Review: SSL 18 USB Audio Interface

Review: Andrew Bencina






The SSL 18 USB Audio Interface is currently the ‘top dog’ of a series of USB interfaces that began with the SSL2 and has slowly grown, and been subsequently upgraded, over recent years. The more pedantic amongst us may wish to point out that the SSL BiG SiX delivers a high performance SuperAnalogue mixer/USB interface hybrid that exceeds the SSL 18 in some aspects – not the least of which is cost. Notwithstanding, this conscious distinction between SSL’s analogue legacy and its current foray into accessible digital interfaces is clear.
CONSOLE YOURSELF
Tailored to the production suite, the 1U SSL 18 brings the SSL USB offering in line with the wider market, including those who share their console heritage – like Focusrite and Audient. I make this note because while clearly being a fully featured AD/DA interface, the philosophy driving the SSL 18 remains clearly rooted in console thinking. Unlike interfaces from digital natives, such as RME, the focus here is not to exploit every possible advantage of a digital device. You can’t freely route or duplicate every incoming or outgoing signal to every possible software, or hardware destination; and standalone operation is possible, rather than optimised.
Offering 26 inputs (eight Mic/Line channels, two with switchable DI inputs, two channels of ADAT I/O and coaxial S/PDIF I/O) and 28 Outputs (10 DC-coupled line level via TRS and the digital channels), when configured at 44.1/48k (18/20 I/O at 88.2/96k, 10/12 I/O at 176.4/192k), the ‘next-generation’ converters support recording at up to 32 bit and 192k. One caveat being that once you exceed 96k you must forego the use of the low-latency SSL 360° software mixer, or accept that signals will be down-sampled accordingly. The channel count described relates directly to the number of channels available for software recording or playback and omits the Talkback Mic/Line input (recordable via software switch), two line level insert returns, MIDI I/O via 3.5mm TRS, Wordclock via BNC and two front-panel headphone outputs (with impedance switching and line level options).
In what has become a common design approach, the two Mic/Line/Instrument inputs are available on the front panel via Neutrik combo connectors. Eight input Gain controls fill the left of the front panel, marked 0-10 (all front panel controls using Alps potentiometers). This is the first hint at an analogue way of thinking. No detents. No digital readouts. Just listen and set. The buttons beneath each of these pots select the active channel, or channels, for configuration using four function buttons (three of which can be user modified to select between three of four available options) and indicated by the LED illuminated channel configuration and meter panel. Yes, you can intentionally or accidentally change settings on multiple channels, at once – so pay attention! While the five-segment LED meters could not be described as high resolution, this panel is extremely clear, capable of displaying input or output metering for most, if not all, channels and simply displays all important input (Mic/Line/DI select, Phantom, Polarity, HPF, 4K voicing) and synchronisation settings. A larger Master bus output volume control, dual headphone outputs with volume controls and three user assignable function buttons round out the front panel.
I’ll circle back to the hardware feature set and performance, but I think it’s worth focusing first on how the SSL 18 interacts with the SSL 360° low-latency mixer and configuration application to support a particular combination of workflows. On Mac the SSL 18 is plug and play via the USB2.0 Type-C connector (or the provided USB-C to USB-A adapter), while Windows will require a simple ASIO driver install. SSL offers a caution regarding the quality and length of different USB cables, and with some experiments I’d support this warning. Notwithstanding, I also used the unit via a 5m extension cable with no issue. On all platforms, full control requires the download and installation of a separate SSL 360° software package (100MB). Annoyingly, the downloads page for the SSL 18 offered only the Windows driver and user guide so it wasn’t instinctively apparent how I was supposed to unlock the full feature set. On searching, this was further confused by the dual function of SSL 360° as a DAW and hardware controller integrated plugin mixer – it always pays to read the manual.
Once installed, click on the audio interface tab of the non-scalable UI and select I/O Mode. This disables the software mixer and allows you to focus on the settings panel –  something you’ll likely choose to do if you employ outboard input monitoring or wish to benefit from the highest audio resolution settings. I/O mode passes signal directly between the hardware I/O and the equivalent software channels with three additional tweaks: the two headphone outputs can be set to mirror any output pair; while software Input 9-10 can be linked to either S/PDIF, the hardware Talkback input, or a Loopback software output pair, defined separately. A more configurable I/O mode would simplify different standalone configurations (ie., eight-channel mic pre, or ADAT AD/DA converter) but as noted earlier this doesn’t seem to be SSL’s focus. Down the right edge you’ll find a configuration strip and access to additional settings.






NEED TO KNOW
SSL 18
USB Audio Interface






PRICE
A$1790
US$1199



CONTACT
Amber Technology: ambertech.com.au
SSL: solidstatelogic.com



PROS

SSL heritage and quality on a mid-market budget
From pres to headphone amplifiers, it sounds good
Small studio utilities abound



CONS

360° architecture limiting for those more free-thinking and less studio-bound
No MIDI implementation to augment onboard controls



SUMMARY
The SSL18 offers an excellent solution for producers and recordists looking for a studio hub and master section that will remain within both physical and financial reach. With ample hands-on control, MIDI and modular synth compatibility this interface is intended to remain in focus at the centre of your creative process. Importantly, it sounds great and with handy solutions to many small studio needs those who are comfortable thinking “analogue” will be well served.










