Download Navigation
Home | Support | Tech Notes | MOTU Hardware: Clock Source Setting
Document Actions

MOTU Hardware: Clock Source Setting

Your MOTU hardware operates based on the settings made in the MOTU Audio Setup (Mac OS X) / MOTU Audio Console (Win) application. After successfully running the Universal Audio Installer, (found on the Downloads Page), reach for the appropriate application to adjust settings like sample rate and output assignments.

Often misunderstood, arguably your hardware's most important setting is "Clock Source". The clock source setting determines which digital audio clock is being used as your hardware's time base. Here is a quick run-down of the choices you might have available. Keep in mind, the options you see will vary based on which audio interface you are using. Check out the Product Manuals page to read up on the specifics of your hardware.

  • Internal: Internal is the default clock setting, and is an available option for all interfaces. Using this setting, your hardware operates under its own digital audio clock, and is the appropriate choice when recording only analog inputs, or when simply playing audio tracks from disk. Also, when using your MOTU hardware as the master clock source, "Internal" is the appropriate choice. If you don't need to reference an external clock, record digital inputs, or perform any digital audio transfers, Internal is the choice you are looking for.

  • Word Clock In: If your hardware has a BNC Word Clock Input, you will find a "Word Clock In" option. Selecting this option allows your interface to slave to a connected external clock, be that a standalone Word Clock Generator, or even another MOTU interface equipped with Word Clock BNC Connectors. For the latter, set Unit A's clock source to Internal, (as its clocking information will be broadcast through the Word Clock Output), which Unit B can resolve to if its clock source is set to "Word Clock In".

  • S/PDIF, ADAT Optical, TOSLink: Depending on your unit's I/O configuration, you may find several options referencing the digital inputs on your hardware. Choosing one of these options will sync your unit to the clock provided by the digital input. Note: ADAT Optical or TOSLink will only appear as an option if it is enabled as the Optical Input format for one of your unit's Optical Bank(s).

  • SMPTE: Nearly every piece of MOTU hardware can resolve to SMPTE time code (LTC) through an analog quarter-inch (TRS) input. This allows your unit to resolve to any SMPTE timecode source, such as a multitrack tape deck. Use the MOTU SMPTE Setup (Mac OS X) / MOTU SMPTE Console (Win) application for configuration. Keep in mind, it is here where you can also generate SMPTE timecode, and utilize your MOTU hardware not only as an audio interface, but as a digital audio synchronizer as well.

  • Note Mac OS X Users: MOTU's Universal Audio Driver allows your USB or FireWire device to resolve directly to another CoreAudio driver. Considering this, you will find "Built-In Input" (for resolving your hardware to your computer's Built-In Input), and any other connected MOTU or third-party interface listed. Selecting one of these options insures your unit will not drift apart from other audio streams during playback or recording.

Knowing your hardware's clock source setting is imperative. An incorrect clock setting may result in digital artifacts distorting your recordings. More detailed information can be found in the "Making Sync Connections", "MOTU Audio Setup/Console", and "MOTU SMPTE Setup/Console" sections of your product's manual.