Increase low end response of Foxx TM in just octave mode

[eightsevenzero]

Is there a way to increase the low end response of the Foxx Tone Machine only when the octave mode is engaged? Just to sort of even out the vast difference between the low end response in each mode, I know the octave mode needs to bit a bit more high end forward by nature. Thanks!

[Mark Hammer]

The circuit attempts to double the frequency of everything that enters it, including low frequencies.  To accomplish what you want, you would need to either separate the lower portion of the input signal, or the whole clean signal, and mix it in with the final doubled signal.

The Prescription Electronics COB (Clean Octave Blend) does something in this vein, and is likely what you want. 

(I need to point out that there is a character that ought to be included in the name, but isn't.  As a result, many mistakenly think the circuit produces a "clean" octave up.  It does not.  The octave up is nearly identical to that of the Foxx Tone Machine.  Really, it ought to be the Clean/Octave Blend, because it blends in clean signal with octave up.)

[eightsevenzero]

Gotcha, Thanks!

[pacealot]

If it's just a slight amount you want to "correct", my thought (having just been putting my FTM together myself) would be to go the other direction, and add a HPF to the output when in non-octave mode. Perhaps consider raising the volume pot to 100K, then adding a R-C network using a 100K resistor and a cap of your choosing, and use another pole of the octave switch to bypass that cap when in octave mode.

You might want to revoice the tone section to darken everything up a little bit to compensate (I enlarged the cap values on mine slightly to taste, and it had a similar effect), but in any case that approach could possibly even out the two settings.