane glue to glue the stators of only one speaker- the other stators were bonded well and would probably have broken if I tried to break them loose.

I used 3 um mylar film, stretched using a pneumatic stretcher, with resonance tuned while the film was on the stretcher to about 92Hz. The diaphragms are glued using 4693H contact cement that unlike the factory glue, actually bonds to the grid and the diaphragm.

I applied Licron Crystal to the diaphragms and tested resistivity and resonance before and after applying the Licron. Resistivities all came out at either 10^8 or 10^9 Ohms/square. Resonance dropped by about 1 Hz with the added mass of the Licron Crystal. For those who might be concerned about longevity, I have some old drivers that I worked on in the early 90s that used 4693H and Licron coating, and they are still in good shape.







You can see details of my failed and successful methods on my blog page, here.

I'll be installing the drivers back into the speakers and testing with full bias applied over the next couple days.

Another, more powerful Woofer. Also - could I use a compression driver? I have these small speakers. For homework.

Hi all, I signed up here years ago, so I suppose that at some point it's time to say hello.

Hello.

This might be a silly question, but I've been wondering if there are any tips for listening to parts of a multi-way speaker individually?

I've been working on some multi-entry horn ideas, but want to test out various parts individually to get a feel for how they sound before commiting to a complete build around certain drivers.

It got me thinking of using an existing speaker and just EQing out the range of interest and then using it to "accompany" the driver in question.

Please let me know if anyone has ideas about this.

Hi
in attach the first proto of 300B OT with nano
It is 3k primary
5 ohm secondary (single)
Around 40H -100Hz but some adj with gap will be possible.
At the end it will be potted.
The first test are almost fine.






The Freq. answer; there is a little step at 50kHz, but it will be fixed
Zs are 700 ohm (blu) and 1 kohm (red)
At thr moment out of the power stage that will be ready soon



The phase

cancelled due an error

I recently acquired a set of Paradigm 11se Mk-1s from a friends dad. I've read a lot of great things about them but I think they suck. Of course everyone's opinion is going to be different but I think something is wrong with them but I don't know what. Let me explain....

These Paradigms are the ones with the Vifa DT19 tweeter, the Vifa D75 dome mid (the original gray dome) and the milky clear plastic 10" woofer (I'm assuming an Energy driver). Now I know these are often considered forward sounding, and I agree, but in every other respect they are worse then every other speaker I have. The largest of the issues is the dull, lifeless, anemic bass. And yes, they very likely have the original crossovers. I know these are early Paradigms, but a custom spec'd woofer in this big box, with three big ports? Even Chris Roemer's Nano Neo MT speakers have deeper and more powerful bass. [It sounds like I am talking about blown woofers maybe, but they do work and there is no distortion...]

In direct comparison to Energy Pro22 Reference Connoisseurs, the Energy's have a wider, taller, deeper sound stage, tighter imaging, and higher resolution. The 7" pro22 woofers have considerably more and deeper bass, with much more life and texture. My specific Pro22s have Solen caps in the crossover but I bet they are 15-20 years old.

The same impressions apply to my ADC 303x speakers (with brand new crossovers), though not as deep in the bass as the Pro22s. My newer speakers are significantly better then the Paradigm, but I just wanted to compare speakers from the same era. I've used tube and solidstate preamps and amps, even a tube/classD hybrid amp....same impressions. The Paradigms simply do not match up to any other speaker I own.

Normally I would just say they are not what I am looking for but everything I read on line in nearly every form suggests they should be at least equal if not better than the Reference Connoissurs.

So what do you think? Could the Paradigms be ranking so low just from the old crossover, or do you think they honestly are worse than the Pro22s and ADC303x's (with modern crossover parts)? Something else wrong with them?

[for reference, I appreciate a darker speaker with great soundstaging higher then tonality or analytical qualities. I listen to classic rock/modern rock/pop/classical at mid 90s db's]

Hello everyone,


I’m encountering an issue with my Pioneer PD-91 CD player. When it is flat, the disc doesn’t spin when I press "play," only a slight movement is visible. However, as soon as I place the player on its side (about a 45° angle), the disc starts spinning normally and playback works perfectly. Once the disc has started, I can place the player flat again, and it continues to work perfectly without any issues 😕.


I’ve cleaned the lens, but the problem persists. Could this indicate that the PWY 1004 laser is dead, or could it be another issue (spindle motor, alignment, clamp mechanism, etc.)?


I would love to hear if anyone has experienced a similar problem and if you have suggestions on any adjustments I could make to improve the situation. Are there any settings or simple repairs I could try before concluding that the laser is faulty?


Thank you in advance for any advice and feedback!

