Shockmount, standmount and cable are included, but there’s no wind protection as standard.
Will Soyuz’s beautifully crafted four‑capsule mic help turn Ambisonics from a niche interest to a mainstream studio technology?
The brainchild of pioneering mathematicians Michael Gerzon and Peter Craven, Ambisonics extends the idea of Mid‑Sides stereo into three dimensions. And given how much popular confusion there is about Mid‑Sides stereo, it’s hardly surprising that Ambisonics is widely misunderstood. In particular, I think many people view it as something that’s only relevant if you’re working in surround — but nothing could be further from the truth. An Ambisonic signal simply describes the 3D soundfield at a particular point in space, and the beauty of it is that this soundfield can be mapped onto any playback system you like, from a mono speaker to a vast Atmos array.
Formats such as Dolby Atmos are ‘spatial’ in the sense that they generate a three‑dimensional soundscape on playback. In practice, this is typically manufactured by panning mono and stereo sources around a speaker array. Ambisonics, by contrast, is a spatial recording format, and an Ambisonic microphone is designed to capture the 3D soundfield that impinges on it.
The Age Of Ambisonics
In conjunction with Ken Farrer at Calrec, Gerzon and Craven created the first commercial Ambisonic mic, the Soundfield, back in the late ’70s. Now part of the Rode group, Soundfield still make high‑end Ambisonic mics such as the ST450 MkII and SPS200, and were instrumental in the design of the impressive Rode NT‑SF1 back in 2018. All Soundfield mics are first‑order Ambisonic mics, which employ four cardioid or subcardioid capsules in a tetrahedral array. The same is true of models such as the Sennheiser Ambeo, Brahma Studio 4 and Core Sound Tetramic, and you can now buy second‑order Ambisonic mics with eight capsules such as the Voyage Audio Spatial Mic, Core Sound Octomic and Brahma Studio 8. In principle, a second‑order mic offers sharper localisation and thus the potential for greater realism, at the expense of greater complexity and cost.
Before anything useful can be done with the raw sound from the capsules of any Ambisonic mic, it must be processed. In the analogue domain, closely matched gain settings are used to preamplify each capsule’s output by exactly the same amount. Filters are then used to matrix the raw four‑ or eight‑channel signal into a universal pattern known as the B‑format. It’s this B‑format signal that can be thought of as the 3D extension of Mid‑Sides, and which can then be decoded into mono, stereo, or any surround format. If you’re working in stereo, this decoding can mimic any coincident stereo miking array, pointing in any direction you like. In other words, an Ambisonic mic can be thought of a stereo mic that can be reoriented after the fact. (It can do a whole lot else, too.)
These days, the filtering and decoding is typically handled digitally, and for good reason. Since the Ambisonic mic is by definition a coincident array, directional information is represented purely as amplitude differences between the channels, and a high degree of precision and consistency is important in order to maintain the integrity of this information. This is much easier to achieve in the digital domain, albeit that no plug‑in is quite as impressive to look at as the analogue decoder box from a Soundfield MkIII! Whereas some of the Soundfield models still come with a custom‑made preamp and transcoder, most other Ambisonic mics supply only the means to capture the signal from each capsule directly. It’s up to the user to provide four or eight matched preamp channels and A‑D conversion, whereupon digital processing is used to extract the B‑format magic from the raw (A‑format) signal. As a consequence, mics like the NT‑SF1, Ambeo, Tetramic and Studio 4 are more affordable to buy than the high‑end Soundfield models.
Purity Test
It’s probably fair to say that all the Ambisonic mics that have existed up to now have been marketed primarily as tools for capturing sound in an uncoloured, natural, lifelike fashion. They’re not conceived as ‘character’ mics in the way that, say, a valve mic or a large‑diaphragm capacitor mic might be, and they’re not designed to add their own contribution to what we hear. An Ambisonic mic is typically intended to provide a completely transparent — and uniquely versatile — window on the audio world.
That’s not quite so true of the latest first‑order Ambisonic mic to reach the market. Like most such designs, Soyuz’s 013 Ambisonic employs four directional capsules in a tetrahedral array. But unlike any other current Ambisonic mic, it has a transformer‑balanced output stage for each capsule, employing Soyuz’s custom toroidal transformers to add “additional depth with a subtle character that complements any source”. And, whereas many Ambisonic mics use miniature electret capsules, especially at the affordable end of the scale, the 013 Ambisonic features Soyuz’s own, externally polarised (‘true capacitor’) 013 capsules. At 24mm across, these are somewhat larger than those used in many pencil mics, or indeed in other Ambisonic models. Consequently, it’s rather more costly than the NT‑SF1 and its rivals, but is still more affordable than the flagship Soundfield variants.
