Help with inverter CCS+NFB

[aletheian]

Offhand suggestion- drop the values of the feedback resistors by a factor of 100, then plug the 12AT7 back in.

edit: 1k or so of grid stopper on each side of the diff amp wouldn't hurt and might help.

I'll give it a whirl. I do have grid stoppers there--2.2k-- I just left them out for the drawing. I usually like 'aT7's, so I'll see how it goes.

PS SY, I am tryng out your cascoded CCS in a preamp right now... I'm about 10 minutes away from firing it up.

 

[Nafty]

phase inverter

Hello
My experience is for this circuit is that the best feedback is the NO feedback. This circuit keeps the circuit out of oscilation all the time.
You may low the distortion using some ammout of NFb but you loose sonicaly. Yes, I know what you mean; you ganna implant one current source down bellow there... Well is one improvement.
If you need feed back ( after my experience ) you may connect the output plates to the driver plates with resistors from 220K to 600K depending of the relation between gain /distortion/sound that you're looking for. Also if you want to get more precision from the phase inverter, you may add one ( good quality) trimmer of 250k/500K between the 1M resistors. Best tube, 12AU.
Ok everybody, I gonna be out for a wille. I'll see you latter.
Kind regards and remember: Dont frie the poor cat.
Nafty