If you think all 1U rackmounting audio interfaces are the same, SSL have some news for you!
For a few years now, Solid State Logic have had the Midas touch. Whether it’s mixers such as the SiX, BiG SiX and Origin, outboard like the Fusion, PureDrives and Bus+, their ever‑growing plug‑in library, or the UF and UC controller range, SSL have produced hit after hit. And what’s most impressive is that this success has been achieved with fresh thinking and novel designs. Instead of churning out copycat products, they’ve made a case for originality, new features and deep integration. So when I was offered an exclusive chance to test the company’s first-ever rackmounting audio interface, I jumped at the opportunity.
But when I removed the 18 from its box, my face fell. With its neat rows of combi XLR/jack sockets, twin headphone outputs and simple monitoring controls, it just looked so... conventional. Had SSL finally started making me‑too products? Would I have to report that their purple patch had run its course? Well, spoiler alert: it turns out there’s more to the new 18 than meets the eye!
In terms of form factor, the 1U rackmounting 18 certainly follows a well‑travelled path, and you’d have to be a sharp‑eyed witness to pick it out from something like the Focusrite Clarett 8Pre+ in an identity parade. Dig a little deeper, though, and it becomes apparent that SSL’s designers have tried to put some clear blue water between their baby and the rest of the “eight mic preamps plus ADAT” crowd.
Numbers Game
SSL’s desktop audio interfaces take their names from the number of physical inputs available. The 2 and 2+ are simple two‑channel models, while the 12 sports four analogue inputs and up to eight digital ins over ADAT. However, the 18 actually has either 26 or 27 physical inputs at base sample rates, depending on how you count them. The first 26 are made up of eight analogue inputs on the aforementioned combi sockets, plus stereo S/PDIF and two sets of ADAT ports, each of which can accommodate eight inputs at 44.1 or 48 kHz. The 27th, if you count it as such, is an additional analogue input with its own preamp and compressor. Officially, this is intended for talkback use, but it can be digitised and recorded instead of the S/PDIF inputs, and has some unique capabilities (see boxout).
On the output side, meanwhile, the count reaches 28, as there are five pairs of analogue outputs on quarter‑inch jacks as well as the stereo S/PDIF and 16‑channel ADAT outputs. There are also two headphone sockets on the front panel, although DAW software cannot address these independently. Like those on the 12, they are unusually versatile, with three gain options to suit more or less sensitive headphones, and the ability to act as balanced or unbalanced line‑level outputs. The waters are also muddied, in a good way, by the provision of a pair of balanced insert points. Using these involves repurposing outputs 9+10 as sends, and returning the processed signal to a dedicated pair of jacks that feed inputs 1+2. Finally, there’s a word‑clock output on the usual BNC socket, MIDI in and out on the less usual mini‑jack format, and a single USB Type‑C socket for connection to your Mac or PC. The 18 has an internal, universal‑voltage PSU fed from a standard IEC socket.
The rear panel is unusual in hosting an odd number of combi jack/XLR sockets, the extra one feeding the talkback input.
Inward Bound
Solid State Logic have developed a couple of different mic preamp designs in recent years. The preamps from the Origin console, which also form the basis of the PureDrive outboard units, are the successors of the older VHD design and offer not only a colossal gain range but also a variety of ways to colour the sound, by varying the input impedance and applying different saturation options. The SiX and BiG SiX, meanwhile, use the ultra‑clean SuperAnalogue preamp, while the audio interfaces employ a circuit that is different again. I’m not sure if this has a name, but it’s somewhat like a simplified version of the PureDrive design: clean by default, but with a switched ‘4K’ option that introduces a fixed treble boost and saturation to recall the sound of SSL’s 4000‑series consoles.
...in the 18, the interface preamp design offers a 67dB gain range and an astonishingly low Equivalent Input Noise of ‑130.5dBu. SSL describe this as “best in class” and as far as I’m aware, they’re not wrong.
All of these preamp designs have two things in common, the first being superb technical specifications. As implemented in the 18, the interface preamp design offers a 67dB gain range and an astonishingly low Equivalent Input Noise of ‑130.5dBu. SSL describe this as “best in class” and as far as I’m aware, they’re not wrong. The second feature that unites all of SSL’s current preamp circuits is that they use analogue gain controls — switched in the case of the PureDrives, but continuous on the mixers and the audio interfaces. This would have been unremarkable a few years ago, but other audio interface manufacturers are increasingly moving to digital control, which in turn permits full recall and the implementation of technologies such as automated gain setting.
