ARP Little Brother (1975 - 1977)
Keyboardless monophonic expander module designed to add an extra VCO and LFO to ARP synthesizers.
Overview
The ARP Little Brother is a keyboardless monophonic expander module made by ARP Instruments, Inc. from 1975 to 1977. Designed as an add-on for other ARP synthesizers, it was commonly sold with the ARP Axxe and was given away free with the purchase of an ARP Odyssey during a summer 1976 promotion. It was intended to "fatten up" the sound of synths like the Axxe, Odyssey, 2500, and 2600 by adding an additional VCO and LFO. Multiple Little Brothers can be stacked for expanded, modular-like functionality.
Specifications
| Production Years | 1975 - 1977 |
| Synthesis Type | Analog Subtractive |
| Oscillator | 1 VCO with four selectable and stackable waveforms: brass (sawtooth), hollow (square), reed (pulse), and fuzz (pulse with PW modulation); includes sub-octave divider for -1, -2, and -3 octaves |
| LFO | 1 LFO with triangle waveform; LFO out available |
| External Control | CV/Gate, ARP System Interface |
| Additional I/O | CV, Gate, and Trigger inputs; LFO out |
| Controls | Pitch bend/master tuning knob (2-octave range), LFO speed and vibrato depth sliders |
| Missing Components | No VCF, no VCA, no envelope generator (ADSR) |
| Memory | None |
| Effects | None |
| Arpeggiator/Sequencer | None |
Design
The Little Brother contains a genuine ARP 4027 oscillator submodule and uses ARP's System Interface for integration with other synths. It functions by connecting its CV input to an ARP keyboard and routing its audio output into the external audio input of a companion synth, allowing the "big brother" synth to process the signal through its VCF and VCA. The unit uses organ-style tone generation to produce multiple notes from one oscillator. Components include: 1N4148 diode, 1458 op amp, 3086 transistor array, 4024 binary counter, 2N3904 transistor, and various potentiometers. A small hole above the Reed switch allows access to a calibration trimmer.
Context
The Little Brother was designed to augment the Axxe or Odyssey, and could be used with any analog synth having 1V/octave CV output and external audio input. It was marketed as a way to add an extra oscillator and LFO to existing ARP systems, with the ability to stack multiple units for richer sound expansion.
Market
A refurbished unit is currently listed for $1,400 in good condition, with scratches but fully functional. Refurbishment included new sliders, recapped power supply, replacement of all tantalum capacitors (except on 4027), replacement of all CMOS and op amp ICs, a new pitch bend knob, and calibration. Cosmetic flaws include a missing front tag, replaced switches, missing switch cap, non-illuminating power lamp, and panel scratches. Replacement parts are available, including 1N4148 diode ($0.95), 1458 op amp ($2.95), 3086 transistor array ($9.95), 4024 binary counter ($2.95), pitch bend knob ($7.95), and slide potentiometers ($29.95 each).
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