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previous: Shea It's not unusual for presence contr... -- 9/24/2004 7:30 PM View Thread

Re: feedback weirdness

9/24/2004 8:22 PM
loudthud
Re: feedback weirdness
You may have to install a small resistor in series with the presence cap, maybe a 1K, to cure the oscillation. Peavey used an electrolytic, 22uf@25V, to isolate the DC from the feedback loop. Note that without the 22uF cap, adjusting the resonance changes the operating point of the PI.  
 
The only amp I know of that has a resonance control is the PV EVH. Do you know of any others ? US Patent 5,197,102 covers a resonance control but there is a lot of other stuff going on that doesn't apply to tube amps. I'd like to incorporate the resonance control in some of my designs but would like to stay clear of any Mississippi judges.

 
Replies:
steve rathmann thanks for the reply. as I asked of... -- 9/24/2004 10:19 PM