And the gardener.

I have a couple ACA Mini's I've built per the standard build guide and kit and although they sound fantastic, I wasn't a fan of the bare M4 hex standoffs as feet. They slide around too much and I was worried might possibly scratch whatever the ACA Mini was sitting on top of (which for me is typically the preamp). I decided to make some quick "slide on" feet out of 3D printed TPU material. The Thermal-Poly-Urethene material has a slight squishyness to it and has a little extra grip for that reason.

Attached is the 3MF and STL files you can use to 3D print yourself. Very very simple design. Print solid (no infill) by increasing wall count accordingly. They hold very tight on the existing M4 hex standoff and give the ACA Mini just a little more grip and protect whatever it's sitting on top of. You can remove them with a pliers if need be, but I suggest un-bolting them before attempting removal to avoid damaging the board (this are very snug fit).

If anyone wants some of these, I'm willing to send out the first two dozen or so sets for free if the interested party(s) covers the shipping fee (ideally in US only as shipping internationally makes it too expensive).

Hello - I am a hobbyist who loves messing with electronics. I found this forum while attempting to fix my Sonos. I am currently a student studying computer science.

Very informative presentation by Randy Parker the audio engineer (watch on Youtube)

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And very interesting open baffle Qualio speakers, "room correction" the passive way..

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Back story first.
Was building some party speakers from bits and bobs in the shed and some old boxes waiting to be junked. Found some cheap generic XOs on eBay and bought them because I didn't want to muck about on $100- speakers
These NOS from Jaycar
https://www.jaycar.com.au/3-way-speaker-crossover-1200hz-5khz/p/CX2621
I ordered 2 from the seller and using them now and they are "OK" with the drivers I'm using.
BUT
I just got a message from the seller that there had been a mistake in the listing and dispatch and he's sending me another pair.
I have some NOS and slightly used drivers in the shed I was contemplating making up some bigger speakers with.
I can't do anything about the orientation of the inductors easily or at all but I can change the capacitors for something better but is it possible to adapt what is coming to a third order at all? If so what compromises would I have to make?
I'd be using Zobles on the midbass and 50mm dome to get a reasonably flat impedance and using the first generation Vifa Neo tweeter on top.
It seems to me that these cross points are reasonable for the drivers I have, the Peerless dome is a nice even driver as is the Vifa Neo tweeter.
Woofer cross-over will then depend on how the top half works but I have a pair of 12" Carbon fibre woofers here that give good solid bass and I might just use those rather than buying a Peerless woofer.
Thoughts and advice please

Hi,
I have a 3 year old transformer with two secondary windings, 17V 3A and 7V 5A. It was used in a DIY linear power supply for a DAC and a Raspberry PI. I have moved away from that setup so I have this large transformer laying around....

Please give me ideas of what should I used it for. I was thinking about PSU for a cheap class-D board but the voltage is quite low (7V) and it is almost impossible to create dual rails for class AB amps at 15V. Also, it would be ideal if I can use the two secondaries or if I left one open, it probably waste of energy.

Best,
AP

I'm putting together the 3TDX center channel from CSS Audio. It's a 3 way design with 2 woofers, a mid, and a tweeter. The crossover is broken out onto 2 boards - one for the woofer circuit, and one for the mid and tweeter circuit. My question is this - what is considered the best way of wiring this up? Should the input to each board be connected directly to the binding post, or do people usually run one board to the post and then run a wire over to the second crossover board? They will be separated from each other by baffles on opposite sides of the cabinet, so my concern is that wiring them to each other will be more difficult and any potential future disassembly will also be harder. I realize it probably doesn't matter at all, I just don't want to find out later that something important slipped my mind. Thanks in advance.

only here to help member in this thread

https://www.diyaudio.com/community/threads/linearx-vi-box.343017/#post-5921809

with this link

Hi. Anybody still have a pair of Peerless 831727's?

Hi, I'm trying to complete a power supply for the f5t amp need 14pces 0.47ohm 3 watt 5% metal film resistors.

Hi,

I'd like to use single channel instances of the compressor processor, one in each output in the interest of protecting my drivers from errant bits caused by misconfigurations or crashes. It seems that with the included compressor the number of channels has to match the pipeline width which implies it must apply the same parameters to all (or the selected) channels in the pipe. I'd like to experiment with having different attack and thresholds for each type of driver (i.e. hefty subs can tolerate more abuse than delicate tweeters). I can see that putting a 1 to 1 mixer in each channel to narrow the pipe to one channel might do it but is that the only way?

Cheers, Louis

For some time now the text formatting options are greyed out when I’m on my iPad. App is Safari, content blocking is off and Safari asks for desktop website. Strange enough on iPhone everything’s fine. The iPad is recent and updated. Anyone else having trouble with this? Or any ideas how to fix this?

Hello all!

I recently began my speaker restoration journey after picking up a pair of ROR Series D speakers (a boutique brand from the 70s-80s out of NYC) at a thrift shop. While restoring those the bug bit me and I picked up a pair of TDL RTL1s off marketplace to restore as well. I'm excited to get into the space and learn more about DIY audio!

from their website
https://www.allelectronics.com/

After 56 years supplying surplus and new electronic parts and supplies, we have decided to call it quits. We expect to close our doors before the end of August, 2023. Our warehouse still contains lots of material which we need to move. Take advantage of our final clearance sale. This is the time to get some real bargains.​

I bought some of these PP film caps for my DIY FE-22 at 2/$1:
https://www.allelectronics.com/item...n-br-4-uf-250v-polypropylene-capacitor/1.html

Also bought the two versions of their 48V SMPS to try, but all those are probably gone by now.

Hello all,

As per subject line, in the case of a CCS based on a depletion-mode FET feeding a shunt regulator.

The FET has a max 150mA rating and my output stage needs 130 mA, plus the current into the shunt. So was thinking about paralleling two CCS cells, i.e. each FET with its own gate stopper and current set resistor, running at say 90mA each. Common drain connections and of course outputs tied together.

Being CCSes there is no risk of one hogging all the current no? The only gotcha I can think of is the two of them starting to oscillate sympathetically, but I'm not knowledgeable enough to judge if it is a risk or not. There surely are other considerations I don't foresee.

For what it's worth both FETs will be put on the same heatsink close together to keep them at about the same temperature.

Thanks in advance for any insights!