I saw a simple amplifier but thought maybe I can do it better without to many components.
Here is the result. Its not very temperature stable but in class A it gets less hot the louder you play.
So it is just to measure the current in the output transistors = voltage over R8 or R9 and adjust it with P1 to
a little more than Feed voltage / 4 * R speaker. But take half an Hour for the heat to be stable after the last adjustment.
It is easily adapted to other voltages and speaker impedances. Distortion is about 0,1% which maybe some people don't hear.
Noise is extremely low under 5 uv 20 - 20k. Common mode rejection is determined by C2. Frequency response is good 25 Hz to 95kHz -3dB.
View attachment 1418335


But looking at the results it is possible to do it much better. Faster and much lower distortion but a little more noise.
The problem now is that the P1 is very sensitive in adjusting the current.
Now the anti thump + radio interference filter on the input is included. But still pretty simple.
I changed the R12 to 0,82 ohm because I believe the IRF 540 has about 5S at about 1A.

I ran some tests with REW while waiting for the Scarlet 2i2 3rd.
On the Asus motherboard there is a 5.1 that I use in 2.1 (4front/modified) and on the subwoofer there is a 5" Vifa.
Here is the measurement of the card with this configuration.
How do you think?

I want to buy 2 prasis crc pcb with lt4320.

Glad to finally be a part of this community, appreciate the wealth of knowledge on this site!

Hey I'm having trouble understanding exactly how I can control volume from my TV remote. I really wish TV's still had a volume controlled RCA analog output but here we are. I only have an optical out and HDMI ARC port. Is it possible to use one of those HDMI arc to analog audio converters so I can use the RCA output to my amplifier and control the volume with the TV's remote?

Which one of these caps is for the delay of the protection circuit? and what the other cap is for?

I'm looking for a schematic and any info for an 8 Channel Delco amplifier from an older Peterbuilt heavy truck. I think it may be the same as the older GM Monsoon systems used. It's an 8 channel amplifier with built in crossovers. It uses eight Delco 82452 chip amps. This one won't power up and the head unit is displaying "Check Amp Fuse".

I'm confused because I see microphones placed one meter away, and others only 20cm from the speaker.
And while we're at it, any advice on what to take to measure with quality.
the latest generation sound card, which should also be purchased, but I already have clearer ideas, will have the best features.
I just installed REW

I think Ronnie O'Sullivan has done the 147 snooker thing about 15 times. But this one was a particular goodie:

Login to view embedded media
Obviously raising his game with Reanne Evans. Like you would. But he did give her a fair chance! 🙂

The comments are achingly funny too. People who know how hard a 147 is. 😎

I've come up with an unusual amplifier topology involving boostrapped stuff, and that seems to have, shall we say... non-optimal clipping behavior. So it looks like I'm going to need a pre-clipping circuit.

Of course it should not distort at all until it does.

I've sketched a number of attempts, all involving bootstrapping the clipper diodes to reduce distortion by keeping voltage across them constant, which avoids nonlinear capacitance effects, leakage, etc. The bootstrap voltage is itself clipped by another pair of diodes, so when it reaches the limit, the other side of the diodes no longer follows the input signal and they begin doing their job.

The four ones on the left use diodes or transistors as diodes. They're strictly at the input of the amp, so they need an opamp buffer for the bootstrap voltage. The one on the right deletes the opamp by using the amp's output voltage (the power amp is VCVS E1) and using BJT emitter followers as diodes. Basically the two transistors' bases follow the input signal so they do nothing, until the diodes on the right conduct, at which point the transistors limit the input signal.

On the left is a sinewave with a smashed top.



And here is THD vs input level. Simulations are sometimes slightly optimistic, but it looks like "no distortion before it has to begin clipping" is achievable.



Thoughts?

VRDN: bipolar regulator PCB for line level ckts: ±11V to ±20V @ 1.5A with "De-Noiser"

A couple of diyAudio members and I perceived the need for a power supply board aimed at line level applications, such as for example Wayne's BA 2018 linestage. We felt it should include the following features:

• Rectifier diodes on board
• Transformer snubbers on board
• Usable with both dual-secondary and single-secondary transformers (AC-to-AC wall warts)
• True 1.5 ampere output capability, therefore: real heatsinks & big capacitors
• Output voltages field adjustable via multi-turn trimpots

The result is a PCB called "VRDN" - Voltage Regulator with De-Noiser technology. The DN technology was originally invented and published by Charles Wenzel, whose original article called it "Finesse" (link) . DN technology was greatly improved and expanded by diyAudio member Elvee, who named the improved circuit his "De-Noiser" (link) This regulator PCB implements De-Noiser circuitry, as shown in the schematic of Figure 1 below.

Capacitor C13, and everything to the right of C13, are the De-Noiser. Jumper block J3 allows you to easily disable the De-Noiser (jumper installed) or enable it (jumper removed). This gives the pleasant option of performing a before-and-after pair of tests, either with measuring equipment OR with human listeners. Try it one way, then try it the other. Which do YOU prefer?

