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Definitive Technology StudioMonitor 45

Bookshelf speaker

66 Reviews | 1 question - 5 answers

Item # 735SM45

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Our take on the Definitive Technology StudioMonitor 45

Definitive Technology's StudioMonitor 45 packs an astonishingly big punch into a surprisingly small package. It should — it's the result of more than 20 years of research and development by Definitive in their quest to create speakers with a perfect balance of style, utility, and performance.

Precise, potent sound for tight spaces

Definitive Technology's StudioMonitor 45 packs an astonishingly big punch into a surprisingly small package. It should — it's the result of more than 20 years of research and development by Definitive in their quest to create speakers with a perfect balance of style, utility, and performance.

Each rock-solid cabinet features an advanced 5-1/4" mid/bass driver that delivers plenty of impact and detail, plus a 1" pure aluminum dome tweeter for crisp, extended highs that shimmer. If you're a music enthusiast short on living space, these compact gems should be high on your list of speakers to consider.

" In spite of its almost laughably low price, the SM45 is a speaker that demands to be taken seriously…they were unexpectedly full-bodied and offered an astonishing amount of bass reach (down into the upper 30Hz region)—reach few other small monitors can match. …it provides giant helpings of musical richness, relaxation, and enjoyment at a ridiculously modest price. For these reasons and many more, Definitive's SM45s are a no-brainer recommendation for music lovers whose sights are set high, but whose budgets are limited."

— From Chris Martens' review in The Absolute Sound, April, 2013

Definitive Technology StudioMonitor 45

Definitive's second-generation patented BDSS driver with Linear Response Waveguide™ technology gives this speaker exceptional sound quality.

High-tech driver design for impressive performance

The StudioMonitor 45s are chock full of technology that's also found in Definitive's top-of-the-line speaker models. Its 5-1/4" mid/bass driver uses their latest Balanced Dual Surround System (BDSS) driver design, which places a surround on both the outer and inner edge of the speaker cone. This helps the cone remain more stable as it moves, resulting in clearer, more accurate sound — even at high volume levels. The '45's mid/bass driver also gets Definitive's second-generation Linear Response Waveguide™. This mushroom-shaped post in the center of the cone smooths off-axis frequency response for broad, even sound dispersion and a more realistic sonic "image." That means every listener in the room gets to hear balanced, open sound with lifelike vocals and instruments.

Crisp, sparkling highs

Definitive also equipped the StudioMonitor 45 with their latest 1" pure aluminum dome tweeter. This advanced driver is first heat-treated to relax the crystal structure of the metal, then coated with a ceramic that helps produce clear, sparkling highs without a trace of edginess. You'll easily hear the subtle high-frequency details in your music, like the sound of wire brushes gently sweeping the snare head, or the bell-like ring of a brass cymbal.

pure aluminum dome

A second-generation pure aluminum dome tweeter yields smooth, extended treble.

It's all in the details

Definitive paid close attention to other important design elements, too — both visible and hidden. At its heart, the StudioMonitor 45 uses a sophisticated crossover network with audiophile-grade components that include over-sized inductor coils and Mylar film capacitors. These give you a smoother, flatter frequency response, more powerful dynamics, and faster transients, for sound with real presence and immediacy. Sturdy, vault-like cabinet construction also plays a big role in this speaker's performance. The '45's well-damped, cross-braced enclosure features a specially contoured front baffle with tapered sides to minimize diffraction and vibrations that can color your sound and reduce accuracy. Plus its rear-firing, double-flared port is specially designed to enhance low-frequency impact, while keeping bass distortion low.

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Did you know?
Your new speakers will probably sound better after several weeks of use than they do right out of the box. That's because the material surrounding the woofers will loosen up, allowing the drivers to move more fully. Definitive Technology estimates a break-in period of 24 to 48 hours of playback before the speakers will deliver optimum sound quality. For more information and helpful tips, check out this article from Definitive's website about conditioning your speakers.

