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Polk Audio FXi A4

Dipole/bipole surround speakers (Black)

35 Reviews | 5 questions - 16 answers

Item # 107FXIA4B

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Was: $399.99

Special purchase: -$150.00

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Our take on the Polk Audio FXi A4

Add the Polk FXi A4 surround speakers to your home theater system and enjoy dramatic rear-channel sound effects with your favorite movies. These cleverly designed speakers feature two tweeters aimed 45° from each other, for an ideal mix of direct and indirect sound.

Add the Polk FXi A4 surround speakers to your home theater system and enjoy dramatic rear-channel sound effects with your favorite movies. These cleverly designed speakers feature two tweeters aimed 45° from each other, for an ideal mix of direct and indirect sound.

Dipole/bipole operation for flexible placement
A dipole/bipole switch lets you position the FXi A4s on the rear or side walls of your home theater room — you'll get great results either way. If you place them behind your listening postion, set them to bipole mode for distinct, directional sound. Or set them to dipole mode for side placement, and they'll create a more diffuse soundfield for convincing wraparound effects.

A high-tech approach to accurate sound
Polk carefully designed the drivers using laser testing to help identify and eliminate resonance points. The acoustically inert MDF cabinets fight internal vibrations that can compromise performance. It all adds up to enveloping surround sound that fully immerses you in the movie action.

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Product Highlights:

  • bass-reflex (ported) design
  • frequency response 60-26,000 Hz (-3dB)
  • recommended amplifier power: 20-125 watts
  • two 1" silk/polymer dome tweeters
  • 5-1/4" Dynamic Balance® polymer composite woofer
  • 8-ohm impedance
  • sensitivity 88 dB
  • dipole/bipole switch
  • keyhole slot for easy wall-mounting
  • 5-way binding post terminals
  • voice-matched to Polk's RTi tower and bookshelf speakers and CSi center channel speakers
  • 11-5/16"W x 12-1/16"H x 7-13/16"D
  • warranty: 5 years
  • Our 60-day money-back guarantee
Priced per pair

    What's in the Box:

    • 1 Black left surround speaker
    • 1 Black right surround speaker
    • 2 Self-tapping screws
    • 8 Self-adhesive rubber feet
    • Owner's Manual (English/French/Spanish)
    • Template
    • Online registration sheet
    • Polk Audio product brochure

    Perfect surround sound speakers improved my system 100 percent. So good that now I need a better center speaker.

    Lawrence, Murrysville, PA


    Polk Audio FXi A4 Reviews

    Average Customer Review(s):

    (35 Reviews)
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    Hands-on research

    Product Research

    Driver Technology
    Enclosure Design
    Mounting Options

    Driver Technology

    Dynamic Balance: Dynamic Balance is a proprietary Polk Audio technology using laser imaging to determine what combination of speaker materials create the least amount of resonance. Eliminating resonance in speakers results in a wide, smooth response and low distortion.

    Polymer Composite Woofers: Each speaker features a 5.25" polymer composite woofer for smooth wide-range response with low distortion. For high performance durability, each woofer uses a butyl rubber surround.

    Silk/Polymer Tweeters: Each speaker has dual 1" silk/polymer dome tweeters that provide clear, detailed highs and spacious surround effects. Each tweeter uses a heat sink on the Neodymium magnet for superior heat dissipation, power handling and reliability.

    Frequency Response: The overall frequency response is 50Hz-27kHz and the -3dB frequency response is 60-26kHz.

    Enclosure Design

    Enclosure: Each enclosure has a triangular shape with the speaker faces angled at 45 degrees. One face has a tweeter and a woofer, while the other face has a tweeter and port tube opening. A switch for selecting Dipole or Bipole operation is located on the rear of the speaker above the speaker's 5-way binding post speaker terminals. One of the speakers is specifically designed for the "left" channel and the other for the "right" channel.

    Acoustically Inert Cabinets: Each speaker cabinet features all-MDF construction with internal bracings that virtually eliminate sound-muddying resonance. The speakers are finished in either a black or white laminate finish.

    Anti-Diffraction Grilles: The floating anti-diffraction grilles minimize grille diffraction for spacious, 3-dimensional imaging.

    Port: On the side with only a tweeter, there is a single port tube opening for increased and extended bass response.


    5-Way Binding Posts: The gold-plated 5-way binding posts will accept bare wire, pin connectors, spade connectors, banana plugs, and dual banana plugs.

    Mounting Options

    Dipole/Bipole Switch: There is a switch that allows each speaker to be used as a Dipole (out of phase) or Bipole (in phase) speaker. If you're mounting the speakers on the side walls in line with your listening position, the dipole mode will create a diffuse, ambient soundfield. If you're placing them behind your position, the bipole mode fires the drivers in phase to flood your room with surround sound. When used with a Dolby Digital system, the surround speaker setting should be set to small.

    Wall Mounting: The bracket on the back of each speaker has two keyhole slots, allowing the speaker to be mounted on the wall using the supplied 2-1/2" wood screws.

    Our Product Research Team

    At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

    Q & A

    Customer Q&A

    Crutchfield asked  
    Why did you buy this?

