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Definitive Technology StudioMonitor 45

Bookshelf speaker

Item # 735SM45

Definitive Technology's StudioMonitor 45 packs an astonishingly big punch into a surprisingly small package.

Definitive Technology's StudioMonitor 45 packs an astonishingly big punch into a surprisingly small package.

Need help?
Contact our Virginia-based experts.
Discontinued item
1 question - 5 answers

Item # 735SM45

Need help?
Contact our Virginia-based experts.

About the Definitive Technology StudioMonitor 45

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.

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.

Got wire?

Most speakers don't include any. Learn about choosing and installing speaker wire at the Crutchfield Learning Center.
Shop our selection of speaker wire.

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
  • MFR # MCDA

What's in the box:

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

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More details on the Definitive Technology StudioMonitor 45

Stacey B.

Features & specs

Enclosure Bass Reflex
Finish Wood-grain MDF
Color Black
Tweeter Type Dome
Tweeter Size (inches) 1
Midrange Size (inches) N/A
Woofer Size (inches) 5.25
Woofer Composition Polymer
Woofer Surround Rubber
Power Range 20-150
Sensitivity 90 dB
Impedance (Ohms) 8
Frequency Response 35-30k Hz
Connector Type 5-way post
Bi-amp Inputs No
Height (inches) 11-5/8
Width (inches) 6-3/4
Depth (inches) 11-5/8
Weight (pounds) 12.95
Mounting Bracket Included No
Recommended Stand Height (inches) 28.5"
Parts Warranty 5 Years
Labor Warranty 5 Years
The Definitive Technology StudioMonitor 45 replaces these items:

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.

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Customer Q&A

1 question already asked

Would these be a good choice for rear surrounds?
[ JOHN  Feb 08, 2018 ]
5 answers
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.
[ Copus  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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