THE BIG BRIAR SERIES 91A
I recently acquired this mint condition, walnut cabinet Big Briar (Moog Music) Series 91A theremin.
It is 62.5 inches from the floor to the top of the vertical antenna and has an internal speaker
(the speaker grill can be seen at the bottom right side of the cabinet).
This is the front panel showing volume and pitch controls and the four timbres. Moog Music's Steve Dunnington, who originally put this instrument together back in the 1990's, recently adapted the headphone jack as a pitch preview (i.e. a tone that bypasses the volume control).
This is the inside of the instrument. Unlike the original RCA theremins, Robert Moog's SERIES 91 instruments do not produce their tone using the heterodyne principle although the gestural controls function identically. The signature of the late Dr. Moog, dated June 1997, can be seen on the inside.
This shows the pitch and volume circuitry.
The metal cover plate has been removed to show the pitch circuit board.
This is the rear of the instrument showing the dropout walnut access panel. The black wooden box beneath the pitch and volume PC boards houses the built-in speaker. The late Dr. Moog designed a modification to voice number two on the Series 91 theremins to emulate the sound of Clara Rockmore's custom instrument which Leon Theremin built in the 1930's. I asked Steve Dunnington if it would be possible for him to find the original schematics for the changes and make the modification himself. I was delighted with the results of his work and here is an mp3 of what the “new” voice number two sounds like.
This is from Giacomo Puccini's opera MADAME BUTTERFLY.