By way of intro, my name is Mark and have been mainly in the computer biz for the last 40 years however I have a sweet 2nd gig repairing audio gear. After rescuing and restoring an SL1200-MK2 for my own use, someone brought me one and challenged me to make it spin at one rpm. Long story short, 5rpm is about as low as I could get it.
I posted the results on a turntable website and apparently this was considered some sort of heresy...oh,well!
I posted the results on a turntable website and apparently this was considered some sort of heresy...oh,well!
Welcome aboard & glad you came. You'd like my pal Jim, who removed the AC motor from the bandsaw in his wood shop, replaced it with a high-torque, high-HP DC motor, and then designed and built an electronic phase locked loop + power amplifier to drive the motor. The result was, a continuously variable-speed bandsaw which ran at the exact speed you selected regardless of load.
He had an amazing demonstration: he'd turn it on, and then feed in a big whomping 8x8 post. The damn thing ran at the same speed whether it was cutting nothing-at-all, or cutting an 8x8. I'm sure similar design principles could apply to continuously variable speed audio turntables, but perhaps with more elaborate signal processing to detect and eliminate wow, flutter, subsonic rumble, and speed variations when downforce changes, even at low (-90dB?) error levels.
He had an amazing demonstration: he'd turn it on, and then feed in a big whomping 8x8 post. The damn thing ran at the same speed whether it was cutting nothing-at-all, or cutting an 8x8. I'm sure similar design principles could apply to continuously variable speed audio turntables, but perhaps with more elaborate signal processing to detect and eliminate wow, flutter, subsonic rumble, and speed variations when downforce changes, even at low (-90dB?) error levels.
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