This is an appropriate range for most applications. For example, 5V. is the typical maximum Control Voltage input to many CV to MIDI converters such as our MIDI Brain and represents 5 octaves of pitch with the typical analog synth. This range of control is beyond the abilities of even the most accomplished thereminist. Clara Rockmore's theremin had not quite 3 octaves of pitch range. A Tmax will give best results as a CV controller when tuned for Controller Mode as outlined in the manual.
Correct oscillator nulling is very important for full control voltage range.
In this circuit a single LM324 op-amp package provides 3 CV booster amps and an alternative to the Velocity sensitive Gate signal of a stock Tmax. The new Volume Gate is based on the volume hand's position, not it's change in position, an easier skill to master. Probably so, the Velocity sensitive Gate takes some practice to master. For best results the Tmax should be tuned to Controller Mode, as detailed in its manual. Remember that this Gate responds to changes in Volume hand position.