Review: Korg ARP 2600M
A faithful and compact reissue of the ’70s classic can now be the jewel in crown of contemporary synth studios.
Manufactured from 1971 through 1981, the legacy established by Alan R. Pearlmann’s ARP 2600 rubs shoulders with the most revered of the vintage synth kingdom. When a true Synth-GAS (gear acquisition syndrome) fiend boasts of the finest instruments in their collection, if they’re fortunate enough to have one, it will be among the first to leave their lips in the heat of their synth-flex. Furthermore, they would have paid a significant sum for it and endured a money pit of servicing to keep it running. When you consider this is a 50-year-old synth, it’s astonishing that not only the OG versions are still relevant, it’s incredible that they’re still functional!
While its forefather, the gigantic ARP 2500, might have dwarfed the ARP 2600 in stature and function, it was a distillation of its most functionally valuable modules at a substantially lower expense and complexity. Famous for its cameo on ‘Close Encounters of the Third Kind’ (as the means to communicate with the alien visitors), the triple-panel version of the ARP 2500 was a state-of-the-art instrument. However, it required a thorough knowledge of signal flow to get a sound out of it. The ARP 2600 democratised the most potent aspects of the ARP 2500 with a significantly smaller footprint, lower cost and much easier to use!
Elemental to the ARP 2600’s success was its semi-normalised architecture — without any patch cables connected, even musicians inexperienced with synthesis could pull a rich palette of tones out of it. Conversely, those curious to explore sound design further could get busy overriding the normalled signal flow via patch cables. With even just a few patch cables, you could radically alter its behaviour and pallet.
The ARP 2600 featured three VCOs, each with a trio of normalled inputs for frequency modulation — possibly its most defining aspect. In addition, a five-part mixer feeds combined the (normalled) outputs of the VCOs, Ring Modulator and Noise source into its low-pass ladder filter.
Inspired initially by Moog’s design, its 24dB/octave filter design (the 4012) was a point of controversy, and ARP came under the scrutiny of Bob Moog himself. While initial exchanges were terse, healthy mutual admiration between Bob and Alan evolved. In later revisions (post-1974), ARP substituted the original filter with their 4072 design. Opinions vary on this decision since many consider the character of the original ladder filter to be sonically superior, having a thicker tone and more sweet spots. Others prefer the latter design, offering more outlandish, growly tones, particularly when overdriven, despite being notorious for having a higher noise floor.
While lacking a dedicated LFO in the primary chassis, its VCOs de-couple from keyboard CV independently to serve as LFOs with upper-frequency limits reaching well into the audible spectrum. A pair of envelopes (ADSR and AR) provided additional contour-based modulation in addition to a comprehensive voltage processor section (providing summing, inverts and a lag/slew processor), a sample-and-hold circuit, and a unique, electronic switch providing a modulatable toggle between two signal paths. Patching the output of the sample-and-hold circuit into it (sampling the noise source by default) achieved random switching of whatever you feed it, be it audio or control voltages.
Designed from the outset to process external sounds such as speech, vocals, guitars and drums, the ARP 2600 had a patchable preamp (with settings for 10, 100 and even 1000 times amplification) and a super-tight envelope follower which invited musicians outside electronica to experiment with its possibilities. In addition, its primitive electromechanical spring reverb circuit provided additional fairy dust with a mystical essence synonymous with its folklore, although having no adjustment beyond the effect level.
NEED TO KNOW
Korg ARP 2600M
Semi-modular Analogue Synthesizer
While it sold for a tidy sum, on par with a deposit on a home back in the early ’70s (retailing for US$2600, equivalent to around US$16500 in 2022), it was a feature-packed instrument aimed at professionals, attracting the most distinguished names in the industry. You’ll hear it all over works by Stevie Wonder, Jean Michael Jarre, Pete Townsend, Keith Emmerson, Mike Oldfield, Joy Division, Depeche Mode, Weather Report, Vince Clarke and Rick Wakeman. Most famously, thanks to its preamp circuit enabling the connection of microphones, in tandem with its ring modulation circuit, it gave birth to the voice of R2D2 thanks to the talents of sound-designer Ben Burt.
While analogue mono and polysynths dominated hits of the early 80s, beginning with the release of the Yamaha DX7 in 1983, musicians developed a thirst for the fresh palette of sounds (and convenience) delivered by digital synthesis methods. It wasn’t until in the late ’80s, with the emergence of Acid House and the rave movement that followed the Summer Of Love, that pioneering electronic dance musicians, reliant on instruments with knob-per-function tweakability to inject movement and progression into their works, rediscovered the magic of the ARP 2600 and similarly knob/fader laden synths. Iconic acts of the era, including 808 State, Orbital, Underworld, and Hardfloor, exploited its organic magic.
