Boston Acoustics M340

Floor-standing speaker

  • Boston Acoustics M340


  • Boston Acoustics M340


  • Boston Acoustics M340

    Extended Wide Bandwidth (EWB) dome tweeter

  • Boston Acoustics M340

    Mass-loaded 4-1/2" polypropylene midrange

  • Boston Acoustics M340

    Pictured without grille

  • Boston Acoustics M340

    Separate internal midrange chamber


Our take on the Boston Acoustics M340

by Dave Bar
Boston Acoustics

Floor-standing speakers — still standing tall

Sure, floor-standing tower speakers buck the industry trend toward smaller, visually inconspicuous speakers, but they're hard to beat if great sound is your primary goal. Tower speakers produce powerful sound with excellent bass, making them a great choice for serious music lovers and for folks who want high-impact home theater.

Not just another face in the crowd

Sporting a glossy black lacquer finish with leatherette trim, Boston Acoustic's graceful M340 floor-standing speaker makes a stunning addition to just about any space. But this sleek tower isn't just another pretty face — its lifelike sound will make you make you sit up and say "wow." Whether you're listening to a string quartet or watching the latest action flick, you'll hear clear, highly defined midrange and smooth, extended highs complemented by tight, tuneful bass. The M340 is equally at home used as a stereo pair or as front left and right speakers in a multi-channel home theater system.

Advanced tweeter design for spacious, detailed highs

Boston's Extended Wide Bandwidth tweeter

Boston's Extended Wide Bandwidth dome tweeter lets the M340 really sing with silky, transparent highs. Unlike most tweeters, this one has a dimple in the middle that stabilizes the linear motion of the tweeter for significantly lower distortion, improved dispersion for a deep, expansive soundstage, and greater clarity over a broad range of frequencies.

A musical midrange with a room of its own

Boston mass-loaded midrange and midrange sub-enclosure

The M340's exceptionally musical midrange comes courtesy of its mass-loaded 4-1/2" midrange driver. This uniquely designed cone features four small rectangular “tabs” on the inside edge of the surround that add mass to achieve smoother frequency response at the top of the driver's operating range. This mechanical mass-loading approach eliminates the need to add more electronic components (and complexity) to the crossover, resulting in cleaner sound and superior imaging in the critical upper-midrange frequencies.

Along with its mass-loaded cone, the M340's midrange also gets its own separate internal chamber. This acoustically isolates the midrange from the woofers inside the cabinet to prevent them from interfering with each other and muddying the sound. The separate midrange chamber also doubles as a reinforcing brace near the top of the cabinet to add rigidity and reduce cabinet vibrations even further.

Multiple woofers deliver tight, accurate bass

The M340 delivers precise, hard-hitting bass thanks to its four matched 4-1/2" woofers and an acoustically tuned port. Combined, these four woofers have approximately the same radiating surface area as a single 8” woofer. But by using multiple smaller drivers, the M340's front baffle is kept narrow to improve its sound dispersion into the room and give it a more slender, room-friendly profile. Another advantage to this design is that the four separately positioned woofers generate multiple floor reflections (also known as floor bounce). This minimizes the speaker's sensitivity to room placement for smoother bass response than is typical from a single larger driver. 

Better cabinet construction = better sound

Cabinet vibration, or resonance, is the enemy of clear sound. It distorts and colors the sound of instruments and vocals. Boston's M Series speakers fight vibration with LoQ™ cabinet construction. By using two sheets of MDF (medium density fiberboard) with a special damping adhesive layer between them, Boston created an enclosure that provides the acoustic deadening of much thicker materials without the drawbacks of added weight and increased size. The result is a relatively compact, lightweight speaker that has a very low resonance — or in speaker-speak, a low “Q.”

In addition to the Lo-Q cabinet material, Boston also used a scanning laser vibrometer to critically position the M Series cabinets' internal braces where they provided the most benefit. Then they added heavy-duty absorptive cabinet fill to eliminate internal standing waves. These advanced cabinet building techniques and materials result in speakers with impressive transparency and a large, detailed soundstage.

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  • 1" Extended Wide Bandwidth soft dome tweeter for excellent clarity and low distortion
  • 4-1/2" mass-loaded polypropylene midrange provides smooth overall response with minimal coloration
  • four 4-1/2" polypropylene woofers minimize sensitivity to room placement and optimize bass response
  • bass-reflex (ported) enclosure
  • separate internal chamber isolates midrange driver from the woofers to prevent interference
  • Boston Lo-Q™ cabinet construction reduces vibration and eliminates unwanted resonance
  • high-gloss black lacquer finish with leatherette trim
  • frequency response: 45-30,000 Hz (±3dB)
  • sensitivity: 88 dB
  • impedance: compatible with 8-ohm outputs
  • recommended amplifier power: 50-350 watts
  • 5-way binding post speaker terminals
  • 8-13/16"W x 40-5/16"H x 11-7/16"D
  • weight: 46.3 lbs.
  • warranty: 5 years
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
Enclosure Bass Reflex
Finish MDF/Leatherette/Lacquer
Color Black
Tweeter Dome
Tweeter Size (inches) 1
Midrange Size (inches) 4.5
Woofer Size (inches) 4.5
Woofer Composition Polypropylene
Woofer Surround Rubber
Built-in Powered Sub No
Video-Shielded No
Connector Type Post
Bi-amp Inputs No
Parts Warranty 5 Years
Labor Warranty 5 Years
Power Range 50-350
Frequency Response 45-30,000 Hz
Sensitivity 88 dB
Impedance (Ohms) 8
Amplifier Power ---
Height (inches) 40-5/16
Width (inches) 8-13/16
Depth (inches) 11-7/16
Weight 46.3 lbs
Product Research
What's in the box?

Download owner's manual

  • Floor-standing loudspeaker
  • Detachable grille (installed)
  • 4 Rubber feet (pre-installed)
  • 4 Spiked feet
  • Owner's Manual (En/Fr/Sp)

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 open the box, verify contents, 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.


Three-Way Speaker Design: This three-way speaker combines a 1" Extended Wide Bandwidth dome tweeter with a 4.5" midrange and four 4.5" woofers for smooth, natural sound, and dynamic bass. Experience rich sound while enjoying music, movies, and more with the M340 floor-standing loudspeaker from Boston Acoustics.

  • 1" Extended Wide Bandwidth Dome Tweeter: The M340 floor-standing loudspeaker is equipped with Boston's signature 1" Extended Wide Bandwidth (EWB) dome tweeter, which is designed to cover a broad range of frequencies, reduce distortion, and improve clarity in the high registers. Unlike most tweeters, the EWB has a small dimple in the middle and a large radiating surface that extends from the center to the outside perimeter of the diaphragm. This design enables the tweeter to track subtle treble details and reproduce the highest frequencies with ease.
  • 4.5" Midrange Driver: A 4.5" polypropylene midrange employs mass loading to dampen harmful resonances and achieve a smoother frequency response at the top of the driver's range.
  • Quad 4.5" Woofers: The M340 also features an array of four 4.5" polypropylene woofers that produce multiple floor reflections that minimize sensitivity to placement and optimize bass response. The woofers feature aluminum shorting rings for dramatically lower distortion and a clearer sound.

High Quality Crossover Networks: Very high quality crossover networks featuring low loss film capacitors and low distortion laminated silicon steel core inductors are utilized for greater clarity and minimal coloration.

Lo-Q Cabinet Construction: The M340's Lo-Q cabinet is built to reduce vibrations and eliminate unwanted resonances. The M340 has a cabinet made of Lo-Q, a material consisting of two pieces of medium-density fiberboard joined together with a thick layer of damping adhesive in the middle. This material significantly reduces cabinet vibrations to virtually eliminate unwanted resonances allowing the M340 to create a larger, more vivid soundstage. The cabinet also contains heavy-duty absorptive fill and internal braces which have been strategically positioned to maximize the speaker's strength and optimize sound.

Isolated Chambers: An internal chamber acoustically isolates the midrange from the woofers to prevent interference and serves as a reinforcing brace near the top of the cabinet to add rigidity and reduce vibrations even further.

Gloss Black Finish w/ Leatherette Wrap: The M340's gloss black finish and curved side panels with faux leather wrap can complement almost any decor.

Rear-Firing Port: The Boston Acoustics M340 employs a rear-firing port for higher efficiency and greater bass response. Because of the rear-firing port, the speaker should be placed at least 3" from the wall.

Binding Post Speaker Terminals: The Boston Acoustics M340 floor-standing loudspeaker is fitted with a set of binding post speaker terminals that will accept bare wire (up to 10AWG), banana plugs (single only), spade-connectors, and pin-connectors.

Rubber & Spike Feet: The M340 floor-standing loudspeaker comes with pre-installed rubber feet which are ideal for hardwood floors. Spike feet are also included for placement on a carpeted surface.

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Boston Acoustics M340 Reviews

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5 out of 5

Boston M340's

Written By Jim, Oklahoma on Wednesday, April 23, 2014
Crutchfield Customer Review (What's this?)
I bought some Infinity Primus P363's to replace some older Boston power towers I had. While they were VERY good speakers, they weren't what I was looking for. Crutchfield was very gracious and helpful about letting me return them. The problem I was having, my wife didn't want a powered sub sitting around and I was accustomed to 2 of them. My wife came back to these Boston's, and of course I wanted them, but at a grand each, they were out of our budget. We have had 2 set's of Boston's over the last 17 years so we were more than satisfied with them. We looked around some more but didn't really see anything. A couple of day's later these speakers went on sale, BOGO. We bought them right away regardless of the lack of reviews. I googled them myself and the reviews were stunning. Once I received them and hooked them up, I was amazed. These speakers are simply awesome!! They are some of the best speakers I have ever heard. Whether you are playing a Blu-ray movie, concert, or a CD, or your iPod. They are amazing. The bass is very strong and the mids and high's blend seamlessly. I can say with these speakers, I don't miss not having a powered sub For the money, they are an absolute steal. I would by these speakers again and again any day. Thank you Crutchfield for putting such a stellar high end speaker in the range of a everyday guy!!!
Speaker Terminals make for easy hook up
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1 out of 5

sent back

Written By MZH, Baltimore, MD on Thursday, January 30, 2014
Crutchfield Customer Review (What's this?)
sent back. nice tight bass. mids were unrecognizable. highs were extremely muffled......they sounded great with certain tracks, but 80% of my music sounded horrible. fit and finish was very nice.
2 out of 10 people found this helpful
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5 out of 5

Blown away

Written By jmink999, Hammond Indiana on Tuesday, December 24, 2013
I am completely blown away with the performance of these speakers
1 out of 3 people found this helpful
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For a more in-depth review and enhanced detailed information on the Boston Acoustics M340, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_065M340/Boston-Acoustics-M340.html ).