ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
previous: Heiko Frost Hey there,Darn, I thought I... -- 5/10/2003 7:30 PM view thread

Re: Help! Negative Feeback Switch Popping!

5/11/2003 7:53 PM
Enzo
Re: Help! Negative Feeback Switch Popping!
Your drawing merely says to phase inverter, but you gave no indication of how you injected it there. My suspicion is you have a DC problem.  
 
The point of injection on the PI circuit probably has some DC voltage on it. when you flip the switch the voltage divider your three resistors make change the DC resistance to ground - through the speaker winding of the OT and the speaker itself - and thus the current through that node. There may even be some inductive kick from the OT and spkr. In normal circuits, the cap is not needed because there is no switch. Or if there is a presence control it varies smoothly.  
 
My guess is that a cap in series might help. On either side - pick one - of your switch circuit, insert a cap of sufficient size that it doesn't muck with your freq response. .05? .22? I am guessing. Five minutes with a cap and clip leads will tell you if I am right or wrong. For test, use anything since we only need to find out if it cures popping. If it does, then worry about the value.  
 
At least that is my thinking.

 
Replies:
Heiko Frost ENZO, you are the Man! -- 5/11/2003 8:04 PM