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Universal Audio Apollo X8

Universal Audio’s freshly minted Apollo X range hits the spot with ‘HEXA Core’ processing, superior conversion and surround monitoring.


November 26, 2018

Universal Audio launched its first silver Apollo units in early 2012. What was at that time an interesting new competitor in the crowded field of audio interfaces has since become an industry-leading behemoth with tens of thousands of units seeing use every day in both home studios and professional facilities. Key to the original Apollo’s success was its utilisation of advanced hardware modelling UAD plug-in software via built-in SHARC processing cores. While other companies were working along similar lines, the depth and sonic authenticity of the UAD reverbs, compressors and EQs was a real step up from the majority of plug-ins available at the time and the word quickly spread throughout the audio world. 

2015 saw the first major hardware revision with the launch of MkII blackface units featuring improved specs, new conversion, improved monitoring features, seamless multi-unit expansion, the debut of the eight-preamp 8p model, and a slightly tweaked front panel layout. At the same time, the Unison preamp modelling software (dormant at the time of the original release) started to really come into its own with realistic emulations of classic Neve, API and UA preamp models, as well as availability on the Hi-Z inputs, giving users diverse tracking options from the same 1U box. 

Fast-forward to 2018 and UA has upped the stakes again with the release of the Apollo X range. The Apollo x6 is aimed towards the more budget-conscious with two mic preamps and a slightly smaller I/O count. The x8 reviewed here features four preamps and eight independent analogue I/Os to cover most recording bases while the x8p packs eight preamps for larger sessions. The x16 ditches the preamps altogether, instead offering 16 channels of line inputs and outputs on DB-25 ports. In keeping with previous Apollo models, the 16-channel model is fitted with the company’s flagship converters that will out-perform the rest of the new range, including the x8. The Apollo X range ships with the Realtime Analogue Classics Plus plug-in bundle and a one-year parts and labour warranty. 


First impressions of Apollo x8 are that things haven’t changed much at all, at least externally. The build quality is excellent and there’s a new backlit logo stage left but otherwise this unit’s front panel layout is pretty much unchanged from the previous MkII model. Very Dark grey is the colour of choice which is fine by me (the original silver colour was always an irritant in the otherwise exclusively black membership of my racks). The economical yet simple-to-use rotary controls and buttons are laid out as before. Ditto the informative and clearly legible central backlit screen. Round the back wordclock, S/PDIF and ADAT ports are as-you-were with the only real difference from previous iterations being the pair of upgraded Thunderbolt 3 ports. The bottom line here is that the original layout was very effective and UA hasn’t seen the need to rejig things front or back. In designing the new range, UA’s engineers instead focused their energies on a number of key areas ‘under the hood’ including upgrading and standardising DSP processing power across all units, redesigning the power supply and adding extra features such as selectable SMPTE standard +24dBu operation, 7.1 surround sound monitoring capability and the handy addition of a built in talk-back mic.


The headline acts of the new Apollo X range are undoubtedly the six processors snuggled on the PCBs of all four new models. Using UAD plug-ins is a highly addictive audio experience so it’s only natural that users want more processing power to harness more plug-in instances. While the number of UAD cores has grown to six with these new units, it is worth noting that ‘HEXA Core’ simply refers to six processors, not an upgrade of the processors themselves leading to some confusion and griping online.

The same SHARC chips are still utilised meaning there is no performance improvement within each processing chip in the Apollo X range. Users who love stacking plug-ins on the preamp inputs will still experience the familiar limitation of only being able to utilise a maximum of one processor per input channel so there is no sharing of the load between processors in input mode. While power-hungry users may have issues with these limitations not being addressed on the new machines, a 50% increase in UAD-2 processing power over the old Quad models is nothing to sneeze at. It is also worth bearing in mind that UA has a track record of unleashing powerful new software capabilities from its existing hardware, so my educated guess is that the Apollo X’s new architecture will likely allow down-the-line feature upgrades.

Need to Know


    Expect to pay
    Apollo x6: $3299
    Apollo x8: $3999
    Apollo x8P: $4999
    Apollo x16: $5499


    CMI Music & Audio:
    (03) 9315 2244 or
    [email protected]

  • PROS

    Upgraded DSP, converters & clocking
    SMPTE standard +24dBu operation
    Compatible with older Thunderbolt-equipped models
    Talkback mic built in
    5.1 and 7.1 monitoring capability

  • CONS

    Thunderbolt cable not supplied
    Still uses older processing cores
    Not compatible with older PCs
    No plans for surround UAD-2 plugs


    The Apollo line continues to flourish with the latest hardware upgrades improving sonic and DSP processing performance. New surround monitoring, +24dB operation and built-in talkback mic add even more pro-requested features to an already impressive product.


