ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

 
Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
previous: DAN MY SF DELUXE HISSES MORE THAN MY OT... -- 12/21/1997 1:36 PM View Thread

Re: SF FENDER INSTABILITY

12/21/1997 3:17 PM
R.G.
email
Re: SF FENDER INSTABILITY
If you put the caps back on the power tubes and the hiss goes away, and the distortion is gone, then yes, you're having oscillation problems. You don't say it explicitly, but your note leads me to believe that this problem started when the caps were removed.  
 
The only really good way to tell if you're having parasitic oscillation is to put an oscilloscope on it.  
 
As to tracking it down, first go read the Tube Amp Debugging page, working yourself down to the description of parasitic oscillation and how to get rid of it. You're probably going to have to do some wire rerouting and/or shielding.