Similar levels of technical excellence are maintained elsewhere, too. All the analogue inputs boast a dynamic range greater than 120dB, while the analogue outputs achieve 125dB, and THD+Noise is below ‑100dB on the mic inputs and below ‑106dB on the line ins. Perhaps more pertinent to everyday use, however, are the ability of the headphone amps to deliver levels up to +18dBu, and the fact that on both the input and the output side, the 18 is designed to operate at professional alignment levels where 0dBFS corresponds to +24dBu. This is an unusual, perhaps even unique feature on interfaces in this class, which are more normally aligned to +18dBu or less, and means that you’ll never run into problems trying to integrate studio outboard with the 18. And if you run into the opposite problem, whereby the interface threatens to melt your monitors or overload downstream equipment, it’s possible to switch the first two output pairs to a more conservative +9dBu alignment instead. All of the analogue outputs are also DC‑coupled, meaning you can use them to transmit control voltages to analogue synths.
Like other recent SSL interfaces, the 18 is billed as a 32‑bit device, but this just refers to the converters that are used, and it’s not intended to be ‘unclippable’ in the way that some field recording devices are. The benefits of the high‑spec converters are the same whether you choose to record at 24‑ or 32‑bit.
All Rounder
I mentioned deep integration as a common theme of recent SSL products, and the glue that binds them together is a software environment known as SSL 360. If you use any of SSL’s channel strip or bus compressor plug‑ins, or third‑party equivalents hosted in the SSL Link plug‑ins, these will appear in the Plug‑in Mixer page of SSL 360, and can be manipulated using controllers such as the UC1 [reviewed in January’s SOS]. Connect a 12 or 18, and you’ll see another SSL 360 page available. This is the equivalent of the control panel utility provided with other interfaces, and naturally, it too presents a mixer‑like interface.
The 18 Mixer tab in SSL 360 is loosely modelled after a large‑format console, which is no surprise given the company’s heritage.
The virtual mixer resembles a rather gloomy SSL console — sadly for middle‑aged eyes, it’s not possible to brighten it up — and allows you to independently show and hide four types of channel: analogue inputs, digital inputs, playback returns and auxiliary masters. The talkback input also has its own dedicated channel. There are three stereo auxiliary busses, routed respectively to the two headphone outputs and to line outputs 3+4. These are fed from sends that appear above the channel faders, meaning there’s no need to tab to alternate fader views in order to set up cue mixes. As already described, gain control is out of the purview of SSL 360, but buttons on the channel strips allow you to toggle 48V phantom power, the high‑pass filter and 4K mode on the analogue inputs. Inputs 1 and 2 also offer the usual high‑impedance mode for direct guitar recording. This mode is only switchable in software, but the rest can be adjusted from the front panel: each channel has its own selection button, whereupon global buttons toggle these settings for the selected channels.
Three further buttons on the front panel relate to the 18’s monitor control functionality, as do separate volume controls for the main monitor and headphone levels. The buttons can be reassigned within 360, but since there are only four options for the three buttons, this is of limited usefulness. The monitor control on offer is nevertheless relatively generous compared with some interfaces in this bracket, with cut, dim, mono and alternate speaker switching. If used, the latter toggles monitoring between outputs 1+2 and 3+4, with adjustable trim to compensate for sensitivity differences between two pairs of speakers. The down side is that you lose the dedicated auxiliary bus that can otherwise feed outputs 3+4, which cannot be reassigned to another output pair. In practice, this is unlikely to be a problem, since the aux is mainly useful during tracking and speaker switching during mixing.
Odd Ones Out
In general, the SSL 360 mixer page for the 18 is slick, comprehensive and easy to use, but there are a couple of quirks. The most obvious of these concerns the Playback Return channels. Your DAW can address a total of 28 outputs, the last 18 being the 16 ADAT and two S/PDIF outs, which are fed directly from DAW outputs and don’t appear in the mixer. The first 10 show up as ‘analog out’ in the DAW, and although they can be set up to address physical outputs directly, this isn’t the default or the usual mode for eight of them. Instead, DAW outputs 1+2, 3+4, 7+8 and 9+10 feed the four Playback Return channels in the 360 mixer, which in turn can feed the main monitor outputs via the faders, and the three auxiliary busses via the sends. DAW outputs 5+6, however, are hardwired to the corresponding physical output pair on the 18, and never appear in the mixer.
