Need some help for analysing a tone stack

[nonoxxx]

Hello,

I try to figure how the tone stack of the Tc electronic/chuggah pre  preamp work , and I have to admit I don't really understand  (I try to simulate it with Lt spice but it's weird lol )...
Here is the schematic https://rullywow.com/wp-content/uploads/2015/05/ChuggaPre-v1.0.pdf

I will try to make a VST plugins of it but for that I need to know how i works :/

I someone can help me

[antonis]

Except of weird it's also fun..

It's a modified Baxanall working simultaneously on Q1 & IC1 gain..

[nonoxxx]

Oh yes , I va never head of baxandal before
I googled it and found some circuit analysis
Thanks a lot

[PRR]

Not a Bax. It is an inverted James inside a NFB loop. Also seen on some Dyna and Quad hi-fi. It gives B/T and also gain about 10, with hi-Z input. It requires Reverse-Audio taper pots to be "flat" with knobs centered.

I don't grok Q1. Maybe it reduces hiss. Maybe it changes clipping action. Doesn't cost much.

[Fancy Lime]

Yepp, the Q1 action is a bit weird. Some interesting discussions here:

https://www.diystompboxes.com/smfforum/index.php?topic=122749.0

and here:

https://www.diystompboxes.com/smfforum/index.php?topic=89712.0

Andy