FLOW STATE
First, and perhaps most important to each individual’s flow, is the assignment of the aforementioned front-panel User button trio. From these one can control three of: trimmable monitor Dim level; Cut, or Monitor output mute; Mono Sum; Invert Phase Left; Talkback on/off; Meter Source – input or output channels 1-8 (with a dedicated Monitor meter hard patched to Outputs 1-2, 3-10 may have been a better option); Alt, a selectable monitor switching option converting Outputs 3-4 into an alternative monitor send; and, 360° SSL 18 UI, an incredibly-handy dedicated hardware quick launch for the software application. I think making all of these options available was exceedingly generous, I just now want them all. Not to mention input channel Polarity – the additional configurable option for the input switches. Yes, they’re accessible from 360° and not every user will need all functions but I want them now! [Calm down Beno. Finish your brussels sprouts first – Ed.] While not currently available, I’d love to see MIDI control enabled for the SSL 18 in a future update.
Slightly more hidden away are settings for metering, the front panel input buttons, Mono Sum compensation (set between -3dB and -6dB), S/PDIF (coaxial/optical), Headphone/Line Output and Impedance settings, Main (1-2) and Alt (3-4) Output levels (either +9dBu or +24dBu), and finally the activation of Line outputs 9-10 as insert sends for Input channels 1-2. Either or both of these inserts may be assigned but they are locked to their respective channels. Unless you own next to no outboard equipment (including guitar pedals and synths) it’s likely that the Insert function will be most effectively used in combination with some form of external patchbay. Of these other tweakable settings, the headphone matching capabilities offered the most significant benefits, during testing. If you’ve yet to own an interface able to optimally drive either Normal, High Sensitivity or High Impedance headphones, experiencing the correctly matched combination is deeply satisfying.



If you’ve yet to own an interface able to optimally drive either Normal, High Sensitivity or High Impedance headphones, experiencing the correctly matched combination is deeply satisfying




MIX THE INS… MAINLY
Since we’re on the topic of working outside the box, SSL 360° is best understood as an up-to-five-bus (three or four stereo output buses, defined by your use of the Alt monitor function, or three stereo and two mono output buses) low-latency software input mixer and master section for your interface. The Monitor (1-2) and two Headphone (A & B) outputs always flow via their associated hardware outputs and level pots with an additional assignable Mirror output available for each pair. This allows you to continue using 360° monitor mixing even when performers are located remotely and headphones are being driven by an auxiliary amplifier. Outputs 3-4 can function as the Alt monitor send, a fourth monitor mix, or, a stereo send or two mono sends for creative processing purposes. Both headphone sends and bus 3-4 also can follow the Monitor mix via a per-channel button, without losing the Monitor Mirror assignment. All buses, and 360° channels, are renamable but these custom names are channel specific and not reflected throughout the UI (ie., beneath Send controls). Individual Mono and Cut (mute) buttons are provided for the auxiliaries which may also be set up as pre or post the Monitor faders. These mixes can be previewed on the main Monitor bus using the AFL (after fader listen) function.













