From Era To Era: A History Of ARP Design

ARP produced a dazzling array of instruments that allowed for a multitude of creative possibilities. Here's a walk through ARP's storied history, seen through some of its instruments.

ARP Family of Instruments (1976) by ARP Instruments PromoThe Alan R. Pearlman Foundation

From Era to Era

Over its 11-year lifespan, ARP created roughly two dozen musical instruments. While there were one or two notable failures, the vast majority of these designs led to ARP becoming one of the greatest synthesizer companies in history. ARP innovations led the market to greater heights, and for a while ARP had the world's best-selling synthesizer lineup. Let's take a stroll through the world of ARP, from the massive impact of its birth to the remarkable potential of its legacy.

Meet the Family

This group photo features the ARP lineup from around 1976. Clockwise from the top: the Axxe, Explorer I atop the String Ensemble, 2600, Little Brother, and Pro Soloist, with the Odyssey at the center. All these products and more are on the tour... with a few important exceptions.

Notably Absent...

This particular story won't say much about the 25002600Odyssey, or symphonic keyboards like the Omni. That's because out of the many ARP success stories, those synthesizers had such a powerful impact on the world that we’ve given them stories of their own. But don't worry, even with those set aside, there are plenty of other ARP synths to learn about!

Al with 2600 and 2500 (1972) by ARP InstrumentsThe Alan R. Pearlman Foundation

The One-Two Punch of the 2500 and 2600

The ARP 2500 (in the background) was the company's first instrument, a massive modular synthesizer with a unique design never before seen in the industry. The ARP 2600 (shown here being played by Alan R. Pearlman) was and is a revolutionary machine, pioneering a new way to work with synthesizers that attracted fans from all over the music world. The impact of these two machines on the history of electronic music was so great that we've dedicated two other stories to them alone. But what came next?

ARP Soloist (1971) by Tonus / ARP InstrumentsThe Alan R. Pearlman Foundation

The Soloist: Out of the Shadow of the Giants

There wasn't anything quite like the Soloist when ARP introduced it in 1970. Unlike the vastly flexible modular synthesizers that came before it, the Soloist was designed to be simple, fast, and expressive to play. A small keyboard that happily sat atop an organ or electric piano, it featured 18 preset sounds accessible with the flick of a switch.

ARP Brochure Soloist page 2 (1973) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Soloist also featured a highly significant innovation that influences synthesizers today. One of the difficulties that players had with existing lead synths was that it was sometimes necessary to play them with two hands, one to play notes and the other to control pitch, vibrato, etc. The Soloist's pioneering Touch Sensor was a pressure-sensitive bar under the keys that allowed the player to articulate notes as they were played, using only the playing hand.

Marketed primarily to organists, the Soloist even came with a built-in sheet music rack. 

This is a demo by Lars Wigren of a recently restored Soloist, running through its features and sounds. 

ARP Brochure Soloist Mk II page 1 (1972) by ARP InstrumentsThe Alan R. Pearlman Foundation

Soloist Mk II

This ARP ad from 1972 features the Soloist Mk II, an updated version of the Soloist that never made it to market. It actually had fewer presets than the original, but had a digitally-controlled oscillator that effectively improved the tuning on the Soloist.

ARP Brochure Soloist Mk II page 2 (1972) by ARP InstrumentsThe Alan R. Pearlman Foundation

This brochure also featured preliminary information on the new Pro Soloist, which would come with added presets and other improvements. It's shown here in a never-released prototype form.

ARP Story Brochure Pro-Soloist (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Pro Soloist

The Pro Soloist, which shipped in a significantly different design than its prototype, was the solo synth ARP had striven for all along. Its stable tuning, expanded preset selection (30 rather than 18), and refined pressure sensitivity made it very popular in studios and on stage, and it was a fixture of many famous keyboardists' rigs for years. With such a powerful synthesizer in the lineup, no need was seen for the Soloist Mk II, which never shipped.

ARP Story Brochure Pro-Soloist (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

This brochure from 1974 shows the layout of the Pro Soloist's controls, which were now placed above the keybed rather than under it. This may have been for engineering reasons, or because non-organists preferred to use a finger to flick a switch that was in easy view rather than thumbing a switch under the keybed, as was often done on organs. While this change didn't appear to affect the Pro Soloist's popularity, ARP's rivals almost always retained under-key controls in their competing models.

ARP Spec Sheet Pro/DGX p1 (1979) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Pro/DGX

The final refinement of the Soloist platform was 1978's Pro/DGX. It featured the relatively-new technology of digital pushbuttons with LED indicators to replace the old toggle switches on previous models, and had a new filter circuit for a warmer sound. It also featured a clear, easy-to-read black and orange finish, a style that was adopted by all other ARP instruments around this time.

