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Input Section
Because of the wide range of head unit output configurations all ARC Audio amplifiers
have an adjustable input sensitivity or “Gain”. The gain is not a volume or a power
limiting control like a throttle. It makes the amp more sensitive to input from the stereo.
With the gain up the amp will reach full output at a lower volume setting on the deck. At
higher gain settings the amp also becomes more sensitive to noise from the car’s
electrical system. Try to run the gain at the lowest setting possible for you system.
There is no correct gain setting. Because
speakers require different power demands to
reach the same output, the gains most often
need to be used to compensate for these
differences. If you tried to set all the gains at half
way you would probably find the system didn’t
sound very good. Using good judgment and
listening carefully to each speaker is still the
best way to tune a system.
Crossover Controls
A crossover is a device that removes unwanted frequencies from a speaker or
amplifier. A tweeter can easily be destroyed by bass notes if they are not filtered out.
Likewise a subwoofer will not sound natural if it is playing midrange notes. A
crossover removes these sounds from the
speaker. As you might guess, careful adjust-
ment is need to ensure that all the speakers
are playing the right sounds and that you are
left with no “holes” or low spots in the
frequency response.
Bass Boost
This amp has a fully adjustable bass boost. Both the frequency and the level of the boost
are adjustable. Start with a small increase in the level control. Then “sweep” the
frequency up and down. Listen carefully for an improvement in the sound of the bass. If
you do not hear any improvement then the
woofer does not need any boost.
Use Bass Boost carefully. The demands on
power output are tremendous. Try to minimize
the use by changing woofer position or the
enclosure size.
Speaker outputs
This amplifier is a multi channel amplifier design. Meaning it has more than one
channel of speaker outputs. It is equipped with a large block style terminal for speaker
connection. Make this connection carefully and neatly. Strip your wire back and twist
the exposed leads and insert into the block terminal while being careful that there is no
loose or frayed strands of wire and tighten the Phillips head screw down on the
terminal till the wire is tightly secured in place. If the wires ever come in contact with
each other the amplifier will go into protection.
Know your total ohm load before you make
any connections.
Input Mode Switch
All ARC Audio amplifiers include an input mode switch. This switch controls the signal
being sent to the amplifier sections. Most 2-channel amplifiers can be bridged into a
single channel however if the signal to the channels is not exactly the distortion will
increase significantly. The mode switch solves this problem by offering 3 modes of
operation.
Stereo
This is simple 2 channel stereo operation. Use this setting for most applications that do
not involve bridging the output.
Bridge (R IN)
On a 2-channel amp only the Right channel input will be split and sent to both outputs.
You need only use the Right gain. On a 4 channel the right RCA will be sent to the front
outputs. The left RCA will be sent to the rear outputs. This is a great way of get high
power to a component set. The amplifier now acts like a 2 channel that makes full power
at 4 ohms.
L+R SUM MONO
This is the mode for bridging a subwoofer. Both the
left and right channels are combined into a mono
signal that is then split and sent to both output. This
will give you a true mono output.
