I know, the issue has been covered several times before on this board, but has never been brought to a satisfying result.

As we all know, ist is more and more getting difficult to get CD drives for making really good hifi units from it. Yes, the big Philips from http://www.daisy-laser.com/ is an option, but an expensive one.
Also we have the cheaper Philips (CD 723) and Marantz (CD 6000) models, but who knows how long they will bei availeable.

So I think the only somewhere reliable source for "pure CD transports" will be computer CDROM drives, which are availeable at prices at 20 bucks - even the better ones.

It is of course not too difficult to use them in a hifi setup if you are happy with the built-in control buttons (which are normally very few), although there are some models out there with a remote control - which may be fine. But in eny case you won't have a display.

So why not try to develop our own universal CDROM controller?

It has been done before (mostly published on Russian, Korean, and Chinese sites - search this forum), but personnally, I have never found a soulution I could reproduce without major problems.

Technically, it should not be too difficult to control the drive via the ATA/IDE interface, for we don't need to transfer data through the controller.

One interesting (in terms of hardware simplicity) approach I have found is here: http://home.cybervillage.de/heesch/english/ide.htm. I have attached the schematic for all non-Eagle users. This unit so far is kind of a RS-232 controlled data storage device - not exactly what we want, but not too bad as a starting point.
As you can see, you need a microcontroller with 23 I/O pins to perform communication with the drive - no problem.
Most probably you will need a second controller for controlling keyboard, display and remote - I remember having seen this approach on a korean(?) site posted some time ago.

The problem is: controlling a drive via ATA commands is possible, but not that simple (at least not for me, as I haven't read all the hundreds of pages of interface specs). I am pretty much into hardware design as well as assembly programming on AVR microcontrollers, so this will be not too much of a problem - but only if someone can tell me exactly what to do.

So if there are some ATA/IDE interface experts out there it should be possible to get this thing started.

Come on guys - let's turn this into a really big thread 😀

For Sale: one pair of brand new ISO FC-20S single ended output transformers.

I ordered them this year. They are still in their unopened original boxes. Selling due to change of plan.

Ask: $600 + shipping (from US)

Finished my 6-channel class-AB amp for 3-way stereo speakers project. 4-th order Linkwitz–Riley crossover network feeds into six 60W (into 8 ohms) power amps, all small enough to fit into bookshelf size enclosure. Full description here.

Many years ago Ron Welborne sold me three matched pairs of VAIC VV302B tube - blue glass.

They have never been installed, just bought and put in a box.

I am downsizing and getting more realistic about my stuff, so I am going to sell these.

Asking $5,000.

Open to sensible offers.

i need the schematic for pyramid 1800x... any help please

https://www.axios.com/2022/07/17/james-webb-space-telescope-nasa-photos-processing



dave

I just watched this video on voice coils being made and it raised some questions: Login to view embedded media
It has been many used since I took any physics, but I think I remember the right-hand-rule and faraday's law. Here's my question:

If the second layer is wound in the opposite direction, then won't the induced magnetic field from the second layer be equal and opposite to the induced magnetic field from the first layer?

Wouldn't the result be 0 inductance and no net magnetic field or force?

What am I missing?

Hello,

I have advanced to a point with my TAN-8550 restoration with the help that I have received here and came to a point to pair it with my TAE-8450 but immediately bumped into a problem.

The TAE-8450 is fine on one channel but the other channel stays quiet (barely putting any output) when the volume knob is below 12 o'clock position. When I pass the 12-3 o'clock, it springs back to life and keeps on working a few days till it repeats this problem again. I looked high and low for a relay but this device does not have one. Before going medieval, do you have a pointer for me, on where to start checking? It looks like a semiconductor issue to me and bought all the necessary transistors, yet, I would hear from you to have a more educated or methodical approach.

Thanks in advance
Dirk

Just a quick query,

Balancing resistors for 2x 220uf electrolytics (in series) on the output of a lm317 regulator. Circuit states 100uf but I have only 220uf hence the serial connection. The caps are rated at 100v(!) Regulator output will be 11v (can be 9-15v but will be 11v, not 12, not 15 but 11, I have reasons)

I dont think balancing resistors are necessary but would like to install them for good practice and completeness.

Using a couple of online calculators, I'm getting values between 1k to 4.5k (2 seperate calcs on illinois Capacitor Inc), and 450k or so using the Rbalance = NVrate-Vbus over 0.0015CVbus.

Obviously three separate methods of calc getting three separate answers means they're all wrong.

Thanks in advance.

I built an amplifer using the following:

1) 36vdc switchmode power supply (see photos)
2) TDA7498E Class d amp
3) ne5532 + lm1036 pre-amp
4) FM/Mp3 decoder board from AliXp
5) 12vdc (power for pre-amp)
6) 5vdc (power for mp3 decoder board)

NOTE: Mp3 decoder board is powered through a seperate 5vdc adapter to remove ground loop noise

Everything works fine except the FM radio. I spent days, trying to figure out the component which was creating the noise. Finally I got myself a portable handheld radio(with the little antenna) and narrowd down on the 36vdc power supply.

I took the power supply out and ran it with a resistive load(nichrome wire) and sure enough, it was the guilty part. The noise would increase as I increased the load.

The power supply has all the filter components in the primary side so why is it still noisy?

photos attached

schematic of power supply
WX-DC2416 PSU -
EasyEDA

Hi Thanks for reading.

Do you have any experience of Zinamp:

ZinAmp SCA Power Amplifier module - Pair | eBay

Claims to be based on quad 405, but cannot find anything about it on the net.
How does it compare to quad 405 or any other amps.

Thanks.

So,long story short,i have speaker EMINENCE KAPPA PRO 18LF-8 and i want to make a subwoofer with him.
First idea was to make a horn speker,Wbin,and after big help of some guys here,and discussing diferent types of enclosure,i come to conclusion that maybe is best way to go with ported enclosure.
First i didnt know how to use any software for designing enclosurer but i take time and now i masterd hornresp and winisd 🙂
So after calculating so many diferent designs,conclussion is,if i want to go loooow,and stay in marriage,ported enclosure is the best way. 🙂
I understand that speaker what i have is not the best speaker for what i want to get,but i will try and see what i can get out of him.
So,now the questions.
I make compromise to go max with 400l box,outside dimension,inside 350l.
I make few designs wich look good to my understanding but,im amateur so here i ask you for your opinion,advice and experience.
So,i make 5 designs for 350l box,tuning frequency from 20 to 30Hz,and port size rectangular shape,width as baffle board and hight as much as i can to get leinght around 40-45cm so i have at least 10cm from back panet to port tunel.
Here i use guidelines from Loudspeaker Design Cookbook,7th edition by Vance Dickason.He said that 2 most important rules with ports are: Area of port must be at least 1/9 of speaker area for minimum nonlineariti in response,but if you want very good port linearity,then port area must be at least 1/4 of speaker area or more.
So here i go with minimum 1/4 surface area ore more.
Second rule he said is minimum distance from back panel to begining of port tunel must be 3",or 76,2mm for metric system,so here i go with minimum 10 cm.
So this 2 rules are fulfill.

