Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Cups on January 06, 2013, 10:18:10 am

Title: Funky feedback tie to screens on Sunn Sceptre
Post by: Cups on January 06, 2013, 10:18:10 am

Hello
My adventures with this Sceptre continues.
I was about to put some resistors on the screens and noticed that the screens are tied to the feedback network via a 390pf cap. Never heard of this. I attached a schematic:
http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/newamps/sunn_sceptre.pdf (http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/newamps/sunn_sceptre.pdf)

I'm debating cutting it. Probably just rolls off some highs in the power amp? I suppose I can work the resistors and the cap without cutting anything.
Suggestions?
And thanks again
Patrick

Title: Re: Funky feedback tie to screens on Sunn Sceptre
Post by: sluckey on January 06, 2013, 10:57:59 am

Yep, even the original Dynaco amp had that 390pF cap. I've wondered about that cap too, but just left it alone. Figured it was just part of the magic. :wink: