Review: Korg ARP Odyssey Module and ARP Odyssei for iOS

Two first-rate reproductions of a classic monosynth.
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Forty years ago, the ARP Odyssey and Minimoog Model D were the Les Paul and Stratocaster of monophonic synthesizers. The Minimoog may be better known today, but the Odyssey always had some hefty advantages. Although the original Model D had one more oscillator and seven more notes on the keyboard, the Odyssey featured oscillator sync, pulse-width modulation, ring modulation, sample & hold, a dedicated LFO, and more stable tuning. Those additional features made it more sonically versatile, with a range of timbres and gorgeous tone that was irresistible to many musicians back in the day.

I like to say I cut my teeth on the Odyssey, because it was the synth that occupied me most when I was just starting out. When Korg resurrected it a couple years ago, I was less than enthusiastic about the new model’s narrow keys. I wanted a module I could use with my existing MIDI keyboards, and now my wish has been granted.

The ARP Odyssey Module combines some of the best features of all three major revisions of the original—distinguishable by the colors of their front panels—in a tabletop model that is too wide to rackmount. It’s almost identical to the original, minus the keyboard. The module is entirely analog, with no digital capabilities other than MIDI over USB and DIN ports. You can choose from two models: a white one that looks like the first Odyssey and a black one that looks like the final revision.

But wait, there’s more! Apple iPad and iPhone owners can join in the fun, too, with ARP Odyssei, an iOS app that accurately emulates the updated classic. It has almost all the hardware’s features and adds an arpeggiator and seven types of effects. Best of all, it can store and recall patch programs. Because the module and the app have so much in common, most of this review pertains to both, and I’ll touch on differences when appropriate.

Hardy Hardware

I’ve always appreciated the clarity of the Odyssey’s layout. Instead of knobs, all continuously variable controls are well-labeled slide potentiometers that feel substantial and smooth. Twenty-three 2-position slide switches toggle between functions that determine modulation routing, select pink or white noise, and so on, with a 3-position slide switch for filter type and a 3-position lever that transposes tuning two octaves up and down.

The back panel has monophonic outputs on 1/4-inch and XLR jacks, a 1/4-inch input for processing external audio, a 1/4-inch headphone jack with its own level knob, a MIDI In jack, and a USB connection. Also in back are 3.5mm ins and outs for control voltage, gates, and triggers, which means the Odyssey can interface with your modular rig. Additional jacks connect an expression pedal for volume and a footswitch for portamento. Unlike the original, the power supply is a wall wart.

First-generation Odysseys have no dedicated vibrato control and a potentiometer knob for pitch bend. The module has a trio of stiff rubber pressure pads called the Proportional Pitch Control (PPC), first introduced in the second revision. They require substantial pressure to engage and don’t transmit MIDI. The left pad bends pitch down, the right pad bends pitch up, and the middle pad introduces vibrato. Their ranges are not adjustable, and controlling pitch accurately is virtually impossible beyond a few semitones, but the vibrato pad works well.

Block Diagram

The Odyssey Module has two voltage-controlled oscillators (VCOs) that generate sawtooth and variable-width pulse waves. The instrument is duophonic, so that pressing two keys plays the VCOs at different pitches—especially effective with oscillator sync and ring modulation. You can switch VCO 1 out of audio range to use as a modulation source for sample & hold. Modulate the frequency of either VCO with the LFO, ADSR, or sample & hold, and modulate pulse width with the LFO or ADSR. (Modulating a synced oscillator with an envelope is a classic sound Odyssey players made famous.) The LFO generates sine or square waves up to 20 Hz. You can route either envelope generator, ADSR or AR, to the filter or amplifier and trigger either envelope with the keyboard or LFO.

Over the course of the Odyssey’s original nine-year run (1972 to 1981), ARP changed the design of its voltage-controlled lowpass filter at least three times. The Odyssey Module lets you switch between filter responses reproducing the three revisions. The VCF can self-oscillate, and a switch engages overdrive. A separate, non-resonant highpass filter has a slider to manually change its frequency, but no modulation inputs.

The sample & hold (S/H) mixer combines signals from the oscillators and noise generator and routes the combined signal to the S/H circuit. Once every LFO cycle or whenever you press a key (depending on the setting), S/H takes a snapshot of an instantaneous voltage from that signal and holds it until the next cycle or key press. The Odyssey uses that voltage to modulate the VCF or either VCO. In the final stage, the Odyssey routes audio signals to a mixer that lets you balance the inputs, select oscillator waveforms, and choose noise or ring modulation.