The board includes two transformer secondary snubbers, namely (MOV1, C1, R1) and (MOV2, C2, R2). Metal Oxide Varistors perform double duty in these snubbers, serving as the across-the-secondary capacitance "Cx" and also acting as voltage clamps, if an AC mains spike or surge occurs. The values of snubbing resistors R1 and R2 were chosen after performing several Quasimodo tests on several different transformers, and I expect these resistor values will work well IN THIS PARTICULAR CIRCUIT, with a wide variety of different transformers. However, if you wish to perform your own Quasimodo tests on your own transformer, and derive your own optimum values for R1 and R2, please go right ahead with my blessings and good wishes. Just remember to insert your actual MOV1 component into your Quasimodo's "Cx" socket.

Figure 1 includes two bridge rectifier components, BR1 and BR2. Each of these implements a "Full Wave" rectifier, meaning it transfers energy from the AC mains to the DC filter capacitors, two times per cycle: once at the peak of the mains sine wave, and once at the trough. The circuit contains two Full Wave rectifiers, one per transformer secondary. One of them produces the positive DC voltage output, and the other produces the negative DC voltage output.

However, when conceiving this board, we envisioned that some hobbyists might wish to build a bipolar regulated supply but feed it from an AC-to-AC wall wart instead. This has the great advantage that it keeps the mains voltage completely away from the DIY chassis; instead of 115VAC or 230VAC, the wires which enter the chassis carry only 16VAC or 18VAC, which is noticeably less dangerous. An AC-to-AC wall wart also allows a smaller DIY chassis with less interior volume, since the transformer is now outside rather than inside the chassis. But an AC wall wart is just a transformer with a single secondary.

VRDN implements the conventional, textbook method for creating a bipolar DC supply from a single secondary transformer. It's called a "Half Wave" rectifier, and as the name suggests, it transfers energy from the AC mains to the DC filter capacitors, only one time per cycle: either at the peak, or the trough, of the mains sine wave. One HWR generates the positive DC voltage output, and the other HWR generates the negative DC voltage output. Exactly as is done in the Objective-2 headphone amplifier, among MANY other examples.

To use the VRDN board with a single secondary, AC-to-AC wall wart, we need to make a few very minor adjustments. They are tabulated in Figure 2 below. As you can see, the only changes are to the list of stuff-and-solder actions. No PCB tracks need to be cut, no soldermask needs to be scraped off. You simply do-not-stuff six components, add three jumper wires (each 2.5mm long) into pre-labeled locations, and stuff two discrete diodes into existing & labeled thru-holes. It's easy.

Figure 3 shows two VRDN boards. The top PCB in the photo is configured for a dual secondary transformer -- notice it has two green Euroblok connectors at the left edge of the board. One connector for each secondary. The bottom board is configured for a single secondary AC-to-AC wall wart. It has only one Euroblok connector and only one snubber at the left edge of the board. Everything else on the two boards is identical.

Figure 4 is a detailed picture of the input circuitry, on a PCB configured for two secondaries. Again notice the two Euroblok connectors.

Figure 5 is a detailed picture of the same region, this time on a PCB configured for a single secondary AC-to-AC wall wart. You can see that the bridge rectifiers are not stuffed, the (MOV2, C2, R2) snubber is not stuffed, and the Euroblok connector is not stuffed. You can also see that the three jumper wires "JOR1, JOR2, JOR3" have been stuffed -- look for pink arrows on the photo. Discrete Schottky diodes (5 amperes, 100 volts rated) have been stuffed -- look for gold stars. One diode is stuffed in holes "A" and "C", the other diode is stuffed in holes "L" and "M". Exactly as required by the options table shown in Figure 2.

The Jumper Options are shown on the schematic as 22 megohm resistors. This is a limitation of the CAD system and, specifically, a limitation of the CAD system USER, namely me. In truth, in real life, on your real PCB, JOR1 is either a zero ohm resistor (i.e. a piece of 22AWG hookup wire with white insulation) or else it is an INFINITY ohm resistor (i.e. an open circuit; nothing stuffed). Same goes for JOR2 and JOR3. Completely disregard "22 megohms" on the schematic. Ignore it. Pay it no attention. Simply remember that JOR1-3 are either opens or shorts. Opens or shorts. Repeat after me: opens or shorts. Look at the photos in Figures 4 and 5. Those options are either not-stuffed-at-all (open) or else stuffed with hookup wire (shorts). You can see them right in the photographs. Repeat after me: opens or shorts.

Figure 6 is a photograph of the output side of the PCB. Individual wire-to-board connections are provided for supply and ground, for each of two stereo channels. Also visible in this photograph are the vertically mounted resistors. This PCB uses the vertical orientation exclusively. Finally if you look very closely, you can see the amber colored Kapton tape on the back of the heatsinks.