Next important thing is that i will use this woofer from 50Hz down.
And now the pictures.

RED - 20Hz tuning
GREEN - 23 Hz tuning
MAGENTA - 25 Hz tuning
BLUE -28 Hz tuning
ORANGE - 30 Hz tuning

















So,as i plan to use it from 20 to 50 Hz only,all this design looks good to me.What i dont understand is how will this afect sound quality,and can i go realy that low whit this speaker.
Lost of sensibility is not problem,becuose its for indoor use and it have more then enough power even with this droop in response.
To me best looks 20Hz tuning,in that enclosure i have only 6dB droop from 50 to 20 Hz.
But,this is where my knowlege stops,it looks nice on screen,it have sense to me,but as i said,im a beginer so i dont understand what will hapen in real world and in sound quality.

My 4 * UM18-22 is on its way to my country, determining how I would build them.

My original plan was to use 0.86"(22mm) MDF to build 4 boxes. Then I found that dual-opposed-subwoofer(DOS) design fascinating.

Though I still need double internal volume, two boxes with volume V is always larger than a single box with volume 2V - I think it's a good way to save spaces.

Beyond that, I noticed that this DOS design cancels out the cabinet vibration.

Does that mean I can reduce the structural stiffness because the design reduces physical strain?

If that's true, is it ok to use 0.59"(15mm) MDF to get more internal volume and make the cabinet lighter?

Of course I would need tight braces but still, 7mm can make quite a big difference.
(If my calculation is right, my DOS UM18-22 would be heavier than 220lbs when made of 0.86" MDF - which is definately too much to handle.)

Hope I could get answers. Thanks!

New in open box. I bought these for an open baffle project that never materialized.

Reduced to $100 + shipping for the pair. Pickup in Napa okay.

These currently sell for $300/pair on Parts Express.

Good morning,

I'm building my first Speaker Project using WinISD and TB W6 623I as a speaker (later i will add a tweeter as well). I would like to share Win ISD Graph just to check if there's something wrong. The first One is the Transfer Function Magnitude, the second is the SPL and the Third one is the Impedance. Cabinet is 10 liters.





Vent Frequency is set ro 15 Hz while Speaker Fs is 46 Hz

I need a better soundcard with 5.1 or better outputs if I am going to use a computer based digital crossover for my subwoofer.
The motherboard only has stereo outputs
All I can find easily locally/via internet are the Creative Sound Blaster.
At around a budget of $150- to $250- am I going to do any better?
I'm probably not going to be doing much if any measuring etc using external microphones and only the Dayton DATS for driver interrogation
PCI-E motherboard and not a top of the line computer but OK

I did post this in the Instrument Amp forum but realized this is more the correct forum
for repair info.

Trying to bring a Acoustic 260 head back to life.
Had a blown fuse, replaced fuse and plugged it using my light bulb series power tester, bulb
stays fully lit.

Pull all four of the output transistors, easy to do as they are plug in socket mounted, short
is gone, bulb briefly lights bright and fades down to barely glowing.

Using a multimeter in diode test mode all transistors show they should be good.
Checked the two driver transistors the same way and they check good as well.

Output transistors are 40411 NPN RCA's

Anyone else dove into one these, schematics seem to be non existent,

Would it be worth just replacing the outputs with something like a set of MJ15024 or 2N3773 transistors and see
where that takes me?

Mike C.

Ok here is something rather interesting. In fact i already build the circuit and it worked pretty well too. It was exactly based on ESP sound pages project 113 which was a headphone amplifier. Initially i build the exact circuit which was the headphone amplifier without altering anything else there. with input signal and a small speaker, it worked more than a headphone amplifier even able to drive small watts speaker too.

Link to the ESP project pages can be found here

https://sound-au.com/project113.htm

Getting digging further, i've changed the power transistor which was originally BD139 and BD140 to TIP35 and TIP36, following by increasing only the supply voltage to the output transistors and retaining the supply voltages to the opamp as usual, the amp worked as it supposed to be and seems now it able to drive higher wattage loudspeakers. Opamp were NE5532. On progress to upgrade to OPA2604 as they can take 24V positive and negative supply.

Now i am wondering is it a good idea to continue in this design path since now in its final form (TIP35 and TIP36 with +/- 24V supply) they worked excellent and what i do is properly bias the power transistors and give them a giant sized heatsink. If it does, why i didnt see this design is being commonly implemented? or if i were to use this concept, what else you all members suggest to upgrade and improve it? thanks

the photo shows with the large heatsink with the larger board is where the power stages sit ... the smaller one is the opamp circuits

I realize this is a difficult and crazy question.

My only system is an ACA 1.8, Bottlehead Moreplay preamp, iPhone and Klipsch RP 600M speakers. I built the amp and preamp because I wanted a fun project and I found out I really like the way they sound, even if it’s just with my iPhone. I got the speakers because of online reviews and the recent sale klipsch had.

All else remaining equal, would swapping in a pair of Klipsch Forte IVs make a substantial difference? Is this a Chevy volt to a Corvette, or a Honda Civic to a slightly more optioned Honda Civic? All analogies welcome.

Hi,

I have the following to sell, because I'm moving to two other projects (a FETSET preamp with class D amp and an UNSET amp):

1. One set of BH EL84 populated at 180€. Can be sold with selected EL84 and 12AX7 NOS Russian tubes (+120€) and custom made toroidal transformers (+400€);
2. One set of BH EL34 populated at 180€. Can be sold with selected 6V6GT and 12AX7 NOS Russian tubes (+120€) and custom made toroidal transformers (+400€);
3. One set of BH EL34 populated at 180€. Can be sold with selected Tung-Sol EL34 and 12AX7 tubes (+200€) and custom made toroidal transformers (+400€);
4. Four sets of BH EL34 with PSU onboard unpopulated at 50€ each set, including a separated stereo board for differential feedback as bonus (the green ones).

All EL34 boards are the ones that includes the PSU.

I can ship everywhere worldwide, shipping cost is excluded but can be estimated here: https://www.poste.it/files/1476549902427/poste-delivery-international-express-listino.pdf

Im looking if someone have to sell one piece. Contact me plese.

