ARP Odyssey Mk II (1975–1978)

Name: ARP Odyssey Mk II
Brand: ARP Odyssey

That snarling, buzzing, duophonic beast with the gold lettering and a filter that once made Moog lawyers twitch.

Overview

Plug in a Mk II ARP Odyssey, flip the power switch, and you’re greeted not with a polite hum, but a low, anticipatory growl from the power supply—like the synth knows it’s about to tear a hole in your mix. This isn’t the warm, round purr of a Minimoog; it’s sharper, more aggressive, the kind of synth that doesn’t ask permission to dominate a track. The black-and-gold front panel, all brushed aluminum and crisp silk-screening, looks like it was built for a studio in 1976 and hasn’t aged a day since. And while it shares DNA with the earlier white-faced Mk I, the Mk II is where ARP got serious about reliability, serviceability, and that mythical Moog-like filter tone—without actually being Moog.

Produced from 1975 to 1978, the Mk II (models 2810–2815) was ARP’s answer to both evolving market demands and their own internal refinements. It kept the same 37-note duophonic keyboard and dual-VCO architecture but quietly upgraded nearly everything under the hood. The oscillators got better tracking, the power supply was beefed up, and—critically—the keyboard circuitry was redesigned to support CV/Gate control as standard, no factory mod required. That last bit matters: if you’re trying to sync this thing to a drum machine or modular rig from the era, the Mk II is the first Odyssey that doesn’t make you jump through hoops.

But the real story is the filter. Early Mk IIs (like the 2810) still carried the original 2-pole 4023 filter—light, bright, a little thin by modern standards. But by mid-1976, ARP swapped it out for the 4035, a 4-pole ladder filter that bore an uncomfortable resemblance to Moog’s legendary design. Rumors swirled about lawsuits, but the truth is ARP paid a quiet licensing fee and moved on. The 4035 gave the Mk II a thicker, more resonant low end and a self-oscillating character that could go from a smooth sine wave to a screaming harmonic edge. It wasn’t just a copy—it was ARP’s version of a muscle car filter, built to cut through live mixes and analog tape hiss alike.

Later in the production run, ARP replaced the 4035 with their own 4075 filter, which became standard across the Mk II and III. While more stable, the 4075 had a known bandwidth limitation—it rolled off hard above 12–14 kHz, especially at high resonance. That meant the rare early Mk IIs with the 4035 filter are now the holy grail for collectors, commanding premium prices. If you find one, check the filter board carefully—some were retrofitted.

And then there’s the duophony. Call it “paraphonic” if you want, but the Odyssey’s keyboard scanning system—assigning one oscillator to the highest note, one to the lowest—was revolutionary in 1975. It meant you could play fifths, octaves, even simple chords with real analog weight, not just stacked monophony. It’s not polyphony, but it’s expressive, and in the hands of someone like Herbie Hancock or Jean-Michel Jarre, it became a compositional tool.

Specifications

Manufacturer	ARP Instruments, Inc.
Production Years	1975–1978
Original Price	$1,695
Polyphony	Duophonic (1 or 2 notes)
Oscillators	2 VCOs with sawtooth, square, pulse, PWM, oscillator sync, ring mod
Filter Type	4-pole VCF (4035 or 4075), 2-pole high-pass filter
Envelope Generators	ADSR and AR (switchable per function)
LFO	Sine, square, sample & hold
Noise Source	White and pink noise
Keyboard	37 keys, duophonic scanning
Pitch Control	Rotary knob (early), PPC buttons (late)
CV/Gate	CV In/Out, Gate In/Out, Trigger In/Out
Outputs	High (RCA), Low (1/4"), External Audio In
Inputs	Portamento footswitch, pedal (VCO2 pitch, filter cutoff)
MIDI	None
Weight	24 lbs (10.9 kg)
Dimensions	34.5" x 13" x 5.5" (87.6 x 33 x 14 cm)
Power	115V AC, 60 Hz (internal power supply)

Key Features

The 4035 Filter: Moog’s Shadow

The 4035 filter is why some people lose sleep over Mk II Odysseys. It’s a 24dB/octave ladder design that behaves almost identically to Moog’s 904A—warm, punchy, capable of self-oscillation that’s musical rather than brittle. When cranked, it delivers a growl that’s more animal than machine, perfect for basslines that need to fight through a mix. But ARP didn’t just copy; they adapted. The filter’s resonance is slightly more aggressive, and when driven hard, it adds a subtle grit that Moog’s smoother design lacks. The catch? These early 4035-equipped units are rare. Most Mk IIs rolled off the line with the later 4075 filter, which, while stable, lacks the high-frequency extension and harmonic richness of the 4035. If you’re hunting for a Mk II, serial number and filter board inspection are mandatory. A 2810 or early 2813 with the 4035 is a different instrument—worth the premium.

