Carlin Phaser Sweep Problem

[Puguglybonehead]

I recently built a Carlin Phaser, from the kit from Moody Sounds. It's a foot-contolled 8-stage phase shifter (kind of like a wah pedal) with an LED control feeding the 8 LDRs. (green LED if that matters) It's got a nice sweet sound, despite having no feedback or anything, but the pot that came with the kit doesn't seem to be right. It's a 100kA. All of the sweep (where the phase shift is noticeable) seems to be confined to about 20% of the treadle movement. (mostly when the LED is dark or near-dark) The rest of the treadle movement does nothing.

Would changing the pot to a different value, larger or smaller, or a different taper, make any difference? Could I fix things by adding a resistor in series with the pot? I don't know the specs of the LDRs that came with the kit. (dark resistance, etc..) I really like having a foot-controlled phaser. It has a nicer tone than the foot-controlled phasers I tried in the `70s. but I would really like to get the sweep problem sorted.

[noisette]

Have you got schematics? The Carlin Phaser google brings up is modulated with lfo or sweep by 10k antilog pot (this could be your problem) and uses a light bulb with the ldrs?
http://www.experimentalistsanonymous.com/diy/Schematics/Phasers/Carlin%20phaser.gif

[Puguglybonehead]

Thanks. I'll give a 10k linear pot a try. I just used what came with the kit. (which came with a similar, incomplete schematic, minus the LFO part and with no value mentioned for the pot)
The original Carlin Phaser from the 1970s apparently used a plastic shade that was mechanically lowered (by moving the treadle) over the bulb to vary the light that was reaching the LDRs.