There always seems to be some confusion on the topic of word clock, what it is and why it’s relevant. Let’s see if we can clarify some of this. First, let’s take a stroll back to digital audio theory 101.
When recording in the digital domain, the A/D convertors of a digital audio workstation are taking snapshots of the incoming audio signal at a specified rate. These snapshots are called samples and hence the term sample rate. So, by way of example, if you have a session that’s recording at 48k, the incoming audio is being recorded (or acquired) at 48,000 samples per second. Makes sense so far, right? Now, in order for all these samples to play back at the same way in which they were recorded (which in this example is 48k) there has to be a common clock source as a point of reference.
Now, I know what some of you may be thinking: “If I don’t own an external clock, how does this process work on a system just using a computer and a firewire or usb interface?” Answer: All digital devices have their own internal word clock-everything from CD players to home computers using just iTunes. Otherwise the playback of the digital audio wouldn’t work properly. Now, this doesn’t always mean the fidelity of that clock is necessarily all that great. Remember: When you purchase a $400 audio interface that has microphone preamps and a bunch of other bells and whistles, you get what you pay for. Convenient? Absolutely. Audiophile? Far from it. But, what happens when there are multiple digital devices in the chain? Good question. Here’s an example we like to use:
Imagine a band with a drummer who can keep good time. The drummer sets the beat, everyone follows along, and they sound great. But suppose each band member decides to use their own metronome and listened to it rather than the drummer. Even if everyone set his or her metronome to the same tempo and tried to start it as soon as the drummer hits the first downbeat, reaction times would vary and they won’t all click at exactly the same time. Furthermore, the metronomes may not be calibrated the same way or be perfectly stable in the first place. So after a couple of minutes, the performances will all start to drift further and further apart. That would become one very sloppy band!
Like said band , all digital components need an accurate clock to keep the data stepping through at a constant rate. Otherwise this sloppiness called jitter occurs and the fidelity and accuracy of what you’re hearing is compromised.
Below are links to download some files that compare the differences between an internally clocked mix and the same mix clocked using the Drawmer M-Clock Lite. I encourage you to download the files (right click on the file name) and listen to the sonic differences. Drawmer makes the only line of digital clocks that follow the AES Grade 1 clock specification-the highest regarded specification known for superior clock performance. People ask me all the time what is a quick and easy way to improve the fidelity of their mixes. I always suggest using a master clock. It’s an easy addition and a sure fire way to make sure everyone in your digital audio workstation is playing on the same team.