OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 192kHz A/D CONVERTER
OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster
Page 5
+41 1 940 20 06
+41 1 940 22 14
http://www.weiss. ch [email protected]
Digital In / Mic
Pressing the “
digtial in
” key activates the digital
AES/EBU XLR input, the key lights red if active. As soon
as a valid signal is present, the sampling rate is dis-
played with the sampling rate keys (see Fig. 6).
If the digital input stage does not lock to any signal,
none of the sampling rate keys are lit.
If the “
digital in
” key is not lit, the analogue inputs are
selected. To activate the microphone input for either
channel, press the appropriate “
mic
” key (if “
ganged
”
is active, pressing one “
mic
” key will select micro-
phone inputs for both channels). Press “
+48V
” if phan-
tom power is needed.
It is usually advisable to use “
low-cut
” when recording
with microphones. If “
low-cut
” is lit, low frequency
content (traffic rumble, building tremors, air-condition
hum and other low-frequency air movement like doors
opening or closing near the microphone etc.) is filtered
out.
Peak Hold
If “
peak hold
” is lit, the numeric display shows the
peak hold value (in dBFS) which is selected by the gain
key: “
input gain
” selects the input peak hold
, “output
gain
” selects the output peak hold (“
threshold
” also
selects output peak hold). See Fig. 1 for positioning of
input and output peak hold in the processing chain.
If input peak hold is selected, values equal to or above
0.0dBFS are indicated by “>=0”. The output peak hold
however can measure values above 0.0dBFS because
of the internal floating-point data format used in the
digital signal processor. This is very useful to set the
output gain.
To clear the peak hold value, double-click the “
peak
hold
” key!
Double-click resets both input and output peak hold.
Input Gain
If “
input gain
” is lit, the rotary knobs control the ana-
logue input sensitivity. This is adjusted in 1dB steps via
a relay controlled attenuator. The selected value is
shown in the numeric display.
The level bargraph is switched between input and
output in the same manner as the peak hold. Thus, if
the “
input gain
” key is lit, the bargraph displays the
input peak meter. If the “
output gain
” key is lit, the
bargraph displays the ouput peak meter (settings can
be different if “ganged” is not lit).
Refer to Fig. 1 on p. 4 for positioning of input and
output peak meter in the processing chain.
Note:
The reference for the input sensitivity display
can be chosen by the user. For that purpose press and
hold the “ganged” key and then switch the ADC2 on.
After a few seconds release the ganged key. Wait for a
few more seconds. Now you can select the reference
with the righthand knob. This allows to set the refer-
ence to e.g. +4dBu. Factory setting is 0 dBu reference.
When finished press the blinking “peak hold” key. The
setting is retained in non-volatile memory.
Output Gain
If “
output gain
” is lit, the rotary knobs control the
digital output gain. This gain can be used for optimal
gain adjustment and to drive the peak limiter (see
below).
The gain ranges from -∞ (off) to +18.0 dB, the resolu-
tion is optimized for fine control around 0.0 dB while
still allowing complete fade-out. A special algorithm is
used for click-free gain transitions (no “zipper” noise).