The 013 Ambisonic’s unique positioning as a vibey alternative to traditional Ambisonic mics is evident from its packaging. Whereas the Soundfield ST450 MkII and its accessories ship in a bulletproof but unglamorous Peli‑type hard plastic case, the 013 comes in a gorgeous wooden box. The mic itself is also very nicely made, and again, its luxuriant curves contrast with the more utilitarian style of mics like the ST450. Whereas the entire capsule assembly on the ST450 is housed within a protective cage, the 013 follows the design of the NT‑SF1 in giving each capsule its own grille and so on. The capsules can actually be unscrewed from the ball‑like hub that holds them in place, though I can’t imagine there’s much mileage in a ‘modular’ Ambisonic mic with swappable capsules! The mic as a whole is a couple of inches longer than the ST450, and although it’s only fractionally wider, the spacing between the four capsules is quite a bit bigger.
A good‑quality shockmount is included, as is a basic standmount, both of which are held in place by a ring that screws onto the base of the mic. One popular application for Ambisonic mics is ambience recording, but if you plan to use one outdoors, you’ll need a good purpose‑built windscreen. Nothing is included with the 013, and Soyuz themselves don’t yet offer any optional add‑ons, but they say that compatible offerings are available from third parties. At 579g, the 013 is almost exactly twice as heavy as the Soundfield ST450, which could be an issue for use on a boom.
Like most other current Ambisonic mics, the 013 doesn’t include a hardware preamp or decoder. Instead, it presents four conventional mono outputs, which need to be fed into four phantom‑powered preamp channels with closely matched gain settings. Supplied with the mic are a multicore cable with 12‑pin connectors at either end, and a short breakout loom that terminates in four colour‑coded male XLRs. The review mic came with a rather inadequate 3m multicore, but production mics should come with a more usable 5m cable, and longer ones will be available from Soyuz. The plug and socket at either end are held in place using locking rings, and resemble the connectors that are used on some valve mics, such as the Neumann M147. To my mind, they are not as confidence‑inspiring as the LEMO connectors that Soundfield use on the ST450. Soyuz say that they have been rigorously tested and thrown up no problems, but you’ll want to make sure they are out of the way of clumsy feet in the middle of the studio floor.
From A To B
The raw A‑format output from the 013 Ambisonic’s four capsules would typically be recorded to a four‑channel track in your DAW, before being matrixed to B‑format and then decoded. To make this possible, Soyuz have teamed up with plug‑in developers Audio Brewers to supply two separate plug‑ins named 013 Transcoder and 013 Decoder. These are variants of the same company’s generic Ambisonics plug‑ins adapted for the 013, and are available in all major native formats, though the Audio Units version is designed specifically for Logic; if you use another Mac DAW, you should load the AAX or VST versions.
These plug‑ins are installed through a somewhat intrusive plug‑in and licence manager called Pulse, which I’ve not encountered before. In order to download and activate them, you’ll need to register your 013 Ambisonic at the Soyuz website and use the licence key that is emailed to you. This is fine as long as you are mixing the material you record, not so fine if you want to share your Ambisonic recordings in their raw state. For example, during the review period I was hired to make some location recordings for a TV production. I used this as an opportunity to compare the 013 with my own Soundfield ST450 MkII, but if I’d wanted to make the 013 recordings useful to the mix engineer, I would have had to bounce every single take through the 013 Transcoder plug‑in before delivery. I would urge Soyuz to make this plug‑in at least freely downloadable without registration.
The 013 Transcoder plug‑in is an essential part of the signal chain, transforming the 013’s A‑format output to a B‑format signal.
Documentation for the 013 plug‑ins is also a bit sketchy. There’s no built‑in help, nor any manual as such, so you are reduced to scouring YouTube videos or searching on the Audio Brewers website for vital information. In particular, the 013 Transcoder plug‑in gives you the option of outputting B‑format in either FuMa or AmbiX formats; it turns out that the Decoder only accepts the latter, but this is not apparent from the user interface. (Quite why the Ambisonics world requires two incompatible B‑formats that differ only in the order of the channels, I’ve never managed to explain.) Two transcoding modes are available: a low‑CPU, zero‑latency one for real‑time monitoring, and a high‑quality one for mixdown. The difference in sound quality between the two is drastic, but the high‑quality mode incurs 4096 samples of latency, which equates to a stonking 93ms at 44.1kHz.
When it comes to decoding, as a long‑term Soundfield user, I’m accustomed to the ‘virtual microphone’ paradigm employed in that company’s Surroundzone and Soundfield By Rode plug‑ins. The Audio Brewers decoder uses an alternative ‘virtual speaker’ paradigm, which probably makes more sense if you’re decoding for surround or binaural playback, though it is arguably less versatile for stereo use. In both cases, you can rotate the virtual soundfield in three dimensions; the Audio Brewers plug‑in also has a Dominance control that allows you to ‘zoom in’, essentially increasing the directivity. Unlike the Soundfield plug‑ins, it offers a binaural output option as well as stereo and numerous surround formats. At the end of the day, it’s often possible to come up with settings in both that sound quite similar; and if it isn’t, Soundfield By Rode is a free plug‑in that doesn’t require registration or a licence key, so the only thing that stands in the way of using it instead of the AB Decoder is the fact that there’s currently no Apple Silicon‑compatible version.
