WEISS GAMBIT ADC2 User manual

digital audio
weiss engineering ltd.
Florastrasse 42, 8610 Uster, Switzerland
 [phone]  [phone]
 http://www.weiss. h / http://www.weiss-highend. om
WEISS
GAMBIT
ADC2
OPERATING MANUAL
Software Version: 3.1
Firewire option update 22.7.2020

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER INTRODUCTION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 2
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
INTRODUCTION
Congratulations on purchasing the Weiss Gambit Series ADC2 A/D Converter !
The ADC2 is a two hannel A/D onverter designed for
most demanding audio appli ations. It uses state of
the art A/D hips in Weiss Engineering’s proven “ orre-
lation te hnique” onfiguration, whi h lowers on-
verter imperfe tions and improves the SNR ratio.
For best noise reje tion, the analogue input signal is
kept balan ed from the input onne tors up to the
onverter hips. A high quality mi rophone preamp is
available as a standard feature.
Additionally, there is a built-in digital two-segment
ompressor / limiter for optimal levelling, employing
adaptive release timing, look-ahead ir uitry and
side hain-oversampling for mastering-quality dynam-
i s pro essing.
Large bar graphs, a well thought-out push button
array and un luttered rotary knobs optimize handling
ergonomi s.
Summary of ADC2 features:
Inputs
•Two balan ed LINE and two MIC inputs on sepa-
rate XLR onne tors.
•MIC input with swit hable phantom power.
•Input sensitivity is settable in ea h hannel inde-
pendently (or ganged) with two rotary en oders.
•Line Input sensitivity: -16dBu to +26 dBu.
•Mi Input sensitivity: -54dBu to +6dBu.
•Separate AES/EBU input on XLR for syn hroniza-
tion and/or audio input to the DSP, whi h allows
for use of the ADC2 for redithering and limiting of
digital signals.
Synchronization
•Internal syn sele table 44.1kHz, 48kHz, 88.2kHz,
96kHz, 176.4kHz, 192kHz.
•External syn from Wordsyn Input (BNC) or from
AES/EBU input.
•Wordsyn output on a BNC onne tor.
Metering
•One input / output level bargraph per hannel
with short peak hold
•One gain redu tion bargraph per hannel.
•Two over LEDs
•Two numeri al displays for peak hold and level
settings.
• Referen e for level setting an be altered

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 192kHz A/D
OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 192kHz A/D OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 192kHz A/D
OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 192kHz A/D CONVERTER
CONVERTERCONVERTER
CONVERTER INTRODUCTION
INTRODUCTIONINTRODUCTION
INTRODUCTION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 3
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
Outputs
•AES/EBU on XLR in one or two wire format
•S/PDIF on RCA
•Firewire (Optional, a kit is available)
DSP
•POW-R dithering to 16 bits, settable to three dif-
ferent algorithms a ording to the POW-R stand-
ard
•SNR enhan ement
•Level bar graph meter
•Two segment ompressor / peak limiter
• Double-pre ision 40bit floating-point pro essing

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 4
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
OPERATION
ADC2 Block Diagram
Fig. 1 ADC2 Block Diagram Schematic
Input Control Panel
This se tion des ribes how to use the input ontrol
panel (see Fig. 2).
Fig. 2 ADC2 Input Control Panel
Ganged
For stereo use, press the “ganged” key. This lo ks
together hannel 1 and hannel 2 gain and threshold
ontrols. Additionally, if “ganged” is a tive, the om-
pressor / limiter links
1
the side hains of the two han-
nels. Typi al appli ations for “ganged” mode are
•stereo (left/right) re ordings with two mi ro-
phones
•stereo insert limiting (during mixdown or master-
ing).
If “ganged” is not a tive, hannel 1 and hannel 2
settings are independent and the ompressor / limiter
works unlinked. Thus the ADC2 an also be used in a
studio re ording / mixing environment as dual hannel
outboard ompressor / limiter.
1
“side hain linking ” means that the same gain redu tion is
applied to both hannels to avoid orrupting the stereo
balan e.