TIPS FOR BUILDERS

Please carefully study the top silkscreen text layer when stuffing and soldering the 1N4004 diodes and the 1N4148 diodes. There is a little "A" next to each hole where an Anode is soldered. You'll find that on every 1N4004 and 1N4148, the cathode (band end) of the diode is the short wire which is stuffed straight thru the PCB with no bends; the cathode is the "butt end" of the vertical diode. The anode wire is the one which is bent into a 180 degree U-Turn, and is exposed for easy probing. The anode wire goes into the PCB hole with the little letter "A" on silkscreen.

First stuff and solder all resistors and axial diodes. Second, stuff and solder the MOVs and the bridge rectifiers (if using!!). Third, stuff and solder the Euroblok connectors and the two pin headers J3 and J4. Fourth, stuff and solder the small (non 2200uF) capacitors, the trimmer pots, and the transistors. Fifth, stuff the regulators-on-heatsinks (next paragraph).

After you bolt the LM317 and LM337 to their heatsinks, including the Sil-Pad insulator and the insulated shoulder washer / bushing, I recommend that you test-fit one of them into the PCB. You will discover that your unmodified assemby doesn't quite fit! You'll need to modify it. Bend the leads of the TO-220, backwards (towards the heatsink) about 1-2 millimeters. Try this. Aha! Now it fits. Put a piece of Kapton insulating tape on the back of each heatsink, over the TO-220 mounting bolt. The two heatsinks are positioned back-to-back and we don't want them to come into electrical contact. Kapton tape prevents that.

Stuff the regulators-on-heatsinks so the heatsink edges are flush with the PCB, but only solder the IC legs for now. Do not solder the heatsink mounting pins yet. Instead, turn the board right side up and look at the heatsinks placed back to back. You want to see a nice wide air gap between the two heatsinks, about 3-6 millimeters wide. When building my boards, I folded a sheet of paper in half, and half again, and again, etc., until I had a bundle 5mm thick. Then I jammed this paper bundle down between the two heatsinks to create a definite gap between them. With the paper in place, enforcing a nice gap, THEN I soldered the four heatsink mounting pins in place. After the solder joints cooled, I removed the paper bundle and voila! A nice, permanent, air gap between the two heatsinks.

Finally, stuff and solder the twelve 2200 microfarad capacitors.

SUMMARY OF FEATURES AND MIS-FEATURES

• De-Noiser circuit with jumper enable/disable
• Diodes on PCB
• Transformer Snubbers on PCB
• Big capacitors on PCB allowing true 1.5A output
• No bleeder resistors on PCB
• Voltage regulator ICs mounted on heatsinks for true 1.5A output
• Heatsink thermal resistance is 8.6 deg C per watt
• This is a four layer PCB, three of which are ground planes
• Gerber CAD files freely available, send to any fab you wish
• No "pilot light" LEDs on DC outputs
• Can use with either dual secondary trafo or AC-to-AC wall wart
• No SMD components; 100% thru-hole
• PCB unique identifier is TZPTR7 ; suffix -A means "revision A"
• PCB mounting holes compatible with Modushop chassis baseplate
• Board size 62 x 142 mm (edges) ; 50 x 130 mm (holes)

NEW INFORMATION

• 2023-12-21: a Forum member has created a new PCB layout of VRDN with only two layers. He has made the Gerber files freely downloadable in (this thread). Be sure to read his Disclaimer and non-Guarantee at the bottom of post #1.

I have a Quad99 system, with AE speakers, which yields a sound akin to analogue and I love it. Unfortunately, the CDs have started to skip after a minute: everything is fine, then it stops and the display goes ape with numbers randomly flashing on the screen. I suspect the laser lens is playing up. I use a CD lens cleaner but it obviously is not man enough to do the necessary. So, do I buy a new CD lens cleaner, or open the CD player up and try to give it a good clean (compressed air? vacuum?). Or, as it seems to work fine for a minute, could the laser lens transport be at fault? If so, how can I confirm?
Has anyone had a similar experience? How easy is it to get inside a Quad99 CD player? Any suggestions???
Cheers

Hello everyone,

I’m working on designing a Class H audio amplifier with a power output of 2000W RMS at 4Ω load, and I need some guidance from experienced designers.

I've previously designed a a 800W RMS Class AB amplifier for outdoor applications. Now, I want to develop a high-efficiency Class H amplifier for professional audio use.

Key Requirements:​

✅ Output Power: 2000W RMS @ 4Ω
✅ Topology: Class H with multiple rail switching
✅ High Efficiency & Low Distortion
✅ Stable Power Supply Design
✅ Thermal Management & Protection Circuits

I’d appreciate any insights on:
🔹 Proper rail voltage selection for efficient power switching
🔹 Best MOSFETs/BJTs for high power handling
🔹 Reliable protection circuits (Overcurrent, DC, thermal, SOA protection)
🔹 PCB layout guidelines to minimize noise and EMI
🔹 Any reference schematics, simulations, or design resources

If you have experience in designing high-power Class H amplifiers, I’d love to hear your advice! Feel free to drop suggestions, references, or even share your past projects.