ARP Odyssei graphically re-creates the Odyssey’s third revision—black with orange highlights—and comes with 99 factory presets. It runs on the iPhone 5s, iPad Air, iPad Mini 2, and newer models.

Fig. 1: The Korg ARP Odyssei for iOS models the sound and circuitry of a groundbreaking analog monosynth, adding program memory, an arpeggiator, effects, and polyphony.

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Although Odyssei duplicates the module’s sliders and switches, it repositions some of them to use space efficiently (see Fig. 1). This is especially true on the iPhone, which distributes all its controls across four pages. The Voice Assign switch lets you select monophonic, duophonic, or polyphonic mode. The app has a Drive Gain slider instead of the module’s VCA Gain slider and Drive switch, and an additional switch and slider route MIDI velocity to either the amplifier or filter.

You can toggle between a simple 37-note keyboard and a 26-note keyboard with a pitch-bend wheel, mod wheel, and octave-shift button (giving it a 9-octave range). You can also replace the keyboard with two assignable x-y control pads.

Tapping on the program name displays a list of all the included presets and any user programs you’ve saved. Tapping the Page Select button on the iPad replaces the front-panel controls with controls for a 16-step arpeggiator and six effects types—3-band EQ, distortion, reverb, phaser, stereo delay (with independent left and right delay times), and chorus/flanger/ensemble, each with a handful of user parameters. The arpeggiator and effects are on separate pages on the iPhone. The arpeggiator is fairly sophisticated, with modes that skip selected steps and the ability to repeat chords as well as note patterns.

Once installed, Odyssei gives you the option of two in-app purchases, Rev1 and Rev2, for $5 each. Rev1 resembles the white-faced model from 1972, and Rev2 resembles the black-faced model with gold trim from 1977. Although the app offers the same three lowpass filter types as the hardware module, Rev1 and Rev2 each come with 49 presets that focus on their characteristic filters. Otherwise, all three versions are identical, and the only reason to spring for the in-app purchases is if you want the additional programs, which are excellent.

Double Your Pleasure

With the Odyssey Module in my studio and Odyssei on my iPad, I wanted to know just how much they sound alike. I routed them both through an iConnectAudio2+ interface, called up a preset in Odyssei, and matched the preset’s slider and switch settings on the module’s sliders and switches. On one preset after another, the results were close, but with a few minor tweaks, they sounded practically identical. Something about the hardware oscillators sounded subtly more solid, and viewing the recorded waveforms in Logic Pro confirmed that they were slightly different no matter how carefully I adjusted parameters. Still, I was surprised that a $30 app could sound so convincingly like a $600 synth.

Patch memory gives Odyssei a tremendous advantage for all Odyssey owners. Although the Odyssey doesn’t store parameter settings, the app can store thousands of Odyssei programs. When you create a program on the module you’d like to recall in the future, simply duplicate all its settings in the app, give the program a name, and save it. When you recall it, just reverse the procedure and duplicate the app’s settings on the hardware. That approach is much more effective than simply transcribing parameter values, because you get to hear a very close approximation of the sound before you manually recall it on the module.

I had hoped to control the module with the app’s arpeggiator, but Odyssei doesn’t transmit MIDI. I also hoped I could process the module’s output through the app’s effects, but unlike the hardware, Odyssei doesn’t have an audio input. It appears in Audiobus only as an input and not as effects.

Best of Both Worlds

I’m excited about both reincarnations of an old favorite. With a choice of three filter types, the Odyssey Module expands on the vintage Odyssey’s functionality and timbral range. It really captures the classic ARP sound, and I love the immediacy of its controls. The Odyssei app comes stunningly close to capturing the same sound and functionality, and it features lots of terrific presets you can re-create if you have the module, too. My advice? Get the app, but get them both if you can.

Snap Judgment

Outstanding sound. Excellent timbral range. XLR output. CV I/O. Solid feel.
CON No patch memory. Too wide to rackmount. Monophonic. PPC pads are no better than they ever were.

Authentic sound and functionality. Polyphonic. Velocity sensitive. Sophisticated step sequencer. Good effects. Unlimited program memory.
CON No audio input or MIDI data output.

Bottom Line

Two first-rate reproductions of a classic monosynth.

Korg ARP Odyssey Module $599
Korg ARP Odyssei for iOS $30