EH Smallstone Color Switch

[Arn C.]

Just curious if there is something that can be done to mod this section a bit.  With the color switch on, It is almost over the top.  I wonder if a pot can be put in this part of the circuit to be able to adjust to taste?

Thanks,
Arn C.

[bioroids]

Yes you can.

Just remove the 27k resistor (R10 on Tonepad's) and replace it with a 100k pot, wired as a variable resistor. Now you have and adjustable feedback control!

Beware of oscillations that may happen if you set the resistance too low, so adjust the pot to max resistance before turning the effect on. You may want to put a small fixed resistor in series with the pot to avoid this, but the value you'll have to figure out by experimenting.

Another way may be changing R11/R12, with a 10k pot wired as a voltage divider and taking the output from the middle lug (I have not tried this, but it should work)

Good luck and hope it helps!

Miguel

[Mark Hammer]

The coor switch does two things.  First it changes the amount of regeneration with one set of contacts.  Second, it changes the sweep width (and the speed a bit too) with the other set of contacts.  Separating those functions via two switches is worth doing.  Indeed, this is more or less what MXR did with their 4-way switch on the Phase 100.

Looking at the color switch, you can see in the schematic that in the higher-resonance position, the switch shorts out a 270k fixed resistor, essentially providing an "expressway" for the signal to be recirculated back to the input stage.  In the low-regen setting, the signal is obliged to pass through that 270k resistor.  No reason why you can't strike a compromise and shunt that 270k resistor with a parallel resistor rather than simply a straight wire.  For starters, try 22k.  In tandem with the 270k resistor, that gives you an effective resistance of around 20k.  That should knock off a bit of the overemphasis for you.

[Arn C.]

Thanks Gents for the suggestions!   You guys are awesome!!!

I will try some mentioned work to the pedal and post how it worked out.

Again, Thanks!
Arn C.