Lynx Aurora 16 & AES16

Photo: Mark Ewing

With even the cheapest soundcards now offering 24-bit, 192kHz recording, is it still worth investing in high-end converters? Lynx certainly think so.

With their Lynx One and Two soundcards (reviewed in SOS November 2000 and March 2002 respectively), Lynx Studio Technology have done more than any other company to dispel the myth that audio converters are inevitably compromised when mounted inside a computer. Lynx products are now to be found in lots of professional recording and mastering studios worldwide. However, many studios still use rackmounted converters or digital mixers, yet with the continued move to computer-based workstations, need a way to interface these to their Macs or PCs. With this in mind, Lynx introduced their AES16, which as its name suggests supports up to 16 input and output channels of AES-EBU digital audio at sample rates up to 192kHz. Now they have completed the circle by offering rackmount converters of their own with similarly high quality to that of their soundcards. The Aurora is available in eight-channel and 16-channel versions, and has already caused a stir in the audio community for offering such high quality at significantly lower prices than some competitors. Partnering Aurora converters with an AES16 card provides various additional features, which is why I decided to review them both together.

Aurora Overview

The Aurora rear panel has a standard IEC mains connector for its internal PSU, BNC word clock in and out, MIDI In and Out (to control the Aurora mixer and update its firmware in the absence of an AES16 card), and a cover for the LSlot port that you can use to add the optional LT-ADAT expansion card, which offers two ADAT lightpipe inputs and outputs and supports high sample rates using S/MUX technology. The remaining ports are all DB25 connectors for Analogue In 1-8, Analogue Out 1-8, AES I/O 1-8, and (on the Aurora 16 only) Analogue In 9-16, Analogue Out 9-16 and AES I/O 9-16. Off-the-shelf cables from various third-party companies are available for direct connection to digital mixers and recorders from manufacturers such as Mackie, Sony, Tascam and Yamaha.

The Aurora connects to the outside world using a bank of D-Sub connectors.Photo: Mark Ewing

Both the Aurora 8 and 16 models feature an uncluttered milled-aluminium front panel, and apart from the number of LED peak meters in the oval window, are identical. A sample rate button has a periphery of LED indicators displaying the current rate, from 44.1, 48, 88.2, 96, 176.4 and 192 kHz, with six sync options. Of these, Ext/2 syncs to word clock at half the desired sample rate, for use with dual-wire AES-EBU devices — the Aurora 16 supports either 16 digital channels in single-wire mode, or eight in dual-wire mode — and LSlot is typically from the optional LT-ADAT card.

The associated Sync Source LED indicators flash in the absence of a suitable clock signal, while the adjacent Synchro Lock LED reflects one of the most potent features of the Aurora. When it detects a valid clock signal, it starts flashing at a low rate as it starts to analyse it, and during the next couple of minutes this flash rate increases several times as the two-stage system (the more typical phase-lock loop first, followed by a digitally controlled crystal-based secondary stage) performs its extensive number crunching, before the LED finally stops flashing once it's achieved the final low-jitter clock state. Synchro Lock works on any external word clock signal and becomes active once you choose any clock source other than the Internal one. It even has a wide mode that can track off-frequency clocks, but its narrow mode works on the standard sample-rate frequencies and can reduce jitter by up to 3000:1.

The attractive oval meter window displays both input and output levels of either the analogue or digital signals, with the brightness of the lower green LED indicating signal strength, and the upper red LED showing signals close to clipping. There's also an IR/MIDI indicator in the same window, as well as the IR transceiver itself, which is used to control Aurora parameters from a handheld, laptop or desktop PC with suitable infra-red capabilities using IrDA protocols (no Mac version of the Aurora Remote software is yet available).

Next to the Meter button is an associated Trim/AES Mode button — with the Meter in analogue position you use it to switch operating levels between +4dBu and -10dBV, while in the digital position it lets you cycle between single-wire, dual-wire input, dual-wire output, or full dual-wire modes, depending on what digital gear you're connecting.

Up And Running

The Aurora 16 works fine as a stand-alone product, but I didn't investigate its infra-red options, since the AES16 card offers more comprehensive control. I connected the Aurora's AES Port A and Port B to the AES16 Port A and Port B using two Lynx AES1605 cables, each carrying eight channels of digital inputs and outputs. Since both have transformer-coupled I/O and Synchro Lock jitter reduction you can apparently place the Aurora converters up to 500 feet away from the AES16 if required.

With the Aurora front-panel Analogue Out set to AES In, the Digital In set to Analogue In and AES routed to Analogue Out you can now use the Aurora 16 as a 16-channel external A-D/D-A converter box directly piped to your chosen computer recording software. The Aurora can also be accessed in a similar way from Lynx Two/L22 cards, using their LStream ports and the optional Aurora External LStream kit (just $60 — no UK price yet), although there are various sample-rate limitations — full details are in the Aurora PDF manual, downloadable from the Lynx web site.

I downloaded the latest Windows 2000/XP version 2 build 13f drivers for the AES16 from the Lynx web site and had no problems installing them in my PC. With the Aurora Sync Source set to its recommended setting of AES A, the Synchro Lock soon locked onto the clock from the AES16 card; you can select a sample rate from your software and the Aurora front-panel indicator will follow.