All analogue and digital input channels are represented as full channel strips within 360°, with analogue channels including buttons for input configuration. If you’re using an external console, or monitoring post-DAW the Mix Routes Off button will remove a channel from the monitor mixer entirely. Each channel has send pots for the two headphone and 3-4 auxiliary sends with mutes and switchable pan control, for stereo sends. The fader section handles assignment to the main Monitor mix. This offers fader mixing for users who have no need for multiple headphone mixes and allows the SSL 18 to function as a simple digital mixer for live performance. Channels also feature Solo and Cut, impacting post-fader auxes, Pan, Mirror Out (perfect for assigning direct outs and many standalone uses) and Monitor bus enable/bypass. There are definitely some circumstances where you might wish that your main Monitor mix was not seemingly hard routed through Outputs 1-2 and its hardware level control. Notwithstanding, if you stop and think, you’ll soon realise that any one of the three post-fader auxes, mirrored to any output (other than 1-2), allows a fader-driven mix that entirely bypasses the Monitor bus, leaving it free for your main DAW output.
Unlike the hardware inputs, only eight software output channels appear in the 360° mixer (available as mono or stereo channels, assigned per pair). Outputs associated with digital connections (ADAT or S/PDIF) and, even more curiously, Playback outputs 5&6 have been omitted. The provided channels are identical to the 360° input channels, with the addition of Direct to Bus channel bypass switches – enabled by default. It’s relatively easy to accept that for simplicity’s sake SSL have limited the number of auxiliary sub-mixes available within 360° but I must confess, I’m still scratching my head when it comes to the absence of so many playback returns. One potential use of the SSL 18 ADAT ports would be to connect a personal monitoring system, like the Behringer P-16I. The addition of all playback channels to 360° would ensure that DAW stems sent to systems like the Powerplay P-16I could be easily previewed in the control room or added to the various SSL 18 monitor mixes.
CAN WE JUST TALK
At the risk of disappointing some readers, I’m primarily going to discuss the Talkback input channel based on its core application. Accessible via a rear input Neutrik combo connector, the Talkback input can be configured for Line or Mic level signals with three fixed software switched gain options (30, 40, or 50dB). Sendable to all Aux buses, the Talkback channel appears as another 360° input channel with the fader operating as an overall level trim (-Inf dB to +12dB). A master Talk button, configurable to the front panel, enables these sends and dims the Monitor output. I found the 50dB setting most useful and also generally enabled the famous SSL Listen Mic Compressor (LMC) circuit, included here. There’s a reason why it was designed – it wasn’t for processing drums! – and it’s effective at balancing out contributions from throughout the control room. I do have a couple of quibbles. The Talkback input levels only meter when the channel is active (button depressed); a restriction that seems at least unnecessary. Additionally, with no send option to the Monitor bus, or Mirror option to Outputs 1-2, configuring the channel as a Listenback input (for live room conversation) would require the sacrifice of an aux and an extra switch of the buses’ AFL to send it to the monitors. There are Listenback workarounds, but they don’t come with front panel button control – again, a broad MIDI control specification may open up such hacks.
It should be noted that the combination of switchable mic/line level input and output recording, via software inputs 9-10, means that the Talkback LMC also can be used for processing any stems or input signals that you’d like to give a good squeeze. I definitely had some fun playing around but as my day-to-day environment is not short of limiting and compression options, ranging from ‘tickle’ to ‘destroy’, I was inclined to focus on its designed use.
COMPARED TO WHAT?
In my experience, audio interfaces have been performing at such an acceptably high standard for so long that the abstract language we sometimes use to describe sonic performance is barely relevant. Regardless, it’s still worth performing some standardised interface tests. With regard to round-trip latency and low-latency audio stability under load, the SSL 18 is comparable to its price-point competition, if not most of the middle of the market. With the availability of near-zero latency input monitoring, this will be of little concern to many but remains relevant if you’re performing interactive compositions or monitoring exclusively post-DAW. As far as features go, the decision to include a MIDI interface (via 3.5mm TRS jacks; Type A – now the MIDI standard for TRS connections) and to utilise DC-coupled line outputs, capable of sending control voltage signals to synthesizers, significantly increases the utility of the device; particularly if you’re short on USB-C ports.
Conversion is excellent and the eight onboard preamps offer 67dB of gain range, ample for the vast majority of microphones. The preamps deliver lower noise and an increase in depth and detail when compared to the other interface preamps I had available. As with other SSL interfaces in the range, each microphone input offers a switchable second voice – 4K analogue enhancement. Derived from its SL4000 series consoles, the emphasis circuit delivers a more forward upper-frequency excitement combined with a subtle harmonic distortion, to contribute some extra heft. I completed a number of calibrated comparison recordings before bothering to read any of the promotional materials and it’s fair to say that 4K delivers what’s written on the tin. While capturing a different feeling, certain source material can feel over-emphasised so, as always, the trick remains to pick and choose how you use it.
One of the empowering things about starting out is that often you don’t yet know what you don’t know. You trust those with experience, ask for the appropriate tool and move forward. I think this is what Solid State Logic have tried to do with the SSL 18, and its close relation the Alpha8 Audio Interface Expander. All you need to decide is if you’re the operator they had in mind.












EXPANSION GAP: ALPHA 8
Expanding your studio channel count via ADAT is an old idea. Both I and many close colleagues have relied upon such solutions for 20 years. Older interface, converter and multi-channel mic preamps from companies like Apogee, RME, Lynx, MOTU, Focusrite and Universal Audio have defied their used-by-dates as a result of their compatibility as standalone ADAT expanders, while affordable solutions from Behringer provide a means to growth without financial stress.
Like the SSL 18, the Alpha 8 Audio Interface Expander is not a new idea. An eight-channel I/O AD/DA optical ADAT interface to complement both their own and other manufacturers’ expandable platforms. What’s unique here is the presence of a fully-functional USB interface, and features like a high-performance headphone amplifier. This is worth more than a passing mention because the type of user who might set up a small production space is likely also to be collaborative, may be a performer, and seeking diverse opportunities to develop their recording and sound design chops. One of the frustrations of the shift from free-floating desktop creator to a racked and patched environment is the feeling that you’re now locked in. The ability to take one half of your digital studio with you, without disabling the whole is exceedingly valuable; particularly if you’re a team splitting the costs of your creative dreams.
The oft overlooked reminder to be aware of the differing hardware latency of distinct converter units still applies.

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