Veteran Eurorackers Tiptop Audio take on the age‑old problem of polyphonic modular synthesis...

To the layperson, any modular system looks futuristic. I don’t think I’ve ever shown even a modest system to one without one or all of the terms ‘spaceship’, ‘cockpit’, ‘telephone exchange’ or ‘complicated’ cropping up in the conversation somewhere. Often it’s followed by a question along the lines of ‘How do you know what all those cables are doing?’.

It’s not often, though, that I myself am faced with a system that strikes me as futuristic; even less so that, at least in the first instance, no, I’m not entirely sure what all those cables are doing. But such was my reaction upon sitting down with Tiptop Audio’s ART range of Eurorack modules for the first time. The ART series is the company’s most stridently bold product range yet, and that’s saying something: it’s no mean feat to confidently reissue a line of celebrated Buchla 200 series modules for Eurorack, nor is it to step out with a novel, now ubiquitous type of stackable patch cable. Many a newcomer — including me, many moons ago — will have Tiptop Audio to thank for their first rack and power supply in the Happy Ending Kit, a uniquely affordable bare‑bones power supply and rack set.

So, what exactly is ART? Well, in short it’s a signal. In fact, it’s two types of signal. No, wait, it’s just one. OK, I’ll come to that. The name is an adaptation of UART (likely a familiar acronym to those versed in electronics), which stands for Universal Asynchronous Receiver‑Transmitter — but that’s by far the least interesting way of introducing the standard. Tiptop Audio’s spiel, if poetic, hardly helps to clarify things: “ART is a new set of ideas, a paradigm,” they say. “At the heart of it is the new ART control signal. Building upon the potential of the new ART signal, a new generation of modules that had never existed before are now coming to life and give breath to possibilities we could only dream of prior to that.”

In short, that means polyphony. Tiptop Audio have come up with a very nifty design — or two — to make it possible to send polyphonic signals around a modular system. It is mightily impressive, but there’s even more to it than that. Tuning and temperature regulation for ART oscillators is a cinch — standardised, even — while signal flow is reconfigured and streamlined in choice areas. Tiptop insist they have put a lot of thought into keeping power consumption as efficient as possible and I can believe it.

So, I have in front of me a selection of ART modules. I will say right off the bat that the system looks simply beautiful with Tiptop’s signature white and gold graphics on black faceplates with white‑ringed jacks — only this time there are sliders, screens and little gold octopodes that remind me of the Spectre symbol in James Bond. The aesthetic is impeccable, with build quality to match. I’ll also take a moment to commend Tiptop on their Mantis case, which I had not used up to now and which is so very flexible, sturdy and ergonomic.

The first thing to notice are the innocent‑looking jacks labelled ART In and ART Out dotted around the system; innocent‑looking, perhaps, because their socket colours might been coloured a little more distinctively than light grey on the CV jacks’ white, but I digress. Here’s the nub: Just one digital ART signal, patched with a good old‑fashioned TS cable from an ART Out to ART In jack, sends polyphony and note event messages, along with a rock‑solid tuning standard and velocity information. Feel free to read that again.

The second thing to notice is the presence of what look like USB‑C sockets. In fact, materially this is exactly what they are; though here the connector is completely reappropriated, with the developer taking great pains to warn us not to confuse the two. These are for the other novel signal format at work in Tiptop’s system, though not its titular one: the fun‑to‑say ‘Polytip’. Polytip cables are analogue multi‑channel audio cables, capable of bussing an eight‑voice polyphonic signal wholesale from module to module (I’m informed it doesn’t stop at eight, but all signs and tentacles point to eight being the standard here). See where we’re going with this?

Getting Patching

It all begins with one of two key modules: the Octopus MIDI‑ART interface, or the ART V/Oct Quantizer. The former has a USB MIDI input (a USB‑B port, mind you, so as not to get confused with the aforementioned sockets) as well as a five‑pin DIN MIDI input, and eight separate ART Out jacks. Alongside are eight CV outs for velocity and eight drum trigger outs. Plug a DIN MIDI controller or computer into the Octopus and it’ll convert its messages into ART signals; each ART output can send monophonic or polyphonic signals, depending on the destination, and it can also voice‑manage polyphony across its different outputs. It can also run a clock from your DAW. Tiptop promise that the Octopus is only the first of many ART controllers in the pipeline, and I’ll be very interested to see what else they come out with. After all, this is the very point of entry into the ART world.

The ART V/Oct Quantizer, instead of interfacing the ART protocol with MIDI, interfaces with CV. Patch a CV sequencer or keyboard from elsewhere in your system into one of the four available channels of 1V/oct and gate inputs to meld them into an ART signal. It can also quantise that CV to one of a litany of scales in accordance with the ART tuning standard.

