ARC Audio FD2200, FD4100, FD2100, FD4150 manual +R SUM Mono

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.

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.

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.

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