The DAC and Upsampler have 3 and 2 Word Clock. The input is terminated with 75 internally. The Vivaldi Master Clock has 2 Groups of outputs, each of which can be set to any of 6 standard clock frequencies. The cable length should not exceed 100 m (330 ft). Word Clock signals are usually generated by crystal oscillators, which use quartz that resonates at a precise frequency (a bit like a digital watch). Word Clock is a continuous square wave pulse running at the sampling frequency. My converter clock was in the sub-picosecond jitter range, about 600 femptoseconds. Word clock can be sent and received via 75 coaxial cabling at the corresponding BNC connectors. To simplify: the clock identifies when each sample should be recorded or replayed. S21:46:35 GMT -6 svart said:Coming from someone who designed their own converters and designs clocking solutions for RF that are 100x better jitter and phase noise than audio requires. Either way, the function of a clock is to switch from high (a logical 1) to low (0) up and down continuously on, off, on, off all day long. Setting the pace for all that follows the clock can be a single trace or a partnership of two traces that carry complementary signals. quite a large difference!Īnyway, the other side of the story is that a lot of people actually prefer a little jitter on the clock as it smoothes out harmonic content and softens harshness. Clocks are essential gatekeepers of the digital domain. However, word clock does more than merely beat time it also identifies the start and end of each digital word or sample, and which samples belong to the left or right channels. To give a bit of comparison, ADAT standard required clocks with less than 1 nanosecond of jitter at 48KHz. The 'metronome' that governs sample timing is called the Word Clock (sometimes conjoined to 'Wordclock', or abbreviated to 'Wclk'). My converter clock was in the sub-picosecond jitter range, about 600 femptoseconds. Power supply and system noise on the I2S data bus are a greater issue since careful PCB layout is needed for optimal performance, but rarely understood by those who've only done audio work. This divides deterministic oscillator jitter by the same amounts, leading to internal system clock jitter to be extremely low, generally almost as low as to be considered negligible in general sampling work. Most modern designs use multi-MHz DPLL-based oscillators then divide the frequency down 256-512 times to reach converter oversampling frequencies, or further down to direct word sampling frequencies. In digital audio electronics, a word clock or wordclock further explanation needed is a clock signal used to synchronise other devices, such as digital. The act of using interconnects, cables, buffering, phase locking, re-clocking through a DLL/PLL to reach usable sampling frequencies, etc., All conspire to reduce clock performance to levels below all but the worst internal clock. Coming from someone who designed their own converters and designs clocking solutions for RF that are 100x better jitter and phase noise than audio requires.Įxternal clocks for audio are almost never worth the cost.
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