I need to replace the 4 filter caps in a subwoofer plate amp. The stock caps are 10000uF, 80V, 30mm caps. I can't find anything close that will fit. Options: 1) use caps that will fit but are 6800uF 80V, 2) use caps that will fit but are 10000uF 63V, 3) bite the bullet and figure out a way to mount the caps in some way other than through the existing holes on the PCB (I don't really want to do this but I will if I have to).

Hello- looking for some of these waveguides. I'm sure many of you have some of these in your stash.
thanks!

Hi I thought of buying the Adcom GFA -5xxx series amps with Mosfet output as they are available very economical prices considering their Chassis and FETs ( the Schematic looks more like PASS designs except Class AB with higher Voltage power rails. How good are they as a Garage amp ? Also can they be modified for more Class A output.
Welcome ideas and suggestions
kannan

In my mind i have a setup with two subwoofers. in my case i still have four dayton audio RS225-8 laying around.
And I want to drive them with an amp, integrated in the case.

After that a D'Appolito MTM setup on top of the bass tower speaker. With two mono-amps, but the question is class d or class AB?

Question 1: Do you think a Class D amp has any disadvantage for such a setup?
(Like a Fosi audio or Aiyama class D amp pcb integrated on the back of the speaker box)

My thoughts: maybe these class-D amps have disadvantages when it comes to high frequencies regarding distortion, damping factor etc. but for signals up to 200Hz, they should be fine. Your thoughts???

Question 2: More or less the oposite of question 1: Does a Chip-Amp (like the LM3886) do a better job for driving the mids and a separate Chip-Amp for the tweeter compared to a class D amp?

My thoughts: These higher audio frequencies are coming closer to the switching frequencies of the class D amp (like a TPA3255) and thus maybe lack clarity or contain more switching noise if compared to a class A/B amp.

Your thoughts? Do you know of any interesting comparisons, maybe measurments, maybe experience, maybe just thoughts on the theory?

Thanks for your input and maybe i could tickle your brain or interest with that question.
Stefan (Funkmaster WhyLee).

Yup, improved iteration of previously made Babelfish M25

Who remembers - 'twas bstrdzd FW M2 with implementation of XA25 main trick - Square Law arrangement of OS mosfets, in simpler words - mosfets in OS put to work without source resistors

Result - looooow THD of OS, but main difference being broader A Class envelope , most prominent in context of 4R load - where regular M2 is KlunK!ing around 12-13W, while B. M25 doing the same around 40W ...... rest to max being KlunK!

This pcb made for easy implementation of Schade arrangement for one OS mosfet, arbitrary chosen to do that with lower one, even if that is making some problems with choice of small mosfet for source follower/level shifter ....... I need one with lower Ugs treshold ( it adds to Schaded mosfet Igs) , and P channel small mosfets with that are scarce, somewhat

Anyway, find enclosed both schmtcs, full one ( all parts on pcb populated) for SET (Schade Enhanced Thingie) and second - few parts omitted - for Babelfish M25 R.2

note - slight tweaks of THD Spectra, for one's Golden Ears, possible with change of output mosfets - down one can use either IRFP9140 or 9240, up can go IRFP240 or 150

about that later

reminder - extensive ( if crude) explanation of biasing mechanismus posted in LuDEF thread , posts #32-#37, LuDEF

Today - all files for Babelfish M25 R.2 ; anyway - read captions - each file is properly named and have caption

edit on 28.04.2021. - SET amp presented from post #20, there is also full proper schematic pic (here just funny non-working thumbnail)

edit on 13.09.2021 - few general setting procedure tips and tricks:

procedure applies to both Babelfish M25 R.2 and SET amp; as seen from schematics, difference in circuit is small; if you need help how to arrange shortie/jumper for signal path in Babelfish M25 when few SET parts are missing - buzz .... in fact - I'll make few ics tomorrow ( I hope) and put here , showing exactly that missing piece of info

-will not teach ya how to solder everything properly - as always -Assembly of Japanese Bicycle Require Great Peace of Mind

-prior to powering up, be sure that you have trimpots set properly:

P102 (P202) - irrelevant
P101 (P201) - set to max; confirm with ohmmeter across R104 - in vicinity of 28R
P103 (P203) -irrelevant
P104 (P204) - set to min ; confirm with ohmmeter - improvise where to put probes

- jumpers JP101/201 - open/not mounted

-as always - best to work with one channel connected to PSU at time; in fact - first step just one channel , in second step - you can freely leave powered/connected already set first channel

- one VMeter across output ( DC offset) , second VMeter across any of current sense 0R22 resistors; use mini-clips/probes

- no load on output, input shorted to GND

- power up thingie; observe DC offset - it will rise slowly and everything up to several volts is normal in this moment

observe VMeter across 0R22 resistor - it will be Dodo reading for some long time; after 60-90-120sec - if you don't see any substantial reading , start fiddling with P104 (P204), one turn at time; of course - you did remember where you rotate itr to set to min value, now rotate in counter direction; - don't ask me which - I don't care, I can't remember, simply because I'm always trusting in DMM, not in my memory how to orient damn trimpot to have screw in proper place ....... and my logic what needs to be decreased and what needs to be increased is always ooked, vs. overall consensus

allow 30sec or so between 1-turn steps, to observe when and how much mV you're getting across 0R22

goal is , , say for 1A5 of Iq - 1A5 * 0R11 = 165mV

keep fiddling to get mV creeping up, and once when you see steady rise for each turn, set da thingy to - say 140mV

once when you're there - fiddle with P103 to get as close to 0mV of output DC offset

that would be preliminary setting of OS, now to input buffer setting :

- power off , put mVmeter across R106(206) test pins ; put second mV meter on jumper pin marked "B" and GND

power on, fiddle with P101 to set 20mV across R106(206) ; done - fiddle with P102(202) to set as close to 0mV for buffer output offset ( second
mVmeter) ; when done - power off, close jumper


*************** connect second channel to PSU, repeat entire procedure******************

when done with both channels , power on , re-set Iq of both channels to have 1A5 or more ( there is really no need for more - Square Law OS is crazy thing, but do what's shaking your cage most) somewhere in temp equilibrium, check output DC offset

slide of both Iq and DC offset - cold vs. hot - is really minimal, but I'm mentioning thermal equilibrium more thinking of importance of final temperature of heatsinks - observe, observe also temperature of output mosfets , that will give you info/confirmation how good and uniform is thermal interface between mosfets and heatsink

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

when done, connect signal, speakers, flip da switch, and enjoy

don't forget Da Porn - no Porn, no Glory

Hi,

The stage is sometimes referred to as SRPP, totem-pole or whatever.
I'm no expert on the matter so I'll just refer to it with the name I read in Merlin Blencowe article, 'half-μ stage'.

Here is a picture of the actual stage, from his article:


Nomenclature aside, I'm interested in using this topology (instead of a usual SRPP), to amplify voltage coming out an AD1865 DAC with resistor I/V.
I'll be using 6Η23Π (soviet equivalent to ECC88/6922) with B+ around 200VDC.

So, my simple question is regarding the Rk1/2 values.
What are suggested values for them resistors??

In SRPP applications using the same tube I have seen values as low as 75Ω and as high as 820 with most common values being around 150-200Ω.
But this is different to an SRPP and I have no idea on how to calculate the right value for them.

By the way, I want to avoid bypassing the resistors.
I have no need for the lower impedance.
Following stage will be high enough (47kΩ minimum).

