But if you Google 'word clock jitter' or something similar, you'll find luicid (pun intended) explanations.ĭtobocman wrote:Use a word clock distributor if there are not enough BNC connectors coming off of your clock source. I'd try to post some examples, but my WC lives under the raised studio floor and is really clumsy to get to. My ears are not te best, and if I heard it, anyone with half an ear could. And when I added the Lucid clock, it was even more obvious. And I know that when I upgraded my clock from straight d8b board to their internal clock card, I could definitely hear a difference, instruments were better imaged, both front-to-back and pan scope. But every good engineer I know insists that there is an audible difference. When they are not precisely in sync, things get a little less transparent - I don't fully understand, myself, it seems to me that as long as you're on the same sample/clock cycle, you'd have 50% of the square wave half-cycle (25% f the clock speed) worth of slop and it should be all fine. Qo wrote:So, in order to be off by even one sample (1 sample per clock pulse), the difference in length between two cables would have to be 3122 meters.It's not a matter of being off by a whole sample, it's jitter from the leading edge of the clock. So, now the difference in WC cable length required to cause a one sample difference at 96kHz is 1040 meters So, let's assume 1/3 the speed of light, which seems to be the slowest of the above three options: 99,930,819 meters/second. Is not a constant, and needs to be calculated So, in order to be off by even one sample (1 sample per clock pulse), the difference in length between two cables would have to be 3122 meters.ĮDIT: There are various different answers regarding the "speed of electricity" (noting, of course, that the charge moves much faster than the electrons that make up that charge) that I've seen e.g.: Hence, at 96kHz, the cable distance between the leading edges of adjacent clock pulses will be about: Just to expand on this a little more, since I'd never really thought about this in these terms.įor simplicity, let's assume that the WC signal travels at the speed of light. Just remember the Highlander Word Clock Rule: There Can Be Only One! The worst method is to daisy-chain, then the clock goes in, is re-triggered and back out - this re-sqares up the signal, but causes a small delay, which translates into digital jitter, smearing the signal. If you don't have enough WC outs for each one individually, start T-connecting first, one T per output (and perhaps even add a T-connector to the ones that are single, just to maintain parity. (I use a Lucid GenX6 with 6 outputs.) The cables should all be the same length, and the proper impedance (I forget if it's 50 or 75 ohms,) this way, everything is on the exact same leading edge of the clock trigger, and jitter is minimized. For absolutely best accuracy and minimal jitter, each item should have its own WC input directly connected to the WC individual outputs - no G-connectors, and especially no daisy-chaining. The first and most important rule of using a word clock is to only have one master clock, everything else slaves from it.
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