Technical information

ManualsBrandsprotech Manualsaudio & home theatreTech10 Electric

Page 28

Com-Tech Power Amplifiers

Reference Manual

Again, this should only be possible when operating

out-

side rated conditions

, as when the amplifier is used to

drive a 1-ohm load, or when an input signal is clipped

severely.

4.4 Controls

The Enable switch is located on the front panel so you

can easily turn the amplifier on and off. If you ever need

to make any wiring or installation changes, don’t forget

to disconnect the power cord. Please follow these steps

when first turning on your amplifier:

1. Turn down the level of your audio source. For

example, set your mixer’s volume to “∞.”

2. Turn down the level controls of the amplifier.

3. Turn on the Enable switch. The Enable indicator

should glow. During the four second turn-on delay

which immediately follows, the indicators will flash

as described in Figure 4.1. After the delay, the

ODEP indicators should come on with full bril-

liance and the IOC and Signal Presence Indica-

tors should function normally.

4. After the turn-on delay, turn up the level of your

audio source to the desired level.

5. Turn up the Input Attenuation controls on the back

panel of the amplifier until the desired loudness or

power level is achieved.

6. Turn down the level of your audio source to its

normal range.

A 21-position detented Input Attenuation control is

provided for each channel. For security, the level con-

trols are located on the back panel. To discourage tam-

pering from the rear, a Lexan cover is provided that can

be attached to the back panel with the included ½-inch

8-32 screws.

Com-Tech

amplifiers have a reset switch for the AC

circuit breaker. If the circuit breaker trips, the Enable

indicator turns off. In this situation, turn off the Enable

switch and reset the circuit breaker. Then, turn the En-

able switch back on. If it trips again or the unit fails to

operate properly, contact an authorized service center

or Crown’s Technical Support Group.

A three-position input sensitivity switch is located in-

side the amplifier’s PIP compartment. It is set at the fac-

tory to a sensitivity of 0.775-volts (8/4-ohm mode).

Fig. 4.3 Input Sensitivity Switch

Please notice that there is a separate 0.775-volt position

for 70-volt mode. If desired, the sensitivity can be

switched to a voltage gain of 26-dB. With 26-dB gain

and 70-volt output, the input sensitivity for all models is

3.5 volts. With 26-dB gain and 8/4-ohm output, the in-

put sensitivity varies among the different amplifier mod-

els. To generate rated 1-kHz power, the input voltage

required is 1.48 volts for the Com-Tech 210, 2.12 volts

for the Com-Tech 410, 2.47 volts for the Com-Tech 810,

and 3.29 volts for the Com-Tech 1610.

It is also possible to configure the amplifier with one

channel set to 8/4-ohm output and the other set to 70-

volt. With this configuration, the input sensitivity switch

should be set to 0.775 volts (70 volt), and the Input At-

tenuation control for the 8/4 ohm channel can be ad-

justed to compensate for the additional gain.

To change the input sensitivity:

1. Turn off the amplifier and disconnect the power

cord from the receptacle.

2. Remove the PIP module.

3. Locate the access hole for the Input Sensitivity

switch inside the chassis opening (Figure 4.3).

Note: The input sensitivity switch is not visible

because it is mounted below the hole. Use your

little finger to reach it.

4. Set the switch to the desired position noted on the

access hole label.

5. Replace the PIP module and restore power.

0.77 V

sensitivity

8/4 ohm

26 dB

gain

SENSITIVITY SWITCH INSIDE ACCESS HOLE

0.77 V

sensitivity

70 volt

FIRST GENERATION P.I.P. MODULES REQUIRE THE

PIP2 ADAPTER

FOR CONNECTION. PLEASE REFER TO REFERENCE MANUAL.

CH-2 CH-1INPUT ATTENUATION

∞