Any suggestions would be appreciated.

Thanks!

I own an 80's cd player, the DENON DCD-910A. It uses the PCM56P as a DAC and it still sounds very good.
I was thinking to use it as a DAC, but I have to find out a way to install a SPDIF input somewhere into the existing circuit.
Since the most of my audio files is stored in my computer, I want to use it as a DAC and isolate the CD.

Is there any way to put a SPDIF input (or USB or HDMI)?

I have attached the circuit and IC pages from the service manual.

Hmmm, well this is what I get for looking through the PE buyout section...

https://www.parts-express.com/Tymph...-Paper-Cone-Woofer-8-Ohms-299-2265?quantity=1

High efficiency (94.8 dB) 8" with a big honkin magnet for $17. I impulse-bought a pair. What am I planning to do with them? I dunno! Loud / Efficient vented 2-way (with active high pass)? Anyone else making plans for this woofer? I searched on here just a bit ago and didn't find much mention of it. Seems like an interesting driver for relatively cheap, let's taco bout it.

Sold

Asking $50 including USA continental shipping.

This is just a sale for the populated buffer, some extra parts, and the Meanwell PS to supply the board. You will need to finish it with a chassis, connectors, etc.


Populated and tested in 2022, not used in a system. Includes the Meanwell PS, extra parts, schematic and BOM as shown.

Shipping to USA only.

Sold

Asking $110 including USA shipping.

I got this essential kit from Patrick way back when, and will not likely build it out, so up for sale.

This is not the newer SMD version of the boards.

Includes: Two 2021 boards, all transistors, Two Cimemag CMOQ-4HPC, and a twister selector board. There is a photo of a "whats included" sheet.

For Sale:
PCB's for a pair of TDA 7293 monoblocks.
$75.00 cdn

Hi, I should change the ceramic caps to my Deq2496.
The image below shows the values ​​I have to go to put.
Part of it is missing, capacity sensing work is not done yet.
The reason is that the original ceramic capacitors are bad.
They are the capacitors that are on the "everything" power supplies.

For this work I bought wima MKT capacitors (polyester), 2.5mm pitch.

Is it a good choice I had to choose the MKP (polypropylene)?
Unfortunately polypropylene is a bit too big and I was hoping that the polyester could do the job well.

One last question:
It would be appropriate that the old ceramic capacitors take them off right? Or am I going to put the wima directly in parallel with the ceramics?
I think the ceramics should be removed!

Thanks for your suggestions! 🙂
😀

Hello Experts,
Im new to building dac streamer based on Gaby's post.Running on NO sound issue. MonitorPI is showing the streaming info when played from Moodeplayer (photo attached) but no sound is coming out. Not sure if I need to do any code change.
Protodac mounted directly to RPI works fine

Please see details below

Login to view embedded media

• Also soldered the UFL Cables to 3 resistors output - it is 1- WS / 2 - DATA / 3 - BCK (photo attached) for the I2S

I researched the forum found the following post and verified all listed item - they are all correct


https://community.volumio.com/t/ian-canada-fifopima-with-protodac-no-sound/65378/3 - From Volumio

• LED of XO1 or XO2 clock - Light up (photo attached)
• The lights that are on (in the Fifo) are:
  -D2 power of course
  -D3 I2S format input

Parts:

1. #48B. PurePi II 5V+3.3V ultracapacitor/LifePO4 battery power supply combo with ultracapacitors/battery holders pre-installed
2. Rasberry Pi 4b - 2Gb

3. FifoPiMa V1.5 Master mode Raspberry Pi I2S/DSD/DoP Re-clocker with ultra-low phase noise XOs​

   1. MonitorPi RaspberryPi OLED audio display/analyzer​

4. Protodac​

Please see attached photo

Asking $40 including shipping.

Two unused LM3886

Four pair of 170 BLs from one of the reputable dealers of old. I did build a number of amps from these same transistors. All test around 7.6 Idss,

I matched quad of LSJ74B from before subgrouping was done. I guess I never checked where they are on the current spectrum.

I have replaced quite a few 4558 opamps with NE5532 and always put a 100nf cap across the rails when doing so. Never had an issue.

When replacing a 4558 with a 2068 is the 100nf cap still needed? I think so but wanted to ask the experts. Yeah I know it is easy to just put it in and it won't hurt anything. I am just curious more than anything.

Thanks.

I have many amplifiers but i can't afford the cost for housing.
Here is an attempt for my own building.
Heatshinks is a donation from the past.
Thank you Toni. 🙂
So far I have spent 25 € on the aluminum, front and back sides as well as the perforated sheets.
10 € for spray primer and paint.
Front and rear are aluminium.
Top and bottom are 3mm steel.

1x pair of Tamura VL-207 variable inductors

variable between 0.5H-5H, 7ma

For those who want to give Sakuma's phono preamp circuits a try!

sold

Almost thirty years ago I got fascinated by the tech around the first Tripath amplifiers.
I'm basically here to gather the knowledge I need for a hobby project of mine I had in mind since then (and that I will never have the time to actually finish). Oh well, they say it's about the journey, not the destination, let's make this trip together...

I’ve seen some threads discussing this but I haven’t found any that definitively answer all my questions. I’m trying to build a tube preamplifier (all point-to-point wiring, no PCBs or anything) for my Hi-Fi setup and I’m not sure what kind of wire to use for internal connections?

It seems there are a lot of options, i’d like to know what gauge wire is best? What material, pure copper or tinned copper? Is braided or solid better? Does it need it be shielded or is this not important? Is this going to be something that significantly affects the sound? I imagine it's not extremely important but I'd hate to compromise the sound cause I used bad wires or something.

Thanks!

He was and is one of my favorites.
https://www.npr.org/2024/12/15/nx-s1-5229593/zakir-hussain-dead-india-shakti-tabla

Hi to all,

quite often, it happens to me that I have to measure the capacitance of large capacitors (1000uF- 22000uF), possibly with a reasonable precision. Unfortunately my beloved multimeter is only capable of measuring capacitances smaller than 220uF.

How can I measure those large values?

Thx a lot in advance to everyone for your precious hints

Hi all,

I was wondering if anyone considers building the valve DAC from Linear Audio volume 13 (which is not a solid-state DAC with a valve-based output buffer, but which uses E88CC valves as the actual DAC). If so, I would be very willing to answer any questions about it. If there is more than one person who wants to build it, you can save a considerable amount of money on the main PCB by ordering it together.

Best regards,
Marcel

Edit, 18 August 2020...5 December 2024:
There are two versions discussed in this thread, the original valve DAC described in Linear Audio volume 13 and a raw DSD variant (also called the DSD-only variant) which was first built by Ray from Somerset, a.k.a. nautibuoy, and Dave who is also from the UK, a.k.a. snax (who had not finished it yet on 18 August 2020). Ray started a group buy for the raw DSD variant, see posts #481 and #661 among others: https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6299387 https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6311952 . An earlier attempt by leadbelly from Calgary to start a group buy for the original valve DAC did not work out, but it was restarted after the raw DSD group buy, see Interest for GB for MarcelvdG valve DAC .

Original design:
As the Linear Audio website will soon be closed, the files formerly accessible via the Linear Audio site are now attached to post #2162 with the former Editor's permission, see https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-7863549

For the record, when I wrote the Linear Audio article, I was under the impression that high-order single-loop sigma-delta modulators had been known since around 1990, but I later learned that Robert W. Harris already made them in the first half of the 1980's. See US patent US4509037 (application filed 1 December 1982, date of patent 2 April 1985) for details.

