Digital audio facilities often require a number of clock sources, which are used to synchronise outboard processors to the system clock rate using external clock inputs. The Drawmer D-Clock is a dual input, twenty output word clock distributor with a 16 character blue LCD display providing a high accuracy reference measurement of the incoming sample rate.
It has both AES/EBU and BNC word clock inputs featuring a zero latency loopthrough output with switchable high impedance to maintain the correct level of the digital signal for onward distribution. Sixteen BNC clock outputs are situated on the rear panel with a further four BNC clock outputs on the front panel for quick patching to other digital devices.
The D-Clock uses a high stability TCXO (temperature compensated xtal oscillator) along with a microcontroller to measure the incoming sample rate to an accuracy of 2ppm and displays the information in three different formats, actual frequency (to one decimal place), nominal frequency +/- ppm error, or nominal frequency plus percentage of pull up or pull down.
Overall, the D-Clock works extremely well, and the unique display provides useful reassurance that all is working as it should be. If you can make use of up to twenty word-clock outputs in your digital environment, this is a very cost-effective and useful item to add to your rack.
The wordclock outputs can be fed from the wordclock input at any sample rate between 32KHz and 768KHz or derived from an AES11 input or stripped from an AES3 audio signal at any sample rate between 32KHz and 192KHz. Using an audio signal to provide the clock means even products without a wordclock output, such as some analogue to digital converters, or one of the many mic pre-amplifiers with internal A/D conversion but no word clock output, can be the master wordclock source for the whole digital studio.
