Sample Rate Control - Art DMPA Instruction Manual

Generally, keep the unit in 24-bit mode (the out position of the switch) unless you are connected to
a system that will truncate the signal to 16 bits. The 24-bit mode has significantly greater dynamic
range.

Sample Rate Control

The Sample rate knob determines both the output sample rate of the DMPA as well as the digital
data format. You can select either AES/EBU (pro) format or S/PDIF (consumer) data format. This
allows the DMPA to interface to a wide variety of digital inputs.
The S/PDIF mode has copy protection turned off, and identifies itself as an A/D converter with 24
bit data.
The AES/EBU mode identifies itself as either locked (when set to an internal sample rate) or
unlocked (when set to Wordclock or ADAT as a sync source). No other channel status data is
sent.
The first step in determining the correct sample rate setting is to choose the data format. If you
plan on using the cannon output (AES/EBU jack) make a sample rate selection on the right half of
the selection range.
If using the coaxial (RCA jack) output make a selection of the left side of the sample rate knob.
The internal sample rate can be set from 44.1KHz to 192KHz. Simply select the correct rate by
turning the knob to the rate you need and the DMPA will use its' internal crystal controlled oscilla-
tor to accurately generate the selected timing.
Be careful in adjusting this control. Some equipment is not capable of the available sample rates
and may produce damaging side effects. Always turn down levels following the DMPA when
changing the sample rate.
External sync sources are Wordclock and ADAT INPUT.
Wordclock is a 5V logic level signal interfaced by a BNC connector on the rear of the unit. The
range of wordclock accepted by the DMPA is 28KHZ to 212 kHz. It is recommended that you use
wordclock whenever possible, as this will minimize interface errors with other equipment.
NOTE: When using the ADAT optical output, the maximum sample rate is limited to about 50KHz. If wordclock
exceeds this the ADAT output (if selected) will fail.
The ADAT Input on the rear panel is used as a timing reference as well as a source of data to be
passed on to the ADAT output of the DMPA.
If the unit CANNOT sync to an external source (either out of range, not connected or a system
failure), the optical Output select switch will blink. (You may see this switch flash once between
changing sample rates, indicating the fraction of a second it takes to settle to the new rate. This is
normal). NOTE: When using the ADAT Input as a sync source, the maximum sample rate is
limited to about 50KHz Sample Rate (selection being set to ADAT - not wordclock or any other
fixed sample rate).
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