Gain control on a May Queen?

[Rockitdog]

Hi Guys.

I finished the May Queen project on GGG and ROG and I love the way sounds. But I find the single output volume control very limiting.

I am very new to the whole pedal building thing (And electronics in general) and am learning quite quickly.
But I was wondering if anyone had built a gain control into that pedal. Or know how I would go about integrating one into my existing pedal or even a new schematic/PCB/pedal?



Any ideas?

I would imagine that it goes in before one of the trannys, to control the amount of voltage that goes into it?
Or could I put a pot between the 9v and PCB power in? Or would that create more or a "Stab" or "Starve" effect? (Zvex)
Dont really know where to start and google comes up with nada.

Excuse my ignorance, but that sounds like sense to me? Am I in the ball park?
Even if anyone has a link to help me along my way.

Thanks in advance
Richard

[markeebee]

The MQ cleans up nicely if you roll back the volume on your guitar, I think that's why the original schemo doesn't include a gain control.

Q2 and Q3 and the surrounding components are pretty much the same as a Fuzz Face (take a look at both schemos and you'll see!) so you could incorporate the same kind of gain control as a FF by replacing the 2k2 resistor with a pot.  Excuse the dodgy drawing:

[Rockitdog]

Ahha! Thanks a bunch! That makes perfect sense.
I'll get breadboarding tonight.

Strange thing, it doesnt seem to clean up at all when dropping the volume of my guitar. My "Muff" fuzz does, very nicely in fact. But the MQ doesnt. Peraps I did something wrong when building it? I followed the steps to the tee. Any ideas why that is? 

You rule! You even drew a diagram. Thanks!!! Really! I appreciate it. 

[Rockitdog]

Ok... I found out what the whole problem was.  I think 

I breadboarded the circuit from scratch and realised that on the original circuit I put a 22n in the place of the 2n2 by accident (Common mistake I believe). I dont have any 2n2's left so I will have to get some tomorrow. But the result of the 22n being in might be the reason for the lack of clean up when dropping guitar volume pot. (Am I right in jumping to this conclusion?)

Because the 5K pot in place of the 2k2 resistor works (Thanks markeebee) but does pretty much the same as the guitar volume pot. No clean up. 

I will get some 2n2's tomorrow and try again. But its been a great learning curve for me.
Once again, thanks for the help.

[markeebee]

Just to be sure......

You're talking about the cap in parallel with your new pot?  Only, it's not 2n2 - it's 2u2.  So that's 2.2 microfarads, which is equal to 2200nf. 

This cap effectively increases the gain of Q3 quite substantially.  2n2 or 22n caps won't be big enough to have much or any effect. 

Also note that really the 2u2 cap should be polarised (i.e. it should have a negative and positive terminal, kinda like a battery).  The negative terminal needs to go to ground and the pos goes to the lug of your pot.

Sorry, you prolly have a handle on this already, but just to be sure.....

[Rockitdog]

Its the cap that runs parallel to the 10K trim. For some reason its not labelled on the schematic. But I saw it on ROG's perfboard layout.
I got the polarized 2u2 in there and the gain pot seems to be doing it's job but it just gets softer, like the volume control and doesn't clean up.

Thanks for the heads up tho. .. Made me double check. It is seeming a little clearer now.
Gunna get some 2n2's tomorrow and see what it does,

Thanks for all the help.