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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...

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

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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

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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

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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Infinity Reference 4555a reviews

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Infinity Reference 4555a

Crutchfield customer from Lancaster, CA on 6/27/2019

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Nice AMP, it sounds better than the old model. Much easier to read and set up. Bob likes it.

Pros:

Cons: When adjusting the dials, it's hard to read the lettering. Needs to be in bold letters.

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0 of 0 found this helpful

Infinity Reference 4555a

Crutchfield customer from Portsmouth, VA on 6/16/2019

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I paired this 5 ch to a JL stealthbox and two sets of focal speakers. The sound is very powerful and just appropriate for a Toyota Tacoma. It fits under the driver's seat.

Pros:

Cons:

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0 of 0 found this helpful

Nice amp in a small package

Crutchfield customer from Imperial, MO on 5/29/2019

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Nice amp in a clean little package. Driving Kicker KS 6x9's, Kicker KS 4.5's, and a Polk 10" sub. Drives the Kickers nice and clean. Expected a bit more from the sub power - yet still nice and clean. Would recommend for sure.

Pros: Small, intuitive, good quality

Cons: Lacks a bit of sub power even at 2ohms. A bit of noise on power up and power down - yet clean otherwise.

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Excellent bang for the buck

Crutchfield customer from Makawao, HI on 4/26/2019

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I got this amp mainly because it has lots 5 star reviews and has good power across the its 5 channels and it's priced is very competitive. Installation was a snap, it's a little larger then I expected but fits perfectly in my Honda s2k. Fine tuning my audio system was a snap, I have been using it for 2 weeks now with a 8 in bazooka and 4 6.5 in fosgate p16 -s and couldn't be happier

Pros: Easy sound set up , plenty of power, each channel independently adjustable

Cons: None

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0 of 0 found this helpful

Great price

Jacob from Carmichael, CA on 1/23/2019

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Purchased this amp for my 1964 Impala to run 2 4" JL C2 speakers in dash,1 Infinity Kappa 6.5" speaker in the rear and 1 JL TW3 12" sub. Purchased this amp for the price point and the perceived quality of Infinity. So far I am happy with the amp as I didn't want to spend a ton on an amp. Not sure what a more expensive amp would bring to the table but this amp drives my system well. I would highly recommend this amp if you are just wanting to have some clean power for your system.

Pros: Simple Nice looking Price

Cons: No bass knob Wire inputs not amazing

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0 of 0 found this helpful

Simple

William from Pensacola, FL on 12/21/2018

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Added this amp to my 2018 4tunner. Fits under driver seat well enough.

Pros: Speaker level inputs makes adding to a factory head unit simple. The 5 channel has multiple configuration.

Cons: None so far.

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Infinity Reference 4555a

Crutchfield customer from Dallas, PA on 12/9/2018

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Nice amp. Allows for adjustment of all 5 channels.

Pros:

Cons:

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0 of 1 found this helpful

Show worth & Affordable

Mike from Commerce, MI on 9/20/2018

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I've always been loyal to JL Audio but when my old sub amp went down, I went to Crutchfield and spoke with Allison who showed me this amp. I was hesitant but after seeing the specs and the price, I purchased it. After install and a few minor adjustments to the filters it's running great. I actually couldn't be happier. Super clean exterior and small. The D-series are the way to go if you require the power but hate seeing your lights dim on every bass note. I highly recommend this unit to anyone looking for a nice upgrade and not wanting to break the bank

Pros: Small, powerful, clean appearance, and super easy to adjust

Cons: None yet

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3 of 3 found this helpful

500w?

Joe from Wichita, KS on 8/26/2018

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Nothing I particularly hate bout this amp, power is way overrated. I have had 500 watt amps b4. This 1 is not.

Pros: Cheap qaulity

Cons: Power overrated.. A lot.

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1 of 9 found this helpful

Great Amp for my job

Crutchfield customer from Hanover, MD on 8/11/2018

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I installed this in my classic Motorhome. Nice improvement paired with some Infinity speakers.

Pros:

Cons:

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1 of 1 found this helpful

Infinity Reference 4555a

Crutchfield customer from Cropwell, AL on 5/22/2018

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Easy installation. Easy to adjust to your liking. Good looking and sounding Amp. Really pushes my JL 10W3 and my Infinity Primus door speakers good and allows for clarity through every range.