Trying to use 1/4 inch and 1 inch microphone capsules without actually soldering. I would like to buy UA0035 which is an adapter to go from 1/4 in capsule to 1/2 in preamp and DB0375 (adapter for 1 inch capsule to 1/2 inch preamp).

In the end, I will be building my own preamp, so I can make do with a broken preamp or just about any broken socket or extension piece. I believe GRAS, Rion and some Neumann sockets will work, too.

The capsules are listed at 5.7 mm 60UNS thread and 23.11 mm 60UNS thread.

Thanks

Looking for used modules in Europe. Thanks

Looking for a pair of these beauties

Hi all -

I have a fairly grunty potted trafo that puts out 50VAC, Im guessing its around 400VA. That will give me about 70VDC once rectified.

I'd like to use it as the core for a new class D amplifier. Yes, I may need to step this voltage down for the right application. I want to spend the money on the PS, MUR diode bridges and Gold Tune caps.

Any recommendations? Im keen on keeping budget reasonable, and am thinking of going down the road of TPA3255, Im aiming for about 300W p/c but am quite cagey on the fairly high THD specs for many of these modules.

Suggestions welcomed. Cheers!

Hello everyone, I am a university student working within a group of three on the design of a class D amp as a graduation project, with the end of goal of automobile application. At the moment, we are in the early pre-design stage which entails considering relevant design options for different aspects of the amplifier.

For the transistors we are using LMG3422R030 GaN transistors capable of operating at a switching frequency of over 1 MHz (copy of the datasheet attached below). We are aiming for a 500W output power on an 8 ohm loudspeaker with as minimal THD as possible without compromising efficiency. After evaluating bridge designs, we have settled on the full bridge design.

These are our main unresolved design concerns as of yet:
1. Modulation scheme: PWM compared to Sigma-Delta
2. Open Loop design compared to Closed Loop design

If possible, references and resources would be much appreciated.

about 9 years ago I sold 40 pairs to someone here .... I need 2 pairs now. Any can spare these?

I am going to start this thread around the circuit shown at BAF 2016,
seen at the end of the talk on the video, and attached here in simplified
form.

I am calling it DEF, which stands for Depletion / Enhancement Follower.
It is a self-biasing push-pull output stage which has some interesting
characteristics, not the least of which is low temperature drift which allows
stable undegenerated operation.

Hi,


I'm building digital music players based on the Raspberry Pi for retrofitting audio equipment (internet radio capability, streaming music from the NAS, better GUI, more functionality). I'm already able to play Audio CDs with a standard USB CD-drive (using VLC) but the startup is slow (detecting the type of CD), the speed too high (can be reduced by using Setcd), in the end it's not playing a good old audio CD.


Now I would like to combine the Raspberry Pi with a CD mechanism. I already learned that the mechanics with laser pickup and the two motors for spindle and rotation are available as spare parts. Whats missing is a control board with the interfaces to the CD mechanics (laser pickup + the motors) and to the Raspberry PI (I2S digital audio signal and control interface with SPI or I2C).


I already found an IC (Onsemi LC78615E) which integrates this functionality. But I didn't found a ready PCB either for this chip or something similar.


My questions:

• has anyone experience with this topic (interfacing Raspberry PI with I2C and SPI/I2C with a conventional CD mechanics)
• are there PCBs available?

Would really be great if I can get some information here.


Edwin

hi all, Selling the following:

pair of Interstage Transformer Monolith Magnetics IT01. Both transformers are new.
Version: Hi-B grain-oriented FeSi dual C-core, air gap for 18mA, ~125Hy(primary inductance)
Datasheet: https://www.monolithmagnetics.com/sites/default/files/IT-01_25.pdf

Items are located in Germany and will ship in EU.

--450€-- shipping included

payment via paypal (pay for friends) or bank transfer

Hello DiyAudio members.
Looking for a little help.
First, I am new to DIY on receivers.
I have a Luxman R-1050.
Everything was working fine then suddenly for the past week sound is only coming from one side.
Doesn't matter if I am on FM/AM or phono. Sound only comes from the one side. Switch the connections on the speakers just to prove it wasn't a speaker problem.
The channel lights seem to indicate that sound should be coming from both channels..
Kinda of hoping one of you experts have seen this before and you are going to tell me to clean a switch or two..
P.S.. No videos of anyone restoring a Luxman 1050 out there.. To bad 😭

Thanks for the help.

Hi All,

I have an integrated amplifier with 2 6,800uF (1 for each rail) capacitors in it's power supply section and I would like to add more capacitance to it, now I know that the best practice would be to replace the 6,800uF capacitors with higher value and similar specs but I would like to know anyways:

1. is it "okay" to parallel another capacitors to the existing ones?
2. can I add a higher capacitance capacitors to the existing ones? let's say paralleling 10,000uF to the 6,800uF.
3. What will be the theoretical"outcome" if I'll parallel different brand and different capacitance(higher) to the existing ones?

Thanks

Is there any good squematic capture app for Android? If possible, compatible with tubes and no lots of stupid digital ICs like microprocessors and the like.

Many thanks for the suggestions.

Hi.

I'm working on a schematic of the existing crossover associated with the Rotel RL-870 Loudspeakers.

Attached is a photo of the sandcast resistors

Instead of a value appearing next to the Ω symbol, there appears to be a W "WΩ" ???

The resistor is ALSO marked " 3R3-J 3W-K-8 "

Is there enough information on this resistor to identify its Ω value?

HI.

IS THERE A BETTER OPTION TO CONNECT THE LUNDAHL LL1671 INTERST TRANS , LIKE CHOKE LOAD FOR A D3A TUBE ( PLATE RESISTANCE TRIODE MODE 1.9K )

PRIMARY IN SERIES AN THEN SECONDARY IN SERIES WITH THE PRIMARY.

OR INTERLEAVED BETWEEN PRIMARY AND SECONDARY ?

I have 15A 240V variac, and I want to limit the inrush current. It seems an NTC thermistor is a simple way to do this. Unfortunately I am even simpler than the calculations needed!
At the moment there is nothing connected to it, but it could be used for powering a large Japanese 100V amp.
So, any help would be welcome.

Last week I tried an experiment with one of my Unity horns that worked out alright. I thought I'd document the results:

In the commercial Synergy horns, the midrange taps are located approximately 3.5" from the throat. This location is based on a series of criteria:

3) the area of the horn at the location of the taps
2) the desired crossover between midrange and tweeter
1) the geometry of the compression driver

It's really hard to go wrong if you put the midrange taps 3.5" away from the throat, and if you don't want to crunch the numbers that's a perfectly good place to put them.

