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Infinity Reference 704a

4-channel car amplifier — 70 watts RMS x 4

Item # 108R704AM

Infinity's Reference 704a amplifier will add plenty of muscle to your music without breaking a sweat, and it'll...

Infinity's Reference 704a amplifier will add plenty of muscle to your music without breaking a sweat, and it'll...

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About the Infinity Reference 704a

Power delivered in style

Infinity's Reference 704a amplifier will add plenty of muscle to your music without breaking a sweat, and it'll look good doing it. This 4-channel powerhouse will send 70 watts RMS to each of the front and rear speakers in your car. Into planning ahead? You could use this amp in 2-channel mode now to drive a couple subwoofers with 200 watts RMS each, then reassign it to your front and rear speakers when you get a bigger sub amp.

Power delivered in style

Infinity's Reference 704a amplifier will add plenty of muscle to your music without breaking a sweat, and it'll look good doing it. This 4-channel powerhouse will send 70 watts RMS to each of the front and rear speakers in your car. Into planning ahead? You could use this amp in 2-channel mode now to drive a couple subwoofers with 200 watts RMS each, then reassign it to your front and rear speakers when you get a bigger sub amp.

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 704a 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 car's factory radio. You can use the separate high- and low-pass filters on the front and rear channels to maximize the performance of your speakers or subs.

Infinity Reference 704a

Reference 704a input and control panel

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Product highlights:

  • 4-channel car amplifier
    • 70 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
    • 200 watts RMS x 2 at 4 ohms in bridged mode (4-ohm stable in bridged mode)
  • Class D amp technology
  • variable high- and low-pass filters (32-320 Hz, 12 dB/octave) on front and rear channels
  • preamp and speaker-level inputs
  • preamp outputs
  • ADAS and HALOsonic inputs for advanced integration in select vehicles
  • wiring and hardware not included with amplifier
    • 8-gauge power and ground leads recommended
  • fuse rating: 30A x 2
  • dimensions: 14-1/8"W x 2-1/4"H x 7-3/8"D
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # REF-704AAM

What's in the box:

  • 4-channel amplifier with two 30A ATO fuses installed
  • Two 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 704a reviews

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Infinity Reference 704a

Crutchfield customer from Black Hawk, CO on 8/23/2019

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Awesome amp.

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Just enough

Crutchfield customer from Enid, OK on 6/25/2019

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Great amp for smaller projects, just enough for the average setup..great sound love infinity products

Pros: Nice boost great sound

Cons:

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1 of 1 found this helpful

Infinity Reference 704a

GREG from IN on 6/15/2019

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Excellent amplifier. I installed Infiniti Reference 6x9's in my truck nearly two years ago and always thought the speakers should have sounded better than they did. I upgraded to this amp from a 2 channel Kenwood, and the 6x9's then came alive. The sound is much more articulate and cleaner.

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Infinity Reference 704a

Crutchfield customer from Van Nuys, CA on 5/12/2019

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Very good product

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INFINTY REFERENCE 704a

Crutchfield customer from Elk Grove, CA on 4/26/2019

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The Infinity 704a was recommended by one of the Crutchfield representatives. It is truly the best value for a well built, superb class D amp. The power rating is true to the specifications. And it is certainly the most unique looking amp that I have purchased. My application is for a 2018 Honda Accord Sport. I'm using the front channels to power Polk dB6502 components and have bridged the rear channels to power an 8" Alpine type R in ported enclosure. I am well pleased with the sound quality, low distortion, and clarity of the Infinity 704a. Excellent choice.

Pros: Power is true to specs, class D, versatility, attractive unique design

Cons: A bit larger than others with similar specs, but not a deal breaker!

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2 of 2 found this helpful

Infinity 704a

Mark from Redding, CA on 8/26/2018

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Love this amp, very clean sound with plenty of power. Thanks Crutchfield

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Infinity Reference 704a

David G. from Line Lxngtn, PA on 8/26/2018

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It is good quality

Pros:

Cons: It did not make the difference I was looking for or and I would have been just as well if not purchasing it for use in my single cab truck.

