User`s guide

APOGEE ELECTRONICS
4
Mini-DAC – User’s Guide
APOGEE ELECTRONICS
5
Mini-DAC – User’s Guide
The clock circuitry of a typical
D-to-A converter must be
designed as a compromise
between the ability to attenuate input
signal jitter and the ability to accept any
bitstream, regardless of it’s stability. The
more the clock is allowed to track timing
variations of the input, the more jitter
remains in the clock at the conversion
stage, with the degradation of conversion
quality as a result. The Mini-DAC’s Dual
Stage Clock overcomes this compromise
by employing one clock stage to accept
the bitstream and store bits in a buffer,
and a second stage to clock bits out of
the buffer to the conversion stage. The
 rst stage is optimized to track timing
variations of the input, while the second
stage is optimized to attenuate jitter and
ensure that conversion takes place with
the lowest jitter clock possible.
Navigating the Front Panel
1) SAMPLE RATE - These four LEDs are used to indicate the six available
sample rates at which the MiniDAC may operate. When the MiniDAC is not
receiving a valid digital input, all the LEDs  ash sequentially in a repetitive
pattern. Once MiniDAC has received a valid input, the automatically
detected sample rate is indicated as shown below.
2) INPUT SELECT – The following digital formats may be selected with
the INPUT SELECT knob; for a more detailed explanation of the various
digital formats accepted, please see the section of this manual entitled
“About Digital Audio Formats” on pg. 12.
1) USB – input is accepted from the USB connector. Simultaneously, the
 rst digital signal (in speci c formats) detected on any other input will
be converted and transmitted to the USB Output. Likewise, when any
other format is selected as input, the signal is also transmitted to the
USB Output. Please see “Working with USB” for more information on
USB Format Conversion.
2) AES DOUBLE – input is accepted from the AES 1 & 2 connectors and
treated as Double Wire format.
3) AES 1 SINGLE – input is accepted from the AES 1 connector and
treated as Single Wire format.
4) AES 2 SINGLE - input is accepted from the AES 2 connector and
treated as Single Wire format.
5) S/PDIF CX (Coax) - input is accepted from the S/PDIF coaxial (RCA)
connector;
6) S/PDIF OPT - input is accepted from the Optical connector and
treated as S/PDIF format.
7) ADAT (pairs 1/2,3/4,5/6,7/8) - input is accepted from the Optical
connector and treated as ADAT format; any pair of channels (1/2,3/
4,5/6,7/8) may be selected as Mini-Dac’s input.
8) S/MUX 88.2/96 - input is accepted from the Optical connector and
treated as S/MUX format at 88.9/96 kHz; only channels 1/2 may be
selected as Mini-DAC’s input
9) S/MUX 176.4/192 - input is accepted from the Optical connector and
treated as format at 176.4/192 kHz.
44.1k 48k 88.2k 96k 176.4k 192k
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