Arguably, the most important variable here is the area of the horn at the location of the taps. The reason that this variable is so important is because you don't want to have a compression ratio that's too high. For instance, you might think to yourself, "Why don't I just put the midrange taps as close as I possibly can? What could go wrong?

The problem with putting the midrange taps too close to the throat is that the compression ratio will be sky-high, and that will lead to huge distortion figures. I found this out the hard way once, I built a couple of front-loaded-horns using the B&C 8NDL51 and I had a compression ratio that was over ten-to-one. Everything sounded fine at low levels, but once you gave them even ten watts of power, the horn made a cracking noise that sounded like the 8NDL51s were trying to split the walls of the horn.

After the Regulator Chip Amp and the Chtringlunator, it is time to translate the JLH topology into voltage regulators (I hope JLH won't be turning in his grave).

The task is pretty straightforward, and the results are excellent.
And since the circuit operates in class A, it doesn't have slew-rate issues.

In practice, R2 and R9 can be halved: the spice model I have for the LM317 reaches its current limit at only 850mA, about half the actual device. This will make the amplifier able to drive a 4 ohm load.

Pics will follow.

Bought the 2 CD version of this album today; really enjoying the new mixes and early takes.

At first hearing, some remixes work better than others, with perhaps too much bass on She Said and Yellow Submarine which muddies the vocals a little. I'm Only Sleeping really stands out, sounding more funky due to the clearer bass. Ringo's cymbals are a little muted on some tracks, again, as in She Said She Said, but the overall drum sound has more impact than previous issues, particularly on I Want to Tell You and Good-day Sunshine.

I really like the way you no longer have voices from one channel and instruments on the other. Instruments, such as the French Horn on 'For No One' are clearer due to the new mix. Good-day Sunshine seems to have more 'oomph', etc etc.

Is it 'better' than the 2009 stereo issue, the original release or the mono; I don't know, but I find it more enjoyable.

The 2 CD issue includes stereo versions of Paperback Writer and Rain, plus early takes, mainly before additional overdubs and instruments were added. The horn-free 'Got To Get You Into My Life' comes across as harder rocking.

Fascinating extras, but not essential. Nice booklet, too.

Other views?

Geoff

Hello everyone,

I am relatively young in the audiophile world, with my main spending habits being headphones and more convenient audio. I currently own a Schiit stack and run a pair of Hifiman Sundaras and a pair of Meze 99 Classics.

I've recently gained interest in amplifier repair and am interested in building a DIY foam panel speaker.

Login to view embedded media

Hai Friends, Today In This Article We Are Going To See This Tpa3116d2 Ic-Based 5.1 Class D, Amplifier Board.




This Board Is Very Compact So You Can Assemble A 5.1 Amplifier With A Mini And Compact Cabinet.
This Board Has Six-Channel Input And 6 Channel Output. You Can Get 50 Watts Of Audio Power Output Per Channel.

For This Board You Should Use Only Four Ohms Speakers And Subwoofers… If You Are Using An 8 Ohms Speaker Then The Audio Result Will Be Low.
So You Should Compulsorily Use 4 Ohms, Speakers, With This Amplifier Board.


This Board Works With A Single Supply Dc. For Better Audio Quality And Results Use A 24v 10 Amps SMPS. Or A 20v 10 Amps Transformer. (SMPS Supply Is Best For Audio Results)


If You Are Not Happy With This 50w Subwoofer Output… You Can Use This Tpa3116d2 Class D Mono Amplifier Board. This Mono Amplifier Board Can Get A Maximum Of 100watts Audio Power Output Per Channel. If You Are Using This Tpa3116d2 Mono Amplifier Board You Should Use A 2 Ohms Subwoofer For The Best Audio Result. If You Don’t Have A 2 Ohms Speaker Then You Can Use Two 4-Inch Subwoofers With A Parallel Connection.
If You Are Ok With 50watts Power Output Then This Single Board Is Fair Enough For You.


This Board Has Many Safety Protections

• Speaker Terminal Short Circuit Protection
• Input Signal Over And Under Gain Protection
• Speaker Terminal Power Supply Short Protection
• Input Power Supply Low And High Protection(Below 10v To Above 30v) So Always Use The Recommended Power Supply To This Board For Longer Ic Life Below 30v.

Now We Are Going To See This Tpa3116d2 Board Input And Output Connection Details​

Audio Output Connection Details
All The Connections Are Clearly Mentioned On This PCB Board.

After All, Connections Are Done Always Switch On This Amplifier With A 100w Bulb Based Series Connection. Because If You Give The Wrong Connection Then The Bulb Will Glow So Your Board Will Be Safe. If The Bulb Is Not Glowing Then You Are Giving The Right Connection To The Board. Always Remember This Method For All Your Boards Before Turning On Your Amplifier.

Click Here To See The Tpa3116d2 Ic Datasheet

So That’s All Friends, If You Want This Board You Can Ask Me In The Comment Section Below…
And If You Have Any Questions About This Board Then You Can Ask Me In The Comment Section…

Some pictures from the rooms where I enjoyed the sound. Otherise no need for words.

Attached is a pic of a new Class A amp prototype inspired by my work with the "Half Nelson" amp described elsewhere in the Pass Labs forum, and also as a result of a little email back-and-forth between me and Papa after last year's Burning Amp. It solves a few of the problems I encountered with the Half Nelson, at the cost of a tiny bit of extra complexity (actually, the parts count is probably very similar between the two - I'd have to open up both schematics and do a head count).The new design also eliminated a lot of nasty coupling caps.Schematic will follow when I get the thing powered up and nail down the bias values. I'm also working on a version of the Half Nelson using the Semisouth R085 jfet, but that one is on hold for a while, as this amp may be easier to spit out. I'm also working on a tube-type design using an R085, but that will be the subject of another thread. Burning Amp should be interesting this year...

Greetings, I seek anyone here that has experience with AUDIOMOBILE gear from the late 70's... Especially needed is schematics and any possible info I can use to get this SA 1000 amp 100% again. Anybody have GEAR?... Might be interested here... an easy SWAP would be nice. It's currently FULLY operational BUT upon hard gain and EQ settings I get a SQUEAL, high pitched, and also motorboating from the BASS end. Only ONE channel of the amp is doing this, the other 5 channels seem fine. NOT the EQ at this point, I THINK its a single channel in one amp thats the culprit.... FLYING BLIND here.... LOL. LMK... Thanks BDBD/2022

I have a modest home theater setup:

• LG OLED655C8PUA TV
• Apple TV as streaming source
• Hypex FA123 amps (connected by optical out from the LG TV)
• DMLs as external speakers

I have the Hypex Infra red remote controller for the amps.