Joris

Long time DIY car audio interest from dirt cheap to insanely expensive, on and off for over 50 years into this. First install was in my mothers 58 Bonneville coupe when I was 16, I am going to be 72 in May. Motorola 8 track and Sparkomatic 6x9's, yeah baby! Back then very few cars had systems, next one was in a 63 Belaire we used to cruise in the big city of Spokane and might the the only one with a system on the main drag whenever we could get up there as we lived 50 miles away in a town of 800. We were the sheat back then🙂

I am going to post up some things I learned over the years, most all from my car audio comp days, that can make it pretty easy to create a great sound stage in many vehicles, some are far easier than others, some pretty tough and I have little dirrect experience in that real though have coached quite a few "world champion" builds in most types of vehicles. And yes, there are those that know more than I do, some with a far longer history in competition, few have done what I did in a very short time, because I made a point to get to know some of the masters, worked with them on projects and paid attention.

I also sold a very high grade sound deadening product I owned and a secondary one I introduced to the car audio world as far as I ever learned that is, tens of thousands of happyt customers around the world. I will of course post my sound deadening recommendations followed by most all of them.

I know what I know and will not pretend I know more than I do, if anybody questions whatever I may post I will take it seriously and if agree will make it known and be glad to learn from them. I will also call out what I see as misinformed or pure BS.

Rick

Since a while now I want to build some speakers but I need some help with the concept. I'm listening to electronic music, sometimes hip hop and sometimes jazz music. You never get that feeling from small speakers so I'm definitely going to build horn speakers. Problem is my studio is quite small, about 15m² now and maybe 20m² in the future.

I like the concept of the Calpamos by Humblemadehifi because it uses the midrange horn down to 650hz. But I definitely want to use a multi sub system with 3 or 4 closed subwoofers. So I don't need a 15" woofer. A 12" woofer like the faital pro 12PR320 in a closed box would be better in the upper bass/midrange I think. But the PH2380 horn is too big for a 12" woofer (opitcally). Would this be a problem?

What should I do now?
- just use the 12PR320 with PH-2380+Faital HF201 (Calpamos with 12")
- use the 12PR320 with a smaller horn and driver combination (like mezzo Calpamos for example)
-or maybe build a horn for the 12" woofer (B&C 12PE32) and combine it with PH-2380+Faital HF201

I want to use an DSP with IIR and FIR filters. Best place for the speakers would be in the corners since the room is not that big. In the other two corners I'm going to put bass traps and in general I want to use 3-4 absorbers. But I'm not sure if get problems with early reflections using a constant directivity horn.

What do you think will work best in a small room? I'm open to other driver and horn suggestions. But most smaller horns just go down to 1,2khz-1,5khz 🙁

Would something like the Martion Orgon but using a multisub instead of corner horns be overkill in small rooms? I could use a 70-80cm tractrix horn with a 12" woofer for 80hz-800hz( I know not enough horn loading for 80hz), the BMS 4591 for 800hz-3khz with a 30-40cm tractrix and a 1" driver with 12-20cm tractrix for 3khz-20khz. Would this work or is it hard to build because of the two ways for 800hz-20khz?

I have an Amprobe (made by Fluke) LH41A that is in the box with all paperwork, display protector never removed. This has not been used, and is in fine working condition. These are around $600 from various retailers. How about $400 plus shipping/PP fees?

Thank you.

Hi All!
I'm incorporating an amplifier into a handheld console I've been developing. I'm trying to keep things simple as the rest of the board has been complex so trying to avoid the need for GPIO to talk to the amp. It takes the PWM signals from a raspberry Pi CM4 through the following driver buffer:
View attachment 1319011
Rather than the audio jack I then intend to run the signals through an amplifier (something like a TPA2012D2):
View attachment 1319015 The idea is I would then take the outputs to drive two onboard speakers but then when I plug in headphones to an audio jack this is rerouted into the headphones. This can be achieved using a headphone jack like the one in this image:
View attachment 1319014
The problem is the outputs from the amp are L+, L-, R+, R- so I'm guessing I need to use some form of op-amp configuration to convert this to a single-ended output. Then I can achieve the above since it will work for the headphones and the drivers.
Am I on the right lines here? Is this a stupid way of doing things? I'm fairly good with PCB layouts and Arduino stuff but for whatever reason when it comes to Pi's and amps that talk over I2C to set everything up my brain switches off.

Perhaps there's an Amp IC out there that offers Speaker Out/Headphone Out along with a detect pin for when the headphones are inserted? No need for any other MCU to handle things?

Hi All, I'm an EE in Mt. View CA.

Occasionally I need advice, sometimes I can offer it - on valves, psu's, amps and CD players. I have some Linn, Quad, Marantz, Leak, all modded and Naim.

Hey hey,

Im from Germany and starting to build my own soundsystem.
I Listen to many styles of music and im into pa System and raves 🙂.

I have build my first Tapped horn 3 Weeks ago.
And have a small collection of 80s and 90s peavey amps.

Im currenlty into headphones systems using Susvara with Cayin300b mkii with Gustard R26. Im a tube addict 🙂 Any one have any Quad sets of 6S2S?

I have built an M2 using a pair of Meanwell LRS units per side and it works great. There is an active thread on the upcoming F5m also using these supplies. A bigger amp like Stasis, Honey Badger or similar 100W+ amp might require a +/-48V supply and with a 4 ohm load we're up to a peak current of 12A per rail. This is available via SMPS and I can both afford it and lift it!

I have two questions:
1. Is it OK to just turn on a high current SMPS from cold and dump 10s of amps of inrush current into the downstream components? Is it deleterious to the health of the SMPS and/or downstream components (am I worrying over nothing?).
2. If it is not OK, then it appears there a need for a something to go between the SMPS unit and the amp boards, perhaps enabling the addition of some local capacitor reservoir for those who feel it beneficial. It would be great if there could be a sanctified version of a soft start board for these applications.

One of the potential advantages of the SMPS is that it can be cheap and although expensive solutions exist with soft start, speaker protection etc., this choice negates the cost benefit. And as Nelson Pass has astutely noted; we're cheap.
😉

Maybe if you take the store soft start circuit and put the SMPS output across AC1 and AC2 and the load across XFR1 &2, leave D2 & D3 open, short D1 & D4 and choose appropriate high current /. voltage versions of the relay and capacitor maybe it does the right thing, but I really don't don't know.

As a cut & paste artist / solder slinger I am aware that I don't know what I don't know, but it appears that this simple (?) module capable of options for different voltages and current and bipolar supplies would be of wide utility given the increasing number of SMPS based audio toys.