Raw DSD variant:
see posts #84 and #86 of this thread for the raw DSD variant, with some updated documentation in post #713.

Main differences between the variants:
Original:
-Mainly designed for PCM; generates its own sigma-delta modulates from a PCM input signal using an FPGA module and an SRC4392
-Supports DSD64 and DSD128 by first converting them to PCM
-Valve clock generator (just because I wanted to make all analogue and mixed-signal functions with valves)
-Quite expensive

Raw DSD variant:
-Designed for raw DSD; it doesn't need any FPGA or SRC4392, because the raw DSD signal is already a sigma-delta modulate
-Can support DSD64, DSD128, DSD256 and DSD512
-Gets its clock from an external solid-state clock generator and buffers it with some more solid-state circuitry
-Much less expensive

Ray uses the raw DSD version with a computer running HQPlayer, so he can use the raw DSD version and still play PCM. Basically he uses the computer to do what my FPGA board does, although the details of the used algorithms are undoubtedly not exactly the same.

Yet another approach could be to use an AK4137 board for the conversion from PCM to a sigma-delta modulate, but no-one has tried that yet. Compared to the FPGA board and SRC4392 used in the original valve DAC, it should be much cheaper, but it is also much less flexible; with the original valve DAC you can change the Verilog code and build in any filter curve you like, any sigma-delta algorithm you fancy or any amount of headroom for intersample overshoots that you want, provided you have enough knowledge of digital signal processing and Verilog code to do so.

Component value updates and known bugs and workarounds:
For both the raw DSD variant and any new builds of the original design, a couple of component values need changing:

R14, R25, R26, R27, R103, R104, R105 and R106 become 2 kohm +/- 1 %, 0.6 W metal film as otherwise the trimming range can be too small
RV1 and RV2 either stay as is (Bourns 3386P-1-502LF) or become Bourns 3296Y-1-502LF, depending on whether one prefers single or multiturn

If the trimming range should still be too small, pulling out E88CCs and putting them back in in a different order can help.

The values of C28, C29, C50 and C51 depend on what filter type is chosen. For the raw DSD variant, Ray used the filter of post #215, which requires 15 nF each for these capacitors. The filters of post #837 would require 5.1 nF instead.

There is a bug in the way the Amanero-style connector is connected in the raw DSD valve DAC (I used an obsolete Amanero datasheet). Pins 12, 14, 16, 18 and 20 of P13 (with the pin numbering as in the KiCAD schematic) should have been left open instead of being grounded. It doesn't matter when you use ppy's reclocker to drive the raw DSD valve DAC, but it does with a real Amanero Combo 384. A workaround is to remove these pins from the header/connector. See also https://www.amanero.com/drivers/combo384-D.pdf and mind the different pin numbering in the Amanero datasheet and the raw DSD valve DAC schematic.

I've caused some confusion with my laziness: for U7, U8, U9, U10 and U11 of the raw DSD valve DAC, I used 3 mm by 3 mm TSSOP-8 footprints with 0.65 mm pitch from a standard KiCad library, while the actual package type is SSOP-8, also known as SM8 or SM-8. They are compatible, but it is confusing. The TI package code in the type number is DCT.

PCB peculiarities:
The main board of the original valve DAC was designed for the Eurocircuits PCB proto four-layer PCB stack-up, which uses double layers of 180 um thick PR7628 prepreg, so in total 360 um thick prepreg. Most other PCB manufacturers use single prepreg layers by default. Although the main board of the raw DSD valve DAC was manufactured by another PCB manufacturer and although it would have been possible to adjust trace widths to get about the same characteristic impedances for the critical lines with single prepreg, we held on to the double prepreg layer because it provides a more reliable insulation than a single layer. Hence, the PCB needs a custom stack-up.

The size of the main board of the raw DSD version is 195.58 mm by 314.325 mm, the size of the main board of the original valve DAC is 264.16 mm by 328.93 mm.

Ray produced a mechanical drawing in FPD and dxf format of the main PCB of the raw DSD variant of the valve DAC, see post #751, Valve DAC from Linear Audio volume 13

0 ohm resistors and jumper settings for the raw DSD version:
For the raw DSD valve DAC, which of the 0 ohm resistors R48, R57, R58 and R59 need to be mounted and which not depends on whether one wants to use the Amanero-style input P13 and if so, whether the bit clock or the master clock is used:

P13 not used: R48, R57, R58 and R59 not mounted
P13 used with the bit clock: R48, R57 and R59 mounted, R58 not mounted
P13 used with the master clock: R48, R57 and R58 mounted, R59 not mounted

Jumpers at P8, P9 and P11:
Using the bit clock or a master clock below 25 MHz: jumper on P8, pins 1 and 2 of P9 shorted, pins 1 and 2 of P11 shorted
Using a master clock between 40 MHz and 50 MHz: no jumper on P8, pins 2 and 3 of P9 shorted, pins 2 and 3 of P11 shorted

When a master clock is used, it has to run at an integer multiple of the bit clock (an even multiple for master clocks between 40 and 50 MHz) and the data have to be stable between 5 ns before and 0 ns after the rising edge of the master clock. When the bit clock is used, the data have to be stable between 5 ns before and 0 ns after the rising edge of the bit clock.

Anything that meets the timing requirements of a DSC2 v2.5.2 also meets the timing requirements of a raw DSD valve DAC running on the bit clock.
Besides, PPY's ReClocker board as described on this website https://puredsd.ru/ in the schematic https://puredsd.ru/BBBreclk.pdf meets the timing requirements of a raw DSD valve DAC running on the master clock.

Supply currents:
The raw DSD variant draws about 1.83 A from the 6.3 V heater supply (could be a bit higher depending on the brand of E88CC), an estimated 49.05 mA from the -300 V supply and an estimated 100 mA from the 5 V supply, see posts #243 and #336 for details.

The currents are higher for the original valve DAC: theoretically 2.73 A from the heater supply (SonnyMarrow measured 3 A, see post #1641), theoretically about 75 mA from the -300 V supply (SonnyMarrow measured 67 mA) and three hundred something milliamps from the 5 V supply the last time I measured it. As this was several configuration file updates ago and as the current drawn from the 5 V supply can change when the configuration file is changed, I recommend counting on 700 mA from the 5 V supply.

For those wanting to experiment with alternative power supplies, please keep in mind that the valve DAC requires -300 V rather than +300 V and that the heater supply has to float, as it gets biased at a large negative voltage by the voltage divider R141, R140, D16, R139, R43, R47. A soft starting and stopping -300 V supply with a rate of change of 50 V/ms or less is strongly preferred to avoid stressing the 74AHCT74 chips that drive the upper E88CC valves. By the way, I've had no hum issues at all with the original valve DAC with its simple CRCRC filtered -300 V supply and AC heater supply.

Reconstruction filters:
For the reconstruction filters of his raw DSD valve DAC, Ray has used RM8 inductors from Don Audio, https://www.don-audio.com/Custom-Inductor-RM8-Core
He uses the filter schematic from post #215 of this thread, with R1 and R4 combined into a single 806 ohm resistor. He designed his own filter boards, those are also part of the group buy.