This leaves me with 3 remote controls.

I can control most of the day-to-day Apple TV functions with the LG TV's "Magic Remote".
No way exists (that I have found) to control the Hypex amps with either the Apple TV remote or the LG TV remote.

I'd very much like to control the three devices with a single remote control.

The attached shows the Phillips RC5 (IR) codes for the Hypex remote.

When I asked Hypex support, whether they could recommend a universal remote I received the following:

I only know of one customer who had sent his OneForAll Evolve to OneForAll HQ for programming the codes. I’d suppose they have added it to their database afterwards but I cannot find any devices under Hypex in their database. And I thought we were in the Harmony database but I don’t know under which device.

Click to expand...

Unfortunately, neither OneForAll nor Harmony have listings for anything Hypex or the Fusion line of amps.

This leaves me needing a universal remote that can "learn" the Hypex remotes functions as well as the LG TV's and Apple TV's.

Any recommendations for such a remote and how to configure it - to do what I need - appreciated.

Also, if anyone has a better suggestion for where on the site this question ought to go, please advise.

So I recently purchased a skar 2000.1d, knowing it had been damaged. The output had been shorted out at almost max output, yet the damaged was surprisingly minimal. There is however a resistor that burnt up, and I've had no luck finding any schematics, and simply got PFO'd when I reached out to skar. Does anyone have one of these handy that can take a look for me? It appears to be labeled R99. I hope this is in the right section. Thank you all for reading!

Hi Gents,
Re above from data Opt is 2.5/3.5k 10 watt, max ip 100 ma.
Question if I run this opt with 300B at 80 ma 425v for targetted 8 watt output
would core saturation set in ?

Thanks

Hi, looking for help. Service manual states injecting 6-8mv into the test points. Never came across such a thing! Any help greatly appreciated!

The short form data of SP8C/SP12C/SP15A are here
https://products.electrovoice.com/binary/SP8C, 12C, 15A EDS.pdf
Unfortunately there are no datasheet of the SP8B online.
Maybe the SP8B use an ANiCo magnet drive unit.

Here are some images online
Building with E-V SP8B
EV SP8B Electro-Voice Vintage Speaker 8" Full Range Whizzer Alnico OHIO | #287161236
retro vintage modern hi-fi: ElectroVoice Popular Electronics Ad October 1955 | Vintage speakers, Speaker plans, Hifi
1961 Ampex Branded 8" 16ohm Electro-Voice SP8B from 8202 Signature Console Photo #2368348 - Canuck Audio Mart
(ampex branded version without whizzer cone)
https://www.canuckaudiomart.com/details/649141966-electro-voice-sp8b/images/798821/

Thank you for upload a datasheet of the predecessor of SP8C and calling some commercial spraker box models equipped with this transducers.

Hi guys, I'm hoping someone can help me with this one.

I'm repairing a Yamaha Natural Sound Control Amp CX-630, it was previously making a horrible DC like cone thumping noise. And after reflowing lots of cold joints especially around Q71/Q72 it came back to life, that is almost.

I've connected it up to a Yamaha AX-400 amp and can hear the music fine but only if the volume on the AX-400 is turned all the way up and the volume on the CX-630 isn't working. Neither are the balance, bass, treble etc, and stranger still when I change the input selection with music playing it doesn't change the music plays on any input selection! The CX-630 goes with a friend's Yamaha model YST-A5.

Any ideas?

Hi, I have just bought an item of of E/Bay on Sept 10th, with the seller only allowing shipping overseas via this Rip Off ''Global Shipping Program''.

The impression is that it is a fast safe service.

However the item cost $100 to ship & I now been advised I will not receive it until early Dec.

I have many times shipped to the US for a similar size & heavier weight item for just $65 & it gets there in 10 to 15 days.

I also can order & have ordered items from Ali Express that cost a fraction of that price & often I get them in 3 to 4 weeks.

I have now started advised sellers of item I am interested in, That I will not make a bid if they do not offer other postal options.
Please join the campaign & insist to not use Global shipping. Remember the power is in the consumer.

For comparison, on the same day I ordered a cart from the UK which was sent via 1st class mail. It arrived in 10 days!!

Cheers

Hello everyone,

I have a question about the push-pull buffer below. It is biased by a voltage divider so it can be run from a single supply. Now there is a 100k resistor between the bases and the voltage divider, but suppose I want to increase the input impedance, is there an objection to put a 1meg resistor or even higher?

Hi, i just bought a pair of EV ZLX12 speakers. 1 is with bluetooth the other is not. When phone is paired with BT (left), i can set the mix out to R and use XLR to send R channel to 2nd speaker to get stereo. Now let's add subs.

My subs are DIY bass horns powered by XLS1500. If i had a mixer, or wanted to use RCA or XLR or even 1/4" input (e.g. from mixer) i would connect source to XLS1500 and use the link/out to each speaker to get stereo.

But if i wanted to use phone with BT, how would i do it with subs? Obviously with BT i have to connect to the L speaker. But theres only 1 mix out on the ZLX12BT so that has to go to R speaker to get stereo. So the only possible line out to sub amp would be the mix out from R speaker. So my sub channel will only be mono, from the R channel.

I guess now my question is, is that ok? It should be ok if i can assume that all content under 100hz will be mono at the source anyway. In which case maybe all that means is i would need to increase the gain at the sub amp by a factor of 2, to get back to the level as if i did input stereo to the amp. Does that make sense?

Is sub bass in music usually/often/always recorded as mono? Or is my assumption false.?

Does anyone know what it takes to convert one of the original Tim P. 834P phono stages from 240 to 120 volts? I have access to one from the UK that has the info below on the back of the phono stage but I don't see a switch. Also, the manual says the unit has been "....set internally for 120/240 volts." This has me confused.

Power: 100-120V
200-240V

I've just purchased a Hafler DH101 preamp kit build. It is in decent working order, however, there is some "bleeding" of input sources. What I mean by that is that I can hear the aux and tape sources (if they are active) while listening to phono. Can anyone recomend what to look for to cure this problem? Also, i was wondering if anyone could recomend some mods. I read something about a moving coil upgrade, but i'm not sure what that is or how it would benefit me.

Hi all
I know, I know this mide be way out of league but I'm gonna build it anyway 😉
I'm not an expert in any way, but I have make couple speakers and they did sound nice to me.
Now as time goes by, I'm starting to lose interest in diy so this will probably be my last diy project...At least I hope as one is more expensive than the previous one 😉

In a couple days I will start making test cabinets but would like, if someone has time to check my plans about volume for drivers and spacing between those. I would appreciate it.

