MASTER CLOCK: This section allows you to select the source of the board’s master
clock: Internal Xtal (crystal), S/PDIF In, or Word Clock. Master clock operation is outlined in the Synchronization section of this manual. Internal Xtal is the default setting. Be sure to select "S/PDIF In" if you will be recording or monitoring an S/PDIF stream, or "Word Clock" if you wish to synchronize your digital audio with a source device that is Word Clock capable.
NOTE: If "S/PDIF In" is selected as the master clock source, be sure to supply a valid S/PDIF signal to the board’s active S/PDIF input. Otherwise, erratic timing and/or improper sample rates will be experienced. The same is true for selecting "Word Clock" as the master clock setting – make sure there is a valid word clock signal present at the Delta 1010’s Word Clock In.
Once a master clock source has been selected, its synchronization status is continually monitored and displayed below the master clock radio buttons. If internal crystal is selected, the status display will always say "Locked." On the other hand, if S/PDIF In or Word Clock is selected as the master clock source, the control panel will display "Locked" only when a valid S/PDIF or Word Clock signal is detected. It will display "Unlocked" when there is no signal at the selected input, or when the signal is corrupt or invalid for any reason.
CODEC SAMPLE RATE: This section indicates the present board sample rate, as set by application software. The sample rate selected here will be used to drive the digital mixer and all outputs. The "Rate Locked" checkbox is used to force a sample rate upon the system. It is disabled by default to allow software access to all supported sample rates. When checked, it causes the driver to only operate at the selected sample rate. This means that any application that attempts to open the Delta 1010LT driver at a sample rate other than the one selected here will fail to do so and will post an error message. "Reset Rate When Idle" is selected when you want the sample rate to return to a particular setting when a software application is not actively using the board. This is particularly handy for keeping the digital mixer running at a specific sample rate.
NOTE: Because the digital monitor mixer runs at the sample rate of the rest of the board, and because sample rate directly affects frequency response, it may be desirable to keep the sample rate at or above 44.1 kHz while using the monitor mixer. This is accomplished by enabling "Reset Rate When Idle" and selecting a sample rate of 44.1 kHz or greater.
S/PDIF SAMPLE RATE: When using S/PDIF In as your master clock, this section tells the driver what the expected S/PDIF input sample rate is. The section is only displayed when the board is set to use S/PDIF In as the master clock source. From the list, select the sample rate closest to that of the S/PDIF input data. The sample rate selected here will be the only sample rate available to the software applications. Therefore, you must set your audio software application to this same sample rate or else the application will display an error message.
NOTE: When S/PDIF In is the master clock source, the digital monitor mixer will run at the sample rate received at the S/PDIF In. Since frequency response and sample rate are directly related, the mixer frequency response will be directly related to the sample rate of the S/PDIF input data.
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