Kerry

There are two mappings. One for the potentiometer, which determines the rotational position of the volume knob, and then a second for the log taper of the audio.

Yes. At the time, that seemed to be the easiest way to get a reasonable taper curve. These days for the work we're doing with HeadAmp, we've mapped several curves against the full 256 step capability of the attenuator.

The parts for the bias supply I can do for less, but not the 400V supplies. This is definitely something I want to give a listen to. Thank you

Wow, really interesting! I’m very curious about the power supplies.

Thank you, guys! Very much appreciated I had a nice day. My granddaughter is over for a few days, which made it very special. Sorry I haven't been very present on the forums.

Could there have been any kind of short? Seems like it blew out the protection stuff along with the pass FET.

Very nice! Congrats

Best wishes for you and your fellow countrymen. Stay safe!

Best wishes Birgir. Stay safe!

You should use a higher Hfe. What you have is ok, but if lower R39 to around 40k to 50k. Highest value that is stable.

Depending on the Hfe of Q23, you might need to lower R39. This could cause instability / oscillations in that area. If you can hear the amp without the headphones in, then it's oscillating. I agree that most multimeters should be able to pick this up (though maybe not accurately). If the amp is wildly oscillating and has very high voltage swings it could possibly damage the amp.

Happy Birthday, Todd

Happy Birthday! Enjoy

Happy (very) belated birthday, Jose

I had some of these made up. PM me. They are a drop-in replacement for the Keystone part, but with a 6mm opening