One of the key issues which was identified early on in this project was the exact design of the closed loop system. A typical closed loop system in an industrial application can use a closed loop system which is constantly feeding back to the controller and readjusting as appropriate.
However, in an audio application this is obviously potentially very disruptive to the playback quality of an LP with a frequently updating closed loop system creating the equivalent of ‘wow and flutter’ from cassette decks of yesteryear. This is clearly unacceptable.
The challenge is therefore one of how set up the closed loop system in a way that it can deliver long lasting and solid performance, whilst at the same time not interfering with playback and becoming a problem in it’s own right.
The answer to this is to setup the system in a way that it uses the feedback intelligently and only modifies the speed in such small increments that it is not audibly noticeable.