Specifications

Prism Media Products Limited AD-2 Dual-rate A/D converter
Operation Manual
Issue 0.2 © Prism Media Products Limited
11 August 1998 Page 42 of 58
7.3. D-D mode Performance Specification
7.3.1. General
With the input and output sample-rates synchronised, the D-D path of the AD-2 is
transparent to 24-bit audio data, unless redithering is selected.
Dither can be selected as 'flat' i.e. optimal triangular-probability-density-function
(TPDF) unweighted noise, or one of four proprietary noise-shaper (SNS)
characteristics may be selected. Noise shaper spectra are shown in section 9. The
dither and SNS characteristics are automatically adjusted independently for the Main
and Aux output paths according to wordlength and sampling rate.
7.3.2. Auto-dither-defeat
The AD-2 automatically prevents unwanted dither being added. In the case of the
output wordlength of either Main or Aux paths being the same or longer than that of the
incoming data, dithering of that path is over-ridden, and the path's 'auto-dither-defeat'
LED is lit. This feature also operates when 'digital black' (i.e. all-zero) input data is
detected, so preserving digital black at the output.
7.3.3. Group delay
Group delay (no SRC): Nominally 68/fs (0.71ms at fs=96kHz)
7.3.4. Sample-rate-conversion
The AD-2s synchronous sampling-rate-converter (SSRC) produces negligible noise
and distortion and is much superior in this respect compared to conventional
'asynchronous' sample-rate-converters.
For the 96kHz to 44.1kHz sample-rate-conversion case:
Dynamic range or signal-to-noise ratio (1kHz@-60dBFS):
141.70dB (unweighted RMS)
Total harmonic distortion and noise (1kHz@ -1dBFS):
-135.0dBFS (0.00002%) (unweighted RMS)
Maximum spurious component (1kHz@-1dBFS):
-157.6dBFS (unweighted RMS)