You probably heard the instrument countless times in B-movies (and a few 60’s pop songs), yet may not know about it. Theremin is an oscillator-based instrument controlled by gesture, invented by Leon Theremin in 1919 (here’s the Wiki article). Commonly regarded as the first synthesizer, it works by the principle of additive synthesis, where the output from a fixed oscillator is mixed with a VFO. The VFO is controlled by the amount of capacitance in the circuit, which in turn is controlled by the distance of the musician’s hand from a dedicated antenna. Another antenna is provided in most versions to control the volume.

Thereminator is a theremin simulator for the iPhone, controlled by touch. Very simply put, the user controls pitch by moving the finger horizontally (right hand on the traditional theremin), while adjusting the volume moving the finger up and down. It provides four basic waveforms and two sound effects to slightly expand on the standard theremin. Additionally, it has scroll and zoom features to control frequency range and resolution. Here’s a description of some of the features,

Waveforms

1: Default theremin waveform
2: “Clara.” A slightly grittier version of (1) in the vein of the RCA theremin
3: Square wave
4: Sawtooth

Effects

Echo: a tap-delay/feedback modeled after 50’s and 60’s spring reverbs
Trem: a smooth-windowing tremolo, in the vein of the fast setting on some ’60s tube amps

Zooming in/out and frequency controls

There are nine levels of frequency resolution for Thereminator. The default is #2 (1350 Hz onscreen). Frequency resolution is increased by tapping on the control area three times, upto a resolution of 69 Hz. The point onscreen where the taps are made determines the central frequency of the new resolution.

The slider towards the bottom of the screen adjusts the left and right extremes of the frequency range. Additionally, the user can tap anywhere on the slider track to move the slider to that position.

Zooming out is done by tapping on the screen by two fingers. Once again, the central frequency of the new range will be determined by the point tapped.

The beginning and ending frequencies for the current range are indicated on the slider track.

Indicators

The current frequency (pitch) is indicated by the digits display on the lower left corner. Current volume is shown by the sliding indicator on the left-hand side.

Reset button

The reset button clears all frequency adjustments and returns the application to the default 100 - 1450Hz setting.

Additionally, Theremin has a portamento algorithm for a quick and smooth transition between removed frequencies. The volume is controlled on a parabolic (rather than linear or logarithmic) curve to provide a more natural cascade on limited screen real-estate. The full frequncy range is 40 - 2000 Hz.