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Operation Manual
Micro-Tech Series Power Amplifiers
page 10
3 Setup
3.7 Set Input Sensitivity
The three-position input sensitivity switch is
located inside the amplifier behind the MT-XLR
module (Figure 4.2 letter “I”). The switch is set
at the factory to a sensitivity of 0.775 volt for
standard 1 kHz power into 8 ohms. (Factory
setting for International versions is 1.4 V.) If
desired, the sensitivity can be switched to 1.4
volts for standard 1 kHz power into 8 ohms, or
a voltage gain of 26 dB. The 26 dB gain setting
is equivalent to a sensitivity of 2.1 volts for the
Micro-Tech 600, 2.5 volts for the Micro-Tech
1200 and 3.2 volts for the Micro-Tech 2400.
To change the input sensitivity:
1. Remove the back panel cover plate (or
input connector accessory).
2. Locate the access hole for the sensitivity
switch inside the chassis opening (Figure
3.7). The sensitivity switch will not be vis-
ible because it is mounted below the hole.
Use your little finger to reach it.
3. Set the switch to the desired position
noted on the label beside the access hole.
4. Replace the back panel cover plate (or
input connector accessory).
3.8 Set Ground Lift Switch
The ground lift switch (Figure 3.7) is located
on the back panel and can isolate the input sig-
nal grounds from the AC (chassis) ground. It
affects only the phone jack inputs and has no
effect on accessory input connectors. Sliding
the switch to the left isolates or “lifts” the
grounds by placing an impedance between the
sleeve of each phone jack and the AC ground.
The Micro-Tech 2400 has two reset switches
for its high-voltage power supplies. Refer to the
Troubleshooting Section in the unusual event
of a tripped breaker.
3.9 Connect to AC Mains
Connect your amplifier to the AC mains power
source (power outlet) with the supplied AC
power cordset.
WARNING: The third prong of the power
connector (ground) is an important
safety feature. Do not attempt to disable
this ground connection by using an
adapter or other methods.
Amplifiers don't create energy. The AC mains
voltage and current must be sufficient to deliver
the power you expect. You must operate your
amplifier from an AC mains power source with
not more than 10% variation above or below
the amplifier's specified line voltage and within
the specfied frequency requirements (indicated
on the amplifier's back panel label). If you are
unsure of the output voltage of your AC mains,
please consult your electrician.
3.10 Startup Procedure
Use the following procedure when first turning
on your amplifier:
1. Turn down the level of your audio source.
2. Turn down the level controls of the ampli-
fier.
3. Turn on the “Power” switch. The Power
indicator should glow.
4. Turn up the level of your audio source to
an optimum level.
5. Turn up the Level controls on the amplifier
until the desired loudness or power level is
achieved.
6. Turn down the level of your audio source
to its normal range.
If you ever need to make any wiring or installa-
tion changes, don't forget to disconnect the
power cord.
For help with determining your system's opti-
mum gain structure (signal levels) please refer
to the Crown Amplifier Application Guide,
available online at www.crownaudio.com.
Figure 3.7 Input Sensitiviy and Ground Lift Switches
0.77 V
26 dB
SENSITIVITY SWITCH INSIDE ACCESS HOLE
1.4 V
UNBALANCED
INPUT WIRING
BALANCED
INPUT WIRING
+
–
TIP
RING
SLEEVE
GND
+
TIP
SLEEVE
GND
THIS AMPLIFIER IS EQUIPPED WITH SELECTABLE INPUT SENSITIVITY. REMOVE COVER PLATE (ABOVE) TO ACCESS SENSITIVITY SWITCH.
CH-2
INPUT GROUND LIFT
(AFFECTS PHONE INPUTS ONLY.)
(MONO)
INPUT
GAIN
CH-1
INPUT
GAIN
LIFT
0
1
2
3
4
5
6
7
8
9
10
11
12
0
1
2
3
4
5
6
7
8
9
10
11
12
GROUND LIFT SWITCH