Below you will find pictures of concept design.
One is a classic box, and the other is a box with tweeter on top to have the option for sliding it forward and back for time alignment (not important as I have DSP..but it look's cool to me 😉.
Front baffle is at 5* angle but tweeter is not angled.

At first I liked the option with tweeter on top, but leter I prefer a more classical design...will see....

Thas will be fully active, analog precision DSP, hypex, SB acoustics with RAAL drivers, all in closed boxes ;

• analog precision 8 chanel DSP
• RAAL 140-15D AM + hypex NC100HF - connected to NC252MP / RAAL_140-15D
• Satori textreme MW13TX-8 + one channel of NC252MP / satori-mw13tx-8-textreme

in a 3-4 Litres closed box
- 2 X Satori textreme MW19TX-8 + second channel of NC252MP / satori-mw19tx-8-textreme
in a like 9 litres per driver, total around 18-20L closed box
- 2 X SBA subwoofers SW26DBAC76-8 / sw26dbac76-8
dual oposite subwoofers in like 20 litres closed box with linkwitz transform (like 9-10 litres per driver)

Crossover points would bi like ;

• sub / 19TX - around 80-85Hz
• 19TX / 13TX - around 500-600Hz ( at about baffle diffraction point ?)
• 13TX / RAAL - from 1.7-2.4kHz will see what sound best

Baffle wide is 220 mm.

What do you think ?
What about driver spacing between drivers in dependence of crossover frequencies ?
RAAL advise me to place center of tweeter at around 95 cm.


And one question how to place all those amplifiers on a plate.
Option A when I have power supply of NC252 and NC500 facing to the top and bottom of plate - speaker cables will cross each other
Option B when I have NC252 and NC500 power supply facing each other - the interconnection cable for subwoofers will be a little longer run by the power supply. Don't know if there will be any interference.

For me option A looks like a safer bet, but option B would be easier to connect once they are inside the cabinet...or not...😉

Please don't be hard on me, I'm not an expert, and I'm doing my best to not become one 😉
Will play with baffle design around tweeter, to achieve something like wave guide or not...will play and will se where it will take me...
The look is like 90% of the sound so 😉, it's more important how it looks then the sound of it 😀

Here is a video of my previous build, so I'm not total noob, but... VIDEO 1 or VIDEO 2

has anyone found the cure for the Boston acoustic VR2000 sub woofer hum all caps and surrounding components have been change and the line in has been disconnected from the power amp board and the unit is still humming i need a schematic so i can check the feedback circuit can anyone help or have any solutions for this problem

Hey everyone,

I just wanted to share this one. I was looking into ways to improve dispersion of large diameter woofers to increase the crossover frequency. I have a set of Cerwin Vega 300 SE speakers for playing around with. They are perfect because the woofers are run full range.

I used a piece of 3/8 cast acrylic, cut it out with a jigsaw. Flame polished the edges and used a propane torch to bend the middle in. I'll post the template.

The results are better than I expected. The waveguides completely removed the 7db peak at 1.5k. the speakers sound much more open and the sweet spot has changed from about 12" to several feet. I didn't do much off axis measuring, since I was using my laptop for the tone generator and it just didn't have enough output to get any consistent results.

I thought the results where pretty amazing so I had my wife come in, and do a blind A-B comparison. She said the one sounded richer, so the wave guides have 2 positive votes. I think these could be the answer for a lot of problems.

Jordon

Simple ... I am in love with the P3A there is no other way arround that .
if the application is ok with 60-100W then so far there is nothing better in my world .....
Before many of you start to say things remeber that in my shop we repair an also listen audio machines
now days between 2500-3000 machines per year
that means that i have been listening the latest 10 years anything that is available , any topology any make, any brand , just say it and we already done it , and obvioulsy not once and not twice ....
I can remind you the reasons because some of us tent to forget why
Smaller amps requiere less safety measures ( vi limiters , miller compensations and so on )
mutliple tranistors suffer from times* the device capacitance so driver stage need to provide the current but also the ability to drive that much of capacitive load
Multiple active devices in the output there no guarantee that will "ring" at the same time .... The more the outputs then amplfier is more pcb depending
Thermals is an issue , rail distribution is an issue , decoupling is an issue , too many active devices and oscilation is waiting for you in the corner
you start with 200-300 MHZ ltp , then you might get away with 100 mhz VAS and drivers and then 30MHZ outputs
made a P3a ltp 300 mhz vas and drivers 200 and outputs 50 mhz just to examine the stability of the circuit
no problems at all and let us not forget that i have been messing around of limmits with the miller compensation
So if you sum those details and add to them minnor refinements that i ve made in the P3A this in total is what makes the P3A the amplifier that fits the picture
remember that other similar EFP amplifiers might preform alike, close or even better but the bootstrap in combination with CFP when it come to sound is unbeatable cobination any way you slice it .
there is a possibilty that a diamond input and a more in generall sophisticated input scheme or + and -VAS will provide precision but the result doesnt give the same feeling
Listeners say that the original combo playes better
But through the years and long discussions about that, obviously we have been there before and more than once .
----------------------------------------------------------------------------------------------------------------------------------
So today's question is "what if more power is needed ? )
there hass been an issue before and if i recall correct you can double the outputs as long as you add 0.47 /5W to every emmiter
i am not sure i want or like that
i could risk to skip that step and go with very close matching on the outputs fit them in a thick fin of alouminoum before the heatsink one on the lower side one on the upper side for the PNP and the NPN alike
That is to ensure that each pair shares the same temperature add that most of them i go with relatively hi bias so that prevents in away that outputs will act diferent

Any other ideas to squeeze more power ?

The title says it all. I'm looking for a GreenStreet LP12 chassis with an SME arm cutout for a Mission 774 arm

Maybe someone has one out there.to sell.. I live in hope...

Ta.

Here is a fun application of a chipamp:

This little circuit is a sinusoidal oscillator that will adapt itself to the resonance frequency, impedance and Q of any driver presented to its test terminals.

It makes the measurement of said frequency fast, easy and accurate.

It could also find other applications: breaking-in of new speakers for example, or as a musical instrument with a variable length tube as resonator.

Have fun!

Paid 620USD about 7 years ago. They got much cheaper in the meantime. Asking 160EUR for the pair. Shipping from Brussels, Belgium.

C17WH-09 08

vifa, scanspeak, peerless

With the IM Option.

THANKS!

