Behold the ARP Omni II

June 30th, 2009


OK, I don’t need a new project this summer, but I’ve recklessly put another one on my plate. I found the ARP Omni II pictured above on Craigslist for a pretty good price due to a couple issues I’ll mention in a minute. So why bother buying an ARP Omni II you might ask? Good question! The Omni II was a popular “string synth” from the late ’70s to early ’80s and was used by bands as diverse as Joy Division and Supertramp. The whole string synth fad came about in the early ’70s as an alternative to the Melotron, which was an expensive and cumbersome tape-based proto-sampler keyboard. The idea behind the first string synth, the Eminent, was synthesize string sounds rather than play back tape recorded strings like the Melotron. The Eminent lead to the Solina which lead to the ARP Omni I/II, which I guess used the basic design of the Solina, but added a couple of additional features. Pretty much every synth manufacture offered some kind of string synth back in the day (probably thanks to disco) including Roland, Yamaha, and Korg. The key to any of these old string synths is the built in analog chorus/phase effects — without it, a string synth just sounds kind of bland.

The Omni II is a bit of an odd beast even by ARP standards. It is basically three analog synths in one box sharing a common keyboard. It’s neither monophonic (meaning it plays one note at a time) or polyphonic (meaning it plays chords) but paraphonic which means that it is capable of playing all the notes on the keyboard using something called divide down technology. Polyphonic synths were quite rare in the ’70s. On of the few was the the Prophet 5, but it was also quite expensive. These string synths used the same technology as transistor based organs used allowing for chords but cost far less than standard polyphonic synths.

So what does my Omni need in the way of repairs? Well for one, all the ‘E’ notes sustain when I play the string sounds, which means there is probably a blown capacitor on one of the circuit boards. This is a pretty common issue with a lot of ARP synths from the ’70s. I guess the Omni was the product that kept company executives in cocaine and champagne, but to maximize profits, I think they cut corners wherever they could — like using cheap capacitors prone to failure. I’m also gonna need to either clean or replace all the sliders. I think someone tried to clean them with WD40 or similar, so now they’re pretty much shot. Right now I’m leaning toward replacing, since pretty much all the parts used on the Omni are still being made. Below are some links for other Omni owners to use when sourcing parts.

ARP Sliders

Arp Omni II Switches

Arp Omni II Chorus Phaser Chip

Arp Omni II Synth and Bass Voice Chip

Arp Omni II Voicing Circuit Chip

Arp String Ensemble Bass Section OP Amp

Arp String Ensemble Knobs

ARP Omni II Problems

Parts List

Hear the Omni II in action on one of the best songs ever…

Love Will Tear Us Apart - Joy Division

Entry Filed under: Obsolete Technology, Electronic Music

8 Comments Add your own

  • 1. Brain  |  July 6th, 2009 at 7:12 pm

    Ned dude.

    ARP is pretty cool, despite the fact that I didn’t like the sound of the first one I heard. But soon I started accepting, and then even liking it. Walter Wanderley played some ARP now and again.

    Good score.

  • 2. Walkathon  |  July 12th, 2009 at 5:03 pm

    Congrats on your Omni-II score, but be warned that restoring that beast is a bit of a questionable rabbit hole (speaking from very specific experience here.)

  • 3. Matt  |  August 20th, 2009 at 2:28 pm

    Hey, I actually have one of these that I’m trying to sell. I’m in Erie, Pennsylvania. Mine powers up but it doesn’t throw any sound…maybe I’m doing it wrong, I don’t know anything about old synths. I’m asking to get as close to $100 as I can….anyway, these are cool looking synths…I love the black and orange…have a good one. - matt

  • 4. Kidd57  |  December 18th, 2011 at 12:35 am

    Interesting. I have an Omni Arp in the garage in its case. It worked perfectly fine when I packed it away. I wonder if everything still works. I think I will have to pull it out and see. Kinda sounds like fun now that I think about it. Interesting.

  • 5. Evan  |  December 25th, 2011 at 6:24 am

    Hi guys!

    I’m trying to fix my OMNI (MkI) which seems to be the typical can of worms exercise.. The synth seems to work fine (prob no power supply issues) but I get the stuck notes (ordered the 22uF caps - on the way in the post), but I also have mostly unreliable button switches, and sticky intermittent sliders, too.
    Can anyone tell me where I can get replacement switches (for the tone selector buttons) and replacement sliders (for all the slider controls) ???

    I have the impression (from previous ARP Axxe issues) that the sliders are very hard or impossible to find.

    If so, can anyone suggest an equivalent (or close to equivalent) slider that will work with my OMNI synth?

    I’m otherwise contemplating just ripping them out and drilling some holes in the centre of the slider opening and mounting a regular rotary pot, but this feels a little sacriligious!
    But if it’s gonna get the synth working reliably, I might go that route.

    Likewise, I could use some SPDT switches (or some kind of momentary switch?) to replace the button control toggle switches, but if I can go for a direct replacement of course I’d prefer to go for that option.

    Thanks in advance!

  • 6. admin  |  December 30th, 2011 at 12:43 pm

    Please check the links in the post for Omni parts. They’re out there — just sometimes expensive.

  • 7. Denny Lucas  |  May 8th, 2013 at 10:00 am

    Greetings. I have and Omni II in need of a set of knobs for all sliders. Found parts list but didn’t see knobs listed. Any suggestions? Am interested in selling.

  • 8. Richard Costiera  |  May 14th, 2013 at 4:50 pm

    I have an arp omni 2 for sale and I am the original owner. I have it in a calzone case. If you are interested in purchasing it please email me.

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