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Studio Concepts: What is Word Clock?

Keeping Your Studio In Sync

Brandon Stoner · 01/10/25

Word clock is a digital audio standard that confuses a lot of people. Put simply, it's a way to connect multiple digital devices to send an electrical signal, or “pulse” to keep them in sync to the same sample rate and channel information.

Here we discuss the type of gear that uses it, how to integrate it into your studio, and why it matters.

What is Word Clock?

As mentioned, word clock is a way to synchronize digital audio equipment to ensure each piece of gear is receiving the same sample rate. The signal traveling from output to input is a square wave with an electronic pulse for the start of every sample. It provides more than just sample rate information though, like channel identification.

If the DAW session runs at 48kHz, all gear slaved to the master device is receiving 48,000 pulses per second. Clocking signal tells receiving devices where each sample begins and sends a consistent flow of sample start information through cabling.

If you’re working with analog hardware (other than your interface), word clock shouldn’t really be a concern. But it’s an important concept when you’re integrating external digital hardware like effects units into your setup, because almost all digital audio equipment has an internal clock.

Word clock transmits over different kinds of cables including coaxial, ADAT, S/PDIF, AES/EBU, MADI, and TDIF. Like with unbalanced cables, the length of the run should be kept in mind. It’s recommended that cable runs shouldn’t be longer than 330 feet, which is in pretty stark contrast to other types of unbalanced cables. Remember, length and quality of cabling always matters!

How Use Word Clock in Your Studio Setup

[Above: the Black Lion Audio Micro Clock MkIII]

Since it’s designed to synchronize digital audio signals across multiple devices, any type of digital audio gear is likely to use it—though not all offer it. It’s most common in professional audio gear, but you can find it in consumer devices like sound cards and other types of playback equipment.

When digital equipment started becoming more popular and studios moved to a hybrid model it was routed to a standalone master word clock. Some still use this setup, but since the audio interface is usually the centerpiece now it and the DAW now function effectively as the master clock.

A single device (in modern studios usually the interface) needs to be considered the “master” clock and all other digital devices need to be “slaved” to it. The most critical element in the clocking chain is the analog-digital converter. So if it’s built into the interface, then that becomes the master. If standalone A-D converters are used it’s best to designate that as the master.

Standalone word clocks aren’t without their issues, and they are susceptible to jitter. While they’re becoming less common, master clocks are essential for syncing audio to video because the audio sample rate has to be in sync with the video frame rate. To make these different mediums work together, a master clock is synced to an external video reference or creates one.

Why Word Clock Matters

It’s an older standard, but word clock is an essential part of a digital audio workflow. If devices aren't receiving the same clock rate you'll likely experience digital audio artifacts like distortion, jitter, clicks, and pops. Not fun.

If you're using multiple interconnected pieces of digital gear it's essential to make sure they're all synced to a master clock so the sample rates are aligned. Nothing kills creativity faster than glitches!

Word clock is all about providing synchronicity between digital audio devices. It can seem confusing at first, but it’s a pretty simple concept. By connecting all of your digital audio gear through the standard you ensure that they are all receiving a uniform sample rate. This is key to avoiding digital artifacts like clicks, pops, and jitter that can ruin production takes and make mixing and mastering frustrating, especially if video is part of the project.