I just joined this site because I'm looking to buy a power amplifier but need help knowing how much power I need. I'm afraid to take the plunge before I get input from someone who really knows how to figure things out.

Hi everyone.
Is it possible to make a bridge amplifier coexist with a current sensor, like husband and wife after many years?. 🙄😀
the purpose is to create an intelligent network for feedback and correcting the current when the speaker impedance changes with frequency.
I read up on current sensors but none of them satisfied me completely then one day Mr ELvee (member of this forum) was kindand he pointed out his circuit to me:
https://www.diyaudio.com/community/...ransformer-based-circuit.356221/#post-6247241
the heart of the sensor is the clamp but for a feedback network a small toroid whose enamelled wire winding has the task of detecting is more appropriatethe signal
generated by the speaker current which is amplified by the two transimpedance opamps , everything else is useless. what I like about this system is the absence of contact and no
resistors in series with the speaker.
I subsequently thought of an alternative which you can see in the photograph. to do a quick test and verify its functioning I used 15 (15 is not a fixed number, it varies according to needs) small plastic toroids (therefore magnetic permeability equivalent to air, no ferromagnetic core) arranged in a row to capture the maximum intensity of the magnetic field.
the windings are connected to each other to form a larger one, a single layer of turns for each toroid. you can see it in action in the first attached video, the terminals are connected directly to the oscilloscope probe so no amplification with opamp.I used a 20-20khz sweep,
I can't tell you what the volume was but I'm sure it didn't exceed 50%. the amplitude of the signal seen on the oscilloscope is adjusted on the volt scale.
to create this type of amplifier I thought of the scheme shown in the second attached video. in the simulator, I used a transformer as a current sensor because I couldn't use anything else and instead of the speaker I used a variable trimmer. apparently if the circuit is applied in reality, it doesn't work and this is a real shame.
this was stated by people accustomed to chewing electronics every day. Mr ELvee also advised me against going down this road, so I'll stop here.
however it seems right to me to share what I have done and the information collected, in this forum there are many brilliant minds who can express an appreciated opinion.

I built the ACA Mini almost clone (many thanks to Papa and Kevin for that). It is a truly great sounding little amp. I love it. So I wanted to go a step further and make the same thing in a proper chassis that I could give to my daughters.
FWIW I laid out my own version of Mini ACA. And I sent out for boards and got them back. I felt I could do better so re-did it and also added a TL071 unity gain inverter to feed a bridged mono-block arrangement.
Does anyone out there want to cooperate on this, i.e. check the schematic and layout and provide suggestions or blessings? I'll probably get 10 boards made (again) so would share pairs at cost. BTW, these are mono boards with JST connectors (or soldered wires could be used) designed to go in a chassis and use conventional heat sinks. Is anyone interested in helping with an engineering review to be sure these turn out as they should? Let me know. I'd like to order the next round of boards soon. Thanks. BTW, I'd be happy to share the schematic and layout for review. Please PM me if interested.

Hi, I’m joining this forum because it is specialised to particular topic (Amps), and many heads in common topic can produce a many interesting ideas and improvements.
Audio is not my only interest. I also like electromagnetism principles like motors, RF….and I do all with transistors mainly.

Hello. My name is Alexandru and I am from Romania. For some time I have been dealing with repairs of audio amplifiers and laptops and I want to join you because you are the best and I have something to learn from you. Thank you.

Folks:

I'm looking for some guidance on a speaker repair project. My daughter and I recently built a chipamp-based integrated amplifier for her (a father-daughter project which was great fun). After a couple of months of use, one of the channels on that amp blew (entirely my fault; I stupidly misread the BOM and used a couple 1/2W resistors, not 2W resistors). My daughter told me that when the amp released its magic smoke, she also saw smoke coming from the rear port on one of her PSB Alpha B1 loudspeakers. The amp has been repaired and I'm ready to tackle that speaker.

The blown speaker measures 0.2R across its terminals. The other speaker measures 3.8R across its terminals. My first question: how do I determine what to repair/replace in the blown speaker? Notably, I haven't tested the presumably good speaker yet. I don't have any test equipment other than a few multimeters.

My second question: regardless of whether the problem with the blown speaker lies somewhere in its tiny crossover, this seems like a good opportunity to upgrade both speakers' crossovers. A closed thread ( https://www.diyaudio.com/community/threads/psb-alpha-b1-internal-pic.137546/#post-4542271 ) provided the values of the caps and resistor used in the PSB Alpha B1; should I just install better quality equivalent-value parts?

Your advice is appreciated!

Regards,
Scott

Hi Folks,
I'm a retired audio designer and new here on diyAudio. I sew there is a shortage of these dual monilitic transistors.
I have some NOS new "Guaranteed Toshiba" 2SK389-GR, 2SA1349-GR & 2SC3381-GR for sale. I used these types in a differential stage, with all monolitic duals (12Pcs), Phono preamp in the 90's. I bought them myself direct from Thoshiba through their Swedish distributor Ericsson Components in the 90's and have carefully stored the leftovers since then.

2SK389-GR - $8/Pc, 2SA1349-GR & 2SC3381-GR at $2 at each.

P/P $4 worldwide as 1:st class mail.

Sorry, have no 2SJ109 of any kind.

😎 JohanB

Hello,

I am Tim and live in Naples FL. Been into building, trading, swapping audio gear since my Teens. Currently trying to fix a Mark Levinson ML-3.

Thanks

Good day.
I recently purchased a Pioneer D-80 DAT. Unfortunately as defective. The device is 100V/50Hz, so I assume that the fault occurred after an overvoltage or by connecting to a 230V voltage.
Replacing the fuse did not fix the problem. There is another, another glitch.
Unfortunately, I can't find a service manual anywhere, so I'm asking for help here on the forum. Does anyone have a service manual for the Pioneer D-80? I'm happy to buy.
Thank you.

JL

Does anyone know of a loudspeaker that works according to this principle:

A voice coil works against a cylindrical accordion. The 'accordion' is of course fixed at the top. In principle an omnidirectional AMT.

The cylinder below is a voice coil.

I have written software for calculating the effects of equalization filters on loudspeaker responses. It uses the Asymptote graphics software to plot and to calculate filter responses.