A cheaper alternative for the inductors could be to buy RM cores and to wind them manually. It's more fuss because you need to separately buy the cores, the clamps, the coil formers (bobbins) and the "enamelled" wire. The Digikey part number for the cores is either 495-76950-ND or 495-76953-1-ND and the manufacturer's (TDK's) part number either B65811J0250A048 or B65811F0250A048. The J model has no centre hole and the F version has a threaded sleeve.

When you only want to drive balanced inputs, you can use Ray's filter without the transformer and with the outputs terminated with 402 ohm resistors to ground instead of an 806 ohm resistor between the positive and negative signal lines. See post #837 for some other filter alternatives with the transformer.

The details of the reconstruction filter of the original valve DAC are in the article and database of the original valve DAC. It uses P26x16, 250 nH/turn^2, N48 potcores for the inductors.

If and only if you use an output transformer and are sure that nothing dangerous can happen when due to a fault condition, there is -350 V at its primary and 40 mA or so flowing through its primary, then there is a way to save money and reduce noise modulation as well. It involves replacing one of the DC blocking capacitors with a short and using a 100 V rated capacitor for the other. See the discussion with acg around posts #1276 ... #1279, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6484934.

For anyone wishing to redesign the filter, posts #1257, #1282 and #1300 may also be interesting.

Digital correction for the reconstruction filter roll-off:
The digital interpolation filters in the original valve DAC have a partial correction built in for the droop of the analogue reconstruction filter. No such droop compensation is possible in the raw DSD version.

Hence, for the flattest possible amplitude response, the reconstruction filter of the raw DSD version has to be flat by itself while the reconstruction filter for the original valve DAC has to have a roll-off that's about the same as the roll-off of the filter that the correction was designed for. Therefore, Butterworth filters give the flattest response for the raw DSD valve DAC and 0.05 degrees linear phase or Gaussian-to-6 dB filters give the flattest response for the original valve DAC. While the phase response of Butterworth filters is not as good as that of Gaussian-to-6 dB or 0.05 degrees linear phase filters, it is still pretty close to linear phase an octave or more below cut-off.

The digital droop correction filter has a magnitude response
1 + 13/256 - (19/512) cos(2 pi f T) - (7/512) cos(4 pi f T) with T = 5 us.
This is only a small correction: 1.009680428 or +0.083678759 dB at 15 kHz, 1.016534293 or +0.142440687 dB at 20 kHz, peak of about +0.644660534 dB at 73.5 kHz.

Output signal transformers:
The DAC is inherently a balanced circuit. I used output signal transformers to be able to connect its outputs to unbalanced as well as balanced inputs. If you only want to connect its outputs to balanced inputs, there is no need for a transformer. With reference to the filter for the raw DSD version shown in post #215, the mid point between R1 and R4 then has to be connected to ground (so you really need two 402 ohm resistors rather than one 806 ohm resistor), R2, R3, C9 and the transformer are not needed and the positive pin of the output connector has to be connected to R1, the negative pin to R4.

Also for the raw DSD version, the filter in the right schematic of post #837 is less sensitive to transformer parasitics than the one in post #215, so I recommend using the right filter of post #837 if you want to use a different signal transformer than Ray used.

Output signal level:
Neglecting transformer losses, if any, the peak output voltage is about 2.5 mA times the parallel connection of three things: the anode resistors of the upper E88CCs, together about 11.2 kohm, the termination resistor, and whatever load you get from the amplifier that's connected to the output. With an 806 ohm termination resistor and a 10 kohm amplifier input resistance, that's about 1.75 V peak or 1.24 V RMS. (This is assuming that the percentage of ones in the DSD signal varies between 25 % and 75 %, as it should according to the Scarlet Book standard.)

I do not recommend using higher impedances to boost the signal level, but using lower termination impedances to reduce the level is very well possible, provided that the reconstruction filter is redesigned accordingly and the signal transformer (if any) can handle it. If you really need a higher signal level, you can use a transformer to step it up, see the left schematic of post #837 and the text of that post.

BOMs and Digikey baskets for the raw DSD version:
See post #845, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6331624 , for lists of the components that Ray used for his build, with the component value updates included, and see post #1165, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6470605 for an update. See post #1159, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6469618 , for additional information from Periklis in Athens.

Functional checks with a makeshift lowpass filter:
A simple RC low-pass filter can come in handy for debugging the digital part of all versions of the valve DAC, see post #369 https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6016188 . With a low-pass filter, a coupling capacitor, an amplifier and a loudspeaker, you can check whether a digital line that should carry a sigma-delta modulate indeed carries a sigma-delta modulate.
In the original valve DAC, there should be a suitable signal at the outputs of U11. Contrary to what I wrote in post #1533, the digital part of the original valve DAC requires the 27 MHz valve crystal oscillator and the signal indicating that the 85A2 has ignited, so it can't work without the -300 V and the heater supply.

Frequency doublers and clock subharmonics:
As the raw DSD valve DAC is quite sensitive to clock subharmonics, especially the second subharmonic (and its odd multiples) when the algorithm that generates the DSD signal is a straightforward single-bit sigma-delta modulator, I do not recommend the use of frequency doublers in the clock generation circuitry. See posts #878, #879 and #884 and post #2850 of https://www.diyaudio.com/community/...jitter-crystal-oscillator.261651/post-6373471 . If you want to use them anyway, any subharmonics have to be filtered off very thoroughly (-100 dBc would be OK, -52.75 dBc would certainly not be OK).

Noise floor:
The noise floor of the valve DAC is low enough not to bother me, but not as low as the noise of some solid-state DACs. A recording of a five-second fragment of the noise of the original valve DAC is attached to post #1428, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6521888

Neon lamps and surprise mode:
The original valve DAC has seven neon indicator lamps. (It is possible to modify the circuit and use LEDs instead.) With configuration file version 2.1 as well as all earlier versions, six of the seven neon lamps are only used for surprise mode. When SW5 is pressed, they indicate what the surprise filter and surprise sigma-delta modulator algorithm are - those are then randomly changed as soon as you stop pressing SW5. When SW5 is not pressed, the six lamps are simply off.

Hence, when you don't want a surprise mode, you only need the clipping lamp. The clipping lamp can in rare occasions indicate you have an intersample overshoot issue and have to switch from loud to medium mode. Q1...Q6, their emitter and base resistors and their six neon lamps can then be left out.

LX45 variant of the original valve DAC:
The original valve DAC uses a TE0630 LX75 FPGA module, but because of problems with its availability, I've come up with a way to use the cheaper and (at the time of writing) more available TE0630 LX45 module instead. The change boils down to only using quantizer sample rates that can't cause aliasing, so the requirements on the interpolation chain can be much relaxed. The LX45 configuration file is version 3 of 12 March 2021, see posts #1519, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6569767 and #1525, https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-6570538 .

The functionality of the DIP switch S1C on the FPGA module and of the neon lamps has also changed. With switch S1C off, the neon lamps behave the same as before, but with switch S1C on, they also indicate what filters are used and in what mode the sigma-delta modulator is when SW5 is not pressed, provided the rotary switches SW1 and SW2 are not in the "surprise" position.

FPGA module configuration:
I've always used a JTAG programming cable to write configuration files into the TE0630 module's flash memory, as explained in the appendix of the TE0630 user manual, but rfbrw pointed out it can also be done without JTAG programming cable, using a free USB firmware updating program, see post #1939.

Additional measurements:
See https://www.diyaudio.com/community/threads/valve-dac-from-linear-audio-volume-13.308860/post-7770174

Good day all.