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 5
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
Digital In / Mic
Pressing the “digtial in” key a tivates the digital
AES/EBU XLR input, the key lights red if a tive. 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 lo k to any signal,
none of the sampling rate keys are lit.
If the “digital in” key is not lit, the analogue inputs are
sele ted. To a tivate the mi rophone input for either
hannel, press the appropriate “mic” key (if “ganged”
is a tive, pressing one “mic” key will sele t mi ro-
phone inputs for both hannels). Press “+48 ” if phan-
tom power is needed.
It is usually advisable to use “low-cut” when re ording
with mi rophones. If “low-cut” is lit, low frequen y
ontent (traffi rumble, building tremors, air- ondition
hum and other low-frequen y air movement like doors
opening or losing near the mi rophone et .) is filtered
out.
Peak Hold
If “peak hold” is lit, the numeri display shows the
peak hold value (in dBFS) whi h is sele ted by the gain
key: “input gain” sele ts the input peak hold, “output
gain” sele ts the output peak hold (“threshold” also
sele ts output peak hold). See Fig. 1 for positioning of
input and output peak hold in the pro essing hain.
If input peak hold is sele ted, values equal to or above
0.0dBFS are indi ated by “>=0”. The output peak hold
however an measure values above 0.0dBFS be ause
of the internal floating-point data format used in the
digital signal pro essor. This is very useful to set the
output gain.
To clear the peak hold value, double-click the “peak
hold” key!
Double- li k resets both input and output peak hold.
Input Gain
If “input gain” is lit, the rotary knobs ontrol the ana-
logue input sensitivity. This is adjusted in 1dB steps via
a relay ontrolled attenuator. The sele ted value is
shown in the numeri display.
The level bargraph is swit hed 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 an
be different if “ganged” is not lit).
Refer to Fig. 1 on p. 4 for positioning of input and
output peak meter in the pro essing hain.
Note: The referen e for the input sensitivity display
an be hosen by the user. For that purpose press and
hold the “ganged” key and then swit h the ADC2 on.
After a few se onds release the ganged key. Wait for a
few more se onds. Now you an sele t the referen e
with the righthand knob. This allows to set the refer-
en e to e.g. +4dBu. Fa tory setting is 0 dBu referen e.
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 ontrol the
digital output gain. This gain an 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 ontrol around 0.0 dB while
still allowing omplete fade-out. A spe ial algorithm is
used for li k-free gain transitions (no “zipper” noise).

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 6
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
Threshold
If “threshold” is lit, the rotary knobs ontrol the
threshold of the ompressor se tion. The value is
shown in the numeri display. If “peak hold” is a tive,
the output peak value is displayed.
The ADC2 has a two-segment dynami s ompressor.
The threshold an only be adjusted for the ompressor
se tion, whi h has a fixed ratio of 2:1.
The limiter has a fixed ratio of ∞:1 with a fixed thresh-
old of 0.0 dBFS.
Because the signal before the output gain never ex-
ceeds 0.0dBFS, the limiter is inactive if the output
gain is 0.0dB.
If the threshold is set to 0.0 and the output gain is
below 0.0 the dynami s se tion is ina tive. This setup
is shown in the input vs. output graph in Fig. 3.
Fig. 3 Compressor with 0.0dB Threshold
To a tivate the limiter, set the output gain to a posi-
tive value. The boost will drive the signal into the lim-
iter. The gain redu tion applied by the limiter is visible
on the yellow bargraphs.
To soften the transmission from linear to limiter seg-
ment, the ompressor an be a tivated by adjusting
the threshold parameter. Fig. 4 shows a setting with a
threshold of –3 dBFS, Fig. 5 shows –6 dBFS. The range
of possible threshold values is listed on p. 14.
Fig. 4 Compressor with -3.0dB Threshold
Fig. 5 Compressor with -6.0dB Threshold
The overall gain redu tion applied by the ompressor /
limiter is shown in the yellow bargraph.
Note that the ompressor uses auto gain make-up:
depending on the threshold, a gain is added after the
ompressor to ensure that 0.0 dBFS input results in 0.0
dBFS output (graphi ally speaking, auto gain make-up
“fixes” the transfer urve at the (0.0, 0.0) point).
0.0
-6.0
-12.0
+ 6.0
0.0
-6.0
-12.0
0.0
-6.0
-12.0
+ 6.0
0.0
-6.0
-12.0
0.0
-6.0
-12.0
+ 6.0
0.0
-6.0
-12.0