Luxuriously, I have a choice of four different oscillators for this demonstration: first there’s the 8HP monophonic ATX1, another gateway of sorts into the ART protocol for reasons I’ll come to. There’s the Vortex, a monophonic wavetable oscillator also in 8HP, boasting two vintage D‑A converters and capacity to accept an SD card for extra wavetable storage. It follows that the larger Vortex 6 — the developer’s first polyphonic oscillator design — is a six‑voice polyphonic wavetable oscillator, with a design inspired by the PPG Wave 2.2 hybrid synth from 1985. Finally there’s an as‑yet‑unannounced module whose name I won’t divulge at this stage, but I will say it’s a magnificent eight‑voice powerhouse that will surely assume flagship status for the range, providing all the sonic power and modulation possibilities I could hope for in a polyphonic analogue Eurorack module. Tantalising stuff.

I’d be lying if I said all of these didn’t perform brilliantly. Also, if it wasn’t already clear from the Octopus’ ability to map note events sequentially over its eight ART outputs, it’s possible to stack any or all of these into a discrete polyphonic instrument, harking back elegantly to the likes of Oberheim’s SEMs, literal building blocks in those earliest days of polyphonic synthesis. At the time of writing, Tiptop Audio offer two Analog Bundles: one with the Octopus and one with the ART V/Oct Quantizer. Both come with three identical ATX1 oscillators, ready to be stacked.

Still with me? It’s a lot to take in, I know. Whether covering the basics with ease or producing rich and resonant complex waveforms, or all‑out angle‑grinder‑style aggression, Tiptop Audio have done astonishingly well straight out of the gate with these most crucial components of an ART system. Remember, though: these are only the first fruits of what Tiptop Audio hope will be a long‑standing and bounteous area of innovation. So I’m reticent to judge the overall validity and staying power of the ART concept on the individual effectiveness of these modules, however impressive they are.

ART For Art’s Sake

As mentioned, the ATX1 provides a good gateway into all things ART since it’s the only module to offer a switch between ART and Volt‑per‑octave CV control (or it can be an LFO, usefully). The ATX1 — though small and monophonic — encapsulates some key ART‑isms. First there’s a gate output alongside the audio output. ‘That’s odd,’ I hear you say. And you’d be right. Ordinarily we’d expect a gate to be sent from the controller in parallel to the oscillator signal itself. But since ART sends note‑on and note‑off messages a little like MIDI, it does make sense to have a gate output on the oscillator itself that can simply be patched onward to trigger, say, an envelope. Neatly, this also helps to keep the cabling from your controller to a minimum.

Another ART‑ism on the ATX1 is a button labelled Hold To Tune. That’s right: with ART, tuning is standardised, automated and — after warming up — impeccably stable. This stability extends even to migrating the module to other systems with different ambient temperatures, where it’ll be able to adapt accordingly. On the ATX1, switching Volt‑per‑octave mode to ART mode turns the topmost Frequency knob into an octave switcher. Because, well, you now don’t need to tune it. I know! Fine tuning is still offered by the knob below, with subtle detuning on one side of its travel distance and semitone increments on the other. And yes, the oscillator itself is analogue. At first I found this all very disconcerting, since it does feel a bit out of my control unlike other ‘regular’ oscillators. Then I realised it’s just very clever indeed. The Vortex 6 has no tuning knobs at all. You just patch it in and, well, there it is. In tune. I couldn’t but crack a smile.

So now to the polyphony, and the Polytip cables. They’re robust, fairly stiff things — about as robust and stiff as I’d hope an eight‑channel cable to be. Tiptop Audio founder Gur Milstein, speaking to SOS Editor In Chief Sam Inglis at this year’s Superbooth event in Berlin, explained that the Polytip’s design was essentially in the name of future‑proofing, with Tiptop Audio wisely taking the European Commission’s standardisation of the connector as its cue.

Milstein and company have done well to keep it self‑explanatory with the Polytips: It’s essentially business as usual, just pluralised. Patch the ART Out from the Octopus or the Quantizer into the ART In on a polyphonic oscillator. Patch the oscillator’s Audio Outs Polytip output into the eight‑channel Octogain VCA; then the oscillator’s Gate Outs into the Trigger ins of the ADSR Octostages Poly Envelope. Patch the envelope CV Outs into the VCA CV Ins. Presto! Polyphony! And if you want to break this out into discrete mono signals, Tiptop’s Octo I/O utility module offers an eight‑jack breakout alongside a three‑way Polytip mult, so you can retain the PolyTip path alongside if desired.

Too good to be true? Potentially. A few aspects of the Polytip format do complicate things a little bit. Having two different types of cable to think about occasionally feels somehow... awkward, even a little limiting. Perhaps it’s because there has always been a wonderful freedom in Eurorack about being able to patch anything to anything, with only one type of cable in the picture (aside from MIDI). With the Polytip, now it’s more like your system is divided into modules that do one thing and modules that do another — perhaps with the exception of modulation. At times, with those latter modules, I found myself wishing there was a mono input as well as a polyphonic input, just to have the option when not working with polyphony. Which is often. Modules like the OBX‑inspired Octostages Poly Envelope or the (once again) PPG Wave‑inspired Octopass Poly Filter do their jobs flawlessly, but it’s not an option to use them with discrete mono signals unless you’re willing to pay the extra for an Octo I/O on either side. On that note, while many of these modules’ list prices haven’t been confirmed at the time of writing, the indication is that they will hover at the premium end.