Charles

I've been digging though my workbench and I've come across a couple semi completed projects that I'll likely never finish.

First up, a pair of RH 807 SE amplifier boards. They were originally for a guitar amp, hence the tagboard construction. Each board is 6'' x 2 3/16", they are on 1/4'' brass standoffs. Pinouts will be provided. Also, do realize that power supply section is not included on these boards, you will need to design your own. The schematics can be found here: RH 807 - Tube Audio ...... RH DESIGN

I am asking $35 plus shipping (Should be around $5-7) for the pair

Close-up:


Second item, are a set of panson audio LME4981X PCBs that are semi populated; 95% of the capacitors and resistors have been installed/will be included. I also have and will include most of the driver transistors. Power/ output transistors will not be included, the guy that was suppose to help me get them seems to have disappeared. However, you can still get them via samples.

I am asking $50 plus shipping for all 3 boards.

Good day to you guys! I normaly post or read about my DIY Microphone Projects, but I have a new... DIY repair to do haha!

I have a Yamaha AG06 Mixer and USB interface. Did communicate twice with Yamaha technical support, and the answer was : "Due to the low cost of the AG-06 they are not economical to repair."

Here is the thing.

When using a dynamic mic, the input 1 is about 10db lower in gain compared to what it used to be, and compared to the input 2. (and obviously I'm not using the PAD button...). Cranking the gain brings the noise floor too high.

When using condenser mics... it gets interesting :

• Samson CO2 : Works well with 48v, aside from being most likely 10db lower gain
• Sennheiser M66/K6 without battery : Nothing with 48v... hear some static at first then it fades away
• Studio Project B1 : Nothing with 48v...
• Deity V-Mic D3 without battery + Rode VXLR+ : Nothing with 48v...

So far I have done :

• Reset the Mixer
• Update and reset the AG DSP Controler
• Tested various cables
• Tested other mixers
• Cleaned the connectors
• Cleaned the circuit board
• Tested voltage output (48v on both pin 1 and 2)
• Forced pins inward/outward

So, no Idea what to do next... is it a capacitor or a resistor somewhere...

Thanks for helping me,

David

I just completed these detailed mods for the SRM-252S driver unit:

Upgrading the Stax SRM-252S

This puts the SRS-3100 system in another league performance-wise.

Comments/questions welcome.

Hello People


I want to know if i can use my Logitech Z-5300 Speakers without SoundTouch remote

i want to isolate the remote so i can use my decoder only beside using the both remotes.

in other words if one lost his remote how will he be able to use the speakers because the power button of speakers is located on the wired remote and if remote is not connected on sub we cant turn it on

i have seen Z-5500 hacked thread so may be someone can help

thanks

Hello, I’m planing to convert my system to be active.

My current system:
CD tranporter —> Integrated amp with built-in DAC —> Speakers.

The active system:
CD tranporter —> Integrated amp with built-in DAC —> Active crossover —> Power amp —> Speakers.

Since my integrated amplifier has no pre-out/main-in channels, I need to use speaker outputs to feed signal to the active crossover instead. According to the attached spec of the active crossover, there are four “high-level” inputs with impedance in each channel of 10-10k Ohms, my questions are whether the 10-10k Ohms is the impedance load presented to integrated amplifier? If yes, should I connect all four inputs or simply connect only two channels, the amplifier is two channels stereo? To my understanding, connecting all four inputs will halve the impedance i.e. 10-10k to 5-5k Ohms on each channel, am I correct? Last question, the integrated amplifier is rated at 100 Wpc, will it detrimental to the electronic crossover?

Well, I finally decided that my M60A was too powerful to be my only guitar amp so I picked up a 1971 CHB-10A off eBay. 10 watts of single-ended and cathode-biased fun. Loudest 10 watts I've ever heard too. Without any changes to the circuit it sounds pretty good, it's a bit bass heavy playing clean but it screams when cranked. Right now it has a Mullard 12AX7 and a Sylvania 7868.

First off, I seem to be having a bit of trouble with the grid (screen grid I believe, I can see it through the holes) overheating when the amp is pushed really hard. It's a cool effect to watch for a while as the tube glows brighter or dimmer along with your playing, but I can't imagine this being good for the tube. I've heard this is common with US made 7868s, but I don't want to buy new production. From what I've seen, EH makes decent ones now but I'd like to stick with NOS. Any way around this?

Stock schematic, preamp and power amp sections:
http://home.rochester.rr.com/groundhog/CHB-10A Pre and Power.gif

Power supply:
http://home.rochester.rr.com/groundhog/CHB-10A Power Supply.gif

Also I've drawn up a quick schematic of how I intend to change the amp to make it more suitable for guitar. I relabeled all the components on this schematic so it may be a bit confusing, sorry. I searched all over the internet for what other people have done with these and tried to take the best out of all of them for a unique amp. The first preamp stage is copied from a Fender 5D2 Princeton, I like a grid-leak bias first preamp stage and I wanted to copy a good one. I made the RCA jack connected in parallel with the 1/4" input just incase I needed to plug in a CD player or something. The phono input circuit is getting removed and I'm using whe hole where the pot was to mount the input jack. I kept the tone control the same for now, I may have to change the cap value but I like its simplicity and the fact it's pretty much bypassed with the knob all whe way up. I copied the second preamp stage including the NFB/bypass cap switch from another CHB conversion schematic I found. Should I keep the NFB wire hooked to the 16 ohm tap if I do this, or should I move it to the 8 ohm tap? I kept the output stage fairly the same although I changed C9 (on my schematic) to a .022 and the cathode bypass cap to a 33/160. I'll probably use a lower voltage rating in the end but that's what someone on another forum said he used with good results. Some of the cap values may change a bit depending on what's available at a good price.

So what do you guys think? Will these mods make this amp more suitable for guitar? Thanks in advance.

-Darren

NOS stocks. sold as it is.
$10 for 1 piece , buyer pay for shipping

Email , lexxtox@yahoo.com




https://www.datasheetq.com/non_pdf_view.jsp?pn=VC5022-2&fac=ETC

Hi all! Owner of an RNHP (Rupert Neve Headphone Amplifier) here. The amp is known to generate significant noise/current from capacitor charge/discharge during power up and power down which passes loud noise and likely DC straight to the headphones. Neve advises unplugging headphones every time the unit is powered on or off, but my home studio is somewhat automated and the RNHP is in a rack out of reach. I also feel like an amp at this price point shouldn't require the user to disconnect and reconnect sensitive headphones before power on/off to avoid damage.

I thought I could just put the headphone plug on relays I could automate to switch in and out, but this apparently isn't functionally the same as disconnecting the plug for some reason. I've detailed below.

