The CV input provides direct access to the control port of the dbx VCAof the 902 for gain control. This provides the
user with the ability to use the 902 as an automatable level control. The dbx VCA provides linear-gain tracking in
decibels over a range of -100 to +40 dB with 1% accuracy. An output of 0 V produces 0 dB of gain through the
VCA. The control port should be driven by an op-amp or other low-impedance source. A bypass capacitor may be
required between the CV input and ground to prevent the audio signal from bleeding into this control port and caus-
ing modulation distortion.
U
SING THE
C
ONTROL
V
OLTAGE
O
UTPUT
The control voltage output is a DC voltage which changes in proportion to the amount of gain change being pro-
duced by the 902. The relationship between this voltage and the amount of gain change is expressed as
CV=50mV/dB gain change. The CV output is low impedance and capable of driving bridged loads of more than 10
k½ and less than .01µf without affecting the operation of the 902.
Figure 3: Control Voltage
Connections
S
PECIFICATIONS
Input Impedance:
20 k½ balanced, >10 k½ unbalanced
Output Impedance:
22 k½, into 600 ½ or greater
Maximum Input Level:
+24 dBu
Maximum Output Level:
+24 dBu into 600 ½ or greater
Frequency Response:
20 Hz - 20 kHz (+0/-3dB)
Dynamic Range:
115 dB
Distortion:
Typically .008 % at 1 kHz
Equivalent Input Noise:
-90 dBu, 20 Hz - 20 kHz Bandwidth, unweighted
Attack Rate:
Program-dependent, 2 ms for 10 dB above threshold, 600µs for 20 dB above threshold, to achieve
63% gain reduction
Release Rate:
925 dB/sec
De-Essing Range:
Operates uniformly over input range of -40 dBu to +24dBu without requiring adjustment
Maximum ÒEssÓ Attenuation:
Variable 0 to 20 dB
De-Ess Crossover Point:
Variable 800 Hz to 8 kHz
Filter Type:
12 dB/ocatve, phase coherent
Gain:
Unity
Controls:
Frequency, Range
Switches:
IN/OUT, Mode (HF ONLY/NORMAL)
Indicators:
IN/OUT, HF ONLY
Metering:
LED Column: 1, 2, 3, 4, 6, 8, 10, 12, 15, 20 dB gain reduction
Power Supply Requirements:
±15 V Regulated at 60 mA; ±24 V unregulated at 30 mA
Dimensions:
Front Panel: 3U high (5
4
Ó, 13.4 cm) x 1
2
Ó W, (3.8 cm); card depth behind front panel: 9
2
Ó (24.2 cm)
Note: specifications subject to change.
902
¨
5
Audio
Input
A
B
C
D
Audio
Output
CV
Out
CV
In