Duophony Done Right

The Odyssey wasn’t the first synth with duophony, but it was the first to make it practical. The keyboard scanning system assigns VCO1 to the highest note played and VCO2 to the lowest. No voice allocation menu, no firmware—just analog logic that responds in real time. It means you can play a fifth, bend the top note, and have the bottom stay locked. It’s expressive, immediate, and in the hands of a player who understands its quirks, it becomes a performance instrument. But it’s not foolproof: play three notes, and the synth picks the top and bottom, dropping the middle. That can be a feature—think of it as an analog arpeggiator with attitude—but it’s not polyphony. And if you’re used to modern synths, the lack of velocity or aftertouch will feel limiting. But that’s not the point. The Odyssey rewards touch, not data.

Proportional Pitch Control: Ahead of Its Time

Late Mk IIs began shipping with ARP’s Proportional Pitch Controller (PPC)—three pressure-sensitive buttons for pitch bend up, bend down, and vibrato. It was a bold move away from the rotary knob of the Mk I, and while some players miss the smooth sweep of the knob, the PPC offers more nuanced control. Press lightly for a subtle wobble, hard for a full-tone bend. It’s tactile, expressive, and once you get used to it, hard to go back from. That said, not all Mk IIs have it—early models kept the knob, and some were retrofitted. If you’re buying, know which version you’re getting. The PPC is a signature of the later Mk II and Mk III, and it’s one of the reasons the Korg reissue included switchable behavior.

Historical Context

The Mk II arrived at a turning point. The Minimoog had proven that compact, performance-ready synths could sell, and ARP needed to evolve. The original white-faced Odyssey (Mk I) was brilliant but finicky—hard to calibrate, prone to drift, and lacking standard CV/Gate. The Mk II fixed that. It wasn’t just a cosmetic refresh; it was a refinement of the entire platform. The black-and-gold scheme wasn’t just stylish—it matched the look of ARP’s other pro gear, like the 2600 and Omni, giving it credibility on stage and in the studio.

At the same time, ARP was under pressure. Japanese synths like the Roland SH-3 and Korg 700 were undercutting them on price. The Odyssey had to be more reliable, easier to service, and more gig-ready. The Mk II delivered. It became a staple in progressive rock, jazz fusion, and early electronic pop—heard on records by ABBA, Ultravox, and Herbie Hancock. It wasn’t just a Minimoog alternative; it was a different flavor of analog—brighter, edgier, more experimental. And while the later Mk III would get a sturdier chassis and XLR outputs, the Mk II was the sweet spot: refined enough to be reliable, raw enough to be inspiring.

Collectibility & Value

The Mk II splits the vintage synth world. Some swear by the 4035 filter and will pay $5,000+ for a clean 2810. Others see the 4075-equipped models as more stable and practical, trading high-end sizzle for reliability. Either way, condition is everything. These synths are 45+ years old, and the weak points are well known.

Tantalum capacitors are the biggest threat. They degrade over time, can leak, and when they fail, they take op-amps and power supplies with them. Any Mk II that hasn’t been recapped—especially the power supply and filter board—is a ticking time bomb. Replacing them with modern electrolytics is standard practice and expected at this age.

The original sliders are another issue. They wear out, get scratchy, and can introduce noise. Some owners retrofit LED sliders for smoother operation and visual feedback—Synthchaser’s upgrade is popular, but purists prefer original faders. Keys are generally robust, but bushings dry out, and contact cleaning is often needed after decades of use.

Serviced, stable Mk IIs with the 4075 filter sell for $2,800–$3,800 depending on cosmetics. A verified 4035-equipped unit in good condition can fetch $4,500–$6,000. Fully restored examples with LED sliders, recalibrated oscillators, and upgraded power supplies command even more.

When buying, ask: Has it been recapped? Are the oscillators stable? Does the filter self-oscillate cleanly? Is the keyboard responsive? And—critically—what filter does it have? Don’t trust the model number alone; open it up or get a service report. This isn’t a synth you buy blind.