Asymptote Software

Here is an example using my LX521.4 speakers. First I measured the speaker response with REW (1/6 Octave averaging) and exported the measured response curves. Then I plotted the curves with my software and added additional equalization. In addition to the two (L and R response curves) files from REW the input to the program was a file that defined the plot -

xmin=20
xmax=20000
ymin=0
ymax=100
y2min=-200
y2max=200
title=LX521.4 Magnesium Cone Base Equalization
filename=LX521.4_Mg_Base_Equalization
draw_phase=0
remove_jumps=0
xlab=$f\textrm{ Hz}$
ylab=$\left | H \right | \textrm{ dB}$
y2lab=$\phi\textrm{ deg}$
pltR=R Jun 27.dat,freq,amp,phase
pltL=L Jun 27.dat,freq,amp,phase

and a file that defined the added equalization (filters) -

*Filter freq gain Q
equal1=pk 7000 6 2
equal2=pk 150 4 1

The output is -



Then I add the tweaks to the miniDSP Flex 8 dsp/crossover I use for the LX521.4. Measured the output with REW again (1/6 Octave averaging) and plotted the results with my program.


I wondered if anyone would find this of interest. So far the filters available are peaking, low and high shelf, low and high Butterworth and Linkwitz Riley. Asymptote is included with the MiKTeX and TeX Live installations.

LaTeX

Here's a link to a video I made.
Speaker makes popping noises as soon as the subwoofer is plugged in.
It doesn't have a power switch. It senses signal and turns itself on.
I took it apart and the PS is making clicking noise.
I suppose this can be the relay, but I've also read it could be arcing in the transformer.
I've read that a bad diode in another brand of subwoofer with auto-on was causing that sub's issue.
But I've also read that a switching PS will do what mine is doing if it isn't getting enough voltage.
Video

This amp was not output.I see rail voltage on the outputs.The op-amps also have supply voltage.

I don’t see no oscillation on the output FETs.

Any suggestions?

Hi,

Re: Uesugi U-BROS-1

Specifications for my preamplifier are not available anywhere, HiFi Engine has copy of brochures, no other data is available. I tried through the staff of Stereo Sound [Japan] but to no avail.

For example, I would like to find out what the phono loading values are. There are three phono inputs 1 and 2 are standard, input 3 is high level, I have no idea what the gain is. Please see photo.

Cheers,

This guy has taken measurements of a large number of headphones and generated tables with the necessary frequency adjustments: oratory1990’s list of EQ Presets
For DSP I'm using Equalizer APO
I can't recognize my headphones the way they sounded!
Mine are Austrian Audio HI-X15.
Reviews praise them, forums spit on them, but in reality they are really bad for music - a pronounced W frequency response and a very over expressed sound...
For all measured headphones there is a generated pdf in which the tuning parameters are given and tabulated - for mine they are 10 points.

I have a set matched-16 TOS JFETs(8xK170BL+8xJ74BL) for sale.
The Idss is 6.9mA.
They are genuine and were sourced directly from Japan.

Asking $140. Shipping from Thailand by registered post is $14 to the US and $12 to Europe.

Please PM me if you are interested.
Thank you

Hi,

I'm new on the forum. My name is Domenico and I write from Italy.🙂

I recently bought an XA30.5 power amp and I have a question related to the needle on the front panel.

Infact I noticed a strange behavior of the needle:

it is almost always positioned on the left side and it does not move (or move just a little bit) when playing music at a very high level.

I know the needle is supposed to move in case of transition from class A to class AB.

The strangest thing is that the needle moves if I hit with my hand the top panel of the amplifier.
(I made a video clip about this, I will try to share it if I understand how to do it! 😛)

Is the behavior of the needle of my amp normal? Or there is a problem with it?

Anyone experienced similar issues or has an idea which could be the root cause?

Thank you in advance for your help!🙂

kind regards
Domenico

Update 13th April 2021

Here is where you can find a guide to soldering up your Phi DecaDAC kit : PhiDAC hex kits with pre-built filters

Update 8th Feb 2021

Prices for PhiDeca DAC :

Kit with ready-made 7th order filter : 480RMB (~$72)
Kit with ready-made 3rd order filter : 260RMB (~$39)

For existing customers of PhiDAC hex only, Deca baseboard kit : 160RMB (~$24)

Fee for assembling kit and testing DAC : 200RMB (~$30)

Update 6th Jan 2021

PhiDAC hex is in the process of being superceded by Phi DecaDAC - the latter using 10 DAC chips in parallel rather than 6 as in the 'hex'. PhiDeca DAC kits are going to be simpler to build and hopefully will be available from mid-Feb. The vast majority of the SMD passive parts (Rs and Cs) plus SOT-23s will be pre-soldered at the factory. This leaves the builder to solder ICs, a handful of discrete semiconductors and the through-hole parts (caps and connectors).

PhiDeca DAC needs a 15V regulated power supply, max current draw is 160mA. A 500mA rated linear wall-wart is suggested.

<original post>
Orders now are open on PhiDAC hex kits with pre-built filters - feel free to PM me. In your message please let me know your location and your choice of payment method and shipping, then I'll have enough info to give you a firm quote.

Preferred payment method is via Transfer Money Online | Send Money Abroad with TransferWise which typically adds a 2% fee. Our receiving currency is USD or Euro. PayPal may also be used, in USD but will attract higher fees, about 16%.

Kit for PhiDAC hex mainboard with 7th order filter pre-built and tested : 470RMB (~$70)
Kit for PhiDAC hex mainboard with 3rd order filter pre-built and tested : 280RMB (~$42)

Kit for PhiDAC hex with both filters 560RMB (~$84)

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

I have prepared (mostly the work was done by my wife) a graphic of how to proceed with soldering your PhiDAC hexkit. Its here : lingDAC - cost effective RBCD multibit DAC design

I am trying to repair a Behringer MA400 headphone amplifier which seems to have blown Op-Amps (CoolAudio V4580).

They are SOP-8 package Op-Amps. Could I use any of these ROHM ones:

LM4565
BA2904
BA4580

For sale two boards with a small PCB error. Connectors .PCB CRCRC dual power supply with small PCB error and Modushop chassis 1NGX247N https://modushop.biz/site/index.php?route=product/product&product_id=542

1, Pearl 3 20€ pcs/I have 2 pcs/
2,Power supply 10€ pcs / I have 4 pcs/
3,Modushop chassis 40€
4, Connestors 7€

Postage price according to the order.

