That's fine; the Echoplex also runs at a constant motor speed. One ofthe heads (I forget whether it's the record or playback head) isphysically mounted on a sliding track, and you manually move it backand forth to change the delay time.
I have two Roland Space Echo.
And, in these machines, the heads don't move. You change the delay time with a knob which controls the speed of the motor.
David C.
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Candor Chasma