- DIGITAL AUDIO WORD CLOCK GENERATOR
- DIGITAL AUDIO WORD CLOCK CODE
- DIGITAL AUDIO WORD CLOCK PROFESSIONAL
- DIGITAL AUDIO WORD CLOCK SERIES
Series distribution requires that your digital devices have both a BNC word-clock input and a BNC word-clock output. When working with multiple slaved devices, the job gets a bit more complicated. Of course, if your digital-device chain only consists of one master and one slave, syncing the two is as simple as connecting a BNC word-clock cable from the output of your master device to the input of the device you are slaving. Once you’ve determined which device is to be your master clock, you will need to sync the remaining digital devices through series or parallel distribution or some combination thereof. This is done with careful listening and A/B testing. You generally need to determine which device has the best clock and to designate that device as the word-clock master. Synchronizing a device to a lesser-quality clock source is likely to degrade its performance, and not all word-clock generators are created equal. Whether you are using BNC or another digital output to generate word clock, it is necessary to designate one device as the “master” word-clock device to which all other digital devices are synced, or “slaved.” Many digital devices perform equally well as a master or a slave, although some devices must be one or the other. Synchronizing Multiple Digital Audio Devices This ensures accurate timing when going from an audio interface to a computer and back. The receiving device buffers the signal, reassembles the sample stream, and then sends the audio signal from the buffer at the appropriate time, as determined by the device’s sample rate. Computer transport protocols (FireWire, USB, Thunderbolt) don’t use an embedded clock for timing instead, they use a process called reclocking, in which the audio stream is divided into packets of data that are transmitted sequentially. Every PreSonus device equipped with ADAT, is also equipped with BNC word-clock for dedicated, stable clocking. BNC connections are made in several impedances but PreSonus devices require an impedance of 75Ω to achieve consistent sync. The cables are rugged and can carry clock signals much farther than standard optical cable. In this system, word clock is sent over dedicated, shielded, coaxial cables with standard twist-lock, BNC-type connections on each end.
DIGITAL AUDIO WORD CLOCK PROFESSIONAL
Word clock is used for a few types of distributed-clocking systems but the most common in professional audio uses a BNC connector.
DIGITAL AUDIO WORD CLOCK CODE
Word clock does not carry location information, the way time code does, nor does it carry audio information it only determines the rate at which samples should occur.
DIGITAL AUDIO WORD CLOCK GENERATOR
(A word, in this case, is a fixed-size group of digital bits.) A word-clock generator creates digital pulses that control the frequency of the internal oscillator of each device to avoid frequency drift. The clocking signal in a distributed clocking system is called word clock. In a distributed system, sync signals and audio signals are separate.
This makes the clocking stream cleaner than a self-clocking system. Commonly used in professional environments with multiple digital devices, distributed clocking systems provide more stable clock because the clocking stream that does not contain audio. Self-clocking is implemented in every digital audio protocol (ADAT, S/PDIF, AES/EBU, etc.), and all PreSonus devices that offer these protocols employ self-clocking systems for those connections.ĭistributed. The receiving device extracts the embedded clock signal from the digital audio. Samples are streaming in real time, with the clock marking the start time of each sample.
In a self-clocking system, the clock signal is embedded in the audio stream. There are three basic clocking systems in common use in digital-audio systems:
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