So what can you do with six UAD-2 processors? Well as I discovered, quite a lot. I tried a few experiments with loading plug-ins into the Console channel inserts and managed 12 Neve 1073 preamp/EQs before I maxed out the DSP headroom. The less power-hungry EMT140 reverb (a personal favourite) managed 30 instances while I got a sore finger clicking up 44 instances of the Fairchild 670 Legacy compressor and then discovered I’d only used up 37% of available DSP! Suffice to say there’s considerable processing power on offer and if, like me, you’ve been carefully spreading out your UAD plug-in instances on a less powerful system you’ll be able to let your hair down a little (or a lot).


The designers’ other main priority with the X range was upgrading the conversion and clocking. UA’s converters have always sounded good but the Apollo X series delivers improved specs across the range with upgraded ESS Sabre chips and a redesign of their associated analogue circuitry. UA is claiming the sound of these new converters is ‘mastering grade’ with the x8’s signal to noise ratio 3dB higher than the mkII Apollo 8 on the AD side, 6dB higher for DA and an impressive 8dB higher on the monitor outputs. The x8 also boasts impressive total harmonic distortion figures of -113 dB (0.00022% @ 23 dBu) on the line inputs and -119 dB (0.00011% @ -1 dBFS) on the line outputs.

Improvements in headroom mean the x6, x8 and x8p boast 129dB DA dynamic range, while the x16 ups the ante to 133 dB. UA’s new dual-crystal clocking circuitry offers improved stability by using separate clocks for 44.1kHz and 48kHz operation (and their corresponding multiples), meaning much simpler maths and therefore reduced jitter and digital artifacts at higher resolutions. While minimal improvements to latency were achieved the x8 still delivers a miniscule 1.1 milliseconds analogue round-trip latency at the 96kHz sample rate. Even more impressively, latency is still 1.1ms when four plug-ins are instanced on a Console input channel. The UAD plugs generate zero additional latency on the input even under heavy DSP processing loads.


AV post-production is an area where the Apollos haven’t really had a big impact but that may be about to change. The Apollo x6 offers 5.1 monitoring and all the other units offer up to 7.1 surround. The surround software is still in the final stages of development and is due to be released in the next few months. As I write this details are still a little thin on the ground but the gist is you will be able to setup a 5.1 or 7.1 monitoring matrix via the software in the UA Console application and assign it to the physical outputs. There won’t be surround versions of the UAD plug-ins per se (which is a bit of a shame) but, as is already the case, they can be used in linked multi-mono mode within DAWs that support this approach. This looks like a bit of a toe-in-the-water move by Universal Audio and they are on record as saying future developments in this area will be driven by customer needs so watch this space.


There are a few potential issues to watch out for when connecting devices via Thunderbolt 3. The first is to check all connecting cables have the Thunderbolt lightning icon. The actual connector type is known as USB-C but not all USB-C cables are Thunderbolt-enabled. Mac computers with TB1 and TB2 ports can run the Apollo X range using a TB2-to-TB3 adapter. When purchasing an adapter ignore the fact that the data direction arrow points the wrong way, the adapters transmit data just fine in both directions. Unfortunately, PC users will need a TB3-equipped computer to run the new Apollos.

For those contemplating expanding an existing system, the new models will interface with older Apollo units equipped with the Thunderbolt 1, 2 or 3 option cards, UAD-2 PCIe Cards, Apollo Twin Thunderbolts and UAD-2 Satellites (Firewire, Thunderbolt and USB). The only incompatible units are USB-model Twins, while Firewire-model Apollos need to be upgraded with the optional thunderbolt card before joining in. While the new units are designed to work with all major DAWs and computers its worth checking the UA website for compatibility with your particular system.


After checking out the specs and playing with the talkback mic and a few software parameters, my first proper experience with the Apollo x8 was a simple acoustic guitar and vocal recording. I hooked the unit up via a Thunderbolt cable (not supplied) to a Mac Pro laptop running Pro Tools, downloaded the Apollo software and was quickly in business. I plugged a Neumann U87 into the Apollo’s built-in mic preamp and placed it about a foot and a half away from the sound-hole of my Martin steel string acoustic. The Martin sounded sweet and balanced with the Apollo capturing every nuance of string and wood beautifully. Having been an Apollo user for many years the sound of the new unit was very familiar, with perhaps a hint of extra definition and dimension to the sound.

I added some layered vocals and a few extra guitar parts to hear how the tones stacked up and found the character of the new converters very pleasing indeed. The next session was with Melbourne synth-pop act the Sugar Glass Project. We tracked electric bass, drums, acoustic and electric guitars plus a rough guide vocal through the Apollo x8 via a variety of mics and preamps. The results were great and I enjoyed using the built-in talkback mic (having assigned it to the multi-purpose Function button on the front panel). It was a vibey session and the band went home happy. With one-off sessions like this it is hard to rate the new converters against the old as there are always so many variables on any given day of tracking, but I was really happy with the sound of the new Apollo. To better assess the character of its converters I did some A/B tests that gave me the chance to sit back and listen more objectively.