Hitting The Mono‑Poly

It all leads me to wonder if the two signal types, monophony and polyphony, were ever begging to be integrated in the first place. Polyphony, while a wonderful thing, should not simply be seen as an upgrade on monophony, marketable as that idea may be. I was disappointed, for example, to see that Arturia’s software emulation of the Moog Model D endowed it with full polyphony: for me that takes away a core part of its identity and significantly detracts focus from sound sculpting — presumably in the interest of placating keyboard players. I even wonder if, rather than assimilating polyphony into a conventional modular setup, Tiptop Audio might actually find themselves paving the way for a wholly separate, fully polyphonic modular ecosystem. Not better: different. That, to my mind, would make a lot of sense, and the Octo I/O would still be rendered a highly useful module for when one does want to link the two formats together.

This is really a separate discussion to that of the innovative ART signal itself, which is not just for polyphony and could therefore exist just fine within any system, Polytip or no. Sure, it can handle polyphony with aplomb, but all its aforementioned benefits have the potential to go a very long way while requiring very little user‑adaptation. If there’s one thing I like more than innovation, it’s innovation that works with what I’ve already got. By this rubric, you might call the Polytip an optional extra for those wanting to dive deeper into polyphonic modular, and if that strikes a chord (geddit?) then all power to you. Gur Milstein has openly said that the Polytip came about in response to the need to manage multiple channels of audio simultaneously, and on that count it’s difficult to find fault with what he and his team have come up with.

The fact that the digital ART signal flows down a conventional TS patch cable is very impressive. Of course, let’s remember MIDI can comfortably flow down a TRS cable, so needless to say the path of polyphony down eighth‑inch jacks is well‑worn. One conspicuous area in which the ART signal outdoes MIDI capability, though, is speed. Anyone with experience in sync’ing a modular system to a DAW will know that every so often a little MIDI‑induced latency is to be expected and mitigated. But the ART signal can keep up with CV — in fact it’s 40 times faster. Which is, to understate it heavily, useful. There are also no channels to worry about. In this regard it’s actually simpler than MIDI, and in practice feels similar, if not exactly the same, as simply patching with CV.

Whether that means it’s ideal for those same entry‑level modular synthesists or recommended only for experienced practitioners, I can’t decide. This is because, on the one hand, it certainly serves to have a substantial understanding of how conventional gates and CV signals tend to behave, as well as how to work within its limitations, since that will surely better equip you to know what to do when some of those limitations are lifted. On the other hand, Tiptop Audio have torn up so much of the rulebook in this area that it feels like there would be little lost in learning the ART standard alongside the other basics. It’s telling that Tiptop Audio flippantly chalk up the ATX1’s ability to accept Volt‑per‑octave signals as being for “legacy compatibility purposes”. In fact, the ART workflow throws into the mix a sufficiently different approach to that of ‘ordinary’ modular synthesis that I can imagine some seeing it as a different instrument entirely: just one that happens to be in 3U and one that happens to be compatible with other Eurorack modules. There are, after all, plenty of polyphonic MIDI‑controlled Eurorack modules out there, as well as digital effects, interfacing modules, multi‑purpose modules and so on, and the line of where these intersect with the Doepfer‑ordained fundamentals is equally blurred.

This is the moment to point out that Tiptop Audio have made the ART standard universally available to developers, which is noble, granted, but also a plain means of shoring up its survival. Indeed, more than encouraging other designers to follow suit, they’re depending on it. After all, an entire protocol needs far more than one developer to establish any kind of longevity. No complaints here about that; this democratic interdependence is one of the things we love about the often cottage industry of modular synthesis — and I do hope other companies get on board with this, big or small. Could we be seeing an ART‑powered Roland Juno Eurorack module? Or perhaps more innovation will take place in the realm of controllers, with MPE‑style ART controllers of all shapes and sizes specifically tailored to working with modular systems.

Tiptop Audio have taken a bold step out here, and they’re on to something.

I greatly respect the innovation and confidence demonstrated by Tiptop Audio to bring this development to completion. It may not be an easy sell to developers, despite Gur Milstein’s assurances that most components are widely available off the shelf, aside from the Polytip cables themselves. But aside from this, many will still argue that the wellspring that is CV, which has begotten modular synth design for 60 or so years, is in no danger of running dry and therefore in little need of this kind of development. I don’t think Tiptop Audio are selling ART simply as an upgrade on monophony, though, and I daresay it’s actually all its other benefits — tuning stability, near‑zero latency and the rest — that will bring even the most hesitant sceptic around into accepting this as an exciting, and freeing, development. Tiptop Audio have taken a bold step out here, and they’re on to something. Watch this space.