记得之前收da2的帖子也有你。时钟同步和外部时钟是从专业领域里”传“到民用hifi的,数字设备越多(包括你说的ad、dsp等等),时钟同步越重要,不然你猜ravenna最重要的特性之一为什么是它的ptp同步。反倒是民用hifi领域,单台da设备用外部时钟是否优于内部时钟是有争议的。
摘了一段关于clock source重要性的介绍:
How Do My Digital Audio Devices Use Clocks?Virtually every digital audio device will have an internal digital clock. (The most common exception is the stand-alone D‑A converter, since most of these rely on the clock signals embedded in the digital audio being fed to them.) In a typical project studio, there will be a clock circuit in any stand-alone A‑D converters, in the audio interface, and in any external digital processing hardware. Those clocks are generally based on pretty accurate and reliable piezo‑electric quartz 'crystals', which vibrate continuously at a fixed and stable frequency determined by the size and shape of the crystal. In digital audio applications, most crystal clocks operate at a frequency around 128 times higher than the standard sample rate, although some operate with greater multiples to provide greater accuracy. The frequency of vibration of a quartz crystal varies slightly with temperature, so for extremely accurate systems the crystal is often placed inside an 'oven', to ensure a consistent operating temperature. For really accurate systems, the much higher frequency atomic vibration of materials such as caesium‑133 or rubidium‑97 is used instead, but this gets very costly and is largely unnecessary in the majority of digital audio applications. When combining or interconnecting digital signals from different equipment or sources, it's vital that the audio samples from each device arrive at exactly the same time, so that their data can be mixed together or otherwise processed. If they don't arrive together, samples from some sources will be missed, and clicks or glitches may be heard. The golden rule is that one device has to be declared the 'master' clock source for the whole system, and everything else must be 'slaved' to that clock source to ensure that everything generates samples at exactly the same time and rate. Think of an orchestra: only one conductor can wave the baton if you want everyone to play in time!
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