Crest Audio Stereo Amplifier Connecting Inputs, Connecting Outputs, Octal Accessory Sockets

Connecting Inputs

Input connections are made via the 3-pin XLR connectors (pin 3+) on the rear panel of the amplifier. The inputs are actively balanced. Pinout and polarity of connection cables should be configured as shown at the right. The input overload point is high enough to accept the maximum output level of virtually any signal source. All models have two input connections; the exception being Model 10004, which has four.

Connecting Outputs

On the models 9001 and 10001, speaker cables must be connected to the single screw solderless lug connec- tors on the back of the amplifiers. For all other models, speaker cables can be connected with banana plugs, spade lugs, or bare wire to the 5-way binding posts. On the Models 8001 and 10004, two pairs of 5-way bind- ing posts are provided for each channel, so that paralleling of speakers is possible. Consult the Wire Gauge Chart to find a suitable wire gauge to minimize losses of power and damping factor in the cables.

Note: See the section on model 7301 for pertinent output connection information.

Ground ()

Positive (+)

Negative (--)

3

2 1

XLR Pinouts

Never connect a “hot” (red) output to ground or to another “hot” (red) output! Always turn off the amplifier before making connections.

Octal Accessory Sockets

Professional Series amplifiers have two octal accessory sockets on the back panel that provide con- venient insertion points for accessories in the signal path between the mode switch and the preamps. Some of the available Octal Socket Accessories include the Crest Audio XO-2 24 dB/Octave Crossover, LX-2.2 24 dB/Octave Crossover with Limiter, LM-1 Limiter, LM-2.2 Dual Limiter, PA-1 Precision Attenuator, CDEQ-2 Constant Directivity Horn Compensation Filter, or the TX-1 Input Isolation Transformer. To use the accessory sockets, first remove the factory-installed jumpers. The list below indicates the socket pinouts:

Pin	Channel A	Channel B
1	Ch. A(-) Inverting Signal Return	Ch. B (-) Inverting Signal Return
2	Ground*	Same as Ch. A*
3	Reserved	Reserved
4	+24VDC @ 25mA	-Vcc High Voltage (Unregulated)
5	+24VDC (Regulated)	+24VDC (Regulated)
6	Ch. A (+) Non-inverting Signal Return	Ch. B (+) Non-inverting Signal Return
7	Ch. A (+) Non-inverting Signal Send§	Ch. B (+) Non-inverting Signal Send
8	Ch. A (-) Inverting Signal Send	Ch. B (-) Inverting Signal Send

2 1

3 8

4 7

5 6

Octal Pinouts

*From input ground; reference ground for DC voltages at octal pins 4 - 5. § From Ch. A (+) non-inverting input.

For normal operation (not using the accessory sockets), jump Pin 1 to Pin 8 and Pin 6 to Pin 7 on both sockets (indicated by the dot- ted lines in Figure 7; the jumpers are set this way at the factory). To invert the input polarity, that is, to make XLR Pin 2 (+ ) and Pin 3 ( - ), remove the existing jumpers and jump Pin 1 to Pin 7 and Pin 6 to Pin 8. If the jumpers are misplaced, use solid wire; 4mm2 (metric) or No. 10 (AWG) will suffice. If the wire is too small, it will not fit snugly in the socket holes and may fall out; if it is too large, it may distort the socket contacts.

NexSys

Professional Series amplifiers are compatible with NexSys, Crest Audio’s dynamic hardware/software package that allows for sound system control and management from a Windows-based PC. The octal socket is used to connect between the amplifier and the NexSys supervisor via the NS-CCM-2 Control Module.

Page 10 Crest Audio Pro Series Power Amplifiers