    To complete my Polk surround sound [ HENRY  Jul 30, 2018 ]
    I wanted Surround Speakers that offer a solid dispersion and would compliment my MartinLogan XLM's for LCR, but without the Motion FX price tag. [ RICHIE  Jan 31, 2018 ]
    I am unable at this time to go to a 7.1 setup so I am taking a chance on these. Reviews were good on Youtube and Crutchfield so when they went on sale I figured it was time. [ Michael  Jan 24, 2018 ]
    To enjoy full background sound [ Terry  Jan 13, 2018 ]
    Upgrading the surround speakers in my Polk Audio system [ stickywicked447  Jan 10, 2018 ]
    recommended by polk audio to match the RTia3 [ David  Dec 04, 2017 ]
    Polk makes good audio equipment. $150 savings on these speakers is a great deal !! [ John  Dec 01, 2017 ]
    Looking for a good surround speaker and Polk's reputation is excellent to say the least Reading through the reviews I didn't see any negative feedback at all [ Chad  Nov 26, 2017 ]
    On sale, good manufacturer, upgrade for rear channel sound [ Jeremy  Oct 17, 2017 ]
    Polk Audio Rocks [ ERIC  Oct 12, 2017 ]
    Quality Polk products [ Jeffrey  Sep 17, 2017 ]
    On-Line Reviews and Feedback from customers;. Sale Price. [ Mike  Sep 17, 2017 ]
    Cost and quality. [ L  Jul 29, 2017 ]
    From reviews and should work good for my surrounds and back speaker [ Keith  May 09, 2016 ]
    To match and compliment my existing Polk Audio gear. (3) 265rt's (L-C-R), (2) 255crt's in ceiling (Atmos) and (2) PSW505 subwoofers, for a complete 5.2.2 Home Theatre setup! [ Greg  Apr 10, 2016 ]
    Upgraded receiver to 7.2 from a of speakers are 10 year old Polk and wanted to maintain the same quality that I have been satisfied with for a decade [ JOE  Mar 22, 2016 ]
    Good reviews, and matches/compliments the RTI A9's and CSI A6 I purchased as well [ James  Feb 27, 2016 ]
    Have seen great reviews and can not wait to setup. [ ZION C  Jan 24, 2016 ]

    5 questions already asked

    Work great for side and back. [ steve  Jun 05, 2018 ]
    Yeah I don't think I'd do that. These are big- look at the measurements- these are bigger than the fronts you want to buy. I have them as 90 degree side surrounds in a 7.1 setup and they're great. They're also designed to be back a little further and make a 5.1 system sound more like a 7.1. If I were you would get those A3's but use them as your Surround Backs and then get either the A5 or A7's for your fronts (I have the A7s and love them). [ Kellan  Jun 05, 2018 ]
    They come with mounting plates but I'm sure stands would work as well. [ James  Feb 19, 2017 ]
    I have mine mounted on the wall, but I would imagine that they will work just as well if placed on a shelf or stand. They are fantastic speakers and you will not be disappointed! [ FRANK A  Dec 29, 2016 ]
    I have mine mounted. I think they'll work fine either way. [ Robert  Dec 29, 2016 ]
    I have mine mounted to the wall. If the floor stands you have except a wall mount bracket that would work as well. [ Randy  Dec 28, 2016 ]
    Either way. I have mine on the wall. Have these in my vacation home. I have Rti a3 at home also on the wall. Polk make the best all around speaker. [ PATRICK  Dec 28, 2016 ]
    Either way will work. I wall mounted mine. [ jason  Dec 28, 2016 ]
    The speakers are very solid and fairly heavy. I mounted mine on a wall with the integrated bracket, but I'm sure they would do fine on a properly sized speaker stand. [ Rick  Dec 28, 2016 ]
    These can be placed on a stand, table or shelf, as well as wall mounted. [ GEORGE  Dec 28, 2016 ]
    Stands should be ok, depending on location. Like any surround speakers.. location, location, location!!! Stands of course will be fine and work, so Good Luck!! [ Greg  Dec 28, 2016 ]
    1. The Polk FXi A4 will make a satisfactory match for the LSi front speakers. 2. However you would achieve more seamless sound effects when you also add LSi surround speakers. I would recommend the Polk LSi M702 F/X as your surround speakers. [ NORBERT  Jan 31, 2016 ]
    i have all polk speakers and think they all match up well to each other, You cant go wrong. i use the FXI A4 on the sides and back. Love all 4 of them! I have the Polk Monitor 70 as my mains and the Polk CS2 as my center. go for it. [ Martin  Jan 30, 2016 ]
    yes they will and they sound very good [ RICHARD  Oct 07, 2015 ]
    I forwarded your question to an Advisor and they responded with the following: I would try to stay within manufacturer as much as possible. The reason for this has to do with voice matching your speakers. Ideally you want the same type of components in your speakers so that a motorcycle traveling front to back on your speakers will sound the same all the way across. The tweeter on the Polk FXi A4 will be a bit softer of a material and may give you too much of a warm sound versus the bit brighter sound of the Primus you already own. I would look at the Infinity Reference R152 which has a tweeter is made with much closer material than the Polk which will allow it to mesh better. If you would like to discuss further you can contact an Advisor directly by phone (1-800-324-9695) or online chat. [ Krissy  Oct 06, 2015 ]  Staff
    Yes, both are a good match with the 75T. The FXi A4 is similar in price rage to your 75T. I have the FXi A4's and they produce excellent surround sound. i feel like i am sitting in a movie theatre. [ JOHN B  May 17, 2015 ]

    would like to send you to a different page.

    Go there