ALL SOLD

Two sets of Regulated PSU boards to release.
Picture shows 5 boards, I am keeping 3 for my own use.
US$75 for the two boards, shipping is covered (registered + tracking)
Paypal Friends & Family please.

The schematic by Koifarm who unfortunately is not in this forum anymore.



Information on the board can be found here:
https://www.diyaudio.com/community/threads/an-other-lm78xx-regulator.403825/page-4#post-7516467
https://www.diyaudio.com/community/threads/improving-the-chinese-jung-super-regulator.394755/

I pulled my old cd63mk2 heavily modded from the moving boxes after some years. Unfortunately the cd mechanism is failing on me. I actually already replaced the laser with an eBay one but get exactly the same

When closing the tray (with or with disc), the motor spins back and forth a bit, and then starts accelerating like there is no tomorrow, and not stopping. It does this regardless of whether there is disc loaded or not.

Error code 02 and sometimes 10… where do I start with this one?

Hi everyone, I recently picked up a Hafler 9180 that is sending HV DC to the right output during startup; amp is in great physical shape otherwise. I'm hoping to get some opinions on my debugging before throwing new parts at it since this is my first experience with a soft start.

From what I can tell, the voltage is coming from something turning on too early, shown by the first dip in the yellow trace at node 1 in the schematic versus the one big voltage drop in the purple trace at node 3 when the soft start comparator trips and turns everything on. Interestingly, the drain of the Q22 PMOS that turns on the input stage drifts down toward the - rail when the amp is turned off as does the cascode stage shown in the blue trace, while the drain stays close to 0 V; these both stay close to 0 in the left channel. I'm thinking this may point to an issue in Q7 or 8, but they seem to be testing okay, so my next thought was there might be too much channel resistance in Q22. Pretty much every component I have probed so far, including passives, tests the same as the working left channel. This amp doesn't have the substrate bias passives since it has the discrete components not the dual JFETs. The diodes between Q14 and 15 seem to be holding the bases ~3.8 V apart, which is a bit higher than the left channel. Adjusting the bias from ~260 mA to the recommended 230 mA for both channels didn't noticeably change anything.

This one's got me a bit stumped, so if anyone sees something I may not have looked at yet I'm all ears to test anything to get a better idea of what's going on before throwing new components at it. Cheers!

As a layman it is pain for me to build a input stage with transistors. to match same hfe/characteristic of Transistor, Current Mirror with lot of equations, etc etc... makes me crazy!! then I found a vintage diagram from the internet that inspire to build that amp.
so, which one will be good for the input stage, Transistor or OP-AMP? did I do some thing wrong in the schematic? Please comment.

Thanks
opu

I just got an Audioromy FU29 which was advertised by it's seller as being a SINGLE ENDED amp. I dug around in the thing and from my ohmmeter it sure looks like the 2 plates of the 829 are at opposite ends of the output transformer primary winding, with B+ fed to the tube via the center tap. That is a classic PUSH-PULL topology- NOT single ended!!!!!

Anybody here have any comment?

(It's a nice sounding amp, really, but it's advertised as SINGLE ENDED and it appears it is actually PUSH PULL!)

Dera all,
i would like to understand beyond the technical issues, what changes tonally in sound between a closed box and an aperiodic one such as the Dynaudio variovent.

Thanks

Hi all, I'm afraid this is yet another advice request. I am at the final stages of designing an active 3 way speaker and would like some advice or critique. I'm OK at carpentry and have friends with more experience, but my DIY experience is limited to a pair of Paul Carmody's Carreras and one CCS Criton 1TDX (as a gift but I made sure to test them first 😉 ). I've also listened to most of the drivers I consider below but not all of them.

Objectives:

1. They need to work well at low volume, 60-75 dB. Occasionally I'd like some more but nothing past 95 dB.
2. My main motivation is to listen to classical music. The Carreras are great but sound staging and instrument separation gets a bit confused with large scale recordings. Also, ideally I'd like more detail on high frequencies.
3. Ideal sound: detailed, dynamic, clean, with good instrument separation but still musical and realistic.
4. Budget is variable - I can save up and wait to get the right driver, but I don't want to go crazy given my limited experience. Currently sitting at ~£2k (w/o amps).
5. Amplification: probably Hypex Fusion. I'm also considering a miniDSP Flex8 + DIY amp based on 3x TPA3225.
6. I want to experiment a bit with XO points and slopes, so I'd like a bit of overlap and avoid drivers with bad cone breakup.
7. I'm OK with F3 in the 40s if it means good quality bass.
8. Volume for the woofer enclosure can vary up to 40L. Ideal is <30L. Mid+Tweeter will be sealed separately.

Current drivers choice:

Given the requirement for low volume listening, after reading just about everything I could on this forum I am looking for drivers with sensitivity > 90 dB, low Rms and high Qms, especially for the mid-low frequencies. I know there's no guarantee but it seems like good guidance. So here's what I have concluded:

1. Tweeter: Bliesma t25b is my favourite I've listened to. Others I have listened to and I like are Hiquphon OW1/2, Satori TW29R-B and the TX version. I'd like good dispersion as I want to enjoy the music even if I'm not sitting in the ideal position.
2. Mid: I would really like to use the Morel EM-1308. Again, just because I've listened to it (paired with a OW1 and a Satori WO24) and was really impressed. But sensitivity is 88 dB and I don't know how good dome midranges are at low volume. Alternatives are Scan-Speak 15M/4531K00 (I like the midrange in my Carreras a lot, imagine not having to also do LF duties) or the imaging of the Satori MW13TX-04, maybe Wavecor? Suggestions are welcome.
3. Low: This is quite critical I think for low volume. Wavecor WF223BD01 is my front runner. Planning to use a ~27L sealed enclosure with a Linkwitz transform as this driver can take a lot of power. I was really impressed by the WF182BD10 clone in the CSS Criton, but that one needs a little bit of volume (as in current) and after many comparisons I think that the T/S parameters of the WF223 should be more favourable. I have listened to Satori WO24 paper and found them impressively deep but not as dynamic as the Wavecor.

Questions:

1. I am a bit worried that the WF223 will have to be crossed relatively high to the EM-1308, at least 6-700 Hz, so it may have the same 'congested' lower midrange I feel in the Carreras sometimes. Especially with the Linkwitz transform. Should I be? Would a ported enclosure help? Any of the other midranges I mentioned would give me a much wider overlap to experiment with, but I just like the attack and detail of the Morel.
2. Are my assumptions about what T/S parameters to look for sensible? Does anyone have experience with the WF223 at low volume?
3. Any other suggestion, question or observation welcome.

