The Alpine MRV-F357 V12 automobile audio amplifier features five full channels of amplification. This allows it not only to power every speaker in a standard four-speaker car audio system, but also to drive a subwoofer. This one-box solution allows car audio enthusiasts to enjoy a full in-car stereo experience without the complexity and expense of installing multiple amplifiers.
The MRV-F357's power output depends on not only how many speakers it drives, but also on the type of speakers. Driving four 4-ohm impedance speakers, it produces either 30 or 50 watts per channel, depending on if it is drawing 12 or 14.4 volts of power. With 2-ohm speakers, it generates 40 or 60 watts per channel, and when bridged to drive only two 4-ohm speakers, it can output 80 or 120 watts per channel. These ratings are on the basis of constant power, and the amplifier can generate approximately twice its rated output during brief peaks.
One of the V2 MRV-F357's unique features is its fifth channel, designed to drive a subwoofer. It can output 100 watts with a 12-volt power source and 150 watts with a 14.4-volt power source. As with the other four channels, it can also reproduce brief peaks at levels as high as 300 watts of output.
Sound quality on the MRV-F357 varies depending on the type of speaker to which it is connected. When driving 4-ohm speakers, it achieves a distortion level of 0.08 per cent. With 2-ohm speakers, and in the fifth subwoofer channel, Alpine specifies that it will not exceed 0.3 per cent total harmonic distortion. In all cases, the amplifier will provide response that is no more that 1 decibel below perfectly flat from 10 to 50,000 hertz and will achieve a signal-to-noise ratio of 100 decibels.
The Alpine MRV-F357 V12 amplifier has six line-level inputs---one for each of its four channels of full-range amplification, and two of which are mixed into the subwoofer channel. It also has a four-pin speaker-level connection for output from a stereo head unit, which does not have preamplifier or line-level outputs. Five pairs of speaker terminals that accept bare wire are also present on the back panel, as are three spade lug inserts for the power connection, ground wire and a remote connection to allow an external device to turn the amplifier on.
For its rear and front stereo inputs, the MRV-F357 has a switchable crossover and gain control. The crossover is infinitely variable between 50 and 200 hertz and can be used as either a high pass or low pass crossover, with a 12 decibel per octave slope, or it can be completely defeated. The subwoofer channel has the same controls as the other channels but adds a bass boost control offering up to 12 decibels of increased bass response and a switch to determine from where it will pull the bass signal for amplification.
Given the MRV-F357's significant power output, it is a relatively large and heavy unit, tipping the scale at 5.9kg. and 284gr. It measures 10-1/4 inches wide, 15-5/8 inches deep and 2-3/8 inches tall. Given not only its size, but also its significant heat production, Alpine recommends that it be mounted in the boot or in another area where air can circulate.