ARP Instruments

ARP 2500

The name ARP is the abbreviation for Alan R. Pearlman, the founder and genius of the company.

The first ARP (1970) was the ARP 2500. A modular synthesizer, with pin patch panels instead of patch cables. Only the central synthesizer can be seen in the picture - there are still "wings" (cabinets) to enlarge, which make the instrument more than twice as big.

The ARP 2500 remained the "hyper-model" of all ARPs until the end of the company. Errors in management, too high prices for polyphony, suboptimal research foci, production errors and the generally difficult melange in an almost "exploding" music industry caused the decline of the relatively small company in 1981.

The ARPs shown here represent only one area of the overall program of ARP Instruments.


ARP 2600

Semi Modular
  • The ARP 2600 (built 1970-81) is a semi-modular, first monophonic, later duophonic synthesizer with 3 VCOs and runs internally with 15V. The synthesizer is able to generate quite complex sounds through the use of patch cables. Without a patch cable, it has internal default connections - therefore semi-modular. He was also taught in the USA as a teaching tool in many schools, so that his degree of recognition almost reaches that of MINIMOOG. It should be noted that the first model series looked slightly different (and blue) and the later series of the gray ARP 2600 were equipped with inferior parts. This was expressed above all by strong ground noise. Also, the later VCOs sounded somewhat weaker, but the originally used Teledyne VCOs were simply too expensive.

    Today, this can be corrected or optimized, but the ARP 2600 has become a very expensive instrument. The last series from this model was also in the black/orange look.

    For this synthesizer, there were three different keyboards. Only the last Model 3620 (photo) was duophone and had an additional LFO.

    The ARP 2600 was my second synth (1985) and I had it for about 12 years. In the beginning of the 90's I also used it a lot "live" - often without keyboard. How synthesizers work technically, I did not know then: everything was Trial and Error. Great.

    This instrument was a heavyweight in the, to date, most compact packaging. It can be heard on countless records and in as many films. Joe Zawinul played it for years in his band "Weather Report", so that the 2600 was part of the characteristic sound of this band. With its three VCOs, it was a (much more powerful) MiniMoog-parallel, but because of the patch cable was never regarded as that. As an "offensive" parallel, ARP brought the Odyssey, which has however only two VCOs - but could be extended by an External Input with a third VCO.

    ARP Odyssey 2811

    & ARP Little Brother

    On the photo is my modified (black/golden) ARP Odyssey 2811. In the connection with Max/MSP, ARP offered the sound, which I had long sought. These were precisely the "lost" sounds (after 25 years of digitization)! The small stage synthesizer was suddenly extremely attractive again.

    This circumstance brought me to Eric van Baaren ( and I realized that these instruments were better for me than ever before - after Eric's interventions they fit me perfectly, as he adapted them perfectly! From Eric, I also got the illustrated ARP Little Brother and an extensive knowledge. So I experienced a veritable ARP spring in 2006-13. This time, however, I got to know the instruments correctly - before I used to play them unaware.

    The ARP Little Brother is the ideal addition to the Odyssey, it delivers the third VCO. Since it has the Oscillator of the ARP 2600, it brings a much more powerful color (and size) into the game and that does well. It was fun to play this instrument, it was quite easy to handle.

    This Odyssey setup also included two pedals (Volume and Expression) and a Portamento Switch. The Kenton KillaMix and the Korg Nano-Pad (both MIDI controllers) were used to control my Max patches without having to look at the computer monitor.

    The material of the sides (with floor) is vinyl! A special feeling. It was my favorite Odyssey setup, although three Odyssey followed. This Ody had three mods: 1. LFO speed (/10, normal, *10), 2. Duophony Switch and 3. Envelope Speed Switch (/10, normal, *10).

    Here is an excerpt I played with this instrument:

    ARP Odyssey 2821

    & ARP Axxe MkII Expander

    In 2009 I got an unused Odyssey 2821 (black / orange). It was purchased in 1976 and wrapped in foil. A fantastic thing - nevertheless all contacts had to be cleaned and some capacitors exchanged. The Odyssey, however, changed its role in my setup and became the Synth-in-Synth after purchasing the MOTM Modular Synth (2010). While more complex things took place on the modular synthesizer, the Odyssey - through its interface - was there for "fast actions".

