audiostar

As you basically have a dual mono setup, try completely separating ground for both channels, and connect then each ground centrally to the chassis (via the 10R resistor as you did or a real circuit breaker). So you will have a star ground per channel which is connected to another star (chassis at IEC connector with both channels master grounds). What you did with separating ground on the pot was the right beginning in this direction.

Could you please check out that XLR cable you connect your DAC and amp, how is it wired internally? Pin 2-2 and 3-3 are ok, question is about pin 1: does it connect to the shells on both sides as well or is it pin 1-1 only and does it connect pin 1-1 on both sides of the cable? Have you tried with another XLR cable? If the cable is right, might be your DAC implements grounding in a wrong (not AES compliant) way; in this case I'll disconnect pin 1 at the receiver's (CFA) side and only leave it connected at the senders (DAC) side. Make sure only hot and cold from pin 2 and 3 go into the amp and make sure there is no hidden connection between pin 1, cable screen, connector shell or chassis at the receiver. This should break any ground loops caused by the sender. @ParsYes, Toroidy have two secondaries. The cable or your DAC is most likely the problem. Strange as well, have you tried with another pot?

You can use FN281-4-06 from Schaffner. It is available in a horizontal or vertical orientation and includes a fuse holder and power switch. Take a look at the pdf spec sheet as the picture isn't correct, showing a different style.

James, make the batteries exchangeable and go to daughter boards as well. The board is too big and too expensive to justify itself for a transistor swap alone.

Yes, I know them. They have good products and some very interesting things! This is an integrated transformer, so all in one, switching mode?

Nice one, JoaMat! What PSU is that?

A comparison between the KSA-5 and the CFA3 would be dope. Anyone having both side by side?

Hey Alex, need some pics of your final amp! Hope everything is good!

What is the difference to 1-770872-0? Looks absolutely identical to me.

Got you 🙂 Good luck with the build, looking good!

Got them and soldered. Those are just phenomenal connectors, solidly held in place by a knob to the board so no moving at all, very solid, HV with enough space between pins, completely isolated pins (doubled by the inserted plugs), keyed, no screws to fiddle with, etc. Just rock solid and my favourite so far.

What for are the other "three" channels, you do a virtual surround setup? Very interesting build indeed. Looks like building ship models in glass bottles. No, but you can do it for the sole sake of overkill.

Exactly, the PSU is outputting 400-450V and R28, R29 are single resistors.

Thanks, James. Need to check the PCBs later on - the CRCW2512511KFKEG is used for R28, R29 in the base board.

Thanks, Pars. Those are all 200V and the CRCW2512511KFKEG is 500V. No idea atm if that matters where it is used.

Kerry, could you please recommend a replacement for the 511K resistor CRCW2512511KFKEG (from the BOM). I was looking into it but couldn‘t find anything near or suitable and Mouser gives me a delivery date for it in March 2024, which is radiculous at best. Thanks @Kerry

Thanks, Kerry. Tried to locate the others:

Hi Kerry, which connectors are you using here for the LV, HV and the output voltages? Look like 4mm pitch. Tried Mate-N-Lok but not really sure as they do not have the fixating hole on the short side like these. Thanks @Kerry

Marvelous, thanks Kerry! Could you post the p/n of the 10k pot or is it the same as the 100k but 10k? Looks like it is the RK16812MG09T. 10k and same 3B tapper and dual unit as the RK16812MG099.

Hi Kerry, how is that 20k resistor wired exactly, from the pots viper to Vcc (5V)? Thanks.

James, now you need to add re-anodization to the process 🙂

Working on a PCB for the pot for controlling Kevin's v2 digital attenuator. It will hold an Arduino Nano v3 piggy bag'ed on to it. Thanks to @migofor testing everything out.

Yes, get the absolute best possible cutters you can get, there is simply no way around if you wang excellent results.

Hi James, from your detailed description, it looks like the cutter being the culprit. It would be the first to swap out.

Which aliminium alloy is this exactly you are working with? 6061-T6 being the standard for CNC machining and excellent all purpose alloy.