From selkir–(at)–elsci.arc.nasa.gov Fri Jul 21 13:47:37 CDT 1995
Article: 58531 of rec.music.makers.guitar
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From: selkir–(at)–elsci.arc.nasa.gov (Rennie Selkirk)
Newsgroups: rec.music.makers.guitar
Subject: Re: Bassman Mod. Question
Date: 20 Jul 1995 22:21:23 GMT
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Dave Cigna wrote in response to the suggestion of removing the negative
feedback in the output stage of a ’67 Bassman:
>
>Put that feedback network back. It’s true that these
>were the “experimental” years for Fender, so they might
>have tried something a little different, but as far
>as I know, every Bassman ever made incorporated some
>kind of negative feedback. Either put it back the way
>it was or install a blackface style feedback curcuit.

I assume we’re talking about the standard black/silverface 820 ohm
resistor between the speakers and the input of the phase inverter.
I recently went BACK to the original setup on my blackface (64
Tremolux) from an 1800 ohm resistor which I had substituted a few
months ago when I was in search of “crunch”. As you’d expect the
higher value feedback resistor audibly increased the distortion
in the amp by reducing the negative feedback signal, and I think
gave me a bit more dynamics, but I wouldn’t describe the effect as
-pleasingly- increased crunch. I would rather call it increased
sludge! With the return to the stock setup, I find I like the
increased fidelity, especially at higher volumes. Keep in mind
I’m driving this amp with a guitar/pickup setup (archtop with 490s)
that you might say is the electric guitar equivalent of very rich
chocolate cake.

I guess the moral of the story is that Leo and his people knew what
they were doing back in 1963 when they introduced the blackface amps
with all that negative feedback, though it may be that the feedback’s
benefits vary from one amp model to the next, since they put the
820 ohm resistor in all the 6L6 blackfaces without regard to power.
I don’t have the experience to say one way or another. However, I can
say that for my Tremolux, it’s definitely beneficial.

HJBoogie

From Fri Jul 21 13:47:51 CDT 1995
Article: 58616 of rec.music.makers.guitar
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Subject: Re: Bassman Mod. Question
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Date: 21 Jul 1995 15:22:01 GMT
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In article <3umkt3$h0--(at)--nramp.arc.nasa.gov>, selkir–(at)–elsci.arc.nasa.gov
(Rennie Selkirk) wrote:
>
> Dave Cigna wrote in response to the suggestion of removing the negative
> feedback in the output stage of a ’67 Bassman:
> >

I’ve modded my Silver Face Super Reverb so the feedback resistor can be
switched in and out of circuit. I used the “bright” switch on the normal
channel for this. Best of both worlds.

_Paul