    For this Odyssey, I had a third (and fourth) VCO from a Axxe MkII, which I had converted to an Expander - interesting but not as convincing as the Little Brother. It was indeed a feast for the eyes, but overall I was not happy with the full metal Odyssey. Although it was all fresher - on all three black/orange models, which I had, but already with the optics (I felt the orange yelled) and the haptics were cold - I had trouble.

    Everything had begun in response to the vulnerability of the 2811 (black/golden). I wanted a second instrument. There were several Odyssey - and all were different. Also, from the same series. I learned that the components can sometimes have up to 10% deviation.

    As a result, the big conversion started, Filter, VCA, everything was exchanged among themselves or against other components and now it became still more interesting: the different assemblies sounded differently in the different instruments also! It was thus practically impossible to make two instruments of the same kind. The instruments appealed to me in their reverse order. The most deprecated Ody was the best, even after the exchange of the (best) Filter against a worse one.

    So it depends on the art of the technician, on the available components and the luck that the components also harmonize with the rest of the instrument. Appearance is another thing. To clarify: the instruments sounded, respectively behaved different - they all sounded great! The Odyssey runs internally with 12V.

Odyssey Patches and Tutorial (1973)

Roger Powell's booklet and tape as video


    The ARP Odyssey Series

    2800 - 2813 and 2820 - 2823

    The Odyssey Series are a little confusing - so much so that even today is often a confusion when it comes to the model designation. The names "Mk I" and "Mk II" are particularly "wrong" - the safest is "Whiteface", "black/golden" and "black/orange". Nevertheless, these three groups still differ.

    Model 2800 - 2813 (1972-78)

    The first Odyssey (model 2800, built 1972-74) is called "Whiteface". It has a 12dB SEM Filter and on the left a potentiometer for Pitchbending. In fact, the last models "Whiteface" have already been built with "black/golden" covers. Otherwise everything was the same.

    With the series 2811 (built 1975-77) a 24dB Filter was introduced - the Series still came with Pitch-pot. When exactly the three Touchpods (PPC) replaced the Pitch-pot, I've forgotten - it has subsequently mixed anyway, because the PPC were also to be upgraded.

    The black series also involves two Filter changes, triggered by a court ruling: the first Filter had been classified as a Moog copy and banned. As far as I know, there are three different Filters, two of which are coveted. The first (Moog) and the last (4075). A matter of taste.

    Model 2820 - 2823 (1978-81)

    With the "black/orange style some external, distinctive changes came along: the vinyl lower part had given way to a full metal housing, which was much more maintenance-friendly, since it could be opened more easily, almost like a hood. The keys stuck out slightly, which in practice relatively frequently led to damage of the keyboard. The 2820, however, wasn't as fragile as its predecessors - even the fader caps were somewhat thicker. There are hardly any differences in sound, but the technical layout had been improved more efficiently.

    A significant deterioration though was the keyboard itself. It was much lighter and much more rickety than the old models and this became even worse with every series. So: for technicians an improvement: more stable, more efficient, more service-friendly. For pianists: almost a shock - the technically unchanged, Pratt Read keyboard had become a noisy plastic pile. Touring musicians often had damage to the keyboard. Only the unpacking from the case contained enough dangers.

    Here are three keyboards in freshly made condition - first Odyssey 2811, then 2821 and 2823. I find the quality differences are clearly heard. As much as I liked the 2823 - the keyboard was brutal and somehow the access or destroyed. - the keyboard was brutal and somehow the access or destroyed.

    Fresh keyboard bushings on the 2811, 2821 and 2823

The Odyssey Mods

What exactly is that?
  • The Mods

    Since the possible modifications are difficult to conceive, I have once created a sketch for the Odyssey, which shows all the switches and controls from all the modifications I discussed with Eric ( The Multi-Mode Filter SE4109 is still in the beta phase, but promises to be a real highlight because it represents different ARP filters (according to ARP original plans). I am also very curious about the new, further developed VCA, because the Odyssey's VCA is certainly its weak spot. This can be compared with the Axxe, whose VCA grasps much better.

