It was controlled by connecting the control voltage (CV) output of an ARP synthesizer's keyboard to the Little Brother's CV input.

The Little Brother had a single voltage controlled oscillator (VCO) with selectable waveforms, and a sub-octave divider that could produce up to three additional tones simultaneously at -1, -2 and -3 octave intervals.

When used with other ARP synths to "fatten up" their sounds, the Little Brother's audio output had to be patched into the external audio input of its companion synthesizer, essentially adding an extra VCO and LFO to the system.

However, it could be used with any analog synthesizer that had the necessary 1v/octave CV output and external audio input connections.

This article relating to electronic musical instruments is a stub.