owner: Charles Aithie

"The name Quadra is derived from the fact that the instrument is actually four separate synthesizers in one microprocessor-controlled system. This instrument gives the musician the ability to write, edit, store, and activate the sounds of four synthesizers in live performance. [It is sort of like a combination of an Omni and an Odyssey]

"The Quadra's four sections are: a bass synthesizer, string synthesizer, polyphonic synthesizer, and two-voice, touch sensitive lead synthesizer. A stereo, voltage controlled phase shifter is also included, designed for the Quadra's special requirements.

"The bass synthesizer can be programmed to control the two lower octaves of a five-octave split keyboard, ranging from electric to string bass settings.

"The string synthesizer produces the rich, deep string sounds for which ARP is famous, and can be used with the built-in phase shifter for exceptionally dramatic string choruses.

"The poly/synthesizer section provides the musician with a quick change of envelope control parameters at a touch of a switch. Brass, Piano, and synthesizer sounds can be processed through the phase shifter, sample/hold and other circuits for a variety of polyphonic synthesizer and keyboard effects.

["It was a top-octave subdivider system (basically an electronic organ) with a single VCF, VCA and ADSR for all notes. All notes passed through a single set of envelopes with the first keys struck in a chord triggering the envelope. Fine for block chords, but a "strummed" chord was impossible. Also it read the KB CV to the filter off the highest key pressed, making for funny results played two handed chords at once. The Quadra was about two or three years too late to make a difference, as both Sequential Circuits and Oberheim had real programmable polyphonics on the market by 1978." ----Joseph Swails, a former ARP salesman]

"The lead synthesizer section is actually a two-note, lead-line variable syntheszier, with pressure-sensitive (second touch) control of dynamics over three octaves, and full five octave range when the bass synthesizer section is not in use.

"The Quadra's lead capability includes twin-channel portamento and, coupled with a microprocessor, allows intervals and octaves to be programmed from the keyboard in real time. A built in sequencer permits instant sequential effects which follow every key depressed. The sequence can be memorized and held while the keyboardist plays additional string and polyphonic lines on top of the latched sequence. [Unfortunately there is no external sync for the sequencer.]

"At the heart of the Quadra is a computer programmer, a device which unites preset and variable synthesizer technology. Prior to a performance, the musician sets up the desired sounds in each section and stores these sounds into any of the 16 programmable positions. The sounds are memorized and can then be recalled by touch. [Memory settings let you know which sliders are active. It does not set the positions for you, but rather, it just lets you know which ones to move.]

"Each section of the Quadra is individually programmable and mixable through the output mixing controls centrally located on the control panel. Additional synthesizers can be interfaced with the Quadra through ARP systems interface jacks. Pedal and footswitches control inputs for a variety of Quadra functions are easily acessible on the back panel."-----[from the ARP Quadra promotional brochure courtesy of Kevin Lightner

In addition to the separate outputs for each synth, there are separate CV/gate inputs for the Bass and the lead synth voices, and an additional seven Control Voltage inputs.