Drawmer D62 Digital Module - Manual (Page 10)

D62 OPERATORS’ MANUAL 6
1962 FRONT PANEL DIGITAL CONTROLS:
Sample Rate:
This switch selects 48.0KHz, 44.1KHz and EXTernal clock for
synchronising to other digital devices. Any external clock input is ‘cleaned’
by the D62 PLL and output at the rear panel BNC connector marked
WORD SYNC Out.
Reduce monitor volume levels before casually selecting ‘EXT CLK’,
selecting it without any external clock connected results in a nasty 0dBfs
digital noise being output!
Word Length:
Selects the word length (bit resolution) of the audio samples to be 24, 20,
18 or 16 bits. Match this to your digital recording, storage or processing
device. Selecting ‘16’ sends 4 x stereo pairs of tracks to the TDIF or ADAT
output, while 24,20 and 18 sends high resolution tracks to the TDIF or
ADAT for recording on tracks 1,2,3 or 5,6,7.
Source:
Select ‘Chs’ for the most direct audio path (thus: highest performance) to
the D62 analogue-to-digital convertor, or ‘MIX’ which inserts the CHAN
PAN controls to the path. MIX also enables up to 3 additional analogue
inputs (eg. stereo outputs from other 1962 units) to be mixed via the rear
panel Stereo Mix inputs to the master D62 digital output. Pre- or post-
output level control is selectable on two internal jumper links. See
configuration jumpers section on page 9.
In all configurations the audio signal to the D62 passes through a ‘Soft
clip’ circuit, therefore short transient audio peaks will not cause noticeable
distortion on the digital outputs.
Dither:
1 - 12:
This affects the type of dither added to the audio signal when recording
with WORD LENGTH less than 24 bits. Position 1 is generally the best
compromise and places all of the dither noise at the high end of the audio
spectrum, where the ear is least sensitive. In the majority of situations,
this will produce excellent results. The other 10 positions progressively
reduce the level of the dither, spreading it further down the audio
spectrum. Position 11 is standard ‘White noise’ dither and position 12 is
dither OFF. See following DITHER SELECTOR OPTIONS on page 8.
Care must be taken when applying heavy (more than +30dB) post EQ HF
boost to noise shaped dithered recordings as excessive HF levels can be
generated, possibly causing damage to speaker tweeters.
Noise shaped dither is effective when a WORD LENGTH is selected of
less than 24 bits. It effectively decreases distortion and noise on low level
signals when compared with unshaped dithering; an apparent digital noise
floor reduction of 12 to 18dB should be perceived.