It turns out that although the 18 has 10 physical outputs, its DSP resources are only sufficient to support eight mono or four stereo playback channels. The choice to omit 5+6 rather than 9+10 from the Playback Returns relates to a specific use case involving hardware inserts in Pro Tools, which insists on using the same‑numbered inputs and outputs for this functionality. Since the 18 does not have a dedicated line input pair numbered 9+10, it’s not possible to set up a Pro Tools hardware insert on outputs 9+10. With outputs 1+2 and potentially 3+4 reserved for monitoring, the logical choice is therefore to connect a master compressor, EQ or other outboard chain between outputs 5+6 and inputs 5+6. But in this circumstance, a Playback Return channel for DAW outputs 5+6 would be wasted, and one of the headphone busses would be lost. The gapped numbering thus allows Pro Tools users to retain the full functionality of four stereo Playback Returns within SSL 360 while also using one or two channels of hardware insert processing. I suppose SSL might have avoided this compromise either by adding more DSP resources or an extra pair of line inputs, but no doubt that would have raised the cost of the 18.
If you prefer to set cue mixes up in your DAW mixer, engaging I/O Mode simply routes inputs and outputs directly to their counterparts in your software of choice.
The routing is made a little clearer if you hit the 360 button labelled I/O Mode. This completely bypasses all of the mixer functionality, passing physical inputs directly to DAW inputs and DAW returns directly to physical outputs. In this scheme — which you might use if you preferred to set up cue mixes within your DAW — headphone outputs A and B can freely be reassigned to mirror other physical outputs. And talking of mirroring, the 360 Mixer also has its own ‘mirror routing’ feature. Clicking at the bottom of any input channel allows you to route it directly to any physical output on the 18, as well as feeding the monitor and headphone busses as usual. This has obvious applications for feeding an external cue mixing system but could also, for example, be used to set up simultaneous wet/dry recording: you might record the dry signal coming into input 5, whilst simultaneously mirroring it to output 8 and connecting a processor between that and an input, though you’d have to compensate after the fact for the small amount of additional latency in the wet path.
On the topic of latency, the 18 uses macOS’s built‑in Core Audio USB driver, and the familiar Thesycon offering on Windows. Signals passing through its built‑in mixer also incur a tiny amount of additional latency, though this is below 1ms for all sample rates. Selecting the lowest buffer size on a Mac allows you to obtain a round‑trip latency of around 7ms at base sample rates, which feels comfortable for me, and SSL say that the Windows driver will achieve 6ms or less. If you wanted to significantly improve upon this, you’d need to either track down a Thunderbolt alternative or something with custom USB drivers, either of which is likely to be more expensive.
18 Wheels
There is a break point in the audio interface market between what we might call semi‑pro and professional devices. Both price‑wise and in terms of its feature set, the SSL 18 sits at the top of the former category. This means it’s significantly more versatile than many other semi‑pro products, with quite a few capabilities that simply aren’t available elsewhere. The flip side of this is that it’s a little more complex than many alternatives. SSL have done a good job of making the 360 mixer page clear and logical, and I particularly like that everything happens in the one view with no tabbed pages to plough through, but you do need to be familiar with traditional mixer concepts and layout to make sense of it. To someone with little experience of working with audio hardware, the super‑simple approach pioneered by Focusrite with their control panel software might be less intimidating. Focusrite have also done an excellent job of implementing remote control over WiFi from a phone or tablet, something that’s currently missing from SSL’s offering.
Within the ‘eight mic preamps plus ADAT’ category, this is either the most professional semi‑pro interface yet — or the most affordable professional interface yet.
On the other side of the semi‑pro/pro gulf, you’ll find features such as dedicated sockets for line‑level inputs, built‑in speaker calibration, surround monitor control, comprehensive metering and huge channel counts through expansion over network protocols or by cascading multiple interfaces. If you need that sort of functionality, you’re looking at devices like the RME Fireface UFX+, Antelope Orion 32+, Universal Audio Apollo X Gen 2, Apogee Symphony Studio and the Focusrite Red or MOTU AVB ranges, all of which are considerably more expensive. Yet, although it sits on the semi‑pro side of the divide, the 18 actually matches most of these for sound quality and technical specs, and it also plays with the big boys in terms of being able to handle +24dBu alignment. If you’re not going into Atmos production and you’re content with a hard limit of 26 audio inputs, there’s very little compromise involved in choosing the SSL 18 over something much more costly. Within the “eight mic preamps plus ADAT” category, this is either the most professional semi‑pro interface yet — or the most affordable professional interface yet. Either way, SSL are still exceeding expectations.
Do Talk Back
The talkback input has its own channel within the mixer, with three switched mic gain settings, a line‑level option and the all‑important LMC.There’s no built‑in talkback mic on the SSL 18, but you don’t have to sacrifice one of the other inputs in order to use the feature, as there’s a dedicated combi XLR/jack socket on the rear panel.