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 7
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
Sync and Dither Control Panel
Fig. 6 ADC2 Sync and Dither Control Panel
Sampling Frequency
If the analogue inputs are sele ted (“digital in” is not
lit), the A/D sampling frequen y an be set in the syn
sour e blo k:
Sampling Fre-
quency
44.1 / 48 kHz
key
fs x 2 / fs x 4 key
44.1 kHz 44.1 kHz none
48.0 kHz 48 kHz none
88.2 kHz 44.1 kHz sf x 2
96.0 kHz 48 kHz sf x 2
176.4 kHz 44.1 kHz sf x 4
192.0 kHz 48 kHz sf x 4
Table 1 Samplig Frequency Selection
If “digital in” is lit, the sampling frequen y keys display
the sampling frequen y of the AES/EBU input signal in
the same fashion as is shown in Table 1.
Sync Source
As an be seen in Fig. 1, the ADC2 an be syn hronized
externally by other digital devi es. It has two external
syn inputs. External syn is only available for ana-
logue inputs, ie “digital in” key is not lit.
If “AES” is lit, the AES/EBU signal at the “DI 1 / SYNC”
input is used for syn hronization. If “BNC” is lit, the
word lo k signal onne ted to “WORDSYNC in” is used
for syn hronization. Both syn inputs have a loop-
through ouput to syn ronize other devi es.
If none of these two keys are lit, the ADC2 uses inter-
nal syn .
POW-r Dither
To requantize the input signal from 24bit to 16bit
format, a spe ial te hnique is used to avoid distortion,
alled dithering. Many dithering s hemes are available
today, both professional and homebrewed. The ADC2
uses the POW-r s heme, whi h is widely regarded as
one of the best, if not the best
2
, and is used in a varie-
ty of digital equipment.
The POW-r s heme offers three different presets
whi h an be sele ted with the dither keys “pow-r 1”,
“pow-r 2” and “pow-r 3”. The hoi e should be based
on listening tests and preferen e of the re ording
engineer .
Dithering is in “auto black”
3
mode: if digital zero is
detected at the ouput, dithering is switched off. This
ensures that programme breaks are not filled with
dither noise.
“Auto bla k” mode is not available for analogue input
signals.
Also note the effe t of the “DITHER MODE” dip swit h
setting in Fig. 1 ADC2 Blo k Diagram S hemati . If the
dip swit h is in the down position, requantisation to
16 bit and dithering is only applied to the S/PDIF RCA
output, whereas the AES/EBU XLR output still arries
all 24bits. This mode is useful for live re ording to a
24bit devi e with simultaneous ba kup to a 16bit
devi e (like DAT or CD-R). If the dip swit h is in the up
position, all digital outputs are dithered to 16bits.
2
For reviews of POW-r visit www.weiss. h
3
The term “bla k” omes from digital image formats, where
bla k is represented by the value zero.

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 8
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
Why dither?
If the 24bit digital signal is not dithered when re ord-
ing to 16bit media (e.g. DAT, CD-R et ), it is trun ated
instead, whi h leads to quantization distortion (similar
to lipping distortion). Fig. 7 shows a 24bit sine wave
at –85dBFS trun ated to 16bit.
Fig. 7 1kHz Sine wave truncated to 16bit
If the same sine wave is dithered instead of quantized,
the quantization distortion disappears and is repla ed
by wide band shaped noise, whi h is more pleasing to
the human ear (Fig. 8).
Fig. 8 1kHz sine wave dithered to 16bit
To view the frequen y hara teristi s of the three
POW-r algorithms, refer to POW-R Noise Spe trum on
p. 15.
For more information on dithering in general, view the
arti le “The Se rets of Dither” at www.digido. om .
For more POW-r information, please visit
www.weiss. h/pow-r/pow-r.html .

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 9
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
Dip Switches
Fig. 9 Dip switches at the rear of the ADC2
DIP swit h summary:
Switch up down
1 dual wire on XLR
outputs
single wire on XLR
outputs (both arry
the same signal)
2 dither setting affe ts
all outputs
dither setting affe ts
only RCA output
3 WSYNC input on
BNC NOT terminat-
ed
WSYNC input on BNC
terminated
4 AES/EBU input NOT
terminated
AES/EBU input termi-
nated
AES OUT DUAL WIRE
If this swit h is in the up position, the ADC2 outputs a
dual-wire signal. Refer to Table 2 and Table 3 to look
up exa t output onfigurations depending on this dip
swit h.
Sampling
Freq.
DO1
(XLR 1)
DO2
(XLR 2)
DO3
(RCA)
44.1 kHz 44.1 kHz
single wire
44.1kHz sin-
gle wire
44.1 kHz
single wire
48 kHz 48 kHz
single wire
48 kHz
single wire
48 kHz
single wire
88.2 kHz 44.1 kHz
left hannel
44.1 kHz right
hannel
muted
96 kHz 48 kHz
left hannel
48 kHz
right hannel
muted
176.4 kHz 88.2 kHz
left hannel
88.2 kHz right
hannel
muted
192 kHz 96 kHz
left hannel
96 kHz
right hannel
muted
Table 2 AES OUT dual WIRE switch in up position
Sampling
Freq.
DO1
(XLR 1)
DO2
(XLR 2)
DO3
(RCA)
44.1 kHz 44.1 kHz
single wire
44.1kHz sin-
gle wire
44.1 kHz
single wire
48 kHz 48 kHz
single wire
48 kHz
single wire
48 kHz
single wire
88.2 kHz 88.2 kHz
single wire
88.2 kHz
single wire
88.2 kHz
single wire
96 kHz 96 kHz
single wire
96 kHz single
wire
96 kHz
single wire
176.4 kHz 176.4 kHz
single wire
176.4 kHz
single wire
176.4 kHz
single wire
192 kHz 192 kHz
single wire
192 kHz sin-
gle wire
192 kHz
single wire
Table 3 AES OUT dual WIRE switch in down position
1: AES O UT 2 WIRE
2: DITHER MO DE 3: WSYNC TERM. 4: AES IN TERM.