This little piece by Frederic Hervieu has some tasteful melody lines played on the Pro Soloist complementing the Fender Rhodes electric piano. It's not an extensive workout of the instrument's capabilities, but presents its sound nicely in a musical context. Unlike many of the demo videos out there, this one presents the Pro Soloist's sound without any added effects like echo or reverb.

Electromotive: The Soloist and Pro Soloist

This excerpt from the fascinating documentary Electromotive: The Story Of ARP Instruments by Alex Ball covers the Soloist and Pro Soloist in loving detail. You'll see interviews with the designers and hear demos of well-restored examples. Check it out!

ARP Pro/DGX (2019) by GForceThe Alan R. Pearlman Foundation

The Pro/DGX

With the Pro/DGX, ARP closed the book on a series of instruments that put a new spin what it meant to "play a synthesizer." While nowhere near as programmable as their siblings, the Soloists filled a vital need for keyboardists everywhere, and their legacy is still seen today.

ARP Story Brochure Odyssey (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Odyssey: Fame and Evolution

More compact than the 2600 and more powerful than the Soloist, the Odyssey hit the sweet spot for programmable solo sounds for many musicians. In its three versions over the years from its invention in 1973 to the end of ARP in 1981, it embodied a spirit of free and creative performance in a package that was portable, reliable, and above all, musical. We've devoted an entire story to the Odyssey, from its origins to its rebirth in 2015... but for now, let's look at some of the other synthesizers that came along with it.

ARP Story Brochure Explorer (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Explorer I: Smaller, Simpler, Still Sexy

In 1974, ARP released the Explorer I, intended in some sense as a "bridge" instrument between the programmability of the Odyssey and the preset-driven speed of the Pro Soloist. In a familar organ-top form (complete with sheet music stand), it combined offered both preset selection and an easily accessible set of simplified but reasonably comprehensive controls for the left hand.

ARP Story Brochure Explorer (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Explorer I did find its way into a fair number of rigs over the years, but it suffered somewhat from being neither fish nor fowl: it wasn't programmable enough for players who lusted after the Odyssey but couldn't afford one, and it lacked the touch sensitivity that made the Pro Soloist so expressive to play. That said, its sound was simply enormous, capable of producing room-shaking bass notes.

There aren't many good videos of the Explorer I being played on its own, but this tutorial by boogie-boutique on the rare Solina string machine spends some time on its built-in solo synthesizer voice, which is the same one used in the Explorer I.

ARP Story Brochure Axxe (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Axxe: ARP for Anyone

In the Axxe, ARP created a lower-priced lead synthesizer with a unique timbre of its own, based around a single oscillator rather than the Odyssey's two or the 2600's three. Portable and with a clear layout, the Axxe made a lot of fans over the years, and some players actually preferred its sound to that of the Odyssey.

ARP Story Brochure Axxe (1974) by ARP InstrumentsThe Alan R. Pearlman Foundation

This brochure walked potential buyers through the relatively simple audio path of the Axxe, which would become an inspiration for many other small synthesizers over the years – it was a useful and affordable layout, even after advancing technology allowed the construction of truly polyphonic synthesizers.

ARP Spec Sheet Axxe p1 (1979) by ARP InstrumentsThe Alan R. Pearlman Foundation

Later versions of the Axxe adopted the ARP black-and-orange livery, as well as three PPC controls for pitch bending and vibrato (see our Odyssey story to learn more) on the left side. Because the original Axxe had no panel space to retrofit a full set of PPC pads, ARP came up with a tiny single-pad retrofit that could bend up, bend down, or add vibrato, depending on the setting of a nearby switch.

This demo from the AnalogAudio1 YouTube channel runs through some of the many sounds the Axxe can create. It's sweetened a bit with external echo and reverb, a feature common to many of these demo videos.

ARP Little Brother (2019) by GForceThe Alan R. Pearlman Foundation

The Little Brother

The Little Brother was designed as an add-on to synthesizers like the Axxe and Odyssey, although it could be used by many other synthesizers. Feeding its audio into the host synthesizer, which would control its pitch, the Little Brother added another oscillator to the host's sound for a bigger, fatter sound... or even a totally different one, letting a duophonic keyboard like the Odyssey play two sounds in counterpoint.

This video was intended to demonstrate a restored Axxe and Little Brother being advertised for sale by Sippicancottage. We're focusing on the Little Brother, which is played by itself and then together with the Axxe.

