• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Posted new P-P power amp design

Peter - Nice measuring amp! Thanks for the write-up. However, I'm a little puzzled by the output from your spec an. What causes the LF noise (<1-ish kHz) to be 15 dB higher than the HF noise? I would expect 1/f noise to have a slope to it, but in your case, it's more of a shelf.
Are the spikes around the carrier frequency and 2nd harmonic IMD products of the power supply ripple?

~Tom
 
I got mine today too. The *%#&ing postman stuffed the envelope in the black mailbox (no it didn't fit, so he made it fit) so it spent about 4 hours bent in the sun baked mailbox. The board now has about 3/8 inch of warp in it. There are plenty of mounting holes to straighten it out.

Could someone please tell me what the 7-pin circle diameter measures on the PCB.

Yes, they measure 3/4 inch. No, the sockets that I have don't fit. Yes, they can be persuaded to fit. The 12 pin sockets that I have are plastic. I wonder how long it will take for me to melt them!

Observations:

I do have some Panasonic 47uF 500 Volt caps that fit the board. Digikey part number P7442-ND, I only have two so I guess I 'll be ordering some more.

The green screw terminals that I use on the Simple SE and Simple P-P don't quite fit, but in some cases like the input connections they can ** persuaded to fit.

The leads from some monster 300 watt mosfets that I got on sale (TO-247 package) don't fit the holes in the board. Do not force things into plated through holes.
 
I've been looking for somewhere to use this SCR heatsink -- it is reminiscent of some Norsk invader, or distant relative of Siegfried:

An externally hosted image should be here but it was not working when we last tested it.

Good idea! If mounted instead of an original one it will be much more effective than in the original design, even though not the most effective, according to fin orientation for convection flow.