Thanks in advance! 😊🎛️🔊

The Mission 778X is based around the design of the Quad Vena II and Leak Stereo 130 which both use the LM3886 as far as I know. Looking at internal pics I can see 6 forward pins on those two but the 778X has 8 forward pins so maybe a TDA7293? Specifications are similar for all the amps and are made in the same IAG factory. I assume when the 778X was designed, the LM3886 supply issues came into play.

I can't see enough through the vent holes and as it's new I do not want to remove the cover as well I do not have a Torx bit small enough.

Looking for a NOS pair, ideally in the UK or Europe.

Hi Folks,

I'm not an expert on SPDIF nor transmission lines, so bear with me please!

Background:
My good old well working Audio DSP has a digital output port with CS8420 feeding a AES3 (with TXP & TXN) and a Cinch (75Ohm) Output (with TXP) in parallel at Pin26.
The picture "original" shows the output schematic as far as I could analyse the (4-layer) board (pretty obviously with supply and GND layers). GND on the board is split between the output connector area and the circuit area (for unknown reasons) bridged with 0Ohm parts.

My Plan and request for confirmation or advice what to do:
The DSP is planned to drive 5m/15ft long koax stereo SPDIF BNC connections to each of my stereo speakers sporting digital 4-way "mono" x-overs. I.e. whether the speaker is "left" or "right" is selectable in the speaker. So, basically I need two parallel BNC Outs (would remove the cinch connector and disconnecting AES3 circuitry).

Please kindly have a look at the schematics and options I have come up with. I am sure my stuff needs changes to work properly, so I would be very grateful for recommendations "how to do this right".



Thanks a lot for reading all this and I hope you care to answer with any helpful recommendations.
Regards,
Winfried

Looking for 1pcs 2sk60 rank 5 or 6.
Can also trade for ...i have 100pcs 2sk170, some Black Gates, good European triodes, new in box ecc82 Telefunken, e88cc, ecc83, 3pcs rda1541
I have also 1 set of D3 tda1541 boards with 50% ,parts.
Maybe chinese board heavy modified es9038q2m with first generation Bisesik nanocrystalinev output transformers hi-fi tunimg silver gold 10A fuse new in box.
Thank you.

Offered here, for your consideration, an original prototype FirstWatt F6. Built and sold at auction in support of Burning Amp by Papa in 2023.

This amp is of the original design configuration that used SemiSouth JFETs, not the MOSFETs that the commercial F6 used. Note the dual LEDs on the front. I have no proof but I believe Papa assembled this himself. The amp was opened and pictures taken at BA that year, I have not opened it nor messed with it or put it on any test gear, but I have listened to it lots in my main system. There is nothing at all wrong with this amp. To my ears, and in my system, it is the most detailed amp I have heard, but for some mysterious reason I favor the air and liveliness of my F5m and Aleph Jzm more.

I paid $2600. I am asking $2600, plus shipping to your locale (it will come in the factory original shipping box). If you happen to reside in Northern California, I'm open to arranging a pickup but please be patient with me as I work for a living and have some travel coming up. This isn't about the money, it's not a forced sale, I'm not in a hurry, no low ballers, I know what I've got, etc., etc. I've just listened to this amp enough to learn from it and I'm willing to pass (haha! Pass) it on to another aficionado.

Thanks for looking.

First, forgive me that I have not posted here in ages. I'm looking for help with my much loved Threshold FET ten/hl preamp. In my system the outputs of the FET ten/hl are connected to a homebrew converter using Jensen JT-6110K-B 4:1 stepdown line input transformers. The balanced outputs from my transformer box feed a pair of Schiit Tyr monoblocks.

The problem is I have been measuring about a 5 dB drop off from 40 Hz to 20,000 Hz at the outputs of the Tyrs.. My first thought was the problem might be caused by excess capacitance in the cables running from the transformer box. I swapped out cables. I removed the transformer box. I swapped out a lot of things. The only thing that fixed the drop off problem was disconnecting the FET ten/hl and putting in a different preamp. Nothing else made any difference.

Would anyone have thoughts or suggestions?

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

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

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


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

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

Here’s some of the pros of this approach:

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

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

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

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

I've recently came across a new cheap little component tester that does way more than just the usual few basic tests.



This little beauty also can do basic DSO functions and is also reasonably accurate. There's also a signal generator and a full set of electronic diagnostic testing, including cap leakage/ESR, full inductor parameters and decoding IR remote waveforms, automatic pinout recognition of just about any device, including IGBTs, SCRs, diacs, triacs, all sorts of diode types, etc etc etc.

It run off an internal battery rechargeable through USBC and includes cables,, probes and connectors. The menus are very easy to navigate through and most tests are done very quickly. I've been trying to find specific devices it doesn't recognize or can't test. So far I haven't come across any (excluding ICs, but it will detect some lower voltage 3 pin Vregs!)