The main sing-song-like resonant lead line driving Underworld’s seminal rave anthem, ‘Rez’ (1993), had its genesis on an ARP 2600. Orbital’s exceptional albums, ‘Snivelisation’ (1994) and ‘Insides’ (1996), showcased it heavily. It was the secret weapon of the greats! Thus, the ARP 2600 holds an enviable place in the hearts of genuine synth boffins everywhere, spanning genres and generations. This translated to a lucrative market for those lucky enough to own one. Who would be crazy enough to part with an original ARP 2600 unless facing extreme hardship?
But there again, why would you want an original? It will be a maintenance money pit and suffer from all manner of background noise and other sonic inconsistencies as the components around five decades in age demonstrate their end of life performance. If you were to hand over a princely sum for a synth, wouldn’t you prefer the joy of having a minty-fresh specimen?
KORG’S ARP ODYSSEY
After connecting with ARP co-founder David Friend, Korg’s relationship with ARP began in the mid-2010s (sadly, Alan Pearlman is no longer with us). Their first venture was the reissue of the ARP Odyssey with a mini-keybed which was yet another widely acclaimed hit for Korg. The desktop module version came next, followed by the Odyssey FS (Full Scale). Then, at NAMM 2020, Korg stole the limelight, winning ‘Best In Show’ by announcing the limited-edition reissue of the ARP 2600, the ARP 2600FS. It was a grandiose, monstrous synth, shipping in a tour-ready wooden roadcase on castors, including a remake of the original 3620 analogue keyboard with full-size keys. Despite commanding a princely sum of A$5499 (in retrospect, a bargain), worldwide, professional synth players immediately flocked to it, and the entire production run sold out rapidly to preorders. At the time, it was rumoured a mini form-factor version at a lower price would be released.
Finally, at Winter NAMM 2021, mid-pandemic, Korg announced the ARP 2600M. Saddled with component shortages and supply chain issues thwarting manufacturers’ attempts everywhere to promptly bring products to market, it’s only now that a Korg 2600M can be yours!
The ARP 2600M has the same circuitry as the mighty ARP 2600FS, but with a shorter-length spring reverb due to its smaller cabinet, no MIDI Out/Thru, ¼-inch jacks instead of XLR, and a three-way mult instead of a four-way mult. Also, it doesn’t include the remake of the 3620 duo-phonic keyboard (thus, you miss out on the arpeggiator and the additional LFO) that also offers aftertouch as a modulation source. Instead, it has Korg’s microKEY-2 37-key controller keyboard.
POINT OF REFERENCE
Like most musicians, I’ve not had the pleasure of experiencing the OG. Still, I’ve sufficiently acquainted myself with the 2600’s approach to sound design thanks to Arturia’s release of the ARP 2600V after spending countless hours exploring its potential back in 2005.
Arturia’s incarnation incorporated ARP’s 1601 step sequencer module, which I found invaluable for extending its sound design potential. While the 1601 is not a part of the ARP 2600M package, Korg’s hardware range includes the SQ64 and SQ1 analogue step sequencers, but neither matches the hands-on malleability of the slider-based 1601. Let’s hope Korg has plans in the works! Thankfully, the 2600M is voltage-compatible with the ever-expanding galaxy of Eurorack sequencer modules, so for this review, I patched it up to my Westlicht Per|Former, which is more sophisticated than the 1601, albeit an entirely menu-driven affair. In addition, I’ve relished Korg’s previous ARP reissue, the Odyssey, so I’m well acquainted with the essence of Korg’s reissues and how they endure over a lengthy period.
KEEPING IT REAL
Korg has taken every measure to deliver a reissue as authentic as possible, albeit at 60% of the original’s footprint, a welcome touch for the space-challenged among us (or those with a severe GAS problem and space to spare). The size reduction also means that much shorter patch cables are needed to span the extremes of its front panel compared with the original or Korg’s Full-Scale version.
Its front panel and legending is virtually identical to ARP’s design. The Limited Edition version of the 2600M ships in a semi-hard ‘carry-on luggage’ case with extendable handle. Custom-cut foam sections securely accommodate the unit inside the case; however, it doesn’t offer the baggage-handler proof assurance a Pelican case provides.
Korg has avoided embellishing the front panel with its logo, reserving it instead for the rear panel. The primary manual covers little of the functionality of the synthesiser beyond ancillary conveniences, leaving the deep documentation to scanned pages from the crusty pages of an original ARP 2600 manual.
When it comes to connectivity, Korg’s obsession with authenticity ends. On the left side panel, you’ll find a USB-B socket, a MIDI In, stereo output on ¼-inch sockets, and a block of DIP switches for setting the MIDI receive channel and defeating the auto power-off function.
