Power-Tech .1 Series
Power Amplifiers
page 9
Operation Manual
3.7 Set Input Sensitivity
The input sensitivity switch inside the amplifier
is set to 0.775 volt RMS at the factory. (Factory
setting for international models is 1.4V). It can
be changed to 1.4 volts or a voltage gain of 26
dB. The 26 dB gain setting is equivalent to a
sensitivity of 2.1 volts for the Power-Tech 1.1,
2.6 volts for the Power-Tech 2.1 and 3.3 volts
for the Power-Tech 3.1.
To change the input sensitivity:
1. Turn off and unplug the amplifier from the
AC source.
2. Remove the input module on the back panel.
3. Locate the labeled access hole for the sensi-
tivity switch (Figure 3.7). The sensitivity switch
will not be visible because it is mounted below
the hole. Use your little finger to reach it.
4. Set the switch to the desired position.
5. Replace the input module.
3.8 Connect to AC Mains
Connect your amplifier's power cord to the AC
mains power source (power outlet).
WARNING: The third prong of this con-
nector (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 specified 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.
3.9 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 amplifier.
3. Turn on the Power switch. The Enable indica-
tor next to the Power switch 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.
4 Operation
4.1 Precautions
Your amplifier is protected from internal and
external faults, but you should still take the fol-
lowing precautions for optimum performance
and safety:
1. Before use, configure your amplifier for
proper operation as described in the Setup sec-
tion of this manual. Improper wiring can result
in serious operating difficulties. For advanced
setup techniques, consult Crown's
Amplifier
Application Guide
available online at
www.crownaudio.com.
2. Use care when making connections, select-
ing signal sources and controlling the output
level. The load you save may be your own!
3. Do not short the ground lead of an output
cable to the input signal ground. This may form
a ground loop and cause oscillations.
4. Never connect the output to a power supply,
battery or power main. Electrical shock may
result.
5. Tampering with the circuitry, or making
unauthorized circuit changes may be hazardous
and invalidates all agency listings.
6. Do not operate the amplifier with the IOC
LED constantly flashing yellow.
7. Do not overdrive the mixer, which will cause
clipped signal to be sent to the amplifier. Such
signals will be reproduced with extreme accu-
racy, and loudspeaker damage may result.
8. Do not operate the amplifier with less than
the rated load impedance. Due to the amplifier's
output protection, such a configuration may
result in premature clipping and speaker
damage.
Crown is not liable for damage that results from
overdriving other system components.
Figure 3.7 Input Sensitivity Switch
3 Setup