Thank you very much in advance!

Hello all, I need some help determining a design for a center speaker for movie and tv use. I currently have the Polk s35 as a center which I think is a WMMTMMW array, the bass presence is non existence, voices are difficult to hear, and I'm not to happy with its dispersion.

My L and R are the Polk es50. I understand for 5.1 all the speakers should be the same, financial constraints and space prevent me from buying another es50.

The amp used is a Yamaha v477 set at 8 ohms

Room size is large and open

My main goals are:

• Create a center that has a better overall presences than the s35
• Increase dispersion
• limit spending

I'm not trying to make the perfect center and I'm approaching this project as more of a prototype and learning experience (I have only built one pair of speakers before). The advice I'm seeking is general guidance. I have searched on this forum and on google for the best format for a center and I have come to conclude that it is a 3 way center (WMTMW) but I could be wrong and If I should match it to the mains, it should be a 2.5 design (M/W T M/W).

I have:

• two 4 ohm 8 inch woofers,
• two 4 ohm 5 inch mids
• two 6 ohm tweeters.
• an inexpensive 3 way crossover
• Access to woodworking materials and tools

I was planning on wiring the woofers in series to equal 8 ohms, the mids in series to equal 8 ohms, but I don't know if the 6 ohm tweeters can be used. I'm willing to purchase two 4ohm tweeters or one 8ohm if it works with the design,

Thank you for your time,
Please don't spend too much of your time, again I'm only looking for guidance, I don't have the means to measure my design or anything like that yet.

Hey,

Did anyone ever Build an 18" Mogale Super Scoop with an The Box 18-500 from Thomann?

Or can anyone calculate if that works good together or not?

Links:
Super Scoop Plan
The Box 18-500

best regards

I know the formulas are all over google - and there are dozens of sites explaining the log function of a calcualtor.

Math was not my strong suite in high school.

My head is spinning and I just spent the last hour going down google search rabbit holes. Someone please help me.

I am trying to figure out HOW (on a calculator) to determine voltage and power gain using a simple calculator. Jesus why does this have to be so complicated and convoluted?

Voltage gain is explained as

20log10(v2/v1)

What are the order of operations here?

I already understand the obvious here - v2 is divided by v1. The result is then multiplied by... drum roll.. WHAT?!

What the hell is 20log10? How do I enter this on a darn calculator? What is being done here?

20 times log10? 20log times ten?

Whatever the heck the above equates to... * (v2 / v1), correct?

How. On. Earth. Do. I. Enter. This. On. A. Calculator?

Since I am a software engineer, I am trying to at LEAST think of this as a line of code....

20 * log(10) * (v1/v2)
or ?

Has anybody used it as a midrange yet and could offer some insight on how wide a bandwidth it's happy with?
Still thinking about my Tarkus inspired big speaker and These were actually cheaper than the Peerless although I see that they are back to $109- at Wagner I paid less than half that. If I cross them at my usual 300 to 3000 how loud but still clean would I go assuming plenty of clean power?

https://sbacoustics.com/product/6in-sb17nrxc35-8/
Quickly modelling says 103dB at 100 watts but i think Jeffs program isn't working properly as It's telling me to give this little driver 33 litres sealed when Wagners are advising 7 to 10 litres

I'm pairing an ancient Utah 12" with an SB-29 tweet with an Fs of 600Hz and thought a steep crossover at 2200 Hz would keep the so-so woofer away from the goodness of the tweeter. Thus, this 4th Order L-R.

Did I get the electrical build right?

Hi all,
I've been using Thuneau's Frequency allocator crossover software for many years now. It's IIR based and I have been using it to try out crossover tunings before spending the time and money to build a passive version. It takes frd files for raw driver input so it's quick and easy to see what the acoustic response and phasing look as you change the filters. I haven't had luck getting it to work in Win10 or 11 so I've been stuck using an old PC and audio interface. Does anyone use this on a newer setup? Or, is there a modern alternative that offser similar functionality? I do have a miniDSP but the miniDSP software doesn't take raw driver data as input (or at least I haven't figured out how to use it) so it would seem to be a bit more iterative process to tune filters, measure, retune, etc.


thanks,
Dan

Just wondering why a 4.7uf input coupling cap would also have a .1uf cap in parallel with it. Both are film caps.

Hi everyone, I'm posting this in hopes that someone has experiance with repairing head units.

I've had this head unit for some time but just last week it started to show this error after being powered up for only about a minute. With nothing else connected but positive and negative for power. I'm assuming with it saying "AMP Error" then it might have something to do with the internal amplifier. Is there someone that might be able to shine some light on this problem and make some recommendations. Thank you in advance.

Two Hundred and Sixty-Six years ago on this date a group of brave American colonists signed a document that would change the world forever. Eventually, 56 representatives from all 13 states at the time would it sign it. Here is how is started:

When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.--That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, --That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness.

The document went on to list the many grievances that the colonists had with King George III.

And here is how it ended:

We, therefore, the Representatives of the united States of America, in General Congress, Assembled, appealing to the Supreme Judge of the world for the rectitude of our intentions, do, in the Name, and by Authority of the good People of these Colonies, solemnly publish and declare, That these United Colonies are, and of Right ought to be Free and Independent States; that they are Absolved from all Allegiance to the British Crown, and that all political connection between them and the State of Great Britain, is and ought to be totally dissolved; and that as Free and Independent States, they have full Power to levy War, conclude Peace, contract Alliances, establish Commerce, and to do all other Acts and Things which Independent States may of right do. And for the support of this Declaration, with a firm reliance on the protection of divine Providence, we mutually pledge to each other our Lives, our Fortunes and our sacred Honor.

The bold is my emphasis on sentences that I believe to be some of them most important and beautifully written of all times.

Happy 4th of July!

