L U C I D SRC9624

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SRC9624 specs (click for larger view).

Cure For The Jitters
One digital audio recording aspect that never gets enough attention is the need for sampling-rate synchronization within a digital network. To reduce clicks, pops, and jitter distortion when using multiple digital devices, you must sometimes lock the sampling-rate timing to a single master-clock signal (so devices’ conversion states occur simultaneously).

The SRC9624 can lock to an external source through a BNC word-clock connection, through an AES11 port that receives sync data from an XLR cable link, or through a standard AES digital transmission line (the audio information is stripped out at the box). The unit can also generate a master word-clock signal at any of its five internal clock rates, and can resynchronize a jittery input signal that has introduced timing errors (which can cause the audio signal to degrade and sound fuzzy) to any of these rates.

Inside Connections

LUCID SRC9624 sample rate converter $1,995
Features	— — — —
Ease of Use	— — — — -
Audio Quality	— — — — -
Value	— — —
PROS: Simple, straightforward, and elegant. Full range of sample-rate and bit-rate options. Useful as a digital patch bay. CONS: Changing the front-panel settings causes output data (on both data paths) to glitch.

Using my M Audio Delta 1010 interface, I recorded a 24-bit, 96 kHz test session with vocals, flute, and percussion. I then transferred the recorded file to my 16-bit, 44.1 kHz DAT recorder and experienced no downsampling hitches. Next I upsampled and downsampled sounds between several devices at various rates, using all three formats and various master-clock configurations. Again, I had no problems. Data paths A and B were indeed independent and passed data without interaction, except that changing any switch setting on one caused the other to momentarily glitch and mute. I just had to remember to leave the front panel settings alone when an audio signal was passing through the unit.

The input connections for the different formats are completely separate and selectable from the front panel; this simple feature lets you use the SRC9624 as a digital patch bay. For example, you could plug a DAT into AES port A, a workstation into S/PDIF port A, and a CD player with optical S/PDIF into port B, then route signals between them (or route a single input to several devices) by just flipping the front-panel switches. The input status LEDs light up only when data is present at the input, a seemingly minor feature that saves time when you can’t figure out why you can’t get audio into your DAT machine.

I Love Lucid
The SRC9624 is perfect for music, video, and broadcast production houses, where you never know what digital format or sample rate will cross your path. It also saves time and labor. Changing between sample rates, routing between digital devices, and distributing data for making duplicates is just a flick of a switch away.

David Miles Huber is updating his best-selling book, Modern Recording Techniques, for its fifth edition (Focalpress.com). You’ll find his musical explorations at www.51bpm.com.

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