The best part is this tester is that its quite accurate and only costs $43!!!

looking at building some pensil type speakers, and at the moment don't have the drivers called for in any of the designs. Is there some rule of thumb that I can use to modify the box dimensions to get close enough to re-size the box to drivers I do have?

Drivers I want to try currently are Mark Audio CHN-70. There will be others soon enough, I'm sure.

I have modeled a few of the various published boxes in CAD (I use fusion 360), so that I could figure out the net volume (not including the driver), and have not really figured out what speaker parameters are the cause for a bigger or smaller box. I'm guessing the Fo, and the Qts are the more important numbers, but also the Vas?

pensil R70.3 has a volume of 2124 in3, pensil p70.2 has 2098 in3 - Not a huge difference. The original pensil R70 had 1792 in3 and the p70 had 2303 in3 volumes. I have not found the specs on those drivers yet to compare. of the currently available drivers with parameters listed online, the CHN-70 look closest in t/s parameters to the CHP-70 gen 2, though they have slightly lower Qts, larger Vas, smaller magnet, and lighter cone. I could try a box built to the same size as called for in the P70.2, but if I knew how to adjust these properly, it might save a bunch of trouble.


I'm also curious about bracing on these boxes. They don't seem really big enough to need it, but the plans say to refer to how the super pensil is braced, which is easy enough to follow. What I'm not sure about it whether I should keep the overall volume inside the same with the bracing, or increase it based on how much space the bracing takes up.


I have hornresp on my computer, but haven't quite figured out the ins and outs of getting useful information from it yet. I'll mess around with it some more and see if I can figure out how to input models of this kind of speaker (this is a mass loaded transmission line?).

Hi everyone, I'm a new member so let me tell you why I'm here! Since last year I started collecting vinyls and eventually found myself getting into audio equipment but I'm new to this, never really made any repairs myself. I know the basic of electronic but it's all text book, never really tried it out in real life.

For now I want to work on amplifiers mainly for turntables that I found in thrift stores or on marketplace.

That's it, lets see where this goes! 🙂

Hi everyone

I've been working professionally with solid state amplifiers for over 3 decades , and have been surprised by the sudden surge of devices going EOL. I believe that traditional class AB amplifiers are not going away, but are transitioning away from the mainstream to a boutique market. Valve amplifiers saw this happen a long time ago. With that said, there are a lot of high end solid state amps being built, and specialized parts sources are out there to supply them. I would like to list a number of sought after device type easily available, in some cases with a different part number.
They are available from Profusion plc in the UK. We have verified samples of everything listed here in pro audio gear made by LAR audio systems.
LAR audio is reason I had to locate some new sources.

KEC DEVICES (Korea Electronics Corp.):

KTA1381 / KTC3503 300V FAST VAS STAGE TO126 Replacement for the EOL ON devices really fast high voltage VAS
They should be in stock by Jan.

KTA1837 / KTC4793 230V VAS / DRIVER TO220 Replacement for toshiba 2SA1837 / 2SC4793 , good VAS and driver , in stock

KTA1700 / KTC2800 160V VAS / DRIVER TO126 Replacement for 2SA1220A / 2SC2690A , GOOD VAS and driver in TO-126
They should be in stock in Jan

KTB2640G / KTD1640G 150V 130W FAST DARLINGTON OUTPUT TO3P N Replacement for Sanken 2SB1647 / 2SD2560 improved SOA, in stock
This is a really nice output device for simple hifi amps

KTA1943A / KTC5200A 230V 150W WIDE SOA FAST OUTPUT TO3P L (TO264) This is an enhanced version of Toshiba devices, almost identical to 2SA1302 / 2SC3281 in every way , but higher voltage rating.

Unisonic This is not the most serious sounding name for semiconductors, but it is an established OEM supplier in Taiwan.

2SD669/A / 2SB649/A The TO126 versions are a good substitue for 2SA1220A / 2SC2690A There is some confusion about power ratings on the data sheets because they come various packages, including SMD, and the rated power is in free air We have verified that the SOA curves for the 2SD669A apply to all TO126 devices when on a heatsink.

2SA1837 / 2SC4793 The TO220 versions are also like the old favorite, but they are available in various case styles.

I may have post this in the wrong area, but searching threads, most appeared to discuss a specific need for a specific project. I hope I have been helpful to continue on with the construction of fine Transistor amplifiers.

How about this to start it off ?

The Class-A Amplifier Site - JLH Headphone Amplifiers

Hello noob question here.
If a schematic for a tube amp calls for a 300-0-300@ 200ma can a 300-0-300@390ma be used or will the extra ma's cause problems?

Many people say that dome midrange drivers have a sound quality which is unique and desirable. I have heard systems with dome mids that sounded very good, and others which were very ordinary. This thread discusses this topic in detail....link

For the past year, I have been thinking about the Bliesma M74A-6 driver, and simulating various options to use it effectively. To me, this driver offers an excellent way to experience the power and potential of a good dome mid in a high performance application. I like that it operates pistonically over its full range, and the first mode resonance is more than an octave above its likely pass band. This feature sets it apart from its silk and paper dome sisters. I like that it has high sensitivity and high SPL capability. I like that @HiFiCompass has measured very low harmonic and modulation distortion at high SPL. I like that the “A” aluminum dome version is considerably less expensive than the beryllium and textreme versions.

