Series 91A at ebay

Just saw this on ebay while poking around.

http://tinyurl.com/yhovvvb

I see the bidding was to start at $7,500.00! The auction ended on Friday with no bids at all. I think the seller was a bit optimistic.

If I remember well they were sold new for around 3500$. If one takes into account that they have nice housings on on side but that they aren't "real" theremins on the other side, I think that 2500$ would be a more realistic price.

Why aren't they "real" theremins? There were always rumors that the pitch antenna was used to attenuate a rf signal as a function of hand proximity. The resulting control voltage was intended to control directly an audio frequency generator. So there wouldn't be neither a second pitch oscillator nor a mixer stage.

I found this principle of operation fully confirmed when I had been asked to diagnose a Moog 91C with pitch range problems during the NodeFestival in Lausanne, Switzerland last weekend.

Finally I could help the owner by finding out that the main frequency determining capacitor of the pitch oscillator had lost some of his capacitance. I told him to buy 4 capacitors (1pF, 2.2pF, 4.7pF, 10pF) and to solder them one after the other in parallel to the existing capacitor until the pitch range would be within the normal specs.

This one looks rough. Why wasn't it taken better care of if it was a "one of a kind" unit. Scratched all to hell and back.....

P