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Vintage threads from the first ten years

Re: Why-a-duck? Why-a-pot?

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8/30/1999 4:46 PM
CJ Landry	Re: Why-a-duck? Why-a-pot? I want to say I have seen a pedal that used a pressure transducer as the controlling element. For that matter, one could use a pressure transducer that controlled a JFET configured as a resistor and voila! I think I saw such a circuit in an EDN ideas for design a few years back. I will have to do some digging. CJ

8/30/1999 5:04 PM
Gus	why not a pressure transducer like used in cars? a hose to the transducer to a bag/piston assembly/mouth etc use the output to vary the wha control. Gustav C. Smalley 8-30-1999

8/30/1999 9:16 PM
nic	how about the zvex set up with the "probe'? Nice crazy looking coil antennea. nic

8/31/1999 3:21 AM

Interesting idea. Actually a number of budget-to-midpriced synths in the late 80's had breath controller inputs which used breath pressure to generate a control voltage. EM magazine even ran a little article about a CLM6000-based unit that connected with a breath controller.

Now if you could do things with your breath and tongue like the late Rahsaan Roland Kirk or John what's his name from Blues Traveller could do (ladies, I suspect that John's the one you want, not Gene Simmons), AND if you could pack a front and 2 side breath controllers into one little package that strapped into a harmonica holder, there would be no end to the possible tones producable via voltage control.

8/31/1999 2:02 PM
paul perry	I like alternative controllers as much as anyone, but the big problem with pressure ones is that when you step off, or stop blowing, they go to the rest state. At least wah type pedals stay where they are put.

8/31/1999 4:50 PM

Alternative foot-operated controllers

Good point. With force-sensitive technology, one possible solution is to have balanced backward pressure applied to each side. So, a spring in the front, a spring in the back, and the footpedal always returns to the mid-position, applying equivalent pressure to each half of the conductive material. Of course, this may not be where you want it to go, and therein lies the problem of alternate controllers.

Still, within those limitations, there are some interesting possibilities. I remember fondly, the various articles in POLYPHONY many years ago about adding pressure sensitivity to mono keyboards, using piezo discs under the keyboard. There is no reason why one couldn't construct interesting multi-dimensional foot-controllers using pressure-sensitive technology.

To whit, a pressure-sensitive foot-controller could adjust forward/backward, side-to-side, in "joystick" mode, and downward pressure - just like aftertouch on many keyboards. Just imagine a wah-pedal with "aftertouch" control of resonance, and foot-joystick control of formants. Now THERE is your talking pedal!

All this being said, Paul's right about some things. If you want to play "Money for Nothing" in a house band, you need to be able to set your wah just right, and leave it there until you're done.

Looks like your average player is about to need two wahs.

9/1/1999 1:08 PM

Some options for alternative foot controllers:

1) A LED/LDR combo, and a plastic stripe between them that goes from transparent at one end and black at the other end, attached to the pedal. You could use ink jet transparency and changing the taper by changing the "shading" of the stripe - print another stripe and you've got a new taper. Also when the pedal is at a fixed position the fx stays the same. I think it's the Morley approach.

2) LED/fototransistors combos and a plastic stripe with black bars, this fires an up/down digital counter (like in a computer mouse - you could even salvage a mouse for the parts) that selects a memory position and then to a D/A multiplier. You change the taper by changing the contents of the memory. Before using it, you need to "reset" it so it knows where it is, but once in use, if you leave it in a fixed position the fx stays the same. The foot controllers on my ART X-15 midi pedalboard are somewhat like this.

3) What about something like above in a "track ball" format? You could roll the ball with your foot and get two independent whas.

4) A Hall effect device like BOSS used in some of their whas. The proximity of a magnet changes their resistance. Difficult to change the taper. If you leave it in a fixed position the fx stays the same.

5) Strain gauges. Difficult to change the taper. If you leave it the fx resets.

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