D3A-300B Amplifier

[santitrucco]

Kevin are you saying film cap 20uf from 5v of filament to 450v B+ ?

 

[kevinkr]

There's a problem, the rated voltage is far too low - for safety I would recommend at least 100V.

Outside of Elna Cerafines, and Blackgates I have not encountered an electrolytic cap that I thought was as good as a PPIO motor start or polypropylene and foil film cap.

 

[santitrucco]

But the capacitor is from catohode bypass cap to 450v B+ ?

 

[santitrucco]

???

 

[soulmerchant]

for my own DRD or loftin white Set amp i always prefer the usual bypass cap to ground with big film caps than any ultrapath type as it always bring some positive feedbach ( sounds more natural without for my ears).

I find the opposite. Go figure.

In some recent builds I have been cap coupling to a source follower, using negative grid bias, chiefly due to the specs of some power transformers I had on hand.

To be honest, this is quite decent as well. Next step for this will probably be push-pull using mosfet concertina.

 

[soulmerchant]

But the capacitor is from catohode bypass cap to 450v B+ ?

Cathode by-pass goes to ground. You should use 100v rated caps for this as Kevin said.

 

[jwags81818]

I built this very amplifier and mine is stable and the best sounding amp I have ever owned. I did a few things different. I bought a pair of tent labs filament supplies for the 300B heaters and I built a circuit board for the amp portion. I also bought Soviet power supply caps on ebay for the 8uf and the 100uf.
I love this amp. With good dsd source files it sounds like the band is in your living room.

 

[disco]

hear you, pp is popular but se holds its own ground. if you have the speakers it takes.