Sweet Honey Focus Question

[Kipper4]

Can some kind soul please explain how the Focus feature in the MP Sweet honey works ?
Is there a simpler way of doing it so trbhat the overdrive is focused on certain freqauncies?
Its a really nice feature that could go well in other ODs me thinks.

Heres a link to a schematic

http://4.bp.blogspot.com/-Pamc5iEPjRM/T1Itca9L9sI/AAAAAAAAAAw/l9wMnETlw8Q/s1600/sweet+honey+overdrive+schematic.png

Thanks
Rich

[mth5044]

Looks like a clean blend post clipping?

[Kipper4]

Clean blend thanks
So a feedback loop of the clean?
Is all the other R/C networks tied to it affected by the focus pot?

[Keppy]

The Focus pot provides negative feedback to the gain stage through a highpass filter, reducing gain at high frequencies by bypassing the gain control. It's tough to read some of the values, but the filter seems to vary ~100-500 Hz. Combine this with the filter off the inverting input that reduces gain on low frequencies and you have a tone control that simultaneously reduces highs while boosting mids.

I'm not totally sure of the impact of taking feedback AFTER the clipping diodes, though it would seem to add some complexity to how the signal is clipped at each set of diodes.

As far as a simpler version, you don't need the other feedback RC network (150k + 4.7n, if I'm reading the blurs right). You also don't need a two-pole filter off the inverting input, or the clipping diodes to ground. If you ditch those diodes, you no longer need the 1u coupling cap or R13. Those choices will affect the sound of the total circuit, but aren't necessary to the basic idea of the Focus control as far as applying it to other circuits.