Series 91b Theremins

Posted: 2/4/2006 10:52:25 AM

Joined: 2/4/2006

Hello everyone I'm new here. I have been doing some searching on the 91b and can't find much info. Can anyone tell me more about and what this model is worth?
Posted: 2/4/2006 12:54:18 PM
Charlie D

From: England

Joined: 2/28/2005

The series 91 theremins were manufactured by Moog Music between 1991 and 1997, and were the Moog professional model prior to the release of the Ethervox. The 91 came in three different cabinets, cabinet 'a,' 'b' and 'c.' The 91b is based on the late Termen-made models, and is H-shaped. You can see Lydia Kavina playing one in her instructional lesson video that ships with the Etherwave Standard.

The 91a was built in the traditional lectern-shaped RCA-style (it looks a bit like a fancy drinks cabinet!), whilst the 91b was designed by a professional sculptor in a contemporary style. 91a's seem to have been the most popular choice - I have not heard of any thereminist other than Ms. Kavina using a 91b, and have only ever seen the 91c in Moog marketing photos.

The Series 91 theremins are (to my knowledge) schematically identical, and synthesise their tone rather than directly heterodyning it. This means that the 91 series theremins never go completely to zero beat (i.e they don't have a silent area outside the playable zone).

The series 91 theremins have a range of about 4 octaves, which is pretty small for a modern theremin - the old RCAs had around about the same tessitura, and this small range (so I hear) makes the 91 series theremins easier to play than other instruments with a more compressed range of notes.

The instruments have four discrete timbre settings, continuous dials to adjust tuning and volume response, and a headphone jack. The series 91 theremins also had a built in speaker, enabling the thereminist to play without a seperate speaker. A switch on the front panel allows for alternation between internal speaker and external speaker.

As far as I know they are pretty hard to come by, and of course if you wanted to get hold of one then you'd have to be incredibly patient. The original instruments sold for between $2500 and $3050, depending on the model and the colour wood chosen: Walnut or Black (and also Cherry for the 91c) I do not know how much they change hands for now, but I expect it is not too far off that figure.

Several thereminists I know of use series 91 theremins. Carolina Eyck uses one, and has several samples of her playing on the instrument. Peter Pringle also owns a series 91, although the vast amount of post processing he employs means that the original tone of the instrument is virtually indescernable (it's still sounds glorious, but to my ear not very different to any of the other instruments he owns after post-processing). Charlie Lester also uses a series 91 theremin.

Here are some links you may find useful:

I hope that this is of help.

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