Product Highlights:

  • bass-reflex (ported) design
  • second-generation Balanced Dual Surround System (BDSS) 5-1/4" mid/bass woofer delivers clear, accurate sound at high volumes
  • Linear Response Waveguide technology smooths off-axis frequency response for broad, even sound dispersion and more realistic imaging
  • second-generation 1" pure aluminum dome tweeter for clear, extended highs
  • crossover network features oversize inductors and premium Mylar capacitors for audiophile-grade sound quality
  • non-resonant braced construction ensures clean, uncolored sound
  • wood grain matte black enclosure with high-gloss, anti-diffraction baffle and detachable cloth grille
  • frequency response: 35-30,000 Hz
  • sensitivity: 90 dB
  • impedance: 8 ohms
  • recommended amplifier power: 20-150 watts
  • one pair of heavy-duty 5-way binding posts for convenient and secure wire termination
  • 11-5/8"H x 6-3/4"W x 11-5/8"D
  • warranty: 5 years
  • Our 60-day money-back guarantee

What's in the Box:

  • Black bookshelf loudspeaker
  • Detachable black cloth grille
  • 4 Self-adhesive rubber feet
  • Owner's Manual
  • Online Product Registration card

Fantastic little speaker. Sounds much larger then other speakers of the same size. I can not believe the amount of bass this thing makes. I have it on some speaker foam to isolate them from the table they are on as well as am using them as front left/right speakers in a 5.1 setup.

MATT, Mc Lean, VA


Definitive Technology StudioMonitor 45 Reviews

Average Customer Review(s):

(66 Reviews)
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Hands-on research

Product Research

Driver Technology
Enclosure Design
Mounting Options

Driver Technology

StudioMonitor Series: The Definitive Technology StudioMonitor 45 is a compact bookshelf loudspeaker designed for use in audio/video entertainment systems. Because the StudioMonitor 45 is a true full-range speaker with extended low-frequency response, it delivers superb performance both as stand-alone speaker and when combined with a separate subwoofer. Due to its compact size, wide-range, high-power handling, and natural articulate clarity; the StudioMonitor 45 loudspeaker is ideal for use as front, center, or surround speaker in a home theater environment.

2-Way Loudspeaker: Each Definitive Technology StudioMonitor 45 loudspeaker features a 5.25" second generation BDSS midrange driver and a 1" pure aluminum dome tweeter.

  • 2nd Generation BDSS Midrange: The 5.25" midrange driver features Definitive's patented Balanced Double Surround System (BDSS) technology that supports the speaker cone at both the inner and outer edges allowing longer, more linear excursion for greater clarity and finely textured inner detail.
  • Pure Aluminum Dome Tweeter: The 1" tweeter is a pure aluminum dome, which has been heat-treated to relax the crystal structure and then coated with a ceramic to produce smooth, extended highs. A new patent pending Linear Response Waveguide smoothes off-axis frequency response and disperses sound over a wider area for crystal clear intelligibility for every listener in the room.

Phase-Coherent Crossover Networks: The crossover network is the real heart of a loudspeaker as it is responsible for perfectly blending together the sound of the various drivers into a musically seamless whole. The sophisticated crossover network design used in the StudioMonitor 45 loudspeaker features premium audiophile-grade components; such as oversized inductors and Mylar capacitors for audiophile-grade sound quality, with linear phase and frequency response. An integrated Zobel network flattens the impedance of the system so that even budget amplifiers will be able to drive the StudioMonitor 45 loudspeaker (although a premium amplifier will bring out all the performance it has to offer). As a result, the audio signal's phase coherence, transient response, and dynamic integrity is preserved for absolutely lifelike music and home theater reproduction in your home.

Enclosure Design

Non-Resonant/Low-Diffraction Cabinet: The Definitive Technology StudioMonitor 45 bookshelf loudspeaker employs a non-resonant MDF braced enclosure that ensures pure, uncolored performance. The specially contoured high-gloss baffle around the drivers and the tapered enclosure sides enhance sound quality by minimizing diffraction distortion.

Bass Reflex Design: The Definitive Technology StudioMonitor 45 loudspeaker utilizes a doubled-flared, rear-firing port for extended bass response with low distortion.

Note: Due to the rear-firing port, the speaker must be placed at least 2" from the wall.