    The SE2607 module (with the waveforms of the ARP 2600) is also available with switches. Extremists can have two SE2607 (for both VCOs) installed! The mods "highest / lowest note priority" and "mirror" were my requests.

    This is really great when you can say "I would have / would like to ..." - and then you get a new switch, potentiometer or input / output to the synthesizer with just this function. Eric van Baaren can also solve the problem of the often scorned particularity of Odyssey, the 2-octave transposition lever, with a 1-octave switch.

    So that the Odyssey is also suitable for sounds "outside the pop music", it is useful to modify it. The Mod on my 2811 (with PPC instead of the Pitch-pot) executed are: a) Filter and Audiopath upgrade (makes the Ody HiFi), b) Mono-/Duo-Switch, c) Acceleration / Deceleration of the LFO by a factor of 2 (3-position Switch), d) AR/ADSR Speed by a factor of 10 (3-position Switch). With these mods the Odyssey is more powerful and gets its wonderful sound.

    The photo shows "The Norwegian" - an extremely modified Odyssey by Eric van Baaren (

  • Mod-Examples

    The following example shows what it means when the envelope is 10 times longer. The envelope is applied to the pitch of the oscillator and the attack time is set to maximum. First the normal course (approx. 5 sec.), then the extended course (modified Ody = 50 sec.). It would also be possible to modify to 100 seconds. The graphics actually says it all.

    This modification also provides more speed. In the third position of the switch, the normal time is divided by 10 (i.e., the maximum attack time is only 1/2 second). Percussive sounds get much more expression and can be shaped more precisely.

    LFO Speed / FM

    ADSR / AR Speed

ARP Axxe

A small ARP (1975-81)
  • A simple instrument with convincing ARP sound. The Axxe has two Oscillators but only one Envelope Generator. As a result, it is determined in simple, structured sounds, such as bass or solo sounds. The Axxe also has an Input for external Audio signals and can be connected via to e.g. the Little Brother.

    Often one reads that it is weaker than the Odyssey - this is not true at all - but in comparison, it lacks a second Envelope, Noise and Ring Modulation - and all those little Switches. Of course it's more simple - but it has a stronger VCA than the Odyssey. This is why it is still popular today, especially as a bass and solo synthesizer.

    In the Axxe Series it is ok to speak of MkI (black / golden) and MkII (black / orange). There were only these two models. On the picture is my MkI. Also with the Axxe I rather prefer the "MkI". Nice, better keyboard, overall warmer (haptics). I had converted my Mk II into an Expander (see Ody 2821).

Rhodes Chroma

16 x ARP! (1979-80)
  • My first ARP.

    Sound in the realm of the time. Cassette interface, Computer interface for Apple II (!) and filled with boards. I believe that the hardware corresponded to 16 ARPs - thus the overwhelming sound variety came about. However, there were some disadvantages: the immense weight, the technical susceptibility - almost all the Chromas I saw had at least one failed module (that was 2 voices) and the lack of modulation possibilities. Chroma is analog, but with digital surface. So the Parameter to be modulated had to be placed on a designated Slider - there only was ONE Slider (!). Well, yes. There were two Shifter-handles (they were really good - I still miss them today). The Rhodes Chroma was/is a monster in every respect!

    As consequences of the bankruptcy of the company ARP in 1981 some Rhodes Chroma's came on the market in 1983, which only cost ca. a third of the original price. So it was the chance to get an REAL Synth and thus a real base, to find out whether synthesizers are "something for me". I could get the money and got this battleship.

    One year later I made my first synthesizer production for a theatre play by Ivan Klima. A Bang. My Rhodes Chroma was the synthesizer I had the longest. The editing was a pain (because I had not yet an Apple II computer), but the Chroma was extremely well to play - the keyboard was from Rhodes. Despite the enormous weight, I often played it, also outdoors or at illegal concerts, where a possible escape (with equipment) needed to be considered. At that time there was still some help from the audience.

    Moog, EDP, Yamaha, Casio, AKAI