audiostar

Look what UPS just delivered from Digikey... And of course something is missing (3x 2sa1860)!

I bet JoaMat is already changing some caps 🙂

Something like this: Both 285.6 x 116.8 mm

I think I am going to enlarge the front end board so I can stack it on top of two CFA3LargeT boards and mount them exactly the same way as the split boards are mounted. This leaves me the middle of the case for two stacked GRLVs in the front and a toroid in the back. What was the max output a GRLV can be modified to? I think @sorenb did a special power version of it.

Ready to order BOM here, Mouser ID=43398b8123. Everything included for a 4ch amp, except for 24x 2sc4886 and 20x 2sa1860, which are double the cost of the items in the bom above and are pretty much nowhere to be found except for some 2sc4886 at Digikey.

If you mean the Protector3, yes, it cuts off only R+ and L+ to protect the phones. That's enough.

Hmm, while XLR pin 1 is fine going to chassis as it is basically shield, RCA GND should not go to chassis. This is why the RCA sockets have an insulation ring. It goes to circuit ground and is shorted to - half of the channel when the RCA input is engaged. This is a balanced amp, so I would switch all 4 channels (+ and - halves) between the outputs. And I would handle the speakers like balanced headphones, i.e. wire the +/- to the banana plugs and not circuit ground. Especially important when using a balanced source. For when you use the RCA input, the - half would be shorted to circuit ground anyway.

Yes, ceramic sockets have bit of different pin legs which do not fit the board properly. Use the teflon sockets, you can get them from the diyhifisuppy you linked above or on ebay as well. 8 and 9 pin available, check out this seller https://www.ebay.com/itm/223597938937

Make sure the thermal compound paste you are using is non-conductive as well as not all of them are.

Those large boards on top look interesting.

Exactly because of their physical properties and being so thin, I wouldn‘t even think in using them in HV environments with naked tabs and inox bolts. Heck, I am not using them at all, especially if space permits it. Frst comments were already regarding those silicon insulators! Just no way one can tighten up the sands to specs at around 8-9 Nm with those without some damage .

Before you go deep into the rabbit hole with insulation testing, first you check extremely careful all connections through the umbilicals to the amp boards by continuity. Then you load test the PSU with some resistors, do insulation testing and all the other fancy things.

400mV is around 10x too much for the offset. 8 rotations are normal for the bias pot until you start noticing the voltage increase. The pot has around 30 turns or so. 150 to 200mV would be in range.

I would go with the higher.

I would stick to 10k