Firstly, happy belated 2025 to you all.

Need soem advice pls. My Numark mixer, after many years of faithfull service has developed a buzz. Literally just happend a few days ago. Even with nothign connected, no input signal, no speakers, nothing. Only plugged into the mains, and with switch on, I hear a kinda high pitched buzz right by the transformer.

I suspect a transformer issue, but not able to say exactly.

Any help would be appreciated. Thanx

New power transformer I bought several years ago for a 300B stereo tube amp that never happened. It has 115 volt input (can be bridged for 240 volt) and outputs of 6.3V at 4 amps, 320-0-320 at 330 mA, and three 5 volt outputs at 3 amps each, so there is a separate 5 volt winding for the rectifier and each output tube. It is unused and customized for a 300B stereo tube amplifier. Selling for $115, which is less than I paid about 10 years ago. Will ship within the US by USPS flat rate for $20 shipping. Payment by check or MO, no Paypal or online payments pease.

Ok, I got this Dynaco SCA-80Q, and just like any other vintage equipment. I measure terminal voltage before hooking up speakers to it.
What's odd is typically I get at most 50-60 to even 100 mV on most vintage receivers at turn on and it gradually subsides thereafter some to very low 5mV.

But not with this Dynaco SCA-80Q, it gets around 30volts at each terminal at turn on, and gradually lowers down. I'm not confident on hooking up my speakers with these voltages.
The owner says he did but gets some kind of distortion on the sound. He said it might just be his motorhome as it is where he is using it.

Now the question is it normal for around 30volts at the terminals at turn on as it gradually lowers. Or is there something wrong with the unit?
Anything I can do to alleviate such?
Thank you.

I am starting to collect parts for a 6l6 pp amp build.
Looking for input on experiences with current production tubes ( for cost reasons. )
Both sound quality and tube life/quality.

I am looking for a USB to I2s and Spdif board for a project. I currently have a Rigisystems board as used by Audio Research. which..the board is capable of what i need but the ARC Driver/Software has the board limited to just I2S output and I need to output both I2S and Sdif at the same time.

Googling there seems to be 3 current common boards I can find on ebay, amazon and Aliexpress. the CM6631A boards the Xmos versions and many versions or copies of the Amanero boards. this will be mounted internally inside a project so i need just a PCB not a whole box device.

Can anyone recommend any of these devices or something else? has anyone used any of these and can recommend a product?

Internal board, USB to both I2S and Spdif simultanously, at least 24bit 192Khz and will be running on a windows 10/11 machine.

Zc

I have a pair of Tympani IVa's and want to try an experiment.

The Tympani IVa's have two bass panels but one panel is tuned a little higher to improve the mid bass of the system. I have replaced the midrange panels in my system with Bohlender and Graebener RD75's which are capable of operating lower in frequency than the Tympani mid panel. The RD75's are magnificent and don't need the help. I would like to replace the 'tuned up' bass panels with a 'true' base panel to make double bass Tympani IVa's.

I would prefer panels in good working order but as long as it is repairable we can probably work something out. Bass panels out of the frame would be ok too.

Somewhere within a days drive of Dayton, OH would be great but further, or even shipping is not out of the question.

I am looking only for a pair of bass panels, I don't really have any use for complete speakers.

Tympani IVa's only please.

Can someone guide me into adjusting the bias on my EV pa1250t amplifier.... I don't know which is the bias control

Hello,
I am looking for one pair Tokin THF-51S.
Please let me know via PM.
Thank you.

Hi everyone,

Currently in the process of rebuilf some Revel Ultima Studios, that i got on a estate sale here in the UK, with really bad drivers.
Sourcing parts in the UK for these is tricky, but `i managed to find a pair of Revel Gem ( bookshelves) on eBay that use the exact same drivers, but the owner does not want to ship.

If someone is willing to help, please contact me directly and obviously I will pay for your inconvience / help.

Many thanks,
Bruno

List as of June 2018 - Trying to keep this page simple, most links go directly to the download page or to the online calculator page, but some of the sites are worth having a longer look around, with links to other Loudspeaker related pages etc.
- Please post if you know of other tools worth listing.
Also, If you know that any already listed here are inaccurate or problematic please post so note can be added or can be pulled from the list. Thanks.

Abacus, From SpeakerBuilding
Adua Speaker Workshop, at archive
A J Designer, (Enclosure Calculators) here
AkAbaK, (simulation program for electro-mechano-acoustical networks) here
ARTA, (program for the impulse response measurement and for real-time spectrum analysis and frequency response measurements.) here
Assorted Dos and early Win programs on nice old webpage here
AxiDriver, (Axis-Symmetric Acoustic Boundary Element Calculator) here

BassBox Pro, (speaker enclosure design program) here
Baffle Diffraction and Boundary Simulator, here
Basta!, (Tolvan Data), computer program for simulation of loudspeaker systems, here
BIB Calculator Spreadsheets. here
Blaubox by Blaupunkt , on this page (also need DosBox to run on a modern system - available on the same page)
BoxBuilder-Car, (from Speakerbuilder) here
BoxModel,
Boxnotes, ( find the best dimensions for your enclosure) here
BoxPlot, From SpeakerBuilding
BoxSim, (measurement based simulation includes baffle-step calculation) From Visaton's website, or from Boxsim

Calsod, (loudspeaker system optimization and design/ optimize crossover networks) here
CLIO, (measurement system with proprietary hardware) here

Eminence Designer, (loudspeaker enclosure design program) here
Eminence Designer Demo, (loudspeaker enclosure design program) here

Flare-It, (port and flare) page here
Flexsys, Dos based , original page on Archive, here
FuzzMeasure, (audio and acoustic measurement - Mac) at SuperMega, at RØDE Microphones

HOLMImpulse, (freeware program for frequency- and impulse-response measurement) here
Horn Response - (David McBean) - here. Also , nice "How to" thread Here


To Be added to Part Two

Qspeakers (recommended by TechTool) Link is Here

I am thinking of buying a set of Revel speakers. Probably the series 1's so these will be 20+ years old. Yes, they review well and test exceptionally, but there are a lot of bad vibes out there about drivers of this age (and younger) failing. This seems mainly to focus on the 4 inch, upper mid’s and the tweeter. These seem difficult to remove and spares availability is either very limited or non-existent. So, are there any thoughts on these, or is it best to leave well (or otherwise) alone?
Thanks for the assistance.

Hi everyone
How can I create a simple circuit to test a directy heater cathode rectifier diode in working conditions?

For sale is my fully upgraded Yaqin SD CD3 Valve Buffer,

Valves - Shuguang Black Treasure Tubes (CV181-Z) premium grade, (these came in a fancy gift box) cost was £200 inc import fees (approx only 450 hours used on them)

Capacitors - Mundorf MCap Supreme Silver/Gold in OIl, these are Mundorf's top of the range capacitors - cost was approx £250

The valve buffer itself costs over £200, and I think you have to pay import fees on top of that.

Issues - One of the screws is missing as the thread deteriorated (see pics) and another screw does not fully screw in, however the case is fully secure as there are many other screws holding the bottom panel in place.

Some very thin hairline scratches on the chrome transformer cover, not too noticeable.

This item will work well with a variety of integrated amps, (not recommended for power amps)

There is no tube guard included, but comes with a mains lead.