Heavy-Duty Binding Posts: Each StudioMonitor 45 bookshelf loudspeaker is equipped with a pair of heavy-duty, binding post speaker terminals to attach your receiver's speaker wire. The binding post speaker terminals will accept bare wire (up to 10AWG), pin-connectors, spade-connectors, and banana-plugs (single only).

Color-Coded: The speaker's binding posts are color-coded (red/black) for easy identification between positive and negative.

Mounting Options

Table-Top Mounting: The StudioMonitor 45 loudspeaker can be simply placed on a bookshelf, table-top, or speaker stand (such as the Definitive Technology StudioStand, sold separately ). Four self-adhesive rubber feet are included to protect your furniture's surface.

Wall Mounting: The optional PinPoint heavy duty side-grip wall-mounting bracket (121AM41B, sold separately) can be used to wall mount the speaker.

Note: The speaker does not include any type of wall-mount bracket, threaded inserts, or keyhole slots.

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?

Definitive Technology brand speakers have always had a great reputation and quality products. I chose to purchase these 45's today because the price was right and the advice given from Crutchfield reps, sealed the deal. [ DAVID  Aug 05, 2018 ]
I have the older SM 350's and thought these would be a nice addition. Especially with this price! Great deal. Now I'll have a set of 4 speakers in the room. Can't wait to hear them. :) [ DAVID  Jul 26, 2018 ]
I already have a pair and love them. [ Thomas  Jul 23, 2018 ]
I've got the SM55's, and I'm very pleased with them. Bummer they're gone. [ William  Jul 07, 2018 ]
I have def tech StudioMonitor 350's (the equivalent to the 45's) for my front speakers and have been extremely happy with them. So I want these to replace my def tech ProMonitor 80's that I use for surrounds. [ David  Jul 03, 2018 ]
Sounds amazing. [ KARL  Jun 25, 2018 ]
Lots of postive reveiws, great price, an size. I also been wanting to try out D.T. bookshelf speakers for a while now to hear how good they really sound. I'll post up again after I get them. [ Ronald Dale  Jun 24, 2018 ]
great reviews, good price, right size [ James  Jun 07, 2018 ]
I love definitive technology speakers, and this price was too good to pass up. [ Darrell F.  Jun 05, 2018 ]
At the sale price, these are the best value I could find. The combination of the extended bass response (35 hz claimed with a 5.25" woofer), an aluminum dome, plus Definitive reputation for sound quality and nearly 50 4/5 star reviews, made this speaker for me (actually for my daughter, a musician, for college). [ MICHAEL  May 20, 2018 ]
They're awesome [ Mario  May 17, 2018 ]
My second purchase of these speakers from Crutchfield. Love the sound and quality. [ Jeffrey  May 11, 2018 ]
Bass response seems excellent for this size of speaker. [ Mario  May 04, 2018 ]
Reviews, attractive pricing, Crutchfield experience over the years. [ ROBERT W  May 01, 2018 ]
I am using a pair of these speakers for my computer music through the AudioQuest Dragonfly DAC into my mid 90s Denon 2 channel receiver and they simply sound amazing. Upgrading my Bose Acoustimass 7 with non-matching rear speakers for my Denon AVR-3802 system. At a later time I'll look into a subwoofer (can't now due to migraine patient in the house). [ Gary  Mar 12, 2018 ]
Recommended by Definitive Technology for my particular and budget application. [ Armando  Mar 10, 2018 ]
I wanted a small speaker with good sound. Through research and reading reviews I decided to give these a try [ Krista  Jan 24, 2018 ]
Receive high praise from Crutchfield advisors and from comments from buyers. [ JOHN C  Jan 18, 2018 ]
Great reviews, size and pricing [ Edwin  Dec 03, 2017 ]
We have a pair of DT's BP7001SC home theater speakers. These are simply amazing. No hesitation in a "no-hear" purchase for their bookshelf speakers. [ Steven  Nov 27, 2017 ]
Fantastic speakers, I already have one set of these, at an amazing price! [ BRIAN  Nov 26, 2017 ]
The DefTech 45's were recommended last year by Wes for my old system but the Polk Tsi200's (also a good match) were on a good sale, so got those, now replacing some coffin size, original speakers with the DefTech's. [ Heidi  Nov 19, 2017 ]
Awsome price on a quality product [ James  Nov 14, 2017 ]
Great sound and great build quality. [ Kelvin  Oct 30, 2017 ]
Price, Specs, and I have a Definitive Tech Sub [ John  Oct 23, 2017 ]
Size and reviews. [ STEVEN  Oct 09, 2017 ]
prior experience with definitive tech speakers [ Gerald  Aug 12, 2017 ]
Excellent specs, great value! Even more so with this special sale! [ Donald  Aug 02, 2017 ]
Researched and for our application, looks like an excellent choice. Have past experience with Definitive Tech - extremely pleased. thus, buying more! [ Richard  Jul 04, 2017 ]
I chose these to go with my new DT center channel speaker, which I am very pleased with, and as an upgrade for my front R & L speakers. These are just the right size and price for my needs. [ Michael  Jan 22, 2017 ]
Meets our need for size and ohms and the reviews make it clear that these are outstanding value for bookshelf speakers. Plus, the credits for previous purchases, the superb website, and customer service keep us coming back. [ Diana  Nov 26, 2016 ]
Price + freq response for surrounds [ George  Nov 24, 2016 ]
Home stereo system upgrade [ FRANK  Oct 15, 2016 ]
sensitivity, frequency range, height of speaker enclosure, reviews, reputation, cost and ratings [ Gregory  Jul 17, 2016 ]
quantity and quality of reviews, price. [ Steven  Apr 14, 2016 ]
I heard these in a Store not gonna list the name. These speakers make amazing sound for being so small..Ive heard some pretty good speakers & after hearing these even I was impressed. If you want great sound but don't have the room for big speakers,These speakers are what your looking for. (35Hz to 30K Hz) That's better then most Tower Speakers. [ Randall  Mar 07, 2016 ]
Purchased because of the recommendation of an advisor. I wanted a smaller scale stereo, and he recommended these speakers with a receiver. [ Richard  Mar 01, 2016 ]
Compactness and overall value for money, considering the sound quality from the available reviews [ Benedict Amaebi  Feb 09, 2016 ]
Awesome Fr-Rep, nice size, good price. [ MARK  Jan 16, 2016 ]
Positive reviews by Stereophile and Absolute Sound [ Oliver Brent  Dec 18, 2015 ]

