Imagine, if you will, that you have been magically transported back in time — back to a time when the monstrous Ampex Rex and Otariraptor ruled the vast studio lands. Relegated to stalking the basement caves was the diminutive, four-tracked TASCAM-asaurus, with its plaintive hiss and irksome flutter (and wow). Then the mighty Digidactyl swoops…
Right, that’s enough prehistory. What I’m getting at is this: The gulf between professional and home studio recording decks in the analog days was vast and clearly defined – often by a tens-of-decibels noise increase and disturbing quantities of intermodulation distortion. This gulf has been bridged if not completely filled in in the nearly exclusive digital-recording age (I’m talking about the recording system — not rooms, mic collections, talent, experience…).
A last remaining area separating prosumer from professional digital gear is the quality of audio converters and, of equal import, the clocks that drive them. And with so many products using the same or equivalent converter chips, the stability and manner of synchronization can be a top defining difference between digital recording systems.
Studio, mastering, audio-for-broadcast, audio post
8 word clock outputs; 4 AES-3/11outputs; 2 S/PDIF (unbalanced AES-3/11) outputs; can act as 1×4 AES distributor; 1 AES-3/11 and 1 word clock input; clock outputs divided between two banks allowing different clock multiples to be output simultaneously; automatic termination sensing and indication
Since its formation, the Lucid brand of Symetrix has earned healthy respect from the recording community for its high-quality audio converters and clocks, including the popular SSG192 Studio Sync Generator (which I ultimately chose over several contenders for my studio master clock). Lucid’s latest entry into this highly specialized and competitive market is the single rack-space GENx192 Ultra Low Jitter Studio Master Clock ($879).
At over $600 less than the SSG192, the GENx192 understandably lacks some of the higher-end features found on its bigger brother, including Superclock support and NTSC/PAL video house sync generation with pull-up/down correction. At the same time, the new GENx192 boasts interesting features that make this SSG192 owner jealous. First the basics…
The GENx192 Master Clock provides 14 sync outputs (almost twice that of the SSG) on its rear panel. Sync outputs include eight standard word clock outputs (on BNC), four AES-3/AES-11 audio/sync outputs (XLR-M) and two S/PDIF (unbalanced AES-3/11 on RCA) outputs. All outputs are evenly divided into two separate banks labeled A and B. For syncing to external sources, the GENx192 provides two inputs, one for standard word clock (BNC) and one for AES-3/AES-11 sources (XLR-F).
The GENx192’s front panel features a straightforward control set of just three selector switches (Sync Source, A Outputs, and B Outputs) and a block of eight green LEDs — one to indicate lock status and the remaining to indicate current sample rate (at the usual stops between 32 – 192 kHz). The two bank controls allow each bank of eight outputs to operate on different clock multiples simultaneously. Internal clock frequency is selectable from 44.1 – 192 kHz, and the unit can receive and redistribute incoming clock frequencies from 28 – 216 kHz.
Jitter is the ugly stepchild of digital recording. Every digital system has some, and it’s not known for playing nice.
To oversimplify, jitter is any of several unwanted variations in that which should never vary, namely the square-wave pulse synchronizing digital devices. This pulse also tells converters when to load and ingest (A-D) or spit out (D-A) the next sample. Any clock variation causes distortions in how an analog signal is sampled or reconstructed. Depending on the jitter type and amount, degradation can be heard in clarity, stereo separation, intra-channel separation/depth and what can subjectively be described as overall ease of listening.
Use of a multi-output master clock, such as the Lucid GENx192, is the first and best step you can take to reduce jitter. Mirror-image, individual clock outputs from a high-quality dedicated clock (instead of a long daisy chain through disparate gear, some with potentially questionable implementation), coupled with connections though high-quality 75-ohm cables will go miles on the road to reducing jitter.
The GENx192 comes with some innovative features that will help home and pro studio engineers alike get further down that road. My favorite of these is the set of nine tri-state “Termination” LEDs, one for each word clock output and one for the single input. These helpful little guys provide confirmation of termination status — invaluable information to ensure good clocking conditions. An amber light indicates an overvoltage/undertermined condition (or absence of connection on the outputs), and a red light indicates an undervoltage/overtermined condition (or absence of connection on the input). A green light indicates proper voltage and termination conditions. A termination switch is provided for the word clock input.
When syncing to an incoming clock, instead of using the common practice of synthesizing a new signal, the GENx192 uses jitter input filtering, which converts the input signal to a DC control voltage that directly drives the VCOs. In testing, I managed to drive the input with a purposefully crappy cable and source of questionable quality, and experienced no noticeable problems, audible or otherwise, clocking my digital gear downstream.
I found two other features of the GENx192 to be particularly (and potentially) useful. One is its freewheel ability, whereby if an incoming clock is interrupted or stopped, the internal clock takes over seamlessly. The other is its ability to act as a one-to-four AES audio distribution box.
Good clocks — ya gotta love ’em. The Lucid GENx192 fits the bill not only in its performance as a high-quality master clock, but also in its high-count output complement, flexibility and innovative feature set. I simply couldn’t find fault with the box with the exception of its lack of Superclock support. What I did find was a lot to like about GENx192 — especially at a street price as low as $650.
PAR Studio Editor Stephen Murphy has over 20 years production and engineering experience, including Grammy-winning and Gold/Platinum credits. His website is www.smurphco.com.