Here is the Hoffman theremin with the rear cabinet doors open. All the circuitry is original.
The chassis, containing the pitch and volume control coils as well as an array of seven vacuum tubes, can be pulled out like a drawer. To do this, the antennas must be disconnected from the coils.
This photo shows the chassis turned around, clearly showing the seven vacuum tubes as well as the volume and pitch control knobs and the ruby pilot light.
This photo shows the power assembly beneath the chassis along with its UX 280 vacuum tube. The three brown boxes are the two filter reactors and the power transformer. This assembly is connected to the upper chassis by means of the snake visible in the center of the photo. Just inside the cabinet doors, on the right side, is a volume knob that Dr. Hoffman used to control the XLR output for studio recording.
This is Dr. Hoffman's theremin with the front panel removed, showing the built-in speaker cabinet and the speaker transformer (seen left, on the speaker compartment floor). The two brown boxes just above the speaker are the power transformer (left) and one of the filter condensers (right) seen from the back. The speaker that is presently in the theremin is a custom CLARATONE made by Florida thereminist and theremin technician, Reid Welch.
The speaker leaning up against the open storage drawer is Dr. Hoffman's original 10 inch GE speaker. Although I do not use this speaker, I have carefully preserved it since it is part of the history of the instrument. Over time, the cardboard in speaker cones tends to dry out, significantly affecting the quality of the sound.