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Infinity Reference 4555a

5-channel car amplifier — 45 watts RMS x 4 at 4 ohms + 500 watts RMS x 1 at 2 ohms

Item # 108R455AM

Infinity's Reference 4555a 5-channel amplifier will add a lot of muscle to your music without breaking a sweat, and...

Read more from Crutchfield writer, Buck P.

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$239.99

About the Infinity Reference 4555a

Power delivered in style

Infinity's Reference 4555a 5-channel amplifier will add a lot of muscle to your music without breaking a sweat, and it'll look good doing it. This amp sends 45 watts RMS to each of the front and rear speakers in your car, while delivering up to 500 watts RMS to a subwoofer — a much better balance of "speaker-to-sub" power than most 5-channel amps provide. For a high-performance system, you can bridge the amp to 3-channel mode to power your front speakers with 130 watts RMS each, while still driving the sub with 500 watts.

Power delivered in style

Infinity's Reference 4555a 5-channel amplifier will add a lot of muscle to your music without breaking a sweat, and it'll look good doing it. This amp sends 45 watts RMS to each of the front and rear speakers in your car, while delivering up to 500 watts RMS to a subwoofer — a much better balance of "speaker-to-sub" power than most 5-channel amps provide. For a high-performance system, you can bridge the amp to 3-channel mode to power your front speakers with 130 watts RMS each, while still driving the sub with 500 watts.

Special integration features

An ADAS input lets you keep your vehicle's advanced driver assistance system's (ADAS) warning messages after you've replaced the factory receiver or amplifier. You can select which channel plays those messages, so you'll hear lane departure or blind spot warnings through your system loud and clear. And if your vehicle comes equipped with a Harman HALOsonic noise cancellation/enhancement system, you can plug it right into the Reference 4555a and enjoy a super quiet or an engine-roaring ride along with your music.

Works in almost any vehicle

Speaker-level inputs allow this amplifier to work in almost any system, even if you're keeping your factory radio. Separate high- and low-pass filters on the front and rear channels maximize your speaker system's performance. The subwoofer channel features a low-pass filter, bass boost, and phase switch, so you can make the bass sound great in your vehicle.

Infinity Reference 4555a

Reference 4555a input and control panel

READ LESS

Product highlights:

  • 5-channel car amplifier
    • 45 watts RMS x 4 + 320 watts RMS x 1 at 4 ohms
    • 65 watts RMS x 4 + 500 watts RMS x 1 at 2 ohms
    • 130 watts RMS x 2 bridged at 4 ohms + 500 watts RMS x 1 at 2 ohms
  • Class D amp technology
  • variable high- and low-pass filters (32-320 Hz, 12 dB/octave) on front and rear channels
  • low-pass filter (32-320 Hz, 12 dB/octave) on subwoofer channel
  • bass boost on subwoofer channel (0-9 dB at 45 Hz)
  • phase switch on subwoofer channel (0, 180 degrees)
More Features:
  • preamp and speaker-level inputs
  • ADAS and HALOsonic inputs for advanced integration in select vehicles
  • wiring and hardware not included with amplifier
    • 4-gauge power and ground leads recommended
  • fuse rating: 30A x 3
  • dimensions: 15-3/4"W x 2-1/4"H x 7-3/8"D
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # REF-4555AAM
KEEP READINGREAD LESS

What's in the box:

  • 5-channel amplifier with three 30A ATO fuses installed
  • 3 Spare 30A ATO fuses
  • 4 Speaker wire-to-RCA adapters
  • 4 Self-tapping screws (length=2.25")
  • Quick Connect Guide
  • 2 Infinity decals

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Features
Controls
Connections

Features

Power Output: The Infinity REF-4555a Class D 5-channel amplifier delivers the following power output (RMS Power Output @ <1% THD, 14.4 VDC):

  • 45 watts x 4 + 320 watts x 1 @ 4 ohms
  • 65 watts x 4 + 500 watts x 1 @ 2 ohms
  • 130 watts x 2 @ 4 ohms bridged

Protection Circuitry: The amplifier features protection circuitry for thermal overload, over/under-voltage (<9V or >16V), amplifier output circuit failure, and short circuits. The Protect LED on the top of the amp glows red if the amp goes into protection mode.

