Car Audio Buff

First Look

The ARC Audio KAR 400.4 is a Class AB, 4-channel amplifier housed in a sleek clear anodized aluminum chassis. The understated style looks classy and refined. The front two channels include a 12dB per octave fully variable crossover from 55Hz to 550Hz. The front channels also include a 45Hz bass boost that allows up to 18dB of maximum boost. The rear channels include a 12dB per octave fully variable crossover from 55Hz to 5500Hz via a “x10” frequency multiplier. The RCA connections and signal adjustments are located on one side of the ARC Audio KAR 400.4 while the power and speaker connections along with the 40 amp fuse are located on the other side. The gold plated power and speaker screw terminal connections can easily accept either bare wire or fork terminals.

A Closer Look

What you can’t see in pictures is how solid and sturdy this amplifier feels. All the connections are positive. All the controls feel precise. For those who are familiar with amplifiers the ARC Audio 400.4 may seem a little different. Typical amplifiers generally assign the front channels for midrange and tweeters and the rear channels for subwoofers. In the KAR 400.4, it is exactly opposite. When looking at connecting the amplifier, this makes sense. I generally hook up the midrange and tweeter first. (The rear channels are on the bottom level of connections) and tune them. Next I add the subwoofer and blend them with the midrange and tweeter. The different configuration of the KAR 400.4 made this easier. Another nice feature is the ability to bridge the front channels to the right RCA and the rear channels to the left RCA. This make it easy to transform the KAR 400.4 into an extremely power two channel amplifier for satellite speakers.

Installation

The installation of the ARC Audio KAR 400.4 is simple. The metal mounting tabs are solid and placed at the four corners of the amplifier. The connections are well marked and easy to use. The ARC Audio KAR 400.4 gives you the right amount of controls to extract the best sound from the amplifier. If you are unsure about your installation capabilities, it is recommended that you have an Authorized ARC Audio Dealer perform the installation.

Sound Quality

This performs as well as it looks. On the test bench, the ARC Audio KAR 400.4 delivered 70.2 watts x 4 into 4-ohms with less than 1% distortion. Into 2-ohms, the KAR 400.4 delivered 107.5 watts per channel into four channels. This KAR 400.4 exceeded is rated power around 40%. Very impressive. Into 4-ohms bridged, the KAR 400.4 delivered a respectable 248.5 watts per channel into two channels for a total amplifier power of 497 watts. At peak power the ARC Audio KAR 400.4 average slightly above 70% efficiency drawing 27.8 amps at 4-ohms stereo and 47.7amps at 4-ohms bridged. At one-third power the amplifier’s efficiency dropped to 32%. This level of efficiency is typical of a Class AB design. Only in one category did the ARC Audio fall short of its rated performance. Using the CEA-2006 standards, I measured the signal-to-noise ratio at 92 dBA. This was 3 dB shy of its rated 95dBA.

When auditioning the ARC Audio KAR 400.4, the sound was smooth, detailed and crystal. There were no audible noises during turn-on or turn-off. On bass tracks, the KAR 400.4 delivered good impact and control. While the amplifier did run warm, never did the KAR 400.4 sound strained or thermal.

Summary

The ARC Audio KAR 400.4 is a solid performer. This amplifier has enough power and is flexible enough to drive your complete system. Or, you could use it as the beginning to a high-power, high end system of sonic goodness. If you are looking for a great sounding amplifier with the ability to grow, the ARC Audio 400.4 would be an excellent choice.

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