Works with 110V or 230V electrical outlets

Item will be sent by courier and fully insured, can ship worldwide

eBay link is below for a safe purchase, pick up available from Glasgow )UK)

Price is £370 and I am open to sensible offers

https://www.ebay.co.uk/itm/267080761178

SRPP ANZAÏ tube preamplifier...

Bought for cheap, in working condition but in need of TLC and "crude-awkward Idiophile improvements" removals, it's a restoration / modification job coming :







Schematic :



The SRPP ANZAÏ preamplifier was highly regarded in the 80s-90s - at least here in France.

Designed in Japan by Mr. Katsutaro Anzaï and popularized by Mr. Jean Hiraga, our well-known Audio Expert, the circuit uses a passive RIAA corrector, without FB, offering reputedly a wide dynamic range and a high output / input level capacities, a performance barely found on more classic Phono preamp circuits...

Work is on progress : cleaning, dismantling, complete rewiring, power transformer replacement, shielding, new face plates...





Wait and See...

T

Selling 1x Willesden Transformer Company Power transformer

Pretty heavy, with some nice possibilities:

Primaries : 2x 5-0-100-110-120
Secondaries : 0-20-470-510-550 / 200ma
0-200-225-250 / 20ma
0-90-110-130 / 50ma

2x 0-CT-6,4 / 5A
0-6,35 / 6.4A
0-6,3 / 300ma

Center has 4 blind turrets, with rectifier diodes in place

Asking 85€, will ship worldwide

Hello everyone,
Since my music listening room has now become a children’s room, I’m parting with some of my projects, which are either fully built or still unfinished.
As I’ve built some of these projects multiple times, a few of them are not housed in enclosures yet. If you're interested, please also check out my other listings.
——————————————————————————————————————————
For sale:

1 Paradise R3 Phonostage (although it's R3, the PCBs are still labeled as R2; more details can be found online).
Consists of 6 PCBs: per channel (L+R) 1 transformer board, 1 main board, and 1 Calvin buffer board.

• Boards are untested / never used.
• Populated with high-quality components:
  • PRP PR9372 resistors
  • Matched JFET transistors
  • Matched PNP/NPN transistors
  • Matched V-Cap CuTF copper foil Teflon caps
  • Vishay MK1837 caps
  • ELNA Silmic II
  • Nichicon FG
  • Nichicon BG
  • ...
• 4 Hammond Coils 158T
• 1 Document – including parts list, assembly instructions, and notes (self-created).

Spare components included:

• PRP 9372 150R (8 pcs)
• OPA 134 (2 pcs)
• BC327 and BC337 (matched, marked by value)
• BC327-40 (27 pcs, HFE 450 to 465)
• BC337-40 (50 pcs, HFE 457 to 465)
• PF5102 (matched + various single pieces)
• J107 (matched + various single pieces)
• J113 (matched + various single pieces)
• J310 (matched + various single pieces)

Price: €680 (+ shipping).
Location: 1070 Vienna, Austria.
The PCBs and components can be shipped or picked up in person.
Payment: Bank transfer in advance, cash, or PayPal (friends and family).

Feel free to reach out with any questions. Additional photos can be provided upon request and sharing of an email address.
If interested, please send me a private message.

Best regards,
Michael

Note: As with all private sales, no warranty or guarantee is provided. No returns or exchanges.

I have 2 or 3 uni-q units from the R series for sale. I have had over a dozen offers on ebay, but not a single notification they were made. I'm going to guess somebody here might be one of them, or a buyer may find an add here doing some research.

Instant 10% discount for being a member here, and to justify this post. That's less than the offers 🙂

Edit: 19 solid offers missed, and all I know about are 2 that messaged to talk about them. I'm a bit miffed to be honest. Karen letter sent to eBay.

I have a question probably no-one can answer:

Can you think of any reason to have the DIP switch according to the picture or having the switch from the resistors down to ground? The purpose is to have a variable gain.

I just learned that Scott Wurcer of ADI passed away last week.
Scott was the designer of many great audio products like the AD745 series and the AD797.
The spectecular discoveries by the LIGO detectors were to no small part due to his ingenious chip designs.
AD sold more than a billion dollars worth of his ICs!

Scott was also an active member at diyaudio until a few years ago, always willing to help, as long as you were willing to do your part of the thinking.
We lost a great audio guy and a fine person.

Pic: Scott (L) and Laurie (6L6’s wife), on a beautiful sail after Burning Amp Fest some years ago, enjoying SF bay.

Jan

I have for sale stereo amplifer, based on Holton HPA-NXL200 R5.2 modules, precisely installed in custom build beautiful enclosure. I could say this is one of the nicest and solid built of this amplifier around. It`s superb sound desire top notch components, so amplifier consist of Hypex 1200A180 SMPS power supply, with additional 8x1000uF 50V Nichicon FG capacitor bank per channel, bypassed with Epcos MKP capacitor. There is additional push button circuit, so Hypex SMPS can be powered on/off with LED iluminated push button on front panel. Speaker DC protection is provided by Hifisonix DC protection with solid state switch instead of relay. Enclosure was specially made for this amplifier, based on Fischer SK56 heatsinks (CNC machined). All plates (except 10 mm front plate) is made from 3 mm aluminium plates and have extremely fine black power coated finish. For wiring speaker lines, Jantzen solid core wire was used. For power supply wiring, Jantzen stranded wire was used. Dimensions of amplifier are: 33x31x10 cm (WxDxH). Amplifier is in perfect operating condition. Input is provided with high quality Neutrik XLR terminals. Weight of this amplifier is a little over 7 kg, so not big deal with shipping.

Amplifier should put out around 80W/8 ohms and 120W/4 ohms, with current +-45Vdc power supply and 200mA bias per channel. Output power could be increased up to 150W/8 ohms, 250W/4 ohms with maximum recommended +-63Vdc voltage. Of coarse bias should be set up to lower level, due heat dissipation.


Link to the newer (R5.3 boards): R5.3


SOLD



NOTE: I am not responsible for any customs fees, taxes, import duties.

Wanted to share this circuit I’m working on. Cascode output is somewhat unusual and it’s an easy way to get into A2. I just finished the breadboarding and testing/tweaking. I spent a few days designing PCBs and I’ve just ordered some. I’ll post some updates here once I get the PCBs populated. Then I’ll be designing the chassis. Let me know what you think.

I just recently discovered how to use the Butterworth coefficients to simulate a low pass filter and it couldn't be easier. The schematic shows an Eighth order Butterworth filter where the resistors are the Butterworth coefficients that are published in tables. There are 4 second order filters in series and each second order filter gets a coefficient value for its resistor, The coefficients never need changing as long as every inductor equals every capacitor in value. The filter frequency is changed by changing all the Ls and Cs keeping L=C while applying the equation 2*(pi)(Freq)(SQRT(L*C))=1. All the Cs must equal all the Ls for the coefficients to work. This filter works well for measuring the harmonic distortion of a Class D amplifier when using a simulator and it is very straightforward to set its cutoff frequency. The pattern is the same for all even order low pass Butterworth filters. I hope that some one finds this information useful.

This has been resolved. The problem were fake transistors.

