Re: [Harp-L] Re: controlling amp feedback

["Dave Murray" <dmurray777@xxxxxxx>]

Frank Evers wrote:
> .Am Samstag, 7. Juli 2007 schrieb Peter and Connie Ruth:
> > One way to control amp feedback is to put a Graphic EQ in between
> > the mcrophone and the amp.  This way you can decrease the
> > frequencies that feed back before they are amplified.
>
> I don´t second this, swapping tubes at least V1 and probably also V2
> is worth a try. V3 hosts phase inversion, changing it might require
> closer inspection.

Well, I don't see why not. Peter's statement was a true. If you attenuate 
the frequencies that cause oscillation (feedback) you can have a higher 
overall output without feedback. True enough, you can do tube swaps without 
changing bias networks to give an amplifier a different gain curve which 
"can" reduce feedback along with changing other gain characteristics. But 
attenuating the offending frequencies that cause an amplifier to break into 
oscillation goes directly to the heart of the matter without degrading other 
aspects of amplifier performance.

If you like some other method better, that's fine for you, but please don't 
try to give people the impression that selective frequency attenuation is 
not a valid method for fighting feedback, because it is. If I misunderstood 
"I don´t second this", never mind.

Peace and music,
Dave