12B4 Preamp

[Zen Mod]

sorry , Ray - I didn't realize that is you asking , even if I salute your efforts and enthusiasm previously ;

unfortunately , I'm not so familiar with many of 12B4 premp variants , even if I participate earlier in thread , drawing one of first tube shunt regs ( pretty crude and simple , by demand) .
that thread - linked to our Serbian forum , is with CCS load for 12B4 ; I resume origin is from here , big DiyA , and variety of various CCS-es is pretty well xplained in article made by local (P10 and gang) , and you can find it here : http://choky.diyaudio.rs/downloads/d...-CCS-beta3.pdf .
unfortunately , schematics are crucial , so I can't even imagine ways how you are ( already been ) doing things like these .
if you are in mood for that - write specifically how we can help you , and I'll try ..... even if I'm pretty ignorant in many bits 'n' pieces locally available to you , just because I'm living on other side of big splash .

[crazyfrog]

I checked this thread recently looking for an improvement of my 12B4 preamp. Will probably try that CCs cascode but would like to know if someone put another transistor than IRFP9240? Or any suggestions? Thanks.

[Poindexter]

That's a good looking circuit, Eli. Have you tried it without the gridstoppers? If the circuit is naturally stable, the sound will be substantially improved without them.

Respeckfully,

Poinz

[Salas]

Originally Posted by crazyfrog

Or any suggestions? Thanks.

IRF9610 is faster, same Vmax.

[bequerel]

Originally Posted by Zen Mod

maybe this will help you :

12B4A preamp - DIYAudio.rs

pics and schematics aren't in Serbian , and you don't need to register to see graphics

edit: shunt reg is further down the thread , one per channel

This is one of the best DIY executions I have ever seen!!
Have a look at the last page of the thread Zen Mod links to, guys!

[crazyfrog]

I have on hand two Blackgate caps NX 1000 µF 25V. Would it be too much capacitance putting those on 12B4 cathodes?
Thanks
Pierre

[crazyfrog]

Seems 1000 µF is not too much for bypassing but not necessary.