Varitone Pedal

[bcalla]

A friend asked me to build him a varitone pedal.  The example he gave was the de Lisle Notch Box Pedal .   The only schematic I can find is Craig Anderton's passive circuit from his book Electronic Projects for Musicians:



In the book he mentions that there is volume loss through the circuit, which makes something like the de Lisle Notch Box Pedal more desirable.

Does anyone have a schematic for an active varitone circuit?  If not, what would be the best way to couple it with a boost?

NOTE:  Edited post to fix link.

[tol]

I love the varitone! Catalinbread used to make one as well as Snarling Dogs. I've been wanting to make one myself. I'll see what I can find. The snarling Dogs just had a post effect booster like LPB1 if I recall correctly.

https://www.youtube.com/watch?v=WNYKFtxbeSg

[gordo]

Lado Falcon guitars had a cool active varitone but its gooped and I've never found either a schematic or a source.

[stecykmi]

just about any boost after it will work but if it has an input buffer circuit it might help preserve clarity a little more (just a guess but the inductor seems like it loads down the circuit a bunch). a tremolo or overdrive/light distortion effect after it might work too, as long as it has volume gain on tap and you can turn the depth or gain to 0.

[bcalla]

just about any boost after it will work but if it has an input buffer circuit it might help preserve clarity a little more (just a guess but the inductor seems like it loads down the circuit a bunch). a tremolo or overdrive/light distortion effect after it might work too, as long as it has volume gain on tap and you can turn the depth or gain to 0.

Thanks for this, I'm pretty sure I have boost PCBs stashed away.  To clarify, I just need to run the varitone's output into the boost's input, right?

I also have a transformer / inductor question.  The parts list specifies a 5 - 6 H center tapped inductor, but in the text he describes using a transformer with a 10k @ 1Hz primary and a 600R @ 1Hz secondary (specifically this one).  You can see it in the schematic in my original post with the 3 secondary leads unconnected.  I have a 10k-10k transformer (this one).  Since only the primary is used, can I use my transformer?  I don't know if the secondary affects the inductance even if it is not connected to the circuit.

[stecykmi]

just about any boost after it will work but if it has an input buffer circuit it might help preserve clarity a little more (just a guess but the inductor seems like it loads down the circuit a bunch). a tremolo or overdrive/light distortion effect after it might work too, as long as it has volume gain on tap and you can turn the depth or gain to 0.

Thanks for this, I'm pretty sure I have boost PCBs stashed away.  To clarify, I just need to run the varitone's output into the boost's input, right?

I also have a transformer / inductor question.  The parts list specifies a 5 - 6 H center tapped inductor, but in the text he describes using a transformer with a 10k @ 1Hz primary and a 600R @ 1Hz secondary (specifically this one).  You can see it in the schematic in my original post with the 3 secondary leads unconnected.  I have a 10k-10k transformer (this one).  Since only the primary is used, can I use my transformer?  I don't know if the secondary affects the inductance even if it is not connected to the circuit.

ya it's probably better to run the varitone into the boost to help defeat circuit loading, but wow good question on the secondary... i know the secondary of a transformer can influence the primary with something called self or mutual induction but i have no idea what happens when the secondary is left floating... my guess is that it does affect the inductance of the primary since there is a magnetic field created but i'm no lord of magnetism, perhaps someone else knows?

in any case it should still work but the HPF will have a different cutoff, i would try it first and see if all the tones are usable. if it stinks maybe try buying the 600ohm secondary. you could also try some goofy stuff like shorting the equivalent primary and secondary pins together and seeing what happens, that should be roughly the equivalent of two inductors in parallel.