OPERATING INSTRUCTIONS FOR GAMBIT ADC2 24Bit / 1 2kHz A/D CONVERTER OPERATION
Daniel Weiss Engineering Ltd., Florastr. 42, CH-8610 Uster Page 10
 [phone]  [phone]  http://www.weiss. h weiss@weiss. h
DITHER MODE
This swit h determines how dither is applied to XLR
and RCA outputs. Refer to hapter POW-r Dither on p.
7 for further information.
WSYNC TERM.
If the “WORDSYNC in” is not onne ted to another
devi e (via a T- onne tor), this dip swit h must be in
the down position, in whi h ase the signal is properly
terminated.
If another unit is onne ted to the “WORDSYNC in”,
this dip swit h must be in the up position.
Regardless of input syn hronization type, the
“WORDSYNC out” always arries the word syn used
by the ADC2.
AES IN TERM.
If the loop-through output of the “DI 1 / SYNC” input is
not onne ted to another devi e, this dip swit h must
be in the down position, in whi h ase the line is
properly terminated.
If another unit is onne ted, this dip swit h must be in
the up position.
FIREWIRE
If the optional Firewire Interfa e kit is installed, the
Firewire so ket on the ba k of the unit be omes a -
tive.
For the installation of the ne essary driver software
refer to the installation instru tion file on the driver
CD. The CD an be found on the last page of the man-
ual, or download the latest driver from:
https://www.weiss. h/download/ad 2
In the Weiss Firewire IO panel (the driver appli ation)
the ADC2 devi e will be visible on e the Firewire on-
ne tion has been established. The ADC2 be omes the
master lo k for the Firewire data transfers, i.e. the
Firewire interfa e will be automati ally onfigured
su h that it is slaved to the ADC2 output.
In the audio setup of your omputer sele t the Weiss
Firewire Interfa e as the re ording and/or playba k
devi e.
The re ording path uses the ADC2 XLR output as input
to the Firewire interfa e.
The playba k path feeds the data oming into the
ADC2 via Firewire dire tly to the RCA output onne t-
or. There are no ADC2 pro essing features available
for that path. I.e. it is possible to play a file on the
omputer via the ADC2 firewire interfa e to that RCA
output. The RCA onne tor an be jumpered in the
ADC2 unit to arry either the Firewire output or the
standard ADC2 output as des ribed in this manual. If
the ADC2 omes with the Firewire option installed, the
RCA onne tor is jumpered to the Firewire output.
Note that the ADC2 is the master lo k even when
using just the playba k path. So make sure to set the
ADC2 to the sampling rate of the file to be played
ba k.
It is possible to onne t more than one ADC2 to the
Firewire bus (use a Firewire hub or a omputer with
more than one Firewire onne tor to establish su h a
onfiguration). In su h a ase one of the ADC2 is the
master lo k for the whole system, i.e. the slave ADC2
unit(s) have to be syn hronized to the master ADC2 via
e.g. the WORDSYNC (on BNC onne tors) signal. In the
Weiss Firewire IO panel the master ADC2 unit is se-
le ted (designated). All other ADC2 units on the Fire-
wire bus then are automati ally onfigured as slave
units, i.e. their Firewire Interfa es are slaved to the
Firwire bus. Despite that slaving via the Firewire bus,
the aforementioned syn onne tions via WORDSYNC
(or AES/EBU syn ) have to be established. The slave
ADC2 unit(s) have to be swit hed to external syn via
the appropriate frontpanel swit hes.