ADAS: The REF-4555a has an RJ-45 interface for the Advanced Driver Assistance System (ADAS) that can override the audio source input to deliver a message or other audio from a connected ADAS accessory. On the amplifier, you can designate which speaker will output the ADAS signal.

HALOsonic: Infinity full-range amplifiers are compatible with the Harman HALOsonic noise management system found in select vehicles. HALOsonic utilizes a combination of Active Noise Cancellation and Electronic Sound Synthesis to greatly reduce engine noise and road noise in the cabin, making for a much quieter ride. The amp features a 3.5mm connection to interface with the HALOsonic system.

Controls

Gain: The REF-4555a's rotary gain controls let you match the amp's input sensitivity to the output of the source unit. The input sensitivity range of the amplifier is 200mV and up. A small screwdriver (not included) is required to set the gain. There are separate gain controls for the front, rear, and subwoofer channels.

Input Level: The amp will accept low-level (line level) or high-level (speaker level) input signals. The input level switch lets you select the type of input you are using. For a high-level input, there are two settings: Hi1 and Hi2. If the audio system fails to play with an amplifier connected to its output, set the switch to the Hi2 position. The Hi2 position includes a circuit design to fool this type of factory system into "seeing" a speaker connected to its output.

Crossover: The amp features switchable crossovers for the front and rear channels that can be set to low pass (LPF), high pass (HPF), or Full Range. The subwoofer channel has a non-defeatable low-pass filter. You can adjust the cutoff frequency of the crossovers from 32Hz to 320Hz using the rotary controls. There are separate crossovers for the front, rear, and subwoofer channels.

Bass Boost: You can apply up to 9 dB of bass boost to the subwoofer channel, centered at 45 Hz, using the rotary control.

Phase: You can switch the phase of the subwoofer output from 0° to 180°.

ADAS Assign: The ADAS Assign switch is a 4-position rotary control that lets you select which speaker outputs the ADAS message: left front, left rear, right front, or right rear.

Connections

Terminals: The Infinity REF-4555a uses set screw terminals for the +12V power, ground, turn-on (remote) lead, and speaker outputs. The screws can be tightened/loosened with a Phillips-head or flat-head screwdriver (not provided).

Power/Ground: The +12V Power and Ground terminals will accept up to 4-gauge wire. It is recommended that you use a minimum of 4 AWG power wire to the battery, with an in-line 90A fuse installed no more than 18" from the battery terminal. A 4 AWG ground wire (minimum) is also recommended, and attached to a metal area close to the amplifier.

Fuses: The REF-4555a has three 30A ATO (blade-type) fuses installed in the amplifier behind a removable panel. A small Phillips-head screwdriver (not included) is required to remove the panel. Three spare 30A ATO fuses are also included with the amp.

Remote Turn-On: The Remote screw terminal will accept up to 10 AWG wire. Typically, an 18 AWG wire is sufficient for the turn-on lead.

Line-Level Inputs: The amplifier is equipped with three pairs of RCA inputs for connecting stereo RCA patch cables from the head unit to the amp.

Speaker-Level Input: The amp includes four bare wire-to-RCA adapters for connecting the amp to a factory radio or aftermarket head unit without preamp outputs. You should attach each speaker wire from the head unit to each adapter and plug the adapter's RCA plug into the amp.

Sub Input: There is a two-way switch to select the source of the Subwoofer Channel input. If you have a dedicated RCA subwoofer output from the head unit, you can select EXT (external) on the switch and connect the RCA cable to the amp. If you do not have a dedicated subwoofer channel signal, you can select INT (internal) on the switch, and a summed signal will be derived from the full range inputs.

Speaker Outputs: The amp features screw terminals for connecting five speakers. There are markings on the terminals for bridging the front and rear channels of the amplifier. The terminals will accept up to 10 AWG wire.

ADAS Input: The amp offers an RJ-45 port for the input from the Advanced Driver Assistance System (ADAS), if the vehicle is so equipped.

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