This has sort of turned into a dev blog but it seems like there's been interest. The feedback in that video was due to the clean blend. The small one I used was insufficient so next up is the op-amp route. No massive deal on this end, whatever gets a nice result in the end.
I have to ditch the Baxandall/James stack for the tone controls. It cuts way too much level for my liking and only reaches a decent volume with the knobs up a bit more than past half way. So here's a result that is a) simpler to build, therefore b) cheaper (uses the same pots available plus another dual gang 100k audio pot), c) gives justice to the original circuit and d) implements a bit of a tilt like function.
Very simple addition to change over to. What basically happens is you have the usual tone stack, modified to cover the new "body", dual gang 100k audio pot (same type as the distortion pot). When the body potentiometer is off, what happens is the added low pass filter is bypassed. When you add it, it cuts treble (basically means adding bass).
Now, that's all fine, but perhaps we can control a little bit more than that to add some flexibility. While I had the bax in there, I liked the really cranked setting and the ability to bring in some more mids into the equation. When the body is turned down, it acts as a mid cut. This is a common exploit of the BMP tone stack and is the basis behind the "Amz Presence Control"
http://www.muzique.com/lab/tone3.htm
So with only the presence section, we have this kind of effect when the tone is in the middle. Green is down with the cut, red is all the way up. Nice and healthy bass signal. Mmmm
While that shows the mid scoop in action and that is nice and what not, we need something more to add...lets say when we add the low pass filter, we shift the circuit a bit more dramatically. It balances out some of the difference and shifts the treble point.
One of the things about this circuit in particular is that there isn't much action going on in the lows as they are pretty much filtered heavily during the first boost and the clipping stages. Doing something like this should bring in a bit more which after hearing the tilt mod, seems like is needed dearly.
As for the other things. I might dull down the 22u cap for the fuzziness to a 10u cap to give it a little bit more clarity. It seems to be a bit too muddy for my liking. Going to work on some better form of clip mod. Most likely going to be different/asymmetrical diodes at this point but we shall see. All that and a blend that resists feedback. Lots of work ahead.
