Moog’s Spectravox: A slice of classic Moog for its semi-modular line£599/$599, moogmusic.com
It’s been a difficult year or so for Moog Music.
June 2023 saw the company acquired by Alesis and Akai Professional owners InMusic, with sources suggesting that the majority of production would be moving away from the US. That September, reports from the factory floor claimed that over half of jobs were being cut. “Moog [is] about to change forever,” wrote one former employee. Indeed, the following March saw Moog vacate its famous Asheville, NC home on Broadway Street. More recently, it was announced that its physical Asheville store was to close too.

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Moog Music’s official statement following the 2023 layoffs concluded, “We ask that you […] keep an open mind as we put the finishing touches on some of our most innovative instruments yet.” Well, an open mind we shall keep. Besides — to zoom out for a moment — these sorts of shake-ups are nothing personal, and hardly new in the music technology industry (remember when Tom Oberheim finally got the rights to his own name back from Gibson?). What we producers are concerned about is the fruit.
Moog’s shift into developing plugins will no doubt have frustrated many analogue and hardware devotees, with the Apple Vision Pro-oriented Animoog Galaxy being one such invention that will likely have borne the brunt of that. The recent Mariana, on the other hand, showed real promise, and there are auspicious rumblings concerning a new hardware polyphonic powerhouse.
Moog Spectravox
Now comes Spectravox, an addition to what is arguably the biggest success story of Moog’s recent output: its semi-modular line.
Like the preceding Mother-32, DFAM and Subharmonicon, it comes as a Eurorack-friendly unit in its own elegant, wood-sided case. Like those other instruments, it is a compact, rather beautiful piece of Moog. Broadly described as an ‘analog spectral processor’, with the addition of a microphone via its Program input it becomes a capable analogue vocoder. Of all the ups and downs of the last 14-or-so months, could this be the thing to restore our faith in Moog?
‘How so?’, you ask. The answer to that question lies in the circuit at the core of Spectravox: its filter bank. The resonant filter bank, rarely if ever seen today in a 3U format, harks back to the earliest Moog designs, leapfrogging the mass of plunderable Moog history in between. Actually, the filter bank reaches even further back in time, to 1928 and Homer Dudley’s work on the Voice Operating Demonstrator, or ‘Voder’, which preceded the vocoder as a musical instrument with its telecommunications and military use.
An array of narrow band-pass filters that could emulate the characteristics of real world sounds — such as speech — with reasonable accuracy and no shortage of sonic excitement, the Moog 907 10-band Fixed Filter Bank was key to the Moog modulars of yore. In a world still getting its head around the advent of synthesisers, its ability to impart quasi-acoustic resonances to sounds not only helped assimilate electronic sounds into acoustical and musical realms, but also allowed synthesists to model existing instruments more closely. The Moog 907 most famously found favour with Wendy Carlos in her soundtrack for Kubrick’s A Clockwork Orange.
Moog Spectravox
Spectravox really is a little slice of that history. Like the 907 it has 10 bands, and — not that it matters to any but the most ardent purist — these are set in accordance with Dudley’s 1939 Voder specifications. Nice. Each of these is endowed with its own band-pass filter, with the exception of the lowest band, which is a low-pass filter, and the highest band (a high-pass filter).
One major difference, though, is that Spectravox’s filter bank is not fixed, but moveable. Variable resonance and frequency positioning are controlled via a Spectral Shift knob. Spectral Shift makes it possible to sweep the whole lot up and down sequentially through the frequency spectrum, creating something that’s a cross between comb-filtering, flanging and phasing. In layman’s terms, let’s just say it very much sounds three-dimensional.
Being a filter bank, Spectravox expects a sound source, or a carrier, to be fed through it. This is provided on the panel as a single, healthy Moog-grade oscillator, offering pulse or saw wave shapes. You can of course bypass this (or send it elsewhere) and feed Spectravox whatever line-level sound you like via the Carrier input, opening up vast processing possibilities for more or less anything you can think of.
Flick the switch from Filter Bank mode to Vocoder mode and things get even more interesting. The Program input is where the tonal properties of incoming sounds — such as a voice — are analysed through the filter bank and then used to process the carrier signal. Traditionally, this would be the oscillator but with Spectravox it can be anything you like.
Moog Spectravox
Even without either of the above, though, simply turning up the resonance of the filters to ‘ping’ them by themselves creates an incredibly resonant, woody-sounding percussion instrument — and that’s before we get to turning any of these bands’ VCAs up or down to emphasise or de-emphasise them, which results in some incredible tonal variety.
If there’s one thing we find lacking in the filter bank, it’s the choice to use miniature knobs for its VCAs instead of the more substantial and tactile classic Moog knobs, considering how much use they get. Sonically, it’s fair to say the resonance of the filter bank never reaches into particularly aggressive territory, á la that of many other Moog synths, which would have given Spectravox significant extra scope. Instead, its response is excellently tuned, if a little tame.
In Vocoder mode, Spectravox’s range of tonal shaping is immense. Growling snarls, mournful drones, wailing noises — the list goes on. Don’t expect impeccably clean speech, mind. This is old-school analogue vocoding, after all. On account of this, it does require time to find the sweet spots. For instance getting the right noise-to-carrier mix in order to best grab the consonants of speech while retaining tonal richness, or the correct decay time for natural sounding movement.
Moog Spectravox
But this is the name of the game with old-school synthesis. No presets, no digital tuning, just a set of well laid-out controls and a quality array of sound-generating circuits. The patch bay covers just about every base (though not filter resonance, interestingly) and there are VCA inputs and envelope-following outputs for every filter band.
Spectravox’s panel is comparatively sparse next to those of its semi-modular siblings. One internal LFO is provided, normalled to modulate the Spectral Shift, immediately leading us to reach for patch in another LFO from elsewhere. It’s certainly worth noting that Spectravox begs for external gear, and so it may prove to be a gateway into Eurorack for newcomers to the system.
Could Spectravox be the thing to restore our faith in Moog? Quite possibly. It’s the kind of unit whose weighty heritage and fundamental quality makes the Animoog look like it was designed by an over-enthusiastic intern.
If this is the shape of things to come from Moog, then the future is bright, even if it does mirror the past.
Moog Spectravox
Key features

10-band analogue filter bank, offering low-pass, band-pass and high-pass filters
Analogue vocoder to analyse incoming audio and map it across the filter bank
Saw or pulse wave oscillator with two noise types
Single LFO, normalled to Spectral Shift
XLR/jack combination input

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