Thus, I started this project with just one primary requirement, that it use the M74A driver.

Index

I was reading about SLAPS Passive Radiators. Please see attached SLAPS_manual_ENG.pdf. It just has two back to back attached surrounds sharing same PR disk mass.
Attached are front, side and rear images of SLAPS PR, the slots on one surround are just to avoid air compression during operation which will otherwise damp the movement, for our discussion, the slots can be ignored and we can assume that there are two back to back surrounds without these slots.

One effect I immediately see is that this SLAPS will increase effective stiffness of the PR as each surround is bringing its own stiffness. I assume that we can punch in the numbers in a PR simulation program like Unibox and generate the frequency response of the system.

However, I was surprised to read SLAPS_manual_ENG.pdf and found some things deviating from usual theory of PR working and I have listed down only those points below. Can we have a discussion on each point to either accept it as mentioned in SLAPS_manual_ENG.pdf or dismiss it as gimmick? I have also mentioned my understanding for each of the point below in italics.

1) Claim: The revolutionary efficiency and performance are the result of the pneumatic coupling between SLAPS and the active driver.
Wait, 'pneumatic coupling'? I thought this supposed pneumatic coupling was also valid with a normal PR, how does that suddenly improve with SLAPS?

2) Claim: The unique design allows the active driver compression-free movement resulting in deep, dynamic and hard-hitting bass response.
In case of normal PR, the PR size is one greater than active driver, for eg for 12" active driver, a 15" PR is recommended so that we dont get xmax related compression. Whats so different with SLAPS?

3) Claim: Conventional computer modeling software will not work correctly with SLAPS and will in most cases greatly overestimate the internal volume of the optimal cabinet.
Why does double surround PR break simulation?

4) Claim: SLAPS increases a subwoofer efficiency and capability for ultra low frequency reproduction (very deep Sub-bass) without the drawbacks of traditional designs.
So, I read the patent and attached the PR excursion vs frequency plot from the patent, as you can see they show more extension for SLAPS and a steep fall response for normal PR, why this difference in bass extension between both?

5) Claim: It gives you much better performance due to the increased surface area and the fact that the particles of air
inside the enclosure and outside the cabinet moves with the same speed and in a near phase relationship. Phase means that the active device and SLAP work almost concurrently and simultaneously creates respectively pressure and counter-pressure at the same time.
Now, what is being said? I am lost in the phase jargon. And both active and PR dont move in unison, there is air spring the sound wave has to travel that air-spring, of course due to the wavelengths being so large they may appear concurrent due to very small delay, but this is valid for normal PR also. What is so different with SLAPS?

6) Claim: A traditional bass reflex port design, the system is limited in performance due to the air in the reflex port not being in phase or at the same speed of movement as the air in front of the active driver.
As far as I understand the PR does exactly what the cylindrical air mass of air does in a bass reflex port. What limited performance is being described, is it port velocity limit of port?

7) Claim: Active woofer unit should preferably have a resonance frequency (FS) of 30Hz or less and not more than 35 HZ.
In the entire document, TS parameters are never considered or even mentioned and now this limit imposed on Fs, why cant I take Fs of 40Hz and tune PR to 25Hz? Haven't people done that already?

8) Claim: Typically 16 mm MDF or thicker. Particleboard or plywood are also excellent materials.
For long stroke active driver and long stroke SLAPS PR, isn't 16mm too thin, should it instead be saying to use more thickness and more bracing than used typically?

9) Claim: It is important that you do not exceed the maximum specified enclosure volume. The air inside the cabinet acts like a spring and the larger the enclosure the lower the linear output. This also introduces distortion.
10 "inch 20 - 45 liters internal volume sealed cabinet
12" inch 30-60 liters internal volume sealed cabinet
15 "inch 35-100 liters internal volume sealed cabinet
18" inch 50-140 liters internal volume sealed cabinet

As far as I understand the opposite is true, and this is what I read, I dont remember where. Lets assume the volume of air displaced at Xmax of active driver is Vxmax in each direction, then as the cone goes in at Xmax the active driver reduces the volume of the enclosure by Vxmax and the stiffness of the enclosued volume increases, same way, as the cone goes out at Xmax the active driver increases the volume of the enclosure by Vxmax and the stiffness of the enclosued volume decreases. This increase and decrease if substantial, causes distortion. If the enclosure volume is large then the Vmax and the corresponding change in stiffness is negligible and distortion is negligible. Now, if if we reduce the enclosure volume then this Vmax becomes a sufficient portion of enclosure volume causing large changes in stiffness at both the ends at Xmax, thus distortion increases. The Vmax of the driver should not be more than 5% of the enclosure essentially putting a lower limit on tghe enclosed volume. Thus, a large active driver needs larger enclosure and higher Xmax also needs a larger enclosure. Of course, the actual frequency response still has to be simulated. Isn't it the same reason that when Sunfire put their large excursion drivers into very small enclosures they had to improve distortion using servo based electronics/amplifier? How does a small volume benefit SLAPS?