Pros:

Cons:

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2 of 2 found this helpful

Sounds darn good to me

Eric from Hartland, MI on 5/22/2018

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I'm gonna give it 5 stars. This was the first amp I've ever installed by myself and I've only had it in for a few days, but I can say it sounds great in my 2005 Silverado 1500 Z71 Crew Cab. Initially I just upgraded the HU and speakers, but the system was still under powered. I have Infinity Kappa coax in the front and Infinity Reference in the rear. But without an amp, it wasn't where it needed to be. So I installed this using the Crutchfield 4 ga. amp kit. Also installed a 10" RF sub behind the back seat. This amp is installed under the rear driver side deat. Had to tweak the settings on this a bit, but once I got it dialed in, it's sounding great and the system is hitting pretty hard. Not a competition winning system, but for a regular guy like me it rocks. I listen to mostly metal and this thing made my music sound great. I don't have the gain too high, but I did turn up the sub frequency just a bit. Then I tweaked the HPF on the front and rear speakers to filter out a bit of the low frequencies going to them and now I think I'm right where I need to be. Also, all the connections for all wiring seemed legit. I've read reviews on other amps where people struggled to connect the power/ground/etc. No such issues with this. Everything connected great. I have another vehicle (Honda CRV) and I ordered another one of these for that project. Definitely recommend it.

Pros: Looks great, sounds great, everything hooked up great.

Cons: None at this time.

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3 of 3 found this helpful

Great design, better power!

Zachary from Gresham, OR on 4/22/2018

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This amp has so much power!!! Extremely clear sound and never felt it get even warm so far. Only downside is it doesn't have a subwoofer dial so if you want control over that, pick up an rca volume interception box. I am runnin this amp with 2 6.5"s 2 6x9's and 2 12" jbl subs. So much power you can hold your hand in the air and feel the sound

Pros: Powerful, elegant looking, runs cool, easy to tune if mounted right

Cons: No sub dial, no included wires (but that's ok)

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2 of 2 found this helpful

Great Amp! I would recommend!

Christopher from Chantilly, VA on 9/1/2017

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Other then the screws can be easily stripped, its a great amp i would suggest it to other buyers.

Pros: -Looks Great! -Performs great! -Easy Hookup -All the adjustments you need -LOVE the bass Boost!

Cons: -The screws to hold the amp onto a sub box easily stripped.

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2 of 2 found this helpful

Great price

Chris from Camden, SC on 5/18/2017

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So far so good. My last Infinity didn't last long but I'm giving them another shot. Sounds pretty good, I found it's a little hot at 2k but nothing a good head unit won't accomidate for.

Pros: Low Price All the knobs you need - HPF, LFP, input selections, gain, etc

Cons: None so far - I just hope this one lasts

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4 of 4 found this helpful

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Product Research

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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Customer Q&A

2 questions already asked

Q
If I have a Bose stock head unit and I replaced the components in the front doors and coaxials in the rear and I have a sub in the trunk with a 5 channel amp and an audio control lc8i but I want to replace my amp with the infinity reference 4555a. Do I still need the lc8i?
[ Steve  Jul 01, 2019 ]
3 answers
A
You need something if you're doing more then just adding a sub thanks to the Bose system having wonky crossover points. I ended up having noise problems with the lc8i. If I could redo my system I would go with a DSP and bypass the Bose amp altogether. It might cost a little more but you'll have more control over your system and a cleaner sound over what the lc8i can offer.
[ Nathan  Jul 13, 2019 ]
A
From what I was told your factory head unit dampens sound once you get into high volume the audio controller takes out the dampener
[ WESTON  Jul 12, 2019 ]
A
I would keep your lc8i as the 4555a is limited in its ability to clean up the built in factory crossovers in the Bose head unit, since you already have it .
[ Edric  Jul 12, 2019 ]
Q
IF YOU BRIDGE THE FRONT CHANNELS, DO YOU LOSE THE SUB OUTPUT?
[ JASON  Jun 05, 2019 ]
3 answers
A
No sub output is independent of the front and rear channels regardless if they are bridged or not
[ Edric  Jun 06, 2019 ]
A
No it should be fine sub output is separate channel
[ James  Jun 05, 2019 ]
A
The front channels are independent of the sub channel. The sub works in either scenario.
[ Craig  Jun 05, 2019 ]

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