GuvNor tone stack, what's going on?

[ericohman]

Out of curiosity I'd like to know what's going on in the 3 band EQ of the Marshall GuvNor (MKI version).
I recently bought one and it wasn't until tonight that I really played around with the EQ and noticed a different behavior from what I'm used to, I really liked it.

For example, the treble seems to have kind of 3 "areas", 0-4, 4-8, 8-10 and it behaved very different depending on how I had my mids knob set.
I found a very sweet spot that didn't sound fizzy at all, yet not too muddy either... With my JTM45 clone amp it really was in beano "little girl" territory.

So, let's say nothing is wrong with my GuvNor and that way I just described the tone controls is how it is supposed to be... Then, can someone explain what's going on in there? Can it be implemented in all kinds of overdrive/fuzz pedals?


A little off-topic, I found a nice article about clipping (linked from diystompboxes site):
http://www.gmarts.org/index.php?go=217

[GibsonGM]

Yes, the FMV (Fender, Marshall, Vox) tone stack has interactions.  They were (are) based on using a small parts count, a trade-off between response and insertion loss - too much control, and you're eating up too much signal!  You can vary the range a bit with the slope resistor, but I haven't gone that far (no need).

To see the Guv'nor in action, get Duncan's Tone Stack Calculator, http://www.duncanamps.com/

It is free and easy to use...check out the Marshall tab, that is about what's going on with the Guv'nor.  Slide the sliders, or use the "Sweep" command to see the whole she-bang.  Try changing some parts to see the response (1 microfarad would be 1u to the program, etc).

I use a Guv'nor with B and M pre-set by resistors, and 1 knob for the treble...I found the 'sweet spot' on breadboard that you mention and hard-wired it that way. My main pedal for hard stuff!  Sounds like you have it built correctly; that is the way it works.  And the response will change a bit with different amps/cabs.   

[ilya-v]

its been a year, but I'm pretty sure no one will mind 

I also need help identifying what the parts do,
Tonestack Calculator is useless here.

I came across this page: http://www.diystompboxes.com/smfforum/index.php?topic=79298.0
In the end there is a LTspice diagram that show a tone stack response of the guv'nor tone stack,
It help but I would like to fiddle withe the values myself and see the results.

Can someone build the schematic in LTspice and uploaed it so I can experiment?

Thanks.

[ayayay!]

This might help  http://www.diystompboxes.com/smfforum/index.php?topic=89211.0

[mistahead]

On the note of ressurecting posts from (near) dead...
This one:
http://www.aronnelson.com/gallery/main.php/v/mr_adambeck/vero/guvnortone2.jpg.html

Referenced above - I have to assume it is now verified? Seems people got it working for them.

But the real question - what is that jumper between strip one and two there doing (row ? Yep, I'm debugging lol.