I recently build myself a discrete single supply 15w amplifier and it worked great but after about a week of using the pnp output transistor blew up and shorted for no reason(it wasnt overheating and it was running at 40% volume) after that i replaced the transistor with a new one and the same thing happened again after about a week of use(again it didnt overheat and the amp wasnt overloaded) I tried troubleshooting but i failed to find a reason why the transistors keep failing? I think its because they are fake but im not 100% sure(i bough a couple of them at once so maybe all of them were fake but im not sure).If anyone can help me find the issue i would apreciate it!
(sorry if my english isnt the best)


The red circle is the transistor that keeps blowing up

Note: the 2k resistor in the bias spreader is a trimmer to adjust the bias

https://ln271828.net/budget_3-way.htm

Wharfedale woofer
HiVi T20
PE 299-4212 mid with a plastic chrome dustcap
https://www.parts-express.com/03-0510-Speaker-299-4212?quantity=1

"






These were added for the following reasons. The one attached to the cone was intended to dampen the cone. It was spiraled from the apex to the circumference with one revolution. It helped a little but the dip at 1300hz (fig 3) was still present, along with its THD component. It is known that frequency wavelengths and medium dimensions will interact. So, a similarity was investigated. It just so happens that the wavelength of 1300hz is 10.47" and the circumference of the cone at the annulus is 10.4". What is happening is that the annulus is resonating at 1300hz and the transverse wave along the cone is being reflected back into the cone, causing the dip in response. Dampening this resonance in the annulus cured the problem "

Art,
i found one one of your creations ,this doodle dated 1/17/08
Cab is 45x30x43.5

it is for dual peavey low riders?
you named it B LOW RIDER
so it can hit the Low B on 5 string bass ?
31Hz

Hello,

I'm looking for something that's in some ways like a multiplexer (MUX). However, it needs to function in quite the opposite way that is, only one of the inputs (specified using select lines) needs to be disconnected from the common, with the rest remaining connected, as in the picture below.

It would be nice to have some help in knowing if there's a name for this kind of routing and also if any ICs perform this function. Please note that this is not for implementing digital logic but for an analogue application.

Thanks in advance.

As I posted here I would like to improve 5.1 to be superior to atmos. One part of that is to steer channels like DPL2 did. I would like to detect which of 8 channels has the highest voltage, and switch a relay to boost the gain for that channel.

I know a microcontroller can do it, but it's slow. How can it be done with electronics?

Hey all, new guy to the forum, mostly interested in tube amps. Looking to make a set of output transformers for parallel SE amp. Long story short, growing up racing rc cars, we used different wound rotors, some had 10×2 , as an example. 10 turns, 2 conductor. What to try a 2 conductor input winding. One for each tube. With a single output winding.

Thank for feed back.
Jason

I have a chance to get a set of these that need refoamed for 200 bucks, I’m mostly wondering about sound quality and are these worth saving, they look to be in oak enclosures.

Hello.
I was to throw theese pcb fully populated away, theire from a vintage German prema 6001, maybe there is a collector or prema enthusiast out there.
Prema was very good brand, and made their own ADC chips, so they are totally unobtanium if they break.
So here there are some, just want shipping covered.

I've always enjoyed nice headphones and sound, but never considered myself an audiophile. This has changed recently, as I got a hand-me-down Yamaha PF-800 turntable. I spent a ton of time restoring it, but realized I needed to have the system to support a piece of equipment like this. So, with fantasy football done, holidays and vacations over, and having recently finished a long video game, the conditions were perfect for me to fall down this rabbit hole.

My current setup is a Yamaha RXV4A receiver from accessories4less, two hand-me-down Yamaha NS-10M's from my mom's attic, a PSB Image 9C from facebook marketplace, and a PSB Subsonic 8 also from facebook! Might hawk the LR from a cheap 2.1 I built on my desk for my 5.1 surrounds.

Really need help with the PSB Subsonic 8 though! It doesn't power on, but I understand why (I think!) I do not, however, know how to navigate the circuitry to fix it up! Looking forward to talking and learning from you all.

I’m considering a full range build but have some questions for those that use them, have used them or have heard them:

I understand the benefits but what are the real world drawbacks?
Within reason, can they party? I get the impression they are best used gently on gentle music.

Can they be high efficiency? (Currently have a 60w@8ohm ch Lyngdorf (Which actually does very well))
Should I plan on WAW integration from the start?
Why do you like or dislike them?
Small drive unit 4-5” vs 12”?

I listen to anything and everything with the exception of contemporary rap and, most, chart music (especially that awful auto tune stuff) Also, not a fan of all the ‘go to‘ audiophile demos but appreciate their purpose.
My room is approx 7.2M x 4.5m and Im listening across the 4.5M width
Typical listening is at 70-80dB allowing for a bit of headroom.
Any EQ would be done using REW and Roon with playback through the baby Lyngdorf TDAI-1120.
After years of separate components I love the simplicity of the TDAI units and will be swapping to the TDAI-3400 at some point.

Many thanks,

Have a lot of led’s. Who is in need of these?
5 euro per 100? Have a couple of 1000.
The IR LEDS are 5 euro per 20

Let me know via PM what you need.
Green, yellow (3mm) and IR

Hello and thank you for coming by.

After many days and hours of working on a layout for a stereo 2-channel guitar tube amp build, I am left with one issue that is leaving me slightly uncomfortable. While I believe 90% of the layout was able to follow good electrical layout guidelines for which I'm fairly confident off, there is the issue of the input tubes, 12ax7 (or 5751) being within 1 1/2" from the output transformer. Each amp is 20 watts and will be used at fairly low volume, never being over driven to any extent. Its a Marshall Plexi preamp circuit with a basic push-pull pair of 6V6;s at the outputs. Although my 3-4 amp builds have been very successful and quiet, I am not an expert in transformer magnetic field emissions and susceptibility so I thought taking some precautions would be a good idea. After all, it will be my personal gigging amp so, I have no issue with adding precautions even if it doesn't necessarily require it.

Just from initial research on possible ways to address the potential for a problem, I see that there are materials uses for shielding, sheets and foils that are chosen for particular frequency bands and applications. I see mu metal sheets mentioned quite a bit, and for the audio range, materials such as Netic, finemet and Metglas, which appear to be forms of steel that are chosen for shielding in the audio range. I also see mentioned that the thickness improves the performance as well as the geometry of the material. One source said that the application of these materials should be set around the element that you are trying to protect and not the source of the magnetic field emissions.

In my case, the tube (12ax7) is the device I'm attempting to protect, and the source of the magnetic field is an output transformer about 1-2 inches away.

In light of this, is there any approach that occurs to you that you think may provide a solution for protecting the 12ax7 from the output transformer?

Thank you and I appreciate you taking the time for this. I have my heart set on making this stereo amp a good performer to put all the nice stereo time-bases pedals to use that are available now.

Thank you,
Best,
Phil Donovan

SOLD

Asking $120 including USA shipping.

Schiit Modius (not Modius e) DAC. Black, case in 9/10 shape.

Works as it should. I am the second owner. I powered it through the usb to my computer, but it can also use separate 5v via usb-c cable as included in sale. It also comes with the 4 page mini booklet for the Modius e but I don't see any functional differences.

No original box, I will pack very carefully.

USA shipping / sales only.

Here a building thread of the DFH-10 clone with the Lii Platinum-10.
Yesterday I bought a pair from a good friend.

Here the first rough concept.
I not have made a final decision about the material / color combinations.
But the first rough step is here, some bracing is missing according design but will be added.

Hello, I'm repairing a Technics Se-A3 amp with an hs channel. I have 2 2sa1112 transistors that have a low hfe too low compared to the technical sheet and on the second channel also on the 2sc2592 pair, in your opinion can I replace them without problem with 2sa1306 B and 2sc3298-B?