10)Claim: By placing SLAPS right next to the active woofer so you run the risk that at the acoustic resonance frequency there may be a negative interference which and the can lower the overall sound pressure level of the deepest bass tones. The lower the resonance is set, the less likely it is that there will be an issue. Best results are obtained by placing it on the back or side of the cabinet.

Firstly at box resonance the active driver moves the least, it hardly produces sound, the entire output at this frequency is from SLAPS so where is the claimed cancellation coming from. And if we move the SLAPS to rear even then both the drivers output is within 1/4 wavelength, so if cancellation has to somehow occur, it will occur the same way with a rear mounted SLAPS, no?

Thanks in advance,
Warm Regards,
WonderfulAudio

I’m about to embark on building the Lampucera DAC, as described by Serbian YouTube star iiWi, You can see the video here:
Login to view embedded media
He claims this is the best DAC he has ever had in his listening room.

The DAC is a precursor to the Lampizator line developed by Lucasz Fikus. Details, documentation, from iiWi here:
https://drive.google.com/drive/folders/1MvSMdEsZ8DPtGMXrzUgQ7ceyAVS86uxO?usp=sharing

Ebay starting kit from HKaudio1 (Lawrence, who has been very responsive):
https://www.ebay.com/itm/1863217614...zPANM_6Rl2&var=&widget_ver=artemis&media=COPY

I’m probably not going to use Lawrence’s included tube output stage, instead following iiWi’s version with the 6N6P [but maybe experiment with the eBay one first].

My first two question areas, for which I am seeking advice:

1. What do you recommend as a source for metal chassis that is easy to mod, and large enough for transformers and giant capacitors as iiWi had?
2. If you look at the schematic, it is based on 220V transformer on input. I have US 120V input. What transformer changes are needed?

• A. Best to stick with toroidal transformers? Seems like a lot of audio guys prefer laminated. Can you recommend any source that is up to the standard here?
• B. I assume it’s easy to find a 120V to 6.3V transformer for tube heater. Any suggestions?
• C. It looks like the anode supplies start with 120V. Does that mean I don’t need any transformers for them?

If anybody has done this, and/or has advice to offer, I’d be most appreciative.

I'm a 2 year student of Ho Chi Minh university of Technology, Electrical & Electronic Faculty. I have passion on making amplifier so that is the reason why i choose that faculty.
It's nice to meet youuu.

I got this amp with the power supply and output sections both having blown fets. I replaced the fets and now when I power it up the power supply starts fine for the first 3 seconds Drawing .4 amps. But when the output stage kicks on the amp draws current for a tenth of a second and the output side shuts down. And keeps cycling this way

Dear all,
more for experimenting than of any practical value I would like to ask
this nice community for inputs & opinions on two related, highly theoretical projects,
the first one realistic, the second one utopia. I asked ChatGPT a bit for answers, but I'm not sure
how accurate the information gained is.

Project #1 (software):
Task: Retrieve digital audio samples of very high quality.
Split the audio range (20 Hz - 20000 Hz) of these samples into non-overlapping, logarithmically spaced bands of a variable number "n".
"n" variable for experimenting, f.ex. n = 1 up to 1000.
Measure total amplitude of every single band and apply this amplitude to a sinus wave of each
band's center frequency. Add all these new sinus waves together again to receive a summed signal which is a 'reduction'
of the source's audio signal (Fourier etc.).
Base Questions: How many bands "n" at a minimum are necessary to understand voice signals again from this source signal reduction
& resynthesis ? And how many at a minimum for 'rather' uncompromised audio quality ?
(Interestingly modern cochlear implants (of course no HiFi quality) use the very low number of 8 - 22 different frequency bands,
that are overlapping, however, and thus correspond possibly to 6 - 12 different bands only, effectively !)

Which software(s) then could do this job for sample source signals efficiently and accurately, but not necessarily in real time ?
(the problem is of course more complex, because not only amplitudes but also the phases of the signals also are important
across these manipulations).

Project #2 (practical utopia):
To build a loudspeaker with a large multitude of single low cost chassis.
Each chassis emits only one single fixed frequency, and each is triggered by an upstream
(cheap & as small as possible) amplifier that receives modulating input only from single sinus waves
(from Project #1).
Question: What is the minimum number "n" of chassis with logarithmically spaced fixed sinus signals
to recover 'rather' optimum audio quality (20, or 40, or 200, or 1000) ?

thank you kindly for any input & critique,
good night,
FrankieS