I feel like headphone protection is relatively underdiscussed and I'm trying to use this as a learning opportunity. I'm wondering if anyone with more electrical engineering knowledge than I have can weigh in on the feasibility of these ideas or others. There is significant information available about the design and circuits in this thread.

Here are some of the ideas I've tried:

• Connect each of the 3 headphone conductors to their own 2-way relay. Open relays during power on/off and close the relays after a delay.
  • This seems to me like an automatable way to "unplug" and "replug" the headphones without literally having to do it.
  • All of my experiments with this yield an explosive pop sound when I switch in the headphones the first time after power on, presumably due to the current accumulating somewhere in the circuit and then being released into the headphones all at once
  • I'm not sure if there's a solution to be had here with a 2-way relay and capacitors to drain or shunt the current but I haven't had success with my attempts.
  • Any signal degradation from the relays? Not sure how to pick the right ones for headphone audio signals
• Disconnect headphone plug from jack. Power up. Connect headphones. Disconnect them again before powering off.
  • Inconvenient, but it seems to work PERFECTLY.
  • This doesn't produce ANY noise upon connection of the headphones. Why does this work when my relay solution doesn't? I'd think they're functionally identical.
• Adapt headphone output from RNHP and headphone plug conductors to BNC. Use a logic-controlled video editing router to switch the headphones in and out.
  • This works perfectly with no explosive pop sound upon switching, but ONLY if I engage the 75 ohm termination switches on the router.
  • I am not sure why this matters. Any ideas?
  • Don't know how to measure the signal path in the editing router to assess sound quality
• Utilize an inline headphone protection circuit such as the E12 muting/protection circuit
  • Presumably a circuit like this would handle whatever current is generated during power on/off without sending it to headphones
  • I can't seem to find any prebuilt solutions for this
  • Not sure if this adds components to the signal path which I feel like isn't necessary
• Modify a speaker protection circuit like this one for use with headphones
  • Perhaps switching it in and out via 2-way relays so it is not inline?

I know there are various elements of this problem I'm not understanding fully, so please feel free to correct anything I'm not getting.

I'll endeavor to post any updates from my ongoing testing.

Thanks,

MI

I want to use 2 of the outputs from my ADAU1701 board to send a signal to my sub via RCA cables. What do I do with the 3 leads from the board vs the 2 connections on the RCA terminal?

Greetings!

Hi folks ..

I am new to this space .. I have an Arcam AV40 with Dirac, which works great with my basement. It is simply awesome and I have received lots of compliments from all my friends.

Now I also have a PA system (JBL EON 208) .. it is a nice two-speaker system with an Active mixer. I would like to use some Convolver or Room Correction when we use it in the basement for the Karaoke system.

So the question is what is the cheapest way to use freeware, to be able to perform room correction before it hits JBL EON.

So which software to use so the output from the Laptop is passed through the Convolver

Any advice is appreciated

The whole idea is to make a mini tube amp that's everyone can built for their office/bedroom.

Highlights:
-Open schematics
-Low component count
-Very affordable
-Extremely easy to build
-Sounds great
-Solid, Sexy & Sleek
-Wife friendly

Topology: SET Ultra Linear
Signal Tube: 6J8P <-very affordable
Power Tube: KT88 <-decent price
Power: 2 x 6.5W

Feature:
-2 pairs selectable stereo input
-Balanced XLR & Phono Headphone output (Wires Tap from the speaker output)
-4ohm/8ohm
-Bluetooth PCM5102/ES9023 in future*.

Built:
-strictly no "audiophiles parts" in the built


Things that are still under optimizing:
-slight of 50hz/100hz humming when the ear is put 2cm next to the speaker drivers, not ideal for headphone users. Still figuring a way to remove to hum without rectifying the 6.3Vac. Planning to lift the heater voltage referencing to a common that is far above the cathode voltage.
-Very limited bandwidth to 15khz@-3dB although one can hear sparkling and vivid highs from this amp.
-PCB Layout needed to optimized for easier installation and better layout.
-Chassis need a handle

The whole amp is functioning and the sound is surprisingly really very nice, spacious, great soundstage, sparkling high, fluidy mid, and i believe it can sound better than many of the commercial solid-state power amp out there easily. (I know everybody claim the things that born out from their hands are the best. 🤣 ) But its really good, the schematics is in this post and you might want to try it out.

I'm still figuring and compiling any possible way to further improve the performance and outlook, any suggestion is much appreciated.

A bit progress here:

CNC cut on a ready made waterproof aluminium enclosure


laser cut bottom faceplate with gold anodizing and black rubber feets.


And older model with high gloss black powder coat.


Bottom PCB, with chokes, connectors and SMD components on it.


Top PCB, with Tube mounting on it.


PS: I don't wish that there is anyone taking this out for commercial purposes.

Hi,

I'm going to test a new vacuum tube amp build, and would like to avoid problems with 50Hz and HF noise I had in the past. Power supply and amp prototype will be housed in separate boxes made with 3mm thick Neobond (porous plastic with 0.5mm aluminum on both sides). Neobond is surprisingly light and sturdy, is easy to process (mill, drill, etc.). Aluminium foil on both sides will serve as EM shielding. Foil on outer side remain intact, yet on inner is being cut with V-mill in order to bend sheet into a box. So where necessary I scraped coating in order to restore conductivity (e.g. on corners with aluminum brackets of 2020 type, DIN rail mount, etc.).
Power supply is assembled on prototyping PCB, stacked type 2xHV (220V toroidal transformer, secondary 2x159V, plus additional 42V/35V for adjusting output voltage, 60V BIAS, 3x6.3V filament). PS output terminals will be DIN rail splice quick connect type.
Since toroidal transformer supports up to 8A on each 6.3V tap, and will power up only 1 channel, I plan to power all vacuum tubes from single 6.3V tap.
For safety reason amp PCB will be mounted on additional riser plastic plate, not on the bottom of the box directly (further away from metallized surface).

Now the question: how do you recommend to make routing between these parts of the whole assembly: 220V power line ground, power transformer Faraday shield, power supply chassis, amplifier chassis, BIAS GND, amplifier GND, filament artificial middle tap (from 2 x 100...200 Ohm resistors). IMHO HV power and BIAS GND must be connected near terminal of PS PCB board (or may be amp PCB?).

Photos of some parts attached. Amp itself is on early assembly stage so there is nothing to show right now.

Thanks in advance for any help.

Hi gents,
Sorry if this question makes me seem stupid 😃
How do I test these transistors with a dmm?
I have a bunch of them and Hitachi ones .