Re: Bax in a box - active baxandall tonestack

Posted by Freppo on Dec 26, 2013; 4:40pm
URL: http://guitar-fx-layouts.238.s1.nabble.com/Bax-in-a-box-active-baxandall-tonestack-tp7264p7463.html

I made a bunch of changes to the "Bax in a Box" circuit (how it really should have been designed IMHO) and made a new layout from my schematic. It sound much better and more natural now with the controls set flat and has a more useful trimmer and better sweep of the tonepots. :)

Here's the layout (not yet verified)


I made the layout with multilayer ceramics in mind for the 1uf values.
But you could use electrolytics / tantalums there. Check the schematic for orientation.

Schematic:


I've placed the tonestack in the negative feedback loop of the inverted input thus making in a true active eq, capable of both cutting and boosting. Since the output from the tonestack is inverted 180 degrees I remade the input buffer (which is needed to get the right impedance for the tonestack) to also go through the inverted input, making the final output in phase with the input. I also put the trimmer in the first gainstage which works much better like a gain/volume-pot basically.

cheers
/ Fredrik