swissonic aD 96, User Manual

Page: 10 / 22

with the tip corresponding to pin 2 of the XLR («posi-
tive» or «hot» signal), the ring corresponding to pin 3
(«negative» or «cold» signal) and the sleeve corre-
sponding to pin 1 («ground» or «shield»). The cable
should be configured as shown in Figure 3B.
The input level of the AD96 is selected for compati-
bility to most «pro-level» output gear. There is one
notable exception: Some (older) analog tape machines
don’t have output level trims, and provide peak levels
well in excess of +20 dBu, especially when used with
high level recordings. For these cases, a passive
attenuator, or pad should be used.
At the other end of the spectrum, the «semi-pro»
(-10 dB) gear will not have enough output to fully utilize
AD96’s dynamic range. AD96 provides a way to
increase the input buffer gain by circa 11 dB by chang-
ing jumpers from the PCB. Note, the «+4» really
means +4 dBu, while the «-10» means -10 dBV.
0 dBV equals roughly 3 dBu, so the difference be-
tween «+4» and «-10» is actually 11 dB.
To change gains, open the case and move the jumpers
corresponding to the channel for which you need a
gain boost from position 1-2 to position 2-3. The
jumpers are labeled JP1-8, corresponding to channels
1 to 4 (JP1 and 2 for channel 1, etc).
Mixing balanced and unbalanced equipment is generally
a bad idea, as the two systems aren’t compatible.
Such mixing is the most frequent cause of hum
in audio systems. However, in a non-ideal world, it
cannot usually be avoided.
The best way to do it, albeit the most expensive, is to
use an isolating transformer (Figure 4). It can also be
used to raise the signal to «pro» levels (+12 dB of
voltage gain is achieved by a 4:1 transformer).
The alternative to transformer coupling is to use a
special cable, set up as shown in Figure 5. If you get
hum, try the ground-lifted version in Figure 6. You will
almost certainly need to boost the input gain of
Level Matching
Connecting
to unbalanced
equipment
Figure 4: Using an
isolating transformer.
Figure 5: Unbalanced
to balanced cable
setup (preferred).
11
red
black
red
shield
two conductor shielded twisted cable
red
black
two conductor shielded twisted cable
Male
3
1
2
Male
A: RCA to XLR connection
B: TS to XLR connection
3
1
2
red
black
shield
black
Case lug
mat connect
to chassis
(not required)
Not
connected
to chassis
(plastic jack)
chassis
grounded
to pin1
earth grounded
metal enclosure
Balanced Unbalanced
1
2
3
Transformer