In The Field
Providing meaningful specifications for an Ambisonic mic is a challenge, because properties such as frequency response and effective self‑noise are dependent on the decoder settings. Soyuz quote a sensitivity of 20mV/Pa, a maximum SPL of 143dB and an A‑weighted equivalent noise of 16dB; these are similar to the specs of the standard 013 FET pencil mic, and Soyuz confirmed that they relate to the performance of the individual capsules rather than the mic as a whole. Inasmuch as a direct comparison is possible, they pretty much match the specs of the more affordable Rode NT‑SF1, and improve on it as regards SPL handling. It’s still a couple of dB less quiet than the Soundfield ST450, but in practice, is unlikely to be significantly noisier than a typical small‑diaphragm mic, and self‑noise was a non‑issue in all the recordings I made with it.
The ST450 MkII is still the gold standard against which other first‑order Ambisonic mics are measured, so I was intrigued to see how the 013 Ambisonic would compare. Among other things, I used the two together on a choral recording, to document band rehearsals, to capture an upright piano and as drum kit overheads, and in each case, two things struck me about the respective sounds of the mics.
First, as I’ve already mentioned, frequency response is a bit of a moving target in Ambisonics, but when I matched decoder settings across the two mics, there was a clear difference in their sound character. The 013 has a livelier and more present timbre, with a lot more going on in the 5‑10 kHz area than the Soundfield. At the same time, it seemed less extended at the very top end, above 12kHz or so, and was noticeably less weighty in the lower midrange. Whether or not this was a good thing was quite context‑dependent. For example, when I put both mics up in the middle of a rehearsal room, the presence and sparkle of the 013 were clearly preferable to the Soundfield’s more subdued tonality, which sounded muddy in comparison. But on the choral session, the 013 felt a little aggressive and thin, while the Soundfield remained rich and smooth even when the trebles were belting out their high notes. On drum kit, the Soundfield delivered meatier snare and tom tones, while the 013 offered more rock & roll thrill.
The 013 Decoder plug‑in uses a ‘virtual speaker’ paradigm rather than the ‘virtual mic’ model employed by some other decoders.
The other difference that was apparent in all of my tests related to stereo presentation. Assuming you choose to decode it that way, the Soundfield presents an effortlessly wide stereo picture. With a suitable source such as a choir, orchestra or other large ensemble, you can spread the signal out across the entire stereo field, with an expansive quality that you might not expect from a coincident stereo mic. In comparison, recordings made with the 013 always seemed to occupy a slightly narrower window, almost as though someone had moved the speakers a little closer together; and this wasn’t something that could be rectified by modifying the decoder settings. Localisation of individual sounds within the stereo field was also subtly but consistently better on the Soundfield.
Grand Ambitions
Looking back at my 2018 review of the Rode NT‑SF1, I find I made almost identical comments about that mic, too. Like the 013, it has a slightly less coincident capsule spacing than the ST450, and I wonder whether this affects its ability to present such a wide stereo image. I also recall the NT‑SF1 having a slightly leaner and more forward sound than the Soundfield, though perhaps not to the same extent as the 013; whether this too is a function of the different geometry, or simply reflects the fact that the mics use different capsules, who knows.
What the 013 does offer that you won’t get from any other Ambisonic mic is that emphasis on character.
In comparing the two, it must be remembered that the 013 Ambisonic is around half the price of the ST450 MkII, but also that the 450 includes its own hardware preamp and transcoder. If you don’t already own a preamp that can offer matched gain across four channels, buying one will add significantly to the 013’s cost. Even so, the 013 will likely be the more affordable option — or perhaps I should say the less unaffordable option — but it in turn is a lot more costly than the NT‑SF1 and other first‑order rivals.
What the 013 does offer that you won’t get from any other Ambisonic mic is that emphasis on character. I don’t know to what extent Soyuz’s transformers are responsible for its presence lift in the 5‑10 kHz region, but it’s a distinctive sound and one that suggests a slightly different intended role compared with the NT‑SF1s of this world. While they’re out there capturing forest soundscapes and market ambiences, the 013 Ambisonic seems more of a studio‑oriented beast, adding its characteristic sparkle to drum kits, pianos, acoustic instruments and anything that demands versatile stereo recording. If you have this sort of money to spend on a high‑quality studio mic, it will offer you something you won’t get from yet another U47 clone!
Pros
- Beautifully made.
- An interesting alternative to clinical‑sounding Ambisonic mics, with a colourful character and presence.
- Can accept very high sound pressure levels.
- Good‑quality shockmount and case.
Cons
- Transcoding plug‑in only available to registered owners of the mic.
- No windshield included.
Summary
Soyuz have made an interesting and ambitious attempt to create a characterful Ambisonic mic that is particularly suited for music recording in the studio.
Information
$2799
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