Arc Audio is a fairly new player on the car audio block. From its start in 1998, the people at Arc Audio were determined to build audiophile quality amplifiers and electronics rivaling the best on the market. In this month's review we put the 4-channel ARC4150-CXLR, which the company rates at 75 watts per channel into 4 ohms, on the bench. This amp uses a class AB, Bipolar design and features a somewhat complex preamp section that includes the crossovers and variable bass-boost.
FeaturesHeavy duty gold plated RCA connectorsMicroprocessor controlledRemote bass boostCompact designBroad crossover range: 50Hz to 5.5kHzInternal crossover with Full/Low/High range output
Opening the gift box of the ARC4150-CXLR reveals the rich deep blue color of the amp's exterior. The heatsink is virtually free of fins that clutter most amplifiers, leaving the amp with a rather simple, yet rugged look. The gold screened logo in the center of the amp is nicely complemented by the gold plated screws, terminals and plated RCA receptacles. The size of the ARC4150-CXLR is somewhat compact for its output power rating with a footprint measuring 16.5" x 8" x 2.35".
Unbolting the bottom chassis plate from the Arc uncovers a very clean circuit board with high quality through-hole and surface mount components. Because of the compact design, an additional PCB for the crossovers and bass boost circuitry was required. A microprocessor was set in place to monitor the internal temperature, power supply, remote bass control, and protection circuitry.
The power supply is a typical pulse width modulated type that is regulated down to 12 volts while delivering full rated power. Arc Audio gets our praise for the eight high quality, low ESR, 105 C capacitors used in the output section of the supply. It is these types of quality components that assure great performance with minimal degradation over the life of the amplifier.
The output stage uses four 25-ampere bipolar transistors per channel, held in place with heavy gauge pressure clamps. A messy, thermally conductive grease was used to increase the heat transfer from the transistors to the heatsink. The grease conducts heat well, but can be a technician's nightmare.
One end of the amplifier contains the power and output connections. The connectors are standard gold plated spade lug terminals used in many amplifiers. At the opposite end of the amp are the audio input connections. These are very high quality machined RCA's that mount to the side panel of the heatsink rather than the PCB (where they can break away from the board when too much pressure is applied).
Input Selection and Electronic CrossoverOne glance at the left side of the amplifier sent me scrambling for the manual that I should have looked at before benching the amp (old installer habit; look at the manual only when you aren't exactly sure what you are doing). Switches and dials encompass the remaining portion of the left side next to the RCA inputs. This is home to the input and crossover selection.
The input selection was more versatile than most of the other amplifiers we've tested: The ARC4150-CXLR can be configured as summed bridged mono (the left and right channels are summed together), left bridged, right bridged, or stereo. When the front channels are bridged, the source will be the front right. When the rear channels are bridged, the source is the front left. Two-channel with bass can also be chosen through rear source select, allowing the use of the remote bass level control.