Unlike the other analogue inputs, talkback can only be configured in software, but a visit to its SSL 360 channel reveals a lot more going on than you might expect. There is switchable phantom power and three gain options, respectively applying 30, 40 and 50 dB boost to mic‑level inputs, or you can tell the 18 to expect a line‑level input. The biggest bonus is a button labelled LMC, which activates SSL’s notoriously aggressive Listen Mic Compressor. As the name suggests, this was originally part of the listen‑back system on SSL consoles, a ‘reverse talkback’ arrangement that allowed the engineer in the control room to hear what quietly spoken drummers were muttering in the live room. Its use on a Peter Gabriel session with Phil Collins and Hugh Padgham resulted in the invention of gated reverb, the compressor bringing up the ambience on the drums after each hit before a gate cut it off again.
The ability to route a line‑level signal through the 18’s talkback channel means you can use the LMC as an insert processor on previously recorded material as well as on microphones. And, whereas Padgham had to cajole the techs at London’s Townhouse Studios into rewiring their SSL to make it possible to record the listen mic, this one is delivered straight to its own DAW input as well as the 360 mixer. That is, as long as you select Talkback as 9/10 Input Source in SSL 360; the other options are the S/PDIF input and a Loopback input. Note that although the talkback channel has a ‘fader’ in the 360 mixer, it does not feed the main monitor bus, which is as well, since activating the LMC in those circumstances would easily provoke feedback. Instead, the fader is essentially a global trim that adjusts the level of all the talkback sends at once, but does not affect the level going to your DAW.
With my dispassionate reviewer’s hat on, there’s an element of novelty about the inclusion of the LMC on the talkback channel. As anyone who’s ever recorded drums will know, the idea makes perfect sense for listening to a drummer trying to form a coherent sentence, but extreme compression is perhaps less often needed in the other direction. However, I’m not sure that SSL really expect anyone to use it for comms. What the 18’s talkback feature really offers is a bonus recording input with instant vibe. In a busy session, there isn’t always time to muck around with outboard compressors or guitar pedals in search of that smashed room‑mic sound. The LMC delivers it on a plate, without taking up an input that could be used for something sensible, as well as making it available as an insert processor at mixdown.
Alpha 8 Audio Expander
By the time you read this, the 18 will have received its official launch at the NAMM Show, where Solid State Logic are also due to announce a companion product. The Alpha 8 is described as an “audio interface expander”, and features eight balanced analogue inputs and outputs on quarter‑inch jacks. This is a product category that has been rather neglected in recent years, with modern ADAT expanders typically offering built‑in mic preamps rather than line‑level I/O. However, in typical SSL fashion, the Alpha 8 is much more than just an ADAT expander.
It does indeed have two pairs of optical output sockets, allowing the full eight‑channel input count to be maintained over Lightpipe at sample rates up to 96kHz, but that’s not the half of it. The Alpha 8 offers two‑way conversion between analogue, ADAT and S/PDIF formats, with flexible routing and a headphone output that can be used to check what’s going where. And on top of that, it’s also a USB audio interface in its own right — which, when used as such, makes all eight analogue, eight ADAT and stereo S/PDIF inputs and outputs available simultaneously, for a total of 18 ins and outs. Mac owners who have both an 18 and an Alpha 8 can therefore create an aggregate device to use both simultaneously over USB for a theoretical 44 inputs. Those using the Alpha 8 as a more conventional expander will also appreciate the fact that it has word‑clock out as well as in, meaning there’s no need to muck about with ‘T’ connectors in order to clock further units. On the analogue side, the Alpha 8 not only matches the 18 in being able to cope with professional line‑up levels, but allows every input and output to be independently aligned to any of +24, +20, +18 or +9 dBu. It also offers similarly excellent audio specifications.
Pros
- Excellent audio specifications.
- Supports professional +24dBu line‑up levels.
- Comprehensive and well‑designed cue mixing functionality in SSL 360.
- Dedicated talkback input with Listen Mic Compressor available as a recording source.
- Many other nice touches including insert points and very versatile headphone amps.
Cons
- Does not offer digital preamp gain control or related features such as auto‑gain.
- No remote control or iOS functionality.
- SSL 360 mixer might present a learning curve for anyone not au fait with the conventions of mixer design and layout.
Summary
Solid State Logic have added their own twists to a familiar audio interface format, offering class‑leading audio specs and a heap of unique features.
Information
£899.99 including VAT.
Headline Audio +44 (0)1908 477142.