Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jennings on December 14, 2022, 02:26:22 am
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I’ve just restored an early 60s Watkins Copicat tape echo unit (schematic attached)…the only mods I made were to update the rectifier diode and grounding scheme. The original has no mains ground, relying on the connection to the amp jack socket screen only.
Anyhow, I wondered whether anyone has any thoughts on modification to allow speed variation?
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> speed variation?
Why? The tape runs the same (long term) speed at the record and play heads. You want speed high enough for decent treble (remember that real reverb usually has decaying highs); low enough for decent tape life.
How? The motor is almost certainly line-locked to the 50 or 60 Hz power line. OK, you can change spindle or capstan diameter, but if not perfect the flutter and wow is audible.
You can put a switch in the motor feed and kill power. The run-down may be a comical sound effect.
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The speed variation comes from wear of the mechanism of a Binson Echorec, and is reproduced in clones. It can be subtle and quite pleasing.
One of my favorite pedals is the Gurus Amps Echosex (of course, an Italian company). It is totally electronic, with no tape, but is somehow able to deliver believable wow and flutter in the delay signal. There are others . . .