Macro-Tech 3600VZ Power Amplifier
Page 23
Reference Manual
Fig. 4.3 Input Sensitivity and Ground Lift Switches
tions where extremely low-impedance loads and sus-
tained high output levels result in current draw that ex-
ceeds the breaker’s rating. Again, this should only be
possible when operating
outside rated conditions 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 wiring or other installation changes, don’t for-
get to disconnect the power cord. The six steps listed
next should be followed whenever you turn on the am-
plifier.
1. Turn down the level of your audio source. For ex-
ample, set your master mixer’s volume to –
¥
.
2. Turn down the Level controls of the amplifier (if
they are not already down).
3. Turn on the Enable switch. The Enable indicator
beside the switch should glow. During the four
second mute delay which immediately follows,
the Signal/IOC
indicators may flash unpredict-
ably and the ODEP LEDs will stay off. After the
mute delay, the ODEP indicators should come
on with full brilliance and the Signal/IOC indica-
tors should function normally (remain off if no
signal is present; flash if a signal is present). Re-
member, the Channel 2 Signal/IOC indicator re-
mains on if the amplifier is in Parallel-Mono
mode.
4. After the mute delay, turn up the level of your au-
dio source to the maximum desired level.
5. Turn up the Level controls of the amplifier until
the maximum desired sound level is achieved.
6. Turn down the level of your audio source to its
normal range.
For ease of use, the
Level controls
are located on the
front panel. Each control has 31 detents for accuracy.
To secure these controls, the Level Control Security Kit
is available (see Section 8.2).
Note: In Bridge-Mono or
Parallel-Mono mode, turn down the Channel 2 Level
control and only use the Channel 1 control.
The
Input Sensitivity Switch
is located inside the back
of the amplifier (Figure 4.3). It is set at the factory to
0.775 volts for rated output into 8 ohms. It can also be
switched to a sensitivity of 1.4 volts, or a fixed voltage
gain of 26 dB (4.8 volts for rated output).
How to change the input sensitivity:
1. Turn off the amplifier and disconnect its power
cord from the AC mains power receptacle.
2. Remove the PIP module (two screws).
3. Locate the sensitivity switch access hole inside
the chassis opening as shown in Figure 4.3. It is
located just above the phone jack inputs.
Note: The Sensitivity switch will not be visible be-
cause 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. The position toward the
front panel sets the sensitivity to 1.4 volts for
rated output, the middle position provides a volt-
age gain of 26 dB, and the position toward the
back panel sets the sensitivity to 0.775 volts for
rated output.
5. Replace the PIP module and restore the power.
The
Input Ground Lift switch
is located on the rear
panel (Figure 4.3) and can provide isolation between
the input signal ground and the AC ground. It affects
only the phone jack inputs and has no affect on the in-
put connectors on the PIP module. Sliding the switch to
the left isolates or “lifts” the grounds by placing an im-
pedance between the sleeve of each phone jack and
the circuit ground.
When a PIP module is plugged into the amplifier, only
the noninverted and inverted signal lines are connected
in parallel with the corresponding lines of the input
phone jacks. The signal grounds are not paralleled. For
example, XLR pins 2 and 3 are connected in parallel
with the tip and ring of the corresponding phone jack.
However, pin 1 of the XLR is not connected in parallel
with the sleeve of the phone jack.
* Factory setting for international models is 1.4 V.
