Mark 1 Tone Stack Logic

[Ultramog]

Got my Mark 1 reissue and loving it. Grailtone being something/anything along the Carlton->Ford->(Vintage) Billy F. Gibbons) arc. It wasn't too hard getting an impressively bright and full clean tone. And I'm making some progress on Channel One after watching Andy Timmons' LSC video.

But is there a thread or someone who can explain what goes on with the Tone Stack in terms of filtering, Q and width as the signal moves from Treble through to Presence?

 

[mr_fender]

The tone stack Boogie uses on the Mark series amps is nearly identical to that of the blackface Fenders. Duncan amps has a cool tone stack calculator program that gives some nice graphs for the various tone stack types. You can download it here:

http://www.duncanamps.com/tsc/

The presence control is not part of the tone stack on most tube amps, but rather a variable low pass filter placed on the negative feedback section of the power amp. With the presence control set high, there's less attenuation of highs by negative feedback in the output section relative to the rest of the signal. As a result the amp sounds brighter.

Hope this helps.

 

[Ultramog]

This helps a ton, thanks!