First up I looped a longish passage with electric guitar and keys via my loop pedal into a guitar amp and set up an SM57 right on the cab and a Neumann U87 as a middle distance room mic. The mics were recorded into Pro Tools via channels 1 and 2 of the Apollo x8 as well as the same channels in an original silver face Apollo with identical gain settings. I then overdubbed a simple drum part over the top with the same two mics on overhead and room snare duties. A second test involved one of the most important conversion tasks in my studio — transferring multi-track tape recordings into my DAW. For this test I used an excerpt of a simple vocal, guitar and drum machine recording by South Australian singer-songwriter Louise Adams. Again both Apollo machines were used with identical gain settings on the line inputs and all recordings were done at 24-bit/48kHz resolution. Finally, I recorded a mastered track by Sydney artist Emma Davis through the line inputs to hear how the converters ‘heard’ a more polished final product.

Repeated listening through various sets of speakers and headphones revealed some interesting differences. Most noticeable to me was a subtle tightening of lower-mid and bass frequencies in the x8 recordings. In general the bottom half of the spectrum sounded a little more defined and well articulated. The new Apollo also exhibited a slightly different character in the top end with a tickle more sheen above 10kHz and improved management of things like sibilance around the critical 4-8kHz zone. These differences were far from pronounced. They were subtle but noticeable with careful listening and more or less in line with my expectations of the x8. At this level, enhancements are incremental and unlikely to reveal night and day differences. The Apollo x8 sound shares many qualities with its older sibling but to my ears the fidelity and realism of the sounds has gone up a couple of notches.


Universal Audio’s own plug-in Century Tube Channel Strip diverges from its typical path of meticulously digital modelling classic hardware. While utilising a tube topology in the preamp stage and an opto-style limiter for dynamic control, it has no historical progenitor in the analogue hardware world. The Century is optimised to work hand in hand with UA’s Unison mic preamp modelling system, and as such this plug-in is very much aimed at the tracking stage of the recording process and offers a streamlined set of controls for quick and easy tonal and dynamic massaging on the way into your DAW. The Tube Preamp section sports the usual controls with the high pass filter being noteworthy for its smoothness and usability. The EQ has fixed high and low bands at 10kHz and 110Hz respectively, while the midrange offers a large sweepable range between 300Hz and 7.2kHz making it a very versatile tool. The Opto Leveler is a simple one-knob affair and does a nice job of smoothing out transients and adding beef to sources. Finally there’s a simple output control and these last two stages have informative VU-style metering.

Overall, I found this plug-in to be a very handy tool indeed and quickly grew to like the no-frills grey presentation and the simple array of controls on offer. I tracked a full acoustic-based song using just the Century Channel Strip with Neumann U87 and SM57 microphones and was really happy with the results. Acoustic guitars gained body and shine with some EQ and subtle compression, vocals sounded sweet and present and drums also worked nicely with the Opto Leveler giving me some nice grit and density on overheads and bass in particular. The preamp sound is subtly flattering without adding too much hype or mojo when you don’t want it. Signals can get pretty furry when driven hard through this ‘circuit’ and its not necessarily a pretty sound so you need to watch your input levels. The EQ is basic but very useable while the leveller keeps things nicely in check. The name of the game here is gentle signal optimisation while tracking, so kissing your sources lightly with EQ and compression is the way to go rather than sticking the tongue in (so to speak). The leveller can get a bit grabby above -3dB of compression and too much boosting of those set EQ frequencies across a bunch of tracks will create problems down the line, but if you keep things light it’s a great way to sweeten and groom tracks for an easier ride come mix time. Full marks to UA for coming up with a tasty tube-based design that really takes full advantage of the Unison software/hardware interface.


Universal Audio has once again positioned itself well in a crowded marketplace by updating the Apollo converters and adding value to the new X range. Whether the incremental improvements in sonics, processing power and features are enough to see a mass migration from the older units to the new ones remains to be seen but initial pre-orders are strong in Australia and the units have been very well received overseas. Expect further software releases from UA in the near future that will unleash the full power of the X range with surround monitoring being the next cab off the rank. Who knows, perhaps we’ll see UAD-3 plug-ins before too long as well. Those who do pull the trigger on an Apollo X model will certainly not be disappointed by the sound or versatility of the units but, as always, buyers should be sure to keep a few extra dollars stashed away in the cookie tin for all those tasty UAD plug-ins.


To check out Greg Walker’s comparison between his original Silver Face converters and those on the x8, head to soundcloud.com/audiotechnology


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