The Lynx Mixer utility provides zero-latency 32-channel 32-bit DSP mixing, with comprehensive routing options, real-time software metering, and access to a host of other parameters. It comprises three sub-windows relating to inputs, outputs and general functions. The Adaptor window provides a full read-out of the current system clock information including the Synchro Lock status, and that of the various digital input and output signals currently active.

The Lynx AES16 Mixer utility offers zero-latency mixing with up to 32 channels at 32-bit resolution and comprehensive metering, plus handy scene save/restore functions for live recording and broadcast applications.

The Record/Play window lets you patch any of the 16 Digital or 16 LStream signals to each channel of the on-board 16-channel DSP mixer, and also provides peak metering, mute button and various dithering options for optimally reducing incoming data from 24-bit to lower bit depths. There are also useful dropout counters for both recording and playback, so you know if any glitches have been detected since the start of each process.

The Outputs window provides versatile low-latency monitor mixing options. It lets you mix your choice of up to four record or playback signals from the 16 of each that are available, each with its own mute button, and then offers overall mute, overload indicator, digital level faders (as always, critical recording and mixdown should be performed with these at zero attenuation to avoid throwing away digital resolution), peak-reading meters, and output dither. Usefully, if you use any ASIO Direct Monitoring functions provided by your sequencer, the third and fourth Lynx monitor inputs on each enabled channel are automatically routed and labelled for you.

You can save and restore all your settings as mixer Scenes, and overall the Lynx Mixer is one of the most comprehensive that I've used. However, it remains extremely straightforward to use, unlike many others that cram their functions onto multiple tabbed pages in one window so you never manage to see everything you need at once.

In Use

As I rather expected, the Rightmark Audio Analyser results for the Aurora 16 measured via the AES16 were very good. The dynamic range measured 115.5dBA across all sample rates, while the frequency response had only dropped by -0.1dB at an very low 6Hz and extended to 21kHz with a 44.1kHz sample rate and to 35kHz with a 96kHz sample rate, though it dropped back to 25kHz at 192kHz. THD (Total Harmonic Distortion) and IMD (Intermodulation Distortion) were both very low at 0.0005 percent and 0.001 percent respectively.

All of these figure are roughly on a par with many other interfaces — indeed, my own Emu 1820M manages a 2dB better dynamic range — but they don't tell the whole story, which is why critical listening tests are still so important. It was obvious within the first few seconds that the AES16/Aurora partnership could beat the 1820M with one hand tied behind its back. Imaging was so pin-point sharp I could almost reach out and touch each instrument, and I've never been able to listen so far into reverb tails before, while high frequencies sounded brittle on the Emu 1820M compared with the top-end sweetness of the Aurora.

For Lynx Two/L22 owners who are wondering how the Aurora compares, Lynx told me that in essence the Aurora series is based on the Lynx Two/L22, but takes advantage of several component improvements, including the converter chips, so the Aurora's audio quality is slightly ahead on noise floor and distortion levels.

It's generally recommended that in large systems the A-D converter should provide the clock during recording, and the D-A converter during playback, to minimise jitter— external clocks use phase-lock loop circuitry that may compromise this. However, with the Aurora 16 Synchro Lock active I couldn't detect any degradation at all, whether I clocked it from its own internal clock or externally from the AES16. The AES16 drivers also proved to be extremely good — I easily managed the lowest 32-sample buffer setting in Cubase SX3 for just 0.7ms latency at 44.kHz, as I did in Sonar 5, and although the GSIF 2.0 drivers were unusual in following the ASIO buffer size (most provide a fixed size), they also worked well down to the lowest buffer setting, offering a 2ms latency at 44.1kHz. Meanwhile, Pro 53 provided typical Play Ahead settings of 30ms for Direct Sound and 45ms for MME. The only problem I had was with Sonar and its WDM/KS driver choice, where I experienced severe juddering at all latency settings, but given that ASIO performance in the same application was perfect with 0.7ms latency at 44.1kHz, I suspect few people will worry about this.

Final Thoughts

Each interface in the Lynx range has in turn gained an enthusiastic following among those demanding high-quality audio, and the Aurora series continues this trend. Sixteen channels of A-D and D-A converters of this quality seems a bargain at around £2300, and I suspect Lynx keep prices down by omitting features that you may or may not use. For instance, competing converters from other companies may offer ADAT and Toslink optical I/O as standard, but if this is important to you, you can add it to the Aurora via the LT-ADAT card for around £220. Real-time dithering for CD or DAT reference copies isn't built-in to the Aurora itself, either, but you get it when the AES16 is attached. Likewise, sample-rate-conversion is not offered as standard, but if you partner the Aurora 16 with the AES16-SRC you get eight channels of this at mastering quality if you need it.

Indeed, with its extremely low latency, rock-solid drivers and versatile digital mixer, the AES16 card is an excellent partner for anyone who wants to neatly integrate up to 16 channels of high-end 192kHz converters with PC/Mac software like Cubase SX, Logic, Nuendo and Sonar. Even rival manufacturers like Benchmark Media Systems and Mytek Digital recommend the AES16 for partnering with their own converters.

I would always advise anyone about to buy professional converters to find a dealer who can audition several side-by-side, or offer several for a trial period, as each is likely to sound slightly different and have a slightly different feature set that may sway your final decision. Nevertheless, to my ears the Lynx Aurora range offers something special, and can compete on audio quality with converters from other companies such as Apogee, Lavry and Mytek, but often at a significantly lower price per channel. Lynx have done it again!