Uni-Vibe
A lamp and photocells driving four deliberately mismatched phase stages.
What the circuit does
Four phase-shift stages, but the parts are not matched to each other and the modulation comes from an incandescent lamp shining on photocells rather than from a clean oscillator. The lamp's own thermal lag makes the sweep uneven, so it is neither a symmetrical phaser nor an even tremolo.
What to listen for
A throb that is heavier on one side of its cycle than the other. It was built to imitate a rotating speaker cabinet and does not really manage it, and failing at that is precisely how it became its own sound.
Where it goes
The modulation slot
After the gain and before the delay, so the delay repeats a modulated signal rather than modulating an already repeated one. Reversed, the movement gets applied to the echoes as a block and the effect smears instead of swirling.
Controls
- Speed
- Intensity
- Chorus and vibrato switch