That's why it's best to run an A‑D from its internal crystal clock, rather than an external master clock, if possible, and why good D‑As go to so much trouble to isolate and remove interface jitter. In both of these situations, the signal is being converted between the analogue and digital domains, and precise, jitter‑free sample-clock timing is, therefore, absolutely essential. Where interface jitter becomes important is in the D‑A conversion stage, or when clocking an A‑D converter from an external master clock. Moreover, it doesn't actually matter in the case of transferring digital audio from one digital machine to another, anyway, provided all that is required is to identify each data‑bit value reliably. The diagram above, courtesy of Prism Sound, illustrates the effect.įortunately, interface jitter can be removed fairly easily using phase‑locked loops (PLLs) or other, often proprietary, techniques these days. This process is called 'interface jitter', and it is an intrinsic part of that kind of digital audio interface. The inherent capacitance within the cable reacts with those transitions and the result is small, but varying, time shifts of the transition point. The result is that the transitions depend on both the audio data and the clock data, so the transition rate varies. It's those transitions that define the sample points.īy contrast, AES3, S/PDIF and ADAT all embed the clock pulses within the audio stream by using a type of modulation process. But the important point is that the periods between each transition from high to low (and vice versa) will remain absolutely consistent.
Cable losses will slow the transitions, so what falls out the end of the cable will probably be a little more rounded than what went in. The reason is that word clock is a really simple square-wave signal running at the sample rate. Hosa BNC-59-110 BNC to BNC Cable for Word Clock Application - 10 ft.
75 ohm BNC to BNC Cable for Word Clock Application - 3 ft. Photo: Prism SoundĪSOS Technical Editor Hugh Robjohns replies: Theoretically, recovering the clock from a dedicated clock source via word clock should be easier and better - with less intrinsic interface jitter - than trying to extract an embedded clock from AES3, S/PDIF or ADAT interfaces. Hosa BNC-59-103 BNC to BNC Cable for Word Clock Application - 3 ft. However, passing an AES3 signal down a capacitive cable distorts the waveshape and introduces a timing ambiguity called 'interface jitter'.
BNC WORD CLOCK CABLE FREE
If a clock signal is a perfect square wave, as shown here, clock timing will be jitter free. This item: Geistnote's Apogee Wyde Eye 75 BNC Word Clock Cable WE-BB (0.5m) 45.00 Get it as soon as Friday, Jul 22 FREE Shipping on orders over 25 shipped by Amazon Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter 45. The Klotz World Clock Cable BNC 2m features flexible coaxial cables (stranded connectors) with high-precision characteristic wave impedance - premade with BNC connectors, providing high quality sound and long life span. When clocking an audio interface using an external device, such as a stand‑alone mic preamp with A‑D conversion, is it better to use the dedicated word-clock (normally BNC) connectors, or will the clock signal be just as good coming down the S/PDIF, AES3 or ADAT cable that is carrying the audio signal?
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