Its MIDI implementation, while convenient to have integrated with the modern remake, is rudimentary, which shouldn’t come as a surprise. Note, Pitch Bend and Modulation data are supported, but sadly, MIDI Clock events do not drive the Sample & Hold module’s clock (although clockable externally by its Ext Clock patch point). However, having the mod wheel output freely patchable will keep you satisfied, providing at least one convenient MIDI-based modulation pathway from your DAW.
Most unusually, it has a USB-A host socket intended for attaching USB controller keyboards. Perhaps this decision is driven by not including a reissue of ARP’s 3620 analogue controller keyboard? Some purists may scoff at this design choice since the 3620 allowed duophonic performance (thanks to its Upper note patch point), and it provided an additional LFO. Instead, Korg has simulated the 3620’s duophony within the 2600M itself. The extra dedicated LFO is absent, but for those times you couldn’t possibly do with no less than the three VCOs to create the tone you want, you could always patch in more from your other modular gear.
The 2600M has authentic recreations of both filter types: 4012 and 4072 … you can enjoy the merits of either with the flick of the switch
Thanks to the unique combination of utility modules included within the Voltage Processor section, with some creative patching and an intimate understanding of its signal flow, you can dispel many perceived shortcomings of the synth. For example, by patching one of the Inverters in the Voltage processor section, post VCF, mixed with the direct output, you can create the high pass filter it lacks. Want more than just the two envelopes? Create a third using the envelope follower in tandem with the Lag function of the Voltage Processor. The simple functions within the Voltage Processor are the key to unlocking the potential of the ARP 2600. From there, once you discover the joys of multing signals and the subsequent chaos arising from voltage contamination, you’ll reach a pallet of organic, experimental sounds and myriad happy accidents.
Korg has conformed to trigger and CV voltages following Eurorack standards. As a result, the ARP 2600M will perfectly augment an existing Eurorack setup while also providing the ‘n00b’ to modular synths as the gateway to begin their inevitable financial descent into Euro-GAS. In reality, those who embraced ‘Eurorack Lyfe’ long ago will be those who’ll get the most out of this synth but perhaps in a more compartmental headspace. However, if you’re one of those late to the modular party, even if you swore you didn’t need that rabbit hole in your life (and bank balance), you might find your will buckling!
Like any semi-modular synth, getting your head around the normalled signal flow is akin to nutting out a puzzle. However, once you’ve established your mind-map to the point of fluency, you’ll recognise ARP’s choices are logical and well-considered. A seasoned modular synth freak might welcome the enforced inventiveness and challenge the ‘fixed rack’ the 2600’s modules provide. It’s your choice — either embrace working within its creative limitations and use it solo or give in and extend! Or, better still, team it with a DAW fitted with a DC-coupled audio interface and one of the many virtual modular options.
Just a note on the keyboard: the Limited Edition version of the 2600M packs a budget-priced microKEY2-37 controller. It’s a handy travel companion but, like me, you’ll want to plug in your favourite USB Class Compliant controller keyboard.
ENOUGH OF THE TALK
Before you start patching, open the filter cutoff, drop the resonance and play — it’s immediately apparent that the VCOs have the sonic girth and raucous presence you’d expect from a legendary vintage analogue synth. With multiple patchable wave-shape outputs for each VCO and having five inputs into the VCF, creating big unruly stabs is child’s play. Mostly, it sounds larger than life!
With some inventive patching, the sheer variety of sounds you can coax from this 50-year-old design will amaze you. Evoke bottomless bases with subsonic frequencies that persevere in a busy mix through to soaring lead sounds with that unmistakable squally ear candy you’ve heard on countless hits, with ease. Explore outlandish, far-out experimental studies afforded by its bounty of audio rate modulation sources (and inputs) and opportunities for feedback.
ARP’s design choice to omit a master tuning knob and specific lock-off pitch points for each VCO encourages a more free-spirited approach to pitch. Importantly, when using its VCOs as LFOs, you get a better LFO experience. Tuning each VCO to each other by listening for beat frequencies is as fluid and precise as a guitarist tuning their strings, and, once set, the VCOs hold their tuning surprisingly well.
With so many opportunities to get creative with frequency modulation and feedback, you’ll quickly find yourself frequently exploring options for audio-rate cross-modulation, since it’s so convenient to do so. If you’re yet to probe the textures possible with many possibilities for audio-rate frequency modulation, this synth will bring out your inner FM beast! It’s a veritable playground for exploring complex harmonic spectra.
IT’S ALL ABOUT FILTRATION
The 2600M has authentic recreations of both filter types: 4012 and 4072. Unlike owners of the actual ARP 2600, you can enjoy the merits of either with the flick of the switch. Both provide a gratifying smear at nominal gain and low resonance settings, yet are subtly different. Once you take the signal path for a detour through the Preamp module and edge up the filter resonance a touch, the differences become apparent.
