Using the initial default setting, the master clock is derived from the internal crystal oscillators. Operation in this mode is similar to that of a generic sound card – for instance, when an audio file is played through the Delta drivers, the software application playing the audio file is responsible for setting the sample rate in the sound card hardware. The Delta 1010LT supports these sample rates by using either of its internal crystal oscillators and dividing the rate of that oscillator by some value to derive the proper sample rate.
In situations where S/PDIF In is being used, the Delta 1010LT should usually be configured to get its master clock from the S/PDIF In data stream. The reason for this is simple – an S/PDIF data stream coming from an external source is rarely going to be in sync with the Delta 1010LT (or other digital audio devices in the system for that matter), even if the sample rates are set the same. If the master clock were set to use the internal crystal, then the incoming S/PDIF audio would have "pops," "crackles," and other undesirable audio artifacts present in it. Instead, setting the master clock to "S/PDIF In" will synchronize the Delta 1010LT to the S/PDIF input data and its digital audio will be transferred properly. There is one special case to consider, however. The external unit sending the S/PDIF digital audio to the Delta 1010LT may be "locked" to the word clock emitted from the Delta 1010, or both the external unit and the Delta 1010LT are locked to the same external word clock. In these cases, the Delta 1010LT and the external S/PDIF device are
We’ve discussed internal crystals and S/PDIF In as master clock sources. The third option is Word Clock. Word Clock is the desirable choice when you want to synchronize the Delta 1010LT with the word clock of something else in your system. That "something else" may be a another unit that has a word clock output, or it may be a dedicated house word clock generator.
Finally, the Word Clock and S/PDIF In options may be used to operate the Delta 1010LT at
NOTE: When either the S/PDIF In or Word Clock is selected as the master clock source, the Delta 1010LT mixer’s frequency response will be affected by whatever sample rates you inject at the S/PDIF In or Word Clock In. This is because (1) the digital mixer operates at the same sample rate as the rest of the board, and (2) sample rate and frequency response are directly correlated.
Using the Delta 1010LT with your Music Software Application
Once the Delta 1010LT’s hardware and driver software are properly installed, it is ready for use with your music application software. Some of these applications may require you to highlight or enable the Delta 1010LT drivers within the program, and others may have a utility that analyzes or profiles the audio cards in your system and enables the drivers. Your software should have an audio device driver setup page.
16