Pls help me understand the Guv'Nor

[ubersam]

I have been studying the Guv'Nor schematics (GGG/M.Burgundy & Tonepad versions) for an old black box Guv'Nor that I want to mod; mine has alway been very shrill. As I traced the components on the board, using the tonepad version of the schematic as a guide, I noticed that my board had some small value resistors in place of what should have been capacitors. This should be an easy fix. I also noticed that there is a difference in the schematics. In particular, C3 & C4: tonepad has no C4 and C3 has a value of .068uf, GGG has C3 with a value of .22uf (220nf) and C4 with a value of .1uf (100nf). This brings me to my first question, is there a significant difference in the sound between the two methods? The second question is: which resistor/capacitor combination make up the high/low pass filters that feed 1). the 2nd gain stage; 2.) the clipping stage (and subsequently, the tone-stack)? I will be looking up info on tone stacks to see if I can figure out how to tweak the Guv'nor's tone controls. Thanks.

[GibsonGM]

On the Burgundy schem, I'd try altering the values of C5 at the 1st gain section, and C3 & C4 at the input to the 2nd section.   Increasing their value may give you some more bass response (kill the shrill, so to speak).  Playing with Duncan's Tone Stack Calculator can help you tweak the tone controls...it has the standard Marshall setup included.  Search the forum for "Duncan" and you'll get a link, I'm sure.  Increasing C14 might also increase bass output, after it's been clipped.   Trouble is, if you add more bass on the input side, the clipping character will change...so maybe start at C14 and work back....

Couldn't tell you about the diff. in sound re. C3 & C4 being different....maybe C4 being larger compensates for no C3, seems reasonable.

[QSQCaito]

Duncan's Tone Calculator's web page.

Bye bye

DAC

[Ardric]

I noticed that my board had some small value resistors in place of what should have been capacitors. This should be an easy fix.

Some caps, usually ceramics, come in a package that looks a lot like a resistor, sometimes even with color bands for value.

[ubersam]

I noticed that my board had some small value resistors in place of what should have been capacitors. This should be an easy fix.

Some caps, usually ceramics, come in a package that looks a lot like a resistor, sometimes even with color bands for value.

Intersting... either way, I may just go ahead and swap out the caps with some poly film types.

QSQCaito-Thanks for the link.