Hi all,
I have a home audio/HT setup with Marantz Pre-Amp, Citation 22 Power amp, Bose 901 speakers and a DBX sub-woofer. Audio sources are media play, DVD player and more. The citation 22 amp is from 1989. Last few days, the citation power amp has stopped working; the problem goes like this;

• after power up, as normal the protest light comes on for a few seconds and then goes off.
• as soon as i play any audio source, the protect light immediately comes on and the amp stops.
• I had the same problem about 15 years ago and was able to find a repair shop who fixed. he said he had to replace some capacitors

Now there are no such shops near me. So I ordered one of those repair kits on ebay which presumably has the necessary components. I am familiar with soldering and PCB a little bit, but not sure how to go about locating what needs to be replaced etc.
Does anyone have expertise in this area and can help guide me or point me in the right direction.
Thanks

I suspect there are others like myself who are in a relatively early stage of circuit design and theory. Not having a good foundation of electrical design, I find myself googling quite a bit and of course there is always a term in a definition that requires more googling. With that in mind, I was thinking that with assistance it would be helpful to others like myself, to have some definitions and FAQs in a single location:

Field Effect Transistor (FET):
"FET transistors are classified into Junction Field Effect transistors (JFET) and Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) transistors."
"A three-terminal Active semiconductor device, where the output current is controlled by an electric field generated by the input voltage... FET uses the voltage applied to its input terminal (called the Gate), to control the current flowing from the source to drain, making the Field Effect Transistor a “Voltage” operated device."*


Vertical Field Effect Transistor (VFET):
"The Junction Field Effect transistor (JFET) is the earliest type of FET. The current flows through an active channel between sources to drain terminals. The voltage applied between gate and source controls the flow of electric current between the source and drain of the JFET. By applying a reverse bias voltage to the gate terminal, the channel is strained, so the electric current is switched off completely. That is why JFETs are referred to as “normally on” devices. The JFET transistors are available in both N-channel and P-channel types."*

Junction Field Effect Transistor (JFET):
"The main function of JFET is to modulate the current between drain and source with variations in applied gate voltage, as it is a voltage-controlled device.

(Vgs =0) If no voltage applied to the gate, it allows maximum current through the source and drain.
(Vgs < 0) With the gate-source junction reverse biased, there should be nearly zero current through the gate connection.
(Vgs > 0) And finally, if the gate-source junction is forward-biased with a small voltage, the JFET channel will “open” a little more to allow greater currents through it,resulting in the transistor damage.

However, the PN junction of a JFET is not built to handle any substantial current itself, and thus it is not recommended to forward-bias the gate junction under any circumstances." Source unknown.

Metal Oxide Semiconductor Field Effect Transistor (MOSFET):
"The MOSFET has four terminals: drain, source, gate, and body or substrate. A MOSFET is also a voltage controlled Transistor, but the main difference between a JFET and a MOSFET is that it has a Metal-Oxide Gate electrode which is electrically insulated from the main current-carrying channel between the drain and source by a very thin layer of insulating material, usually silicon dioxide, commonly known as glass."*



Static Induction Transistor (SIT):
This is a partial description from FirstWatt, the comlete article is https://www.firstwatt.com/wp-content/uploads/2023/12/art_sit_intro-1.pdf. Of course credit Nelson Pass

Source:
"Source is the terminal through which the majority charge carriers are entered in the FET."*

Drain:
"Drain is the terminal through which the majority charge carriers exit from the FET."*

Gate:
"The gate terminal is formed by diffusion of an N-type semiconductor with a P-type semiconductor. This creates a heavily doped PN junction region that controls the flow of the carrier from source to drain."*

Vgs:
" is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency." see Wikipedia

idss:
"IDSS (referred to as the drain current for zero bias) is the maximum current that flows through a FET transistor, which is when the gate voltage, VG, supplied to the FET is 0V. When the gate voltage decreases for N-Channel FETs, or increases for P-Channel FETs, the drain current ID becomes smaller and smaller, until after a certain threshold, the transistor shuts off.

The current, IDSS, is important because it's the maximum current that a FET can reach without entering the restricted breakdown region. It is the maximum current in the tolerance range of drain-source voltages, VDS, that can be achieved.

IDSS is referred to as the drain current for zero bias, because the gate-source voltage requires no bias voltage to operate. The gate-source voltage is just zero. No voltage needs to be applied to it. "**

Cascode: Definition/Purpose

Bias:
An initial voltage applied to an output or driver to insure that it is working in the "sweet" spot of it's electrical parameters. Many of the amplifiers on the Pass forum are biased to operate in Class A, see below.

DC Offset:
depending of construction, there will be always some fluctuation of DC offset in real time, but if changes are not abrupt and big, nothing to worry about

in short - amps with NFB tend to behave better (say your Aleph J) than amps without NFB and without any other servo function controlling DC offset ( say M2)

so, if you see DC offset changing slowly in - say - 20mV bracket in time of 1 min, when everything is temp. equilibrium, you're good

and, just a reminder - even if 0mV is desirable value, +/-100mV of DC offset is practically allowed, as industry standard

edit: I know, lack of mileage ...... but your figures of 0.00something mV is, well - not exactly hogwash, but certainly and practically 0mV
Credit ZM

Class A:
By supplying a high enough bias current a transistor will operate in the "sweet" spot of its output and the amplifier will experience no crossover, notch, distortion.

DBT: Description/Proper Usage

Resistance vs Impedance:

* Credit/ Edwin Robedo, Autodesk
** Credit www.learningaboutelectronics.com

Hello ! I am a novice to speaker building and on these past months I have been experimenting with crossovers, speaker wiring and sound arrangements.
I recently upgraded my old stereo console speakers and this started the world of understanding efficiency, sizes, frequencies and passive crossovers.
I have only had the opportunity to work with PVR speakers on this short time, and I have become a fan of their products due to the efficiency specially working
with old tube and solid state amps with low wattage per channel. I do have many questions still on design and matching up, and hopefully I can learn from all the different members on this group.
My main hobby has been turntables and record players and now I have added Speakers understanding.

thank you!

Longtime builder, but old-school 2 way all my life. I started building speakers in 1969, long before all the science of today but they sounded mighty fine to me.

I'm now retired, so I thought I'd try a 3 way sealed design. I'm limited in fabrication tools, but I think you'll see my compromise in this parts list:


Volumes will be 3.7cu ft for the low, 0.7cu ft for the mid. I'll add some bracing, but these cabinets are 3/4" thickness and very well made. My driver choices were done the same as always (seat of the pants judgement), but I also modeled in WinISD and things look good to me.

A major goal is high efficiency, amp will be EL34 2x7w.

All comments are welcome!

Links to components in Post #6

(edited 11-5-2024 to reflect change in 15" and horns)

Hi. I'm Arek and i'm from Poland. It is my first post here since my registration 2013-05-02 3:44 pm xD and since that day I was reading forum regularly. I'm not a educated electronics engineer but only a hobbyist. I have built many many speaker boxes and few amplifiers and i think i had lot's of luck because all work fine xD

Kind regards to all DIYers

Glad to be here. Hi everyone, This is my first post here to introduce myself.

