From Teleologis–(at)–orry.NoEmail Fri Mar 7 12:33:40 CST 1997
Article: 41268 of alt.guitar.amps
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From: “Teleologist”
Newsgroups: alt.guitar.amps
Subject: Re: AA763 vs. AB763 Super Reverb
Date: 7 Mar 1997 12:25:12 GMT
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Matt wrote in article
<5fnqds$537$--(at)--ollum.kingston.net>…
> OK, this is puzzlin’ me.
>
> I have one of each of the above, and in both the schematics and the
> amps themselves I notice a difference that I don’t understand.
>
> The 6L6GC’s in the AB763 each have a 1500 ohm resistor tied to their
> grids, the AA doesn’t.
>
Those are the grid-stopper resistors, one of the few changes which were
added to the AB circuit. Their purpose is to stop parasitic oscillations
which sometimes occur in the AA circuit. Some people claim they effect tone
– I’m curious how do your 2 amps compare??? If you’re having any problems
with oscillation, or for your own peace of mind, you should add them. I’d
personally leave ’em out as long as the amp is behaving. The other change
on some AB model Fenders is different cap values in the tone stacks.