+50 for the phaser ! with a really slow minimum setting on the rate. And if it sounded anything like the Mutron Bi-phase or Phasor II...
here's something potentially interesting I just found
"The Mu-Tron Phasor used transconductance op-amps for the variable element at a time when most people were using FETs.
We were aware of most of the effects that were around, but the phase shifter that we were going after was Maestro's PS- I. MXR also came out with the Phase 90 while we were designing the Phasor, but we gave ours two more stages. Then in '74 came the Mu-Tron Bi-Phase, which was actually Newmans idea. We made it with photo mods because we wanted a really wide dynamic range. Though the technology was semi-obsolete-even at that time-the photo mod helped give the Phasor its own sound because photo resistors don't track each other exactly and each has its own particular time constant and subtle form of non-linearity. We even had a special photo mod custom made for us with six photocells in it.
At first the Bi-Phase prototypes sounded too clean, and we didn't know what to do about it. All the FET-based phasers had a non-linearity to them. In audio terms ours was too good, but in musical terms it wasn't good enough. I decided to put a feedback control around the phase-shift loop so that instead of distorting the signal it emphasized the peaks where the phase shifter didn't cancel the signal. This made the sound more interesting without distorting. Our Bi-Phase was the first phaser with a feedback pot, though Electro-Harmonix got a phase shifter to market before us with a feedback switch.
After the Bi-Phase we made the Phaser II, which was one-half of a Bi-Phase with only an oscillator sweep control. That was probably our most-popular product."