ARP Sequencer (2019) by Robert GilliamThe Alan R. Pearlman Foundation

The ARP Sequencer

Another useful add-on for the ARP synths was the ARP Sequencer, a device that allowed the user to preset a loop of up to 16 notes that could then be stepped through in a cycle to produce repeating melodies. It offered a lot of connection flexibility, and was popular as an addition to many synthesizers beyond ARP's lineup.

ARP Ad Sequencer (1976) by ARP InstrumentsThe Alan R. Pearlman Foundation

This ad explained the Sequencer's value to keyboardists who might have heard of such a device. The graphics were striking (to say the least)!

ARP Spec Sheet Sequencer p1 (1979) by ARP InstrumentsThe Alan R. Pearlman Foundation

ARP Spec Sheet Sequencer p2 (1979) by ARP InstrumentsThe Alan R. Pearlman Foundation

Here's a straightforward demo of all the Sequencer's functions by Sam Ecoff, who's using it to control a 2600.

This video from GForce Software, creators of (among other things) the Oddity and Oddity2 software emulations of the Odyssey, shows the Sequencer driving the Odyssey in a short jam session.

ARP Avatar Brochure page 2 (1978) by ARP InstrumentsThe Alan R. Pearlman Foundation

Not every ARP design was a success. The firm did make a few mistakes in its long tenure, and one of them would make history.

In 1976, ARP committed itself to developing a guitar synthesizer: a synthesizer that any guitarist could play right from their guitar, with no keyboard needed. This idea held out the promise of bringing synthesis to an enormous new market – but ARP’s attempts to tackle the problem led it down an expensive R&D rabbit hole that would eventually do the company irreparable harm.

ARP Avatar Brochure page 1 (1978) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Avatar

The Avatar, released in 1977, was ARP's guitar synthesizer. It offered a single synth voice, controlled by a pitch-to-voltage converter that was triggered by a special pickup mounted to the bridge of any conventional guitar.

ARP Avatar Brochure page 3 (1978) by ARP InstrumentsThe Alan R. Pearlman Foundation

This very elaborate promotional brochure, complete with an offer of a demo record, attempted to convince a skeptical audience of guitarists that having a synthesizer between one's guitar and amp was a good idea.

ARP Avatar Brochure page 4 (1978) by ARP InstrumentsThe Alan R. Pearlman Foundation

The brochure explained in detail how the Avatar's hexaphonic pickup actually listened to each string separately, so as to provide the cleanest possible signal to the Avatar, which would track the pitch and onset of each note and play the synth accordingly. 

ARP Avatar Brochure page 2 (1978) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Avatar sounded great and is prized today – by musicians who control and play it from a keyboard, or a sequencer, or… really, pretty much anything other than a guitar. Its pitch recognition was almost unusable; it “glitched" constantly, requiring the guitarist to use an extremely precise picking technique in order to get it to play accurately. Guitarists also balked at its high price, and at only being able to play one note at a time (unlike the Centaur VI). ARP ended up having to sell its overstock at bargain prices – barely recouping an eighth of what the Centaur VI had cost the company.

Here's the 3-track demo record ARP provided for the Avatar. All keyboard parts on the first two songs were played entirely on the Avatar by Ned Liben (The "EBN" of MTV heartthrob band EBN-OZN), who also plays on the third track, an excerpt from the album No One Said It Would Be Easy by Riff Raff. This is one of the few recorded instances of a guitar actually playing an Avatar successfully, and as it was recorded in a professional studio, we'll never know how many takes or edits it took.

There was actually one thing the Avatar did very well: because its hexaphonic pickup could listen to each string of a guitar separately, it could put a separate fuzz circuit on each string, eliminating the sometimes-unpleasant sound of a fuzz trying to process two or more notes at once. This effect, called Hex Fuzz, resulted in a powerful yet clear singing distortion. It's the source of the fabulous guitar tone on Pete Townshend's hit "Rough Boys" from the album Empty Glass.

Centaur Prototype (1980) by Mark VailThe Alan R. Pearlman Foundation

The Centaur VI: An Experiment in Polyphony

The Centaur VI is the rarest and most mysterious of ARP's products. Specs and detailed descriptions have never been published, and these photographs are among the very few extant pictures of the two prototype units – which are currently inaccessible, in the hands of a private collector.

Centaur Prototype (1979) by ARP Instruments PromoThe Alan R. Pearlman Foundation

While one development unit did have a keyboard, the principal prototype (shown here behind ARP Product Specialist Bill Singer) was intended to be a fully polyphonic guitar synthesizer. This meant that there would be one synthesizer voice dedicated to each guitar string, which would be activated by a pitch-to-voltage converter that would sense the note being played and output a control signal to the synth.

