DIY Footpedal

[Eldon Cangas]

I'm thinking about it for now - after I realized how much tone a pot can suck out of your instrument. I'm considering using a hall effect sensor if only to learn something new.

I'm wondering what the Hilton pedal uses.

Another option might be a photo cell circuit - I still have my footpedal/powerpack from my old Cordovox accordion that could probably be used as a base.

Any thoughts out there??

Thanks! Eldon

[Lane Gray]

I forget whether it was Bobbe or Herby, but somebody was selling reproduced Lil' Izzy boxes, probably the cheapest buffer amp, and still a good one. That's what I use between guitar and pot pedal

[Paul Arntson]

Another option is an inexpensive used Boss PSM5. It has a good low noise buffer amp in it. Guitar goes in "Guitar" or "Return"with the shortest cord you can use and output comes from "Amp". It does need a power supply, though.

[Lane Gray]

IIRC (and I suspect Dave Beaty and Keith Hilton may or may not chime in), the modern active pedals use a pot to control a volume circuit on an op amp chip.
From my recollection the photocell pedals colored the tone even more than the pots, but I last used one in 83 (a Morley).
If I remember it right about Hilton and Telonics, the circuit makes all the difference. If you're gonna make your own, I suspect a LOT of trial and error before you get either transparent tone or colors you like.
I'd sooner buy from Keith or Dave than spend all that time.

[Ivan Funk]

How about a treble bleed (high pass) on the pot?
Some of the highs sneak by as the volume is turned down.



(not my drawing)

[Jack Stoner]

The Hilton does not use a pot to control an op amp for volume as suggested. The old Goodrich L10K volume pedals did use this configuration. The Hilton uses an "infrared" system (what Keith calls his) that controls the volume level. There is an output Op Amp and there are pots to set the various parameters (off point, max gain and tone) but not the actual signal volume control.

I don't know how the Telonics does theirs, but talking to Dave, I suspect its all done "digitally".

The Goodrich LDR volume pedal used a "Light Dependent Resistor" in their circuit. I've worked with LDR's when I worked in Telemetry at a NASA tracking station and they were basically a light source and a resistor that reacted to the light intensity (changed resistance with the light intensity). They were used to isolate the input from the output in the Telemetry device I worked on.

[Dave Beaty]

Lane and Jack make some good points.
Telonics FP-100 series pedals do not use pots, at all, in the signal chain.

The various volume tapers are, as Jack said, invoked under software control, but 'the signal chain is purely ANALOG in it's entirety'. We never digitize the audio, there are no A/D's or D/A's inserted in the direct signal chain of any Telonics product.

Both Analog-to-Digital converters and Digital-to-Analog converters contribute noise to the signal, which raises the noise floor. We abore noise contribution in any form, so digital processing of the main audio chain is taboo for us.
As a result, people using our gear often hear things like "is your system really turned on?" from booth engineers.