Hi everyone.
I've had a forum account for a while, but haven't posted anything yet.
I've built a bit of projects already, the latest is a DAC on AD1862 from this forum.

For measuring Impedance in LIMP, ARTA in its test jig, suggests a 27ohms series reference resistor.

Is there any way I can enter a different Reference Resistor value into LIMP.

Someone suggested to change the value in Setup/Measurement. But I can't find a field where I can enter my exact resistor value.

Regds,

Aade

Partiendo de una potencia de +-45 V, me gustaría armar un amplificador de 100 w con un solo par de 2SC5200 y 2SA 1943. ¿Me pueden recomendar un esquema fiable? Adjunto algunos esquemas que he encontrado de los cuales no tengo opiniones. Serían con solo un par de transistores de salida. Gracias.

Hi Guys
Advice pls. Been researching the above tube. Notice that aside from 01A numbering,
I see SX 201A, UX 201A, CX 301A etc. Are they all the same tube type.


Many Thanks

I use a simple volume control from my streamer to my amp setup to adjust volume. The volume control has RCA input -> 10k pot -> parallel RCA outs. One output goes to a crown power amp to drive subs and the other RCA out goes to a 2 watt SET tube power amp.

I’m getting ready to insert a DAC (Denafrips Ares II) between the streamer and the volume control. The Ares II has a high output impedance (1.2k ohm). Should I switch out the pot in the volume control to a 20k or something else?

Looking forward to a couple of DIY builds, starting with Alec Valencia's. Looking forward to working with and helping members.

Sony VFET amp for sale, I originally bought it from another member on here. Also Included are some unpopulated boards from DIYAudio Store.

$900 USD

This might be of interest to those running older Apple computers. After looking into various options for streaming and audio file playback (including Raspberry Pi), I've decided to give the Mac Mini another go.

One of my requirements is the ability to stream Tidal Max, the native Tidal macOS application does that. But the Tidal app requires macOS 10.15 (Catalina) or better, and the mid 2011 Mac Mini only supports up to macOS 10.13 (High Sierra). Enter OpenCore Legacy Patcher (OCLP)...

However, the first attempt to upgrade the Mac Mini to macOS 14 (Sonoma) using OCLP was a failure, due to the extremely sluggish performance with the original hard drive.

I then installed a new 1TB SSD drive, and after 3 iterations of software installations and upgrades (see below), the machine is now running smoothly. The idea was to upgrade the RAM to 16GB as well, but that is no longer a priority. The native Tidal application works like a charm, and the sound is similar to streaming from the Macbook Pro (mid 2012), output in both instances is via USB to the DAC (Copland 215).

So, installing the SSD drive made all the difference. Next up is a smaller monitor (12-14"), I'm currently using a 20" Samsung.

OS X and macOS installations after installing the new SSD drive:

1) Booting from the built-in macOS Recovery System allows one to download and install the native OS X, which is Lion.
2) The next upgrade was then to High Sierra (to allow installation and use of OCLP).
3) Finally, Sonoma was installed using OCLP

macOS version history

I've got two pair of excellent condition Tektronix 100mHz probes (can also be used with faster 'scopes, but will have bandwidth limits). Excellent performance with earlier analog 'scopes like my 465b, and also my 2236A - see photos.

In my experience, these perform much better than the cheap probes from Asia, and have the autosensing feature lacking in those. These are 1M, 1X or 10X switchable probes, and are complete with retractable tips and ground leads. Treat yourself and your measurements to authentic, high-quality probes. I'm selling because I bought a lot of probes at auction to upgrade my own supply - I'll be dumping 4 pair of cheap probes!

SOLD - thank you.

Hi so I have a hcca1004 on the bench,
Amp powers up and idles at 2amps, makes clean audio on both right rear and left channels.

There's no audio on left front or right front terminals.

On power up the amp lights a solid blue led and a solid green led.

There's another green led which remains off.

Internally the amp looks nice and original, no signs of work, damage or repair.

Any thoughts on where to start with this one appreciated, thanks.

So I bought This amp of somebody and Supposely, he was never used.But we all know how that goes. Anyway, I tore it apart and I have short between ground and positive. I've removed all the IRF3205 cause those were all sorted out. As far as I can see I don't have any shorts where the mosfets were removed.. If perry Is still around I am really Looking forward to your reply Thanks in advance. I only have the multi meter.I don't have an oscilloscope ...it is coming in the mail should be any day now...it's just a 2ch digital cheapo off ebay. Hopefully it's good enough.thanks again.

Hey I'm repairing this amp and the yellow light stays on and the blue light flashes. I think it's the power supply I replaced all mosfets and still same.. the powersupply chip clicks ..any ideas... waiting on my occyliscope but do these amps have any known issues? Thanks I'm new to complicated amp repair so work with me.. my amps I've repaired in the past usually just need fets replaced and good to go but this is an expensive amp and I ordered all the mosfets over 100$ worth and that wasnt the issue...thanks

I want to get either an Ortofon T20 or a T30 for my MC20 Supreme.

Which transformer should I choose, just in theory but not in practice, according to the manufacturer's specs?

MC20 Supreme

Weight: 9g
Stylus type: vdH II nude
Equivalent stylus tip mass: 0.40mg
Frequency response: 20 to 40,000Hz
Output: 0.2mV
Channel separation: >25dB
Channel balance: <1dB
Tracking force: 1.8g (1.6-2.0g)
Tracking angle: 20 degrees

T20

Pick up impedance: 3 Ohm [2 to 4 Ohm]
Output loading: 47k ohm / 150pf
Frequency response: 10Hz to 60kHz
Phase linearity: +-18 degrees
Gain: 32dB
Channel balance: 0.2dB
Channel separation: 50dB
Transformer type: toroidal
Shielding: permalloy + soft iron

T30

Input loading: 3-6-12-24-48 ohms
Output loading: 47K ohm, 150pf
Frequency response: 8Hz to 90,000Hz
Gain: 33-29-26-23-20dB
Channel separation: >55dB
Channel balance: <0.2dB

I am looking for:

1. Service Manual for the Luxman T-235 Tuner
2. Replacement part for the VFD display. Seems burned out.

Thank you for any info,
Ioannis