Re: [Harp-L] Champ Feed Back Loop mod (RICK DAVIS)

[Rick Davis <bluesharpamps@xxxxxxxxx>]

Joe, here is a link to the photo on the blog:

http://bp0.blogger.com/_7YJbuR5TIYc/R2RxoGWGvhI/AAAAAAAAAFQ/Ze_-kYucTQM/s1600-h/Champ-guts1.gif

The negative feedback loop is the yellow wire that runs from the speaker tap
(top, second from right).  The wire goes to the left, around the tube socket
(top, third from right) and down to a resistor on the circuit board.  To
disable Fender's negative feedback circuit you need to clip that wire,
insulate it and tie it off somewhere.

>From the blog:  "Fender’s goal for its guitar amps was a sparkly clean tone,
and one way to do this was with a negative feedback circuit. It was thought
that power tubes introduced distortion, so Fender engineers looped an
out-of-phase portion of the output signal back to the preamp section. That
way the distortion cancelled itself (sort of), but it meant they were
siphoning off some of the Champ’s power for the sake of clean tone."

If you don't care for the tone, which will be slightly louder and grittier,
you can re-connect the wire. Remember, the effect will be subtle.

-- 
-Rick Davis
The Blues Harp Amps Blog
http://www.bluesharpamps.blogspot.com/


On Fri, Sep 2, 2011 at 5:04 PM, joe hagins <joe_hagins@xxxxxxxxx> wrote:

> So I got my Champ today and it sounds pretty good. The speaker wasnt
> original so I put in my Weber 8A125 and it sound pretty. I want to cut the
> Feed back loop wire and looking at the picture on Rick's site I'm not sure
> which wire he speaks of nor where the best spot to cut it would be. SO Rick
> if you are out there can you let me know
>
> Cheers,
> Joey Anchors
>
> http://joeyanchors.wordpress.com/
>