6550s in Twin
From powe–(at)–wdc.com Tue Sep 3 09:41:03 CDT 1996
> When you slap 6550s into a Fender, at those plate voltages, about how much
I used a pair of 6550Cs in my Twin chassis (the only thing left that is
I left the screen values at 470-ohms; B+ was only 460V, and bias was
In models with only a single pair of original power tube sockets, an
> I think Svetlana makes a couple different 6550 versions. Anyone know what
If you do use 6550s in up-side down chassis’, spring retainers are a
Happy playing!
Article: 21974 of alt.guitar.amps
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From: O’Connor
Subject: Re: FENDER MOD TO 6550
Date: Tue, 03 Sep 1996 03:49:44 -0700
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> negative grid bias is required, and where do you set the idle plate
> current? Any mods required to the bias supply? Did you change the 470
> ohm resistor on the screen grids?
original are the power and reverb transformers, and the power supply–
even the case is gone). I was surprised at how well they complimented the
preamp tone that I was using at the time.
-53V just as Fender wired it. No adjustments were necessary for the 6550s
or 5881s. Each tube draws a unique yet appropriate, safe and toneful
current. Reliability of Sovtek 5881s and Svetlana 6550s in this circuit
has been road proven over the last two years.
auxiliary filament transformer will be required. Models like the Twin,
Showman or 100+ Bassman can accept A SINGLE PAIR of 6550s, with the other
pair of sockets empty!
> the differences are?
> Tonally there are no differences. Svetlana has swithced over to the 6550C
exclusively, as far as I know. You might want to check with them for up
to date info. The only technical difference between the A, B and C
versions was the gettering.
must!
Kevin O’Connor