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1 of 4 found this helpful

Best amp for the $ for what I needed

James from Hanover, PA on 8/12/2018

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I bought this amp to push 2 sets of alpine components

Pros: Nice amp and good wattage for my setup

Cons: None

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1 of 1 found this helpful

Infinity Reference 704a

Luis from Union, NJ on 5/21/2018

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Great product.

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1 of 2 found this helpful

EXCELLENT amp!!!

Don from Hurst, TX on 5/13/2018

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A VERY nice, AWESOME priced, well built amp!!! Excellent quality and WELL worth the money!!!!

Pros: Well built, exceptional quality and sounds amazing!!!!

Cons: Kinda heavy!

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1 of 1 found this helpful

Infinity Reference 704a

Crutchfield customer from Ellenwood, GA on 3/18/2018

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Awesome amp!!! It has very clear sound for my speakers. Very small amp. Good power for the size!!!

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Infinity Reference 704a

Marlon from Hagatna, GU on 2/17/2018

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Exactly what I needed to run my mids and highs.

Pros: Great sound at an affordable price

Cons:

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Infinity Reference 704a

Brent from Waikoloa, HI on 1/6/2018

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Seems to be a very good amp for what I am doing

Pros: High quality

Cons: None

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0 of 1 found this helpful

Sounds Great!

T from Lumberton, NJ on 12/1/2017

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I'm using this amplifier in a 3 Channel configuration to drive a set of 6.5 in component speakers and a 10 inch sub. There is plenty of power to be had and the sound quality is excellent. The only question I really have is what the actual power output is in the bridged configuration. Multiple internet sites say 200x2, but the box clearly shows 145x2. Either way, it is more than enough power for what I need and it sounds great.

Pros: Stays cool Plenty of power looks great

Cons: Power output is questionable

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1 of 1 found this helpful

Infinity Reference 704a

Crutchfield customer from Pittsburgh, PA on 11/26/2017

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Quality item, provides plenty of power.

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Infinity Reference 704a

Shawn from Waianae, HI on 6/4/2017

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Easy installation and delivers crystal clear sound production. I am using the high level inputs and the automatic turn on feature worked instantly. Would definitely recommend to anyone looking to add a solid 4ch amp to their system.

Pros: Great looks, small size, stays cool even when driven hard.

Cons: None

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5 of 5 found this helpful

Infinity Reference 704a

Russell from Medford, Oregon on 3/27/2017

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Perfect for my kappa 6x9's. Love the look of it too.

Pros: Runs well at 2 ohms not just 4. I have 2 ohm kappa's and it runs awesome.

Cons: None

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Product Research

Features
Controls
Connections

Features

Power Output: The Infinity REF-704a 4-channel amplifier delivers the following power output (RMS Power Output @ <1% THD, 14.4 VDC):

  • 70 watts x 4 @ 4 ohms
  • 100 watts x 4 @ 2 ohms
  • 200 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-704a 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-704a'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.

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 that can be set to low pass (LPF), high pass (HPF), or Full Range. You can adjust the cutoff frequency of the crossover from 32Hz to 320Hz using the rotary control. There are separate crossovers for the front and rear channels.

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-704a 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 8 AWG power wire to the battery, with an in-line 60A fuse installed no more than 18" from the battery terminal. An 8 AWG ground wire (minimum) is also recommended, and attached to a metal area close to the amplifier.

Fuses: The REF-704a has two 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. Two 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.

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.

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

Pre-Out: A third pair of RCA jacks is provided to output the audio signal to a second amplifier, if desired.

Speaker Outputs: The amp features screw terminals for connecting four speakers. There are markings on the terminals for bridging 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

Q
Crutchfield asked: Why did you buy this?
A
recomended [ glenn  Apr 30, 2019 ]
A
The reviews for it were awesome and I already knew what type of quality I was going to be dealing with when buying an Infinity Audio product. :) [ Joseph  Apr 10, 2019 ]
A
Recognized name [ Gerek  Apr 08, 2019 ]
A
Had the power ratings I was looking for. Good name, good price. [ kathy  Mar 11, 2019 ]

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