Review: Moog Spectravox

A 10-band modified filter bank and synth that’s undeniably Moog… but a bit different.


27 June 2024

Review: Corey Hague

The Moog Spectravox is the fourth in the familiar Moog desktop synth series that started way back with the Mother 32, but don’t step up to the ’Vox expecting yet another synth. Because while it looks just like its family members – 60HP in size, patchbay, plenty of controls and wooden end cheeks – it’s very much the wildcard of the family.

That’s not to say it’s a departure for the classic brand. The Spectravox has its roots way back in the early days of the company, when synth pioneer Wendy Carlos was sharing some thoughts with Bob on how a modified filterbank could add flavour and complexity to a synthesiser system. The resulting device  can be heard all over Carlos’ 1971 A Clockwork Orange soundtrack. The Spectravox also made a limited appearance at Moogfest in 2019, as a slightly different unit created in very low numbers.

All this is to say that the Spectravox concept has long been a part of the Moog ecosystem, although admittedly not as a halo device alongside their more famous synth models. Unless you are deeply connected with the subtleties of early Moog modular systems you probably aren’t aware of it. It’s at once undeniably Moog, but also a little bit different. 


The biggest hint that things are different is the Spectravox’s full title, written handily on the face of the unit – Semi-modular Analog Spectral Processor. It may sport a Pulse and a Saw wave, but it’s not just a traditional synth. It’s also a processor. A spectral processor, in fact.

So what does that actually mean? The easiest way to think of it is as a 10-band filter that you can modulate in different ways across a frequency spectrum. When you first turn it on and have a play, it doesn’t roar to life like the usual Moog synth with shuddering subs and squealing resonance. Instead you get a more subdued range of tones and timbres, although still with a familiar Moog sound. 

Also familiar is the build quality, which is top shelf as to be expected from Moog. Its big chunky knobs are satisfying to interact with and the 10 mini pots feel sturdy and are easy to tweak despite their diminutive size. Overall there’s no mistaking this is a Moog device, regardless of what factory it’s come out of.


Luckily the code leads to a well written PDF that outlines what the ’Vox is designed to do and its rich origins in synthesiser history. There’s a lot to try and understand with the Spectravox, and like so many things in the semi-modular world it really only begins to make sense when you start patching and listening to what is actually happening. While the Spectravox will respond favourably to some basic self-patching, the first real job is to feed it some audio and some CV signals. Or ‘Program’ and ‘Carrier’ to use Moog terminology.

Call it whatever you like, just make sure you feed it, because that’s where the ’Vox comes alive as a unit, presenting new options for interesting sounds and techniques. Flicking the Filter bank or Vocode switch will let you choose between how you’re going to start to manipulate your sounds.


Moog Spectravox
Semi-modular Analog Spectral Processor



    CMI: cmi.com.au

  • PROS

    • Classy/classic sounds
    • Well built
    • Vocoder

  • CONS

    • Niche
    • Need other devices to get the most of out it


    Spectravox evokes the classic Moog sound of the ’60s and ’70s. Feeding Spectravox another source and using its semi-modular capabilities will allow it to shine. Don’t expect instant gratification but do expect a deep sonic exploration.

The Filter Bank setting offers lots of exploration opportunities and will quickly help you understand what sort of sounds it’s capable of producing. Playing with the controls and settings, you’re quickly given an audio history lesson (so many of these sounds go back to the very start of electronic music). Bleeps and bloops and pings and whirrs transport you back to the first time you heard out-of-this-world synthesiser sounds, straight from old records and the BBC Radiophonic Workshop. By playing with the pulse width, spectral shift and the shift LFO rate, you can easily create smooth vowel-y style filter movement or grinding audio rate crunchiness. And the 10-band filter adds or subtracts to sounds nicely, rarely causing any speaker threatening moments or runaway squeals while still altering the signal significantly.


If you want to hit the autobahn and do some vocoding, flick the switch and feed it some appropriate signals. It sounds simple, but you quickly learn that not all programs and carriers are the same, and some experimentation will be required. Or to put it another way, you will likely drive your loved ones crazy if they happen to hear you doing your best ‘Around the World’ robot voice impression while trying to find the perfect blend of program and carrier. Because making it sound like all those famous robot voices won’t be instantaneous, even if you have read the manual and are feeding it useful signals. It’s not to say the vocoder isn’t good or usable, it certainly is, it’s just not a ‘sweet spot’ machine that sounds great no matter what you do. 

And that’s really the charm of the Spectravox. It feels like a deep instrument that you need to learn and explore, revising and testing your approach with it to probe how it reacts to different combinations of sounds and modulators. How does the vocoder sound on drums? How can you use your voice to control an envelope? What happens when an LFO sweeps a rich pad? The only way to find out is to experiment. It’s a sound explorer’s delight, and it’s sure to give you an appreciation of all the electronic musicians who came before.

Call it whatever you like, just make sure you feed it, because that’s where the ’Vox comes alive as a unit, presenting new options for interesting sounds and techniques

The only downside is not a large one, but it should be noted: the Spectravox needs friends to play with in order to really shine. It can absolutely create its own sounds, but to use it as such would be hugely limiting. It will be much happier and more rewarding in a studio that already has some noise-making and modulation options available. A drum machine, a small eurorack setup, a synth and a keyboard that can send CV data would be enough for endless fun with the ’Vox and it’s remarkable how different you can make things sound just by switching inputs around and trying different combinations. 

Gigging keyboard players will also appreciate some of its tricks in a dedicated analogue box that allows for wild sonic excursions or more tame movement and grit. And a Vocoder is always going to find a use on stage, for better or worse.


In some ways the Spectravox is a bit of a paradox: it’s the latest device from Moog, but it feels the most like a vintage Moog device from decades ago. It was clearly born in the days when a synthesiser meant a room full of boxes and cables, but it can happily do things that modern plugins would struggle to do. And while it’s not the kind of device every studio needs, I can see it becoming a secret weapon and a leftfield classic from Moog.


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