Best of both worlds…

Ever wanted a synth that combines modular weirdness with practical musical usefulness, well a prime contender for this apparently dificult combination would be the ARP2600.

ARP 2600 (cover of Service Manual)
ARP 2600 (from cover of Service Manual)

So what makes the ARP 2600 so special? Some features of note include:-

  • VCOs that can be used as VCLFO’s (all three).
  • RING MOD that can be used as an additional VCA.
  • VCA with exponential response for percussion sounds that bite.
  • Excellent interfacing with external audio signals. Including an ENVELOPE FOLLOWER that can trigger the synth from external audio signals (cheesy drum machines are a good source).
  • NOISE SOURCE that goes right down to a rumble and can also be used as a modulation source.
  • VOLTAGE PROCESSORS that can do nearly anything to a control voltage coupled with excellent interfacing with external control sources such as a sequencer. (MIDI interfacing through a MIDI-CV converter is also very straight forward).
  • SAMPLE and HOLD that can accept inputs other than WHITE NOISE and that can be externally clocked.
  • Stability of tuning that is surprisingly good for it’s age and it is fairly easy to fix (although it rarely goes wrong).

ARP 2600 – History

The 2600 was Alan Richard Pearlman’s first attempt at a portable synthesizer following on from the massive ARP 2500 (as featured by Steven Spielberg at the end of ‘Close Encounters of the Third Kind’). To aid portability the instrument was in two parts, a console (31″ x 18″ x 9″) and a four octave keyboard (31″ x 6″ x 3″) each with a cover for protection during transportation.

Part of the company culture at ARP seemed to be “if Bob Moog does it then we don’t” which resulted in all fifty seven control pots being sliders and all eighty one jack sockets being 3.5mm. Some of ARP’s ideas cannot have been that bad because close examination of Roland modular gear such as the system 100 and the 100M shows remarkable similarities. I used Roland sequencers with my own 2600 for some years and can report that they are completely compatible.

The 2600 was one of ARP’s longest lived models. First produced in about 1971 (released at the same time as the rival Mini-Moog) it continued to be produced until ARP went out of business in 1981. During this long production run the 2600 went through several cosmetic and internal changes.

The first version was blue and has become known as the ‘Blue Meanie’. This (rarely seen) version has wooden handles and metal end cheeks. That version was quickly superceded (much to Alan Pearlman’s relief) by the tolex covered grey faced version that is most commonly seen. The ‘grey face’ 2600 went through two versions of keyboard, a simple monophonic version that was replaced by a duophonic keyboard (based on a design by Tom Oberheim). The final version (c.1978) was the ‘orange faced’ version that had a keyboard with PPC pads added to it to give additional perfomance controls (yes, some people did use these instruments for live performance!).

The front panel of the console is divided into ‘modules’ although unlike a true modular synth the panel is in one piece, the module layout is fixed and the modules are pre-patched already into a sensible configuration. However each ‘module’ still has inputs and outputs (using 3.5mm mini-jacks) so that patch-cords can be used to over-ride any of the default connections.

ARP 2600 – Features

The layout of the console is in eight vertical strips and one horizontal strip across the bottom. Starting from the left hand end the contents of the strips are as follows:-

  1. MICROPHONE PRE-AMPLIFIER with three gain ranges, ENVELOPE FOLLOWER that is pre-patched to the preamp output plus a RING MODULATOR with AC and DC coupling and inputs that are pre-patched to VCO1 and VCO2.
  2. VOLTAGE CONTROLLED OSCILLATOR VCO 1 with sawtooth and square wave outputs. There are modulation inputs from KBD, S/H OUT, ADSR and VCO2 (sine) all being fed into a CV mixer that is part of the VCO (another ARP innovation). Frequency can be controlled by coarse and fine sliders plus a switch that selects audio or LF mode. For all three VCO’s audio mode frequency range is between 10 Hz and 10 kHz without any reference to octaves. LF mode is between 0.03 Hz and 30 Hz.
  3. VCO 2 with sine, triangle, sawtooth and pulse outputs. There are modulation inputs from KBD, S/H OUT, ADSR and VCO1(square). Frequency can be controlled by coarse and fine sliders plus a switch that selects audio or LF mode. There is also a PWM control plus a PWM input pre-patched to the NOISE generator.
  4. VCO 3 with sawtooth and pulse outputs. There are modulation inputs from KBD, S/H OUT, ADSR and VCO2(sine). Frequency can be controlled by coarse and fine sliders plus a switch that selects audio or LF mode. There is also a manual PWM control.
  5. VOLTAGE CONTROLLED FILTER / RESONATOR VCF has coarse and fine sliders to control cutoff frequency plus a manual RESONANCE control. Audio inputs are pre-patched into a mixer that is part of the VCF. These inputs are from the RING MOD, VCO1(square), VCO2(pulse), VCO3(sawtooth) and the NOISE GEN. Modulation inputs are from the KBD CV, ADSR and VCO2(sine).
  6. ADSR and AR ENVELOPE TRANSIENT GENERATORS have such extras as a manual push button plus the ability to select the gate source. GATE and TRIGGER outputs are also available.
  7. VOLTAGE CONTROLLED AMPLIFIER has an initial gain contol plus modulation inputs from AR and ADSR. Unusually the sensitivities of the inputs are different, one is linear and the other is exponential. Audio inputs are from VCF and RING MOD.
  8. MIXER and REVERBERATOR has inputs from VCF and VCA and converts the mono output via a PAN control and a stereo reverb spring to stereo.

In the horizontal strip you will find:-

MULTIPLE (four jacks), KBD CV (output), LEFT SPEAKER (volume), NOISE GENERATOR(white though pink to low freq), VOLTAGE PROCESSOR(inverters, mixing plus a lag processor), SAMPLE and HOLD(with it’s own clock), ELECTRONIC SWITCH (bi-directional), RIGHT SPEAKER (volume), POWER (on / off) and STEREO PHONES (socket).A connector for the keyboard is on the left and mains in is on the right.

The earlier keyboard (3604) had only four rotary controls on it TUNE, PORTAMENTO, INTERVAL (fixed) and INTERVAL (variable). The second much better version (3620) had it’s own LFO (freeing VCO-2 for audio duties) with controls (all sliders) over LFO SPEED, VIBRATO DELAY and VIBRATO DEPTH. Additional features included keyboard CV’s for top and bottom notes, a PITCH BEND knob, PORTAMENTO controls plus TRIGGER MODE and REPEAT switches. The very late version of the 3620 added the rubber PPC control pads that first appeared on the Mark 2 Odyssey.

The 2600 has had some fairly famous users in its day and scanning any record collection credits between 1970 and the present day will often reveal ‘ARP 2600’. Some I have spotted include Genesis, Daniel Miller / Depeche Mode, Larry Fast, Steve Hillage, J-M Jarre, Weather Report, Who, Rod Argent, Klaus Schulze, Tangerine Dream and the Shamen to name a few.

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