Matchless Tone Stack problems - help!

[elpops]

Hi all,
I am trying to build a Matchless Clubman circuit, only with 6V6 output tubes instead of EL34. At this point the amp works, but the tone stack doesn't do anything and the volume seems a bilt lower than I would expect. Could anyone help me take a look at the way I have this wired and suggest where I may be going wrong? Or, direct me to a resource where I might figure it out? I looked at the schematic and as far as I can see I have it right, but obviously not.





Alt Clubman Mad Hatter
Thanks for any assistance,
Pops

[loudthud]

The schematic you posted has many unreadable numbers. What should the value of R1 be? On the schematic it looks like 10K and on the turret board it looks like you used 18K. I would think something like 100K would work better.

Here's a link to a readable schematic: http://www.el34world.com/charts/Sche...ss_clubman.pdf

I've seen mistakes in Matchless schematics before. Try 100K.

[elpops]

Hey man,
Thanks for responding. I agree that the 10K / 18K looks a bit light, but there are two or three different schematics for this circuit out there and they all point to that as being OK.

I'm wondering if this has anything to do with the nature of the tone controls themselves, which all look like voltage dividers. It's weird to me that the treble control DOES work (I shouldn't have said the tone stack didn't do >anything<), but the mid and bass don't. I put the mid control in as a pot vs. a resistor, because I like mid control, there was a hole there, and it seemed like a good idea. Maybe I did that wrong...

The volume and master both work, which are on either ends of the row of pots. The next to last pot will be a brilliance / treble cut control but I have to find the right cap.

Thanks for any other advice!
Pops

[loudthud]

C6 is marked as "25uF??" and that ain't right. Probably shouldn't be more than 0.1uF in that position or just replace it with a wire. Check the schematic at the link I posted to make sure you have all the correct value capacitors, especially C2 if the Bass control isn't working and it sounds like the bass is all the way up.

[elpops]

I attached two other schematics which are the ones I was working from, and I ignored that 25 uF because I agreed it wasn't right. Hopefully these two new ones will illustrate where I really am with the build--basically, I used the power section from the 6V6 build and the preamp from the EL34 build.

[J M Fahey]

There's no mid control there.
What did you do?

[elpops]

There's no mid control there.
What did you do?

The second picture shows all of the pots. From left to right they are:
Master Volume Brilliance Treble Mid Bass Volume (input jacks)

The Mid pot is in lieu of the 10K resistor in the schematic. Seemed like a good idea at the time, and it ought to work, so I'm not saying it's wrong, just maybe not hooked up right. Thanks for looking, and for your advice.

[J M Fahey]

You can't think of it as you would a regular Tone control because it is not.
Hence no way to add a Mid control
The so called Treble and Bass controls are really Treble cut only and Bass cut only nets.
When "on 10" they are really "flat"; when on 0 they are cutting big way.
Bass control: consider R12/R13 in parallel. R8 is in series with R12 but at this point it's not big deal.
Combined resistance to ground is around 50K.
It forms a high pass filter combined with C2.
It will cut everything (at 6dB/oct) below 1300Hz
Talk about a Bass cut!!!!
83 Hz (guitar's lowest frequency) is 4 Octaves below, meaning it will be attenuated 24dB
To damp this a little, VR2 (Bass pot) is also feeding that R12/R8/R13 netwirk with "flat" signal, so max. bass attenuation is "only" around 20 dB. Ouch !!!
When Bass is on 10 , which is really 0 resistance (inverted Logic, huh?), a flat signal bypasses C2 and "you have Bass" , which really means you have flat sound.
Even so, C1 is still in series with the resistor network, so Bass is still cut, only now you start "only" below some 150 Hz.

Treble control works in a similar way.
On 10 it really is in series with C5 and "does nothing"; on 0 C5 cuts everything above around 1 KHz.

Crappy tone controls? Yup.
Does the Clubman 35 sound good? Killer amp.
真真真真真真真?????????????????
I was always surprised about Matchless amps.
Friends built clones and brought them to my shop asking me "Juan, I must have made something wrong, this is cr*p, can we check it together?"
And I found nothing wrong.
I didn't find them *bad* but they were bland, undistinguished.
Until I started servicing the few 3 or 4 "Real" Matchless brought into Argentina .
They were owned by *very* good guitar players, and had the original speakers or used them with, at least, a 4x12" Marshall cabinet with Greenbacks or real old 70's vintage Celestions.
Then I noticed: this amp is the perfect "speaker driver", the EQ is the speaker frequency response, and if anything, the tone controls "take away" instead of "adding" so the amplifier does not stand in the way.
The Bass cut in fact takes away mud and the treble cut takes away harshness, simple as that.
And it has no NFB.
Which brings out all the quirks a far from flat Guitar speaker has.

This is the amp most opposite to what a transistor amp does.
Don't know if what I said above sounds clear, that's the way I understood it.

In a nutshell; build it "as is", Mod nothing, hook it to a killer speakers.
The original Matchless cabinet carries a Greenback for bite/brightness and a "heavy" Celestion (G1230H or similar) for beef.
Killer combination.

[Dave H]

What taper pot do you have for the Bass control? The Matchless Chieftain schematic I have says it's 1MRA (Reverse Audio). If you've got an Audio taper pot in there all the effect is going to be cramped at one end.

[J M Fahey]

You are right.
Notice that here we have a Mid control ... and it is also a *cut* type

And the "Brilliance" pot is a "Cut Brilliance" one in fact.

Maybe Mark Sampson discovered something after all

[elpops]

Notice that here we have a Mid control ... and it is also a *cut* type

So if I wanted to add a mid control of some sort to this amp, to make use of the pot and to play with the dense, sometimes grainy mids of it, how might you suggest I wire it?

I re-wired the pots in the preamp and got the treble and bass controls to work. Everything sounds great but I might have done better with a linear pot or a 250K pot on the brilliance control, as it only seems to affect the tone through a narrow sweep.

Here are some pics of the revised version.

This circuit sounds pretty awesome, especially in contrast to my tweed and JCM amps--steely, direct. More of a new country / better-than-Dr-Z tone vs. the blues/jazz tweed and the rock JCM. Compared to the Carmen Ghia I find this to be 'steely' vs. the Ghia's 'harsh' or 'raw.' Not unmusical, but direct and very forward. I'm playing it through a Rola G12-65.

Thanks!

[elpops]

For example, could I use a 250K pot in place of R13 and either keep the 10K value or up it to 50K for R8?