Removing Fender Twin Master Volume

Chris Rohde · Post by **Chris Rohde** » 25 Aug 2002 6:26 pm

I've been looking around for a silverface Twin and have seen a few with a master volume circuit. Does anyone know whether these can be (relatively) easily changed to blackface specs (and the master volume circuit removed) like the non-master volume silverface Twins?

Ken Fox · Post by **Ken Fox** » 25 Aug 2002 10:24 pm

The 135 watt Twins are not an easy change to Blackface specs, as they have no choke and use an ultralinear output transformer. The plate voltages are much higher than other Twins. I feel they are however one of the best steel amps (with JBLS in them) that Fender ever made. They have the clearest tube sound of the Twins. I have done a master volume removal, not to difficult. I could not tell any advantage after the mod, however. The 100 watt Silverfaces are pretty easy to Blackface. The reverb section of the Silverfaces is ran hotter. Some people prefer to leave it that way, as the they prefer the reverb of the Silverfaces. There are numerous sites with info on Blackfacing procedures. The following is a good site for reading about the differences in Silverface/Blackface amps and the info on doing the mod:
http://acruhl.freeshell.org/mga/main/contents.html [This message was edited by Ken Fox on 25 August 2002 at 11:25 PM.]

Michael Brebes · Post by **Michael Brebes** » 26 Aug 2002 6:39 am

The big problem I found with the Master Volume on those amps was that they put a capacitor across the leads, similar to having a Bright switch turned on. Cutting the capacitor does a major upgrade in the tone when the MV is set at anything below 10.

Ken Fox · Post by **Ken Fox** » 26 Aug 2002 9:36 am

I can see why it that was there. Ever notice how your tone becomes more bassy as your volume is turned down? I think this was an attempt to keep the tone a lttle more consistent as the volume was decreased. Just a thought!

Jay Ganz · Post by **Jay Ganz** » 26 Aug 2002 11:36 am

What I've done for some guys (who also
play regular guitar), is just rewire it
so it is connected to part of the circuit
between the preamp section & the output
tubes. The factory installation is just
too far back in the preamp section, so
when you turn it down a little, it sounds
lousy! After I'm done with it, it can
be used as an excellent sounding overdrive.
You just crank up the regular volume &
turn down the Master. And it still sounds
nice and full!

------------------
<a href=http://members.localnet.com/~jsganz/Steelin'.mpg>Push/Pull Video Clip</a>

ajm · Post by **ajm** » 26 Aug 2002 6:23 pm

I'll second Jay's approach. I have a Carvin XV-112E that has a 100/50/25% power switch, but it never sounded good on 25% and was just not done right. I got inspired a couple of years ago and rewired the switch so it's between the phase inverter and the output tubes, so it's sort of a master volume but with only 3 positions (if that makes any sense).

I mounted the resistors on the switch and chose them so that it's now about 100/50/5%. I can crank it up to 10 now with the switch set to 5%. It screams at a volume that won't wake someone in the next room.

David Rich · Post by **David Rich** » 27 Aug 2002 5:33 am

Some other mods you can do are disable the negative feedback loop. The ultralinear out put is a sort of built in neg. feedback. The result is a livelier, looser sound. It will also be a little noisier and a little louder as well.

Kevin O'Connor of London Power recomends converting at least one pair of 6l6's to triode operation. This will give you a little bit darker, warmer sound. I haven't tried this one.

Terry Downs · Post by **Terry Downs** » 27 Aug 2002 8:35 pm

I always thought the master volume on the twin was a great concept but very poorly implemented by Fender. A master volume should be buffered well enough to not cause any tonal changes. Another tube stage would have made that possible. A cathode follower or a class A stage tube following the master volume before the phase splitter would have been a better solution in my mind.

I think the new Fender tube amps like the "Twin Amp" does that very well. I own one and think it is great for a distortion rig as well as a classic "barely distorted" amp.

Chris Rohde · Post by **Chris Rohde** » 29 Aug 2002 10:07 am

Thanks for all the advice!