Useful Matchless Cluman mods?

[elpops]

Hey folks,

I built a Matchless Clubman type circuit with 6V6 tubes in place of EL34s and it's turned out to be a great amp. I'm pleased with how it turned out, so no complaints. But I do find that I'm not a fan of the effects loop, so I took it out. Which leaves two holes in the back of my chassis, and that got me wondering what I could do to fill them. So....

Any ideas for some good Clubman circuit mods where I could install some switches in these two chassis holes and create some useful alternatives to the great stock sound?

I am particularly interested in any mods that boost or reduce gain, boost midrange, create a midrange control, or shift the tone stack similarly to how one can put a pot in place of the slope resistor in a TMB circuit and change the dynamics of the tone stack.

If you're not familiar with this circuit, it sounds amazingly good. It's battled down a dozen other amps in my collection and won both for practice and on stage. I hope others might have some ideas for me.

http://www.el34world.com/charts/Sche...ss_clubman.pdf

Thanks in advance!

[pdf64]

That el34world link didn't work so I used http://www.webphix.com/schematic%20h...ss_clubman.pdf
For more gain, you could switch in a bypass cap for the 1st stage cathode; for less gain, lift the bypass caps across 2nd stage cathode R8.
To adjust the tone stack bass/mid frequency breakpoint, different value of C2 could be switched in; is R8 correct at 10k?

Are those voltages correct?
What's the primary impedance of the output transformer?

The tonal balance looks like there wouldn't be enough treble for me, as the only place where the treble gets lifted above the mids seems to be the bright cap on the volume control - the treble and brilliance controls just cut treble. So for a Les Paul, my guess is that I'd have them both on max and it still be lacking 'jangle'.

How do the controls work out for you?
Pete

[elpops]

Thanks for your ideas, I might try those cap tweaks. As for the tone balance, there is a TON of treble on tap with this amp. So much so that I removed the treble cap on the volume control (I may put that back as a switch). With any amp, including my SG, I think the bigger issue is controlling the midrange--it's on the grainy side and the amp might clean up better with a midrange cut of some sort. Only, on this circuit with the 2-knob tone I can't think of a way to incorporate a mid cut. Any ideas on that?

[pdf64]

Where do you generally set the bass control, eg halfway?
Is it an audio / log type, or linear?
Unless you have it set very low, then increasing the value of C2 should take out some low mids.
My guess is that R12 or R13 may be equivalent to the regular slope resistor; consider replacing one or the other with a 22k resistor in series with a 100k pot to see it that helps to get the tone balance more to your liking.
R8 may be equivalent to the mid resistor, so try subbing it for a 25k pot.
Pete

[elpops]

I have the treble and bass controls at about 80% each, and they are audio taper I think. I had thought of doing the 100K pot / resistor in series for a mids control, and will give that a shot--thanks for the confirmation. Also, I will try that C2 mod as a switchable option--I think the low mids and mids in general get a bit busy in this amp, not in a bad way, but in a way I could use an alternative for from time to time.

I tried a pot in place of R8 but in my application it didn't do much.

[cyclone]

You could use the matchless standalone bridge t mid control, it works very well and will take the mids down to Fender clean levels or make it dirty when wide open. You can put it almost anywhere before the PI. You might want to revisit the slope of the bass and treble controls if you add it. Also, you could bypass/not bypass the first stage cathode resistor for a gain "boost" via a switch as on other matchless amps. You might also try a deep cab with Celestion V 30's, it seems like the tone controls were eq'd around their cabs. Somebody (JMF?) mentioned that a while back and as a guy that was a large Matchless dealer primary amp tech thru the 90's, I wholeheartedly concur. So try different speakers, cabs too.

Like most player amps, people always complain that they are too bright. That's more or less true but you can take away that brightness as needed with the very effective brill and treble and mid controls, if you strip it out by clipping the bright cap it takes away bright that you can't put back, not always bad but something to consider. Most average players can't handle the level of note definition that these and other true guitar player amps give, there's no bug zapper dirty place to hide from their mistakes and bad technique

[darkbluemurder]

You could use the matchless standalone bridge t mid control, it works very well and will take the mids down to Fender clean levels or make it dirty when wide open. You can put it almost anywhere before the PI.

I fully agree on the mid control - see the Matchless Chieftain schematic. I would put it right after the bass control and move the treble control to after the second stage. I would also wire the treble and the volume controls like the tweed Princeton (I think it's the 5F2) - that would let you to reduce the brightness more effectively when the volume control is not turned up fully. I built a Chieftain and found the original treble control not to be very effective. I took out the bright cap on the volume control but sometimes I wish I still had it - I have not got around to implement the 5F2 control set up yet.

Do you use the master volume as in the original? I liked the LarMar PPIMV much better for lower volume overdrive playing. That is what I use in my Chieftain build.

I also support the idea of the gain boost by installing a switch to switch a cathode bypass cap to the first stage cathode resistor.

Cheers, Stephan