ARP Custom Engineering Group Coordinator - John Koumatseas weith Centaur (1978) by John KoumatseasThe Alan R. Pearlman Foundation

ARP's approach to creating this polyphony was to take it head-on: the Centaur VI essentially had six complete synthesizers in one gigantic box, with an unheard-of 115 circuit boards. The prototype (shown here with ARP's Custom Engineering Group Coordinator John Koumoutseas) was so complex and got so hot that its circuits were constantly burning out – according to Alan R. Pearlman's MTBF (mean time between failures) calculations, a production model would last about two hours before something quit.

Centaur Prototype (1980) by mark VailThe Alan R. Pearlman Foundation

The Centaur VI project was eventually terminated, and ARP quickly returned to keyboard designs using their well-proven technology, and leveraged what they'd learned from the Centaur VI.

ARP Ad 16-voice Piano (1980) by ARP InstrumentsThe Alan R. Pearlman Foundation

The 16-Voice Electric Piano: Expressive Innovation

1979's 16-Voice Electric Piano was a very nicely-designed electronic instrument with a choice of 16 different timbres, built-in effects, stereo output, and for the first time on an all-electronic piano, a dynamically-sensitive keyboard and foot pedals that worked like a piano's. Flexible, reasonably portable, very playable, and with an excellent sound, it should have been a major success for ARP.

ARP Spec Sheet Piano p1 (1979) by ARP InstrumentsThe Alan R. Pearlman Foundation

The 16-Voice Electronic Piano's front panel was originally designed to use membrane switches. However, this design proved to be unreliable and was abandoned. ARP eventually moved to leaf switches and provided retrofit kits for Pianos in the field, and a later 4-Voice Piano came with a lower price tag and other design improvements.

ARP Spec Sheet Piano p2 (1979) by ARP InstrumentsThe Alan R. Pearlman Foundation

This 1979 musical segment features a jazz trio with drummer Cleve Pozar and two keyboardists (Michael Brigida on the left and John Shykun on the right) playing a large array of ARP synthesizers: we count one Axxe, one Pro/DGX, one 2600, and two each of the Odyssey, Quadra, and 16-Voice Electronic Piano. The host of this local TV show seems quite stunned by the idea of this "mechanical band," and the trio's performance must have been equally stunning to a 1979 audience.

ARP Solus (1980) by Stefan MacThe Alan R. Pearlman Foundation

The Solus

The Solus, from 1980, was ARP’s last shipping product. It was a quite affordable synthesizer, built into its own road case and featuring a surprisingly powerful voice architecture that some musicians favor over earlier ARP sounds, even today. Coming as it did at the end of ARP’s life, it wasn’t made in large numbers – ironically, that rarity has made it a relatively expensive find for today’s collectors.

Here's a little demo of some of the Solus' features from keyboard resource.

ARP Arpeggio Volume 9 No. 1 p7.jpg (1980) by ARP InstrumentsThe Alan R. Pearlman Foundation

The Chroma: What Might Have Been

ARP's last synthesizer was the Chroma. It was essentially finished by the time the company closed its doors in 1981. The Chroma was a computer-controlled analog synthesizer with a highly-expressive keyboard, a rich polyphonic sound, and a variety of modern digital interface capabilities that were well-suited to the coming era of digital synthesis.

Rhodes Chroma Front View (1981) by RhodesThe Alan R. Pearlman Foundation

When ARP's assets were sold, the Chroma (and a lot of its designers) ended up moving to Rhodes, maker of the famous electric pianos, where it was finished. The Chroma was recognized as a groundbreaking instrument, and turned out to be a reasonable success, especially with the later addition of MIDI; owners around the world still treasure theirs. But aside from the one prototype shown in a few grainy photos, no Chroma proudly displays the ARP logo – it was a door to a new era that ARP never got to open.

ARP Odyssey 2800 Series (2019) by Alex BallThe Alan R. Pearlman Foundation

(Not) The End

Even though its financial woes brought the company to an end just as overseas designs came to challenge all of the American and European makers' synths, the music world has never forgotten the glory days of ARP. Through the decades that followed, ARP's instruments were treasured, passed down from user to user, served as inspiration for hundreds of imitations, took a proud place in the annals of electronic music history... and then, in a wonderful turn of fate, triumphantly returned in 2015. ARP lives on, and with it the vision of Alan R. Pearlman.

Credits: Story

Story by Mike Metlay; editorial contributions by Dina Pearlman and Mary Lock; The Alan R. Pearlman Foundation

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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