Explorer I is a small preset monophonic analog synthesizer, a very "close relative" to PRO-Soloist, but has a very important difference - manual mode.

The unit contains factory presets: flute, trumpet, clarinet, strings, pulsar and lunar. In the manual mode, individual settings for all function blocks are available:

For a voltage controlled oscillator (VCO), a waveform ("brass" - saw, "hollow"/"reed"/"fuzz") is selected and a signal of the built-in pink noise source can be selected.

The section of the envelope generator is common for VCF and VCA featuring the timing of attack, decay, sustain and release.
For voltage controlled low-pass filter (LP VCF), cutoff, resonance, modulation depth by LFO and envelope generator are available. As well as in PRO-Soloist, ARP4034 module was used as the filter, which is considered the most successful filter made by ARP back then. The four-step VCF structure provides a cutoff slope of 24 dB per octave. At high resonance values, the filter enters the self-oscillation mode.

The low frequency oscillator (LFO) has a frequency adjustment and a generator restart switch (LFO starts generating after each key press).

The second LFO, designed to create a vibrato effect, has a switch and a frequency controller.
Portamento and pitch bend (here – a common rotary knob) regulators are also available.

ARP Explorer was used in the works of Philip Glass and Herbie Hancock.