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yes...I still have a Dynaco 120! Very nice 60W / Channel.

Im replacing those 4 caps with low ESR non-polarized mylars, If I can fit them! Lol. 4 -10 uF 150V

Good for super clean 10V output Distortionless 10hz to 50kHz flat. Bipolar +/- 18V power supply rails used for ALL amp sections, DC coupled, and almost zero DC off set at outputs. Amazing preamp, but hard to clean controls 4 sure. I removed the FET timed mute at turn-on, decided to add a...

Yes on all! Great critique. Im almost done breadboarding the 700W upc1235 chip version. I did check the voltage drop circuit powering only the chip. OK perfect at 55VDC. Same as 400w relay board. I already did the cap mod, and a few rewirings. The 1237 chip is on a separate small board to start...

It would be nice to add Level Potentiometers on each side of the attenuation toggle, with a very low cutoff DC-Block....just in case preamp is DC hot. I'm doing this stuff to mine.

Hi George here: I powered up one 700W Relay board at 100V, then put the inputs to a variable supply to have a look. I measured +10V and -7V to trip off relays. I was not happy with that. I decided to try to use the UPC 1237 chip, powered by a separate regulator. That will result in a much lower...

George here, Amateur Radio Operator AB2KC Working at Brookhaven National Laboratory Just Rebuilt 2 PL400 Series 2, 1 400 series 1, and a 700W series 1 (In process) All with Relay Boards, New PS Capacitors, recapped/ or new boards. Designed my own 700W series 1 relay Board... using the UP1237...