Adam's Amplifiers: Tone Stacks
"Baxandall Mid Boost
I had an unused space for another switch on the front panel, so I added a tiny modification to change the frequency response of the tone stack. It simply parallels a 560pF capacitor with the 330pF treble cap. The effect of this is to add a pronounced midrange “hump” with the tone controls flat, and a lessening of the scoop with both controls all the way up. It’s a very simple and effective mod. The effect is centered around 250-450 Hz, depending on the position of the controls. By additionally paralleling another 180K resistor to make 90K between the Bass & Treble pots you can change that to 300-700 Hz."
From Adam's Amplifiers
FWIW C. Smith
"Baxandall Mid Boost
I had an unused space for another switch on the front panel, so I added a tiny modification to change the frequency response of the tone stack. It simply parallels a 560pF capacitor with the 330pF treble cap. The effect of this is to add a pronounced midrange “hump” with the tone controls flat, and a lessening of the scoop with both controls all the way up. It’s a very simple and effective mod. The effect is centered around 250-450 Hz, depending on the position of the controls. By additionally paralleling another 180K resistor to make 90K between the Bass & Treble pots you can change that to 300-700 Hz."
From Adam's Amplifiers
FWIW C. Smith
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