The 4012 circuit has a thick, dark tone with a peakier resonance. Its response is precise and clean. As you’d expect from this design, adding too much resonance dampens low frequencies (although you can get around that with patching, of course). The 4072 circuit sounds thinner with minimal gain, but with the preamp in-line and set to edge into self-resonance, even at moderate gain settings, you’ll unleash the beast within the 4072 as it grumbles and snarls. Back off the resonance and gently tweak the cutoff, and you’ll find a wonderful tapestry of smooth, fruity harmonics that are sure to please.
The bottom row of the 2600M, particularly the Voltage Processor section, is where you’ll find an invaluable box of tricks to modify signals — not only CV signals for modulation but also audio signals. A seasoned modular synth fiend will realise its potential to extend the functionality of the synth, while the newcomer might take time to understand its value. Essentially, it provides attenuators, summing, signal inversion, and lag functions to shape CV or audio signals or scale voltages.
To the left, you’ll find a noise generator that produces a spectrum of noise types from White to Pink to Low Frequency, but like the original, there is no CV input to modulate it. Instead, its output is normalled to the input of the Sample-and-Hold circuit and the VCF mixer.
It’s refreshing and immediate to work with a semi-modular synth with all parameters set by sliders — it’s much quicker to glance at the front panel and interpret the settings. Korg’s choice of sliders has achieved a good balance of resistance versus precision and fluidity. Like their ARP Odyssey reissues, they permit confident micro-adjustments of parameters with the right touch.
Although it has a MIDI In port, I was surprised the ARP 2600M ignores MIDI Clock — missing the chance to clock the Sample-and-Hold section. Of course, after integrating the 2600M into a Eurorack rig, you could fire pulses at the Sample And Hold section’s Ext Clock patch input as a workaround.
While it’s admirable that Korg has accommodated the connection of a dedicated controller keyboard using a USB-A host socket, there’s no means for the attached controller keyboard’s notes to send notes to your DAW via the USB-B socket. It seems there’s no reason this couldn’t be possible since when connected via the USB-B socket, the MIDI Input and MIDI Output ports appear within your DAW. So, if you want to play notes into your DAW, the included microKEY controller keyboard would need to be connected to your DAW instead, with the DAW acting as the MIDI traffic controller. I just settled on using my regular master MIDI controller, using the 2600M as a module, letting my DAW route the traffic.
If you like to power your setup on/off with a master mains switch, you may find it annoying that the unit doesn’t power on without pressing the momentary envelope trigger button. This button is also dual-purposed for selecting the Duophony voicing modes (normal or original) and the ADSR trigger behaviour. You access these settings immediately after power-up by tapping it a specific number of times. Thankfully, these settings persist between power cycles — it’s a bit fiddly and ambiguously documented process to make these settings.
CONFESSIONS OF A SYNTH FESTISHIST?
I must confess that I’m not a die-hard vintage synth fetishist, although, if I showed you my collection, you might think otherwise. Since I’ve been into synths for most of my adult life, I became one by default. As time progressed, many have achieved vintage status. I didn’t actively seek these out because they were vintage nor speculate they would be 20 years later. To my mind, sound and functionality hold sway over mystique and flex-value. However, upon waking each morning and wandering through the studio to grab my first coffee for the day, the ARP 2600M would catch my eye every time. Finally, after 35+ years of my synth-life, I had a minty-fresh ARP 2600 sitting on my bench in prime position (without the maintenance costs).
Perhaps, the central questions are: do I need an ARP 2600 or not? And, which suits me best?
Suppose you’re a Eurorack-tragic with an extensive system already, and you’re beyond the fetishism of collecting legendary vintage synths. In that case, you might find it hard to justify spending extra for the Korg ARP 2600M. Alternatively, if you want a complete voice in a self-contained chassis providing the authentic ARP 2600 sound that presents as an instrument, then Korg’s ARP 2600M is a great choice. If you need your 2600 to be rackmountable then you’ll look elsewhere.
If you desire a faithful reissue that presents as authentically as possible and if you missed out on Korg’s limited reissue of the Full-Scale version, then the 2600M should be top of your wishlist. Not only does it sound phenomenal, but it also looks fantastic, has a higher potential resale value, and is built to stand the test of time. Furthermore, thanks to the premium-quality components employed in Korg’s reissue — with its distillation of the Full-Scale model that sold for over twice the price — it’s evident where your money goes. In other words, can you justify the added cost of the Korg reissue? Yes, you absolutely can. For others, the answer will be just as vehemently in the negative. And, I’d suggest, both are correct. As for me, well, I still can’t keep my eyes off the Korg 2600M.