Popular Post JohnSwenson Posted October 22, 2017 Popular Post Share Posted October 22, 2017 On 10/19/2017 at 4:43 PM, esldude said: https://www.soundonsound.com/techniques/does-your-studio-need-digital-master-clock I don't see anything that changes the thinking of this 2010 article. Even the best connected clocks resulted in worse jitter than letting the ADC/DACs run on the native clocks. The process of locking to an external clock and the timing error from the cabling means at best, the internal slaved clock could only equal itself free running with locking to an external reference. That explains the measured results in jitter in this article. Inexpensive devices have poorer ability to lock to an external source. Some expensive devices do better, but also have a better clock internally to start with. Master clocks are for syncing several devices. The idea you improve sound with clocking locked to a better quality external clock is more audiophool woo. If you disagree, all I need are some good DAC output measurements showing with and without master clock with the master clock being better. PS-I would assume the master clock works with USB input on the Teac just fine. USB doesn't control timing of the Teac. It simply serves as a way to transfer digital data. The Teac runs off its internal free running crystal clock after that. Substitute referencing that internal clock to the master and it will work with USB like all the other inputs. The linked article is way out of date and not even looking at the same things. There are some REALLY good clock synthesizer chips on the market now, which did not exist when this article was written. These chips lock on to the reference clock and can synthesize multiple frequencies while adding extremely low phase noise of their own. There are two types on the market, the jitter attenuating type and the type that assumes you have an extremely low jitter reference. IF you have an extremely good reference the second type will give you better results, but the first type can take a not so great clock and turn it into an output that is much better than the reference! IF the DAC uses one of these internally then feeding it a really good external reference IS a good thing. Of course building that ultra low phase noise OCXO in the DAC to begin with would be even better, BUT having an external connection into one of these chips gives the user more flexibility. The DAC can come with a very good but not insanely expensive clock, which dramatically decreases the price of the DAC. When the user wants to upgrade they can add the insanely expensive reference clock without having to buy a new DAC. I can guarantee that NONE of the devices in that linked article had anything close to what is available today. Most of those "master clocks" that were covered are actually pretty lousy clocks. Their primary goal was to have lots of flexibility in input types and output types so they could be used in many different setups. The circuitry they used was even poor for the time. As far as phase noise goes they bear extremely little resemblance to the reference clocks that are being discussed these days, which JUST output 10MHz, but do it EXTREMELY well. That article goes into great length discussing how a master clock can get degraded by running it through a microphone cable. Nobody here is talking about running a 10MHz reference clock through a microphone cable. The people buying these are going to be using highly optimized extremely wide bandwidth cables which have very small impact on such a signal. Such a cable can be had for $50 from the professional RF companies so it is not particularly expensive to transfer the output from the reference clock to the DAC. All this is predicated on having a DAC which uses one of these modern extremely good clock synthesizers. If it doesn't, then yes, adding an expensive reference clock is going to be useless. John S. darkless, ElviaCaprice, lmitche and 8 others 6 2 3 Link to comment
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