Hello everyone, I'm looking for some infos on the PSU of the Micro Seiki DQ41 direct drive turntable.
My DQ41 has ceased working recently: I'd like to build a new PSU for it, but I don't have any information about the voltages the different output pins of the PSU are supposed to provide.
If anyone has some infos about the DQ41 - or maybe other Micro Seiki direct drive turntables, it would make my life much easier.
The DQ41 I own is from 1980 (I bought it then). Attached is a picture of it short before it gave up.

Hi all,

Finished some Live Oak slabs I've been working on. Mainly focused on practicing new finishes like hardwood, epoxy, etc. Otherwise, a simple bass reflex build with a full range driver. I used the MarkAudio CHP-90 driver with a white paper cone, silver hardware, 2.5" x 6.5" round pipe port. It's about 1 ft^3 net internal volume, 38hz tuned port (with a final output goal of peak at 40~41hz; goal was to get Fundamental E1 from this pair at peak instead of F3 or F6). About 7.5" wide cabinet, by 22" tall cabinet, by 15" depth cabinet. Slabs are larger, 8~9" wide with variations, 28~30" tall at peak of slab crowns, 1.5" depth on the slabs. The slabs are sealed in several coats of epoxy.













Left DATS:



Right DATS:



Near field port vs driver output:



Final response with a little DSP work for my preferences, handles this to about 20 watts before distortion.



Very best,

Trying to find out settings for the KT90 on this tester. Looked for updated charts and just not finding what I need. Anyone have info on this. Also they say that the manual setup section might be the way to go about it. Any instructions on how to use this section. Help

In perfect working order
All original drivers
Recapped ( Mundorf )
New grill cloth ( you’ll get the original cream ones too )

£200 collection Buckinghamshire

I'm wanting to build an EL84 PSET project this year and been going through my schematics. Can anyone suggest a schematic maybe they've had success with? I seem to remember a PSET RH-84, not sure. Or maybe a good SET EL84 and I can get some help here with the changes to add the parallel tube. Thanks!

Hallo everyone, here I come with questions.

Hi . I have this transformer and pcb board is broken . I cant use switch to put it on 220v input . I will be thankful if help me how to run it directly . It has 6 pin . I need to know where to connect N An L also if i need to bridge between pins to put it on 220v mod . Thanks

My new to me Adcom gfa 5500 is having poor bass response. Is anyone experiencing the same. Can anyone help??

What might be a simple tube amp circuit that would best suite a beginner who's never built technology from scratch?
Would be nice if there's some documentation on it available that also treaches the builder on how and why everything works.

I have basic (and some more than basic but on some very specific things) knowledge about electricity, but not on circuit design besides filters.

Hey, everybody. When I connect this circuit, I hear a lot of noise. When I touch the ground with my hand, the noise decreases. Who can complete my circuit to avoid unnecessary noise?

Ahh, sigh... I seem to attract these pesky little amps. Second one in about a month across my shop, 4th one ever. Good news is, this one is mine. ALL MINE!

No clue where to start. Its all here just need to find a way to start taking it apart. Something is loose inside, and then figure out what is what. Nothing looks burned at all. Last owner owned it for 15 years from new, said he spent $6k on it new.

I'm supposed to be getting a schematic for it. Hopeful. Doubtful. Waiting.

Anyone try Huw's Energy Pro 22 tweeter replacement?

https://www.humanspeakers.com/diy/parts/002me22.htm

Greetings, Friends. I've been ruminating on a new power amp. I'd like to use a pair of 18w 5k SE OPTs on hand, and I'd like to use some of these Soviet tubes I've collected, namely Gu-50 power tubes and 6N6P drivers. Stereo amp, tube rectified PS, cathode biased, not too much silicone.

I like this design I found over on ValvesNMore.com



It has the 6N6P as voltage amplifier and cathode follower-driver and the Gu-50 in triode mode with g2 and g3 wired to the plate. But it calls for a 3.5k OPT. How would this circuit behave with a 5k OPT?

This chart from Vtaidy seems to look promising, with 380v on the plate, 80 mA, 52v on the cathode and a 650 ohm 20W cathode resistor



So if I can get a b+ of 420v I should be in good shape. Thoughts?

I've also considered Skunkie's 300b, which does call for a 5k OPT. Could I drop a Gu-50 into that circuit, adding a 12.6v heater supply?

I'd like to use a Noval driver tube, as I have 6N1P, 6N2P, and 6N23P, all dual triodes, as well as the 6E5P Tetrode, and I'd like to experiment with different drive styles with this amp. But the main thing is a good output stage, so my question is, Will the Gu-50 work with the 5k OPT?

Is it possible to use a voltage doubler on the 6.3v winding of the PT to power the Gu-50s? 1.8A@12.6V is required, plus another 1.8A@6.3V for the driver tubes. All tubes will have unipotential cathodes, and it would be nice not to have to buy the additional transformer for the 12.6v supply.

thanks for taking a look!

will

Hello!
I wonder if you can give suggestions for reasonably good tube amplifiers for €400-€700.
Thanks.

Wondering if anyone can recommend a good Hi-Fi schematic for the transformers and tubes I already have?
I'm hoping to go KT88, 12AT7 and 12AX7 for the tubes in a push-pull configuration as I have many of these tubes.
I have a gutted Jolida JD302BRC case that has slots for 4 power tubes and 4 pre-amp tubes I am going to use for the build with the transformers already mounted to it.

My power transformer (Jolida SG-300A) specs is as follows:
6.3V (3.5A)
70V (100mA)
0-10-350-370V (500mA)
110V x 2
0-5-9V (5A) x 2

My output transformers (x2) specs (Edcor CXPP60-MS-4.2K) are:
60W
Primary: 4.2K ohms
Screen Voltage: 40%
Secondary: 4,8 and 16ohm

I was looking at a Jolida 502A Schematic and it looks pretty simple. Looking to max out wattage with these transformers. But wondering if there is a better way to go?
Any recommendations would be great.
Thanks in advance!

Hi,
I'm selling a built Gainclone with rectifiers. The layout is marked with AC-02 2504.
I bought the set many years ago in this forum.

The amplifier works, see the pictures.
Shipping is from Germany, anyone interested?

BR

Hi y’all, I’m Maurice from Canada. I love music and love listening to it on good equipment, meaning I like it to sound good. My dad got me into this, growing up listening to vinyl. The problem is imo, the quality of the products has been on a steady decline as I’ve had 3 receivers and all three have had problems. 2 Marantz and 1 anthem. So I’m here about the anthem max 710. I’m pretty handy and don’t want to pay to fix it. So I need help, I had the anthem playing music, loud -2 dcb, and it suddenly stopped working. When I turn it on now it immediately shuts off. I have opened it and cannot see any obvious faults. Any ideas?

Hi,

I'm selling power transitors from an 90' Sony amp:

2 x Toshiba MOS-FET Type 2SJ201 P Channel for High Power Amplifier Application
2 x Toshiba MOS-FET Type 2SK1530 N Channel for High Power Amplifier Application

See also picture.
Items shipping from Germany. Anyone intersted?

BR

Dear All.I have a Clarion PE-957, the first PLL radio for Clarion.
The unit is a double deck. The external module is for radio and power supply.
I'm looking for service manual.
Someone can help me to find it?
Regards
Luca

Hi,

Looking to buy TDA1541A from a reliable source. I would appreciate any help. Feel free to DM me.

Thank you