1 question already asked

My use: high quality, crisp, full range, bookshelf speakers for music in a 12x16 room; would not hesitate to buy them again for this purpose. Given their size (depth especially; approx. 7"W x 11"H x 11"D), I guess you have quite a bit of space in the room you are going to use them in as rear surrounds... Good luck! [ Glenn  Feb 08, 2018 ]
I have these set up as front speakers and I love them. They have plenty of bass and in a small room you could easily get by without a sub. I think they would be just fine as rear surrounds. [ Ronald Pezda  Feb 08, 2018 ]
Absolutely these are the best sounding bookshelf speakers I have come across in 30 years of searching. Full spectrum and amazing clarity make these a great choice for surrounds or even mains in a smaller setting. [ Timothy  Feb 08, 2018 ]
Hey John: Up Front: Significantly bigger than purpose-built satellites but with deeper, more fulfilling sound quality. I have these guys and they have a fantastic sound. Truly a sweet speaker. But, they are fairly large to get that sound. There's no doubt they would do a great job as satellites but I would make sure to consider their physical depth and my space. If you have time to put together a bit more scratch, consider DefTech's 9040s. I have the former version, SR8040BPs and love them. They're built to disperse sound into a wider field, are more compact(depth and weight wise) and will allow a bit more flexibility in room size I think. If you should decide to go with the 45's, you won't be disappointed with the sound for sure. John W [ John  Feb 08, 2018 ]
Hi John K These would be a great choice for your rear surrounds. They do take some time breaking in before the full sound becomes relaxed. Remember they have a port in the back so placement of the back flat on the wall will cut the bass output in half. I hope this helps. [ EUGENE  Feb 08, 2018 ]

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