Processing and Control for Professional AV Installations
Legacy Hardware

GENx6 Word/Super Clock Generator

The AESx4 is used to distribute AES3 (2-channel digital audio) or AES11 (digital audio clock) between equipment using standard 3-pin XLR connectors. A switch on the front panel allows you to select between a word clock and an AES input. When the AES input is selected, either AES3 or AES11 can be buffered then distributed to the outputs. When the WORD CLOCK input is selected only, AES11 is generated based on the sample rate of the word clock.


Superclock is a format used exclusively by Digidesign in their ProTools series of software and hardware. It is a clock reference that is 256 times the sampling rate. In theory this makes the clock more accurate because there are so many more pulses in the data stream. When interfacing with a ProTools system, make sure the output of the clock generator is set to Superclock. When incorporating regular Word Clock devices along with a ProTools system, it is necessary to support both formats simultaneously. The Lucid GENx6 will only do one at a time, but can be locked together with another GENx6. The GENx6-96 and SSG192 can support both formats simultaneously.

The GENx6 can only be set to output one or the other on all of its outputs. However, the outputs on the GENx6-96 can be switched individually to output one or the other.

Word Clock is the timing reference that keeps the sampling rate constant. If, for example, we were recording at CD quality which means the A/D converter has to take 44,100 measurements of the incoming sound wave every second. If the clock isn’t as stable as it should be, then some seconds will have 44,100 samples while others might have more or less. The end result is a less than perfect digital representation of the wave. The clock frequency is the same value as the sampling rate.

All digital audio gear requires some kind of timing reference in order to accurately maintain the sample rate. Because of this, every piece of digital gear has an internal clock. When digital communications are desired between devices, allowing each subsequent unit to control its own clock can and will result in degraded audio performance. This can be heard as “smearing” of the audio, loss of accuracy in the high end, degraded stereo imaging, and even clicks & pops. Controlling all of the sample clocks from one master timing reference eliminates jitter (timing irregularities) and assures the integrity of the sample rate, yielding better sounding audio.

20ps rms, 50ps peak jitter; 10ppm typical, 50ppm max drift.

Many digital devices now support external clocking. Generally, if the unit has a digital output, it will probably have clock input and output connectors. The most common format uses a BNC type connector (tall, silver barrel on the chassis, twist-lock connector in the cable). This format calls for a special Word Clock cable. You’ll find this connection (external clock input) on digital consoles, DAT machines, CD-Rs, sound cards with digital I/O, processors, and of course, A/D converters.

Yes, the GENx6 / GENx6-96 can synthesize a Word Clock or Superclock output derived from the Word Clock, Superclock or AES input.

The GENx192 can only generate a Word Clock signal from an AES signal. Superclock was not included on the GENx192 since recent Digidesign gear does not have Superclock.

In an ideal world, yes. You cable the system up with equal length cables to avoid any delays in getting the clock signal to the target devices. Using mismatched cables could potentially negate the benefits of setting up a central clock system.

Word Clock cables should be kept as short as possible, not to exceed 15 feet.

You can put “T” splitters in, but due to the reflections and increased jitter this may defeat the purpose for having an external clock. Ultimately each device with a clock input should have its own direct connection to a clock output.