Definitive Technology StudioMonitor 45 High Performance Shelf/Stand Monitor Loudspeaker - Each (Black)

Model: SM45 UPC: 093207089312 Item: 155302


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The Most Advanced Technologies for the Most Advanced Performance

If you love great sound you must experience Definitive's StudioMonitor 45. Its combination of advanced technologies such as our patented Balanced Double Surround System (BDSS) bass/midrange driver, phase-coherent crossover network and rock-solid enclosure deliver a best-in-class sonic performance.

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 design used in the SM45 features premium audiophile-grade components such as oversized inductors, Mylar capacitors for 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 SM45. This preserves the phase coherence, transient response and dynamic integrity of the signal for absolutely lifelike music and home theater reproduction in your home.


Slim Elegant Styling - Rock Solid Performance

The specially contoured high gloss baffle around the drivers and the tapered enclosure sides enhance sound quality by minimizing diffraction distortion. The enclosure's most important job is to be totally inert and resonance free so as not to color the sound. And that's just we did in engineering the SM enclosures. Internal MDF cross braces further stiffen the system. Tap on the side panel of a StudioMonitor 45 enclosure to hear the solid "thud" of a solid, well-damped cabinet instead of the hollow ring of a poorly constructed speaker.


The Proof is in the ListeningThis extraordinary speaker sets a new reference standard for high-accuracy loudspeakers in its class and achieves equally superb performance with both music and movies. The StudioMonitor 45 reproduces a silky smooth, incredibly detailed sonic image at lifelike volume levels with a sense of ease which is truly remarkable. Movies and music are reproduced with unequaled purity, transparency and lifelike realism.



  • Second generation patented 5-1/4" BDSS mid/bass driver with Linear Response Waveguide technology for flat, accurate response with micro-detail retrieval and three-dimensional imaging
  • Second generation pure aluminum dome tweeter for smooth, extended highs
  • Non-resonant braced enclosure ensures pure, uncolored performance
  • High-gloss anti-diffraction baffle and shaped enclosures reduce diffraction for open and spacious imaging
  • Crossover network features oversize inductors and premium Mylar capacitors for audiophile-grade sound quality
  • Integrated Zobel network makes the SM45 easy for amplifiers to drive
  • Double-flared bass vent for extended bass response with low distortion
  • Heavy-duty 5-way binding posts ensure convenient and secure wire termination


  • Sensitivity: 90 dB
  • Frequency Response: 35 Hz- 30 kHz
  • Nominal Impedance: 8 ohms


  • Height: 14 11/16" (37.31cm)
  • Width: 9 11/16" (24.61cm)
  • Depth: 14 3/4" (37.47cm)



Customer Reviews for Definitive Technology StudioMonitor 45 High Performance Shelf/Stand Monitor Loudspeaker - Each (Black)

5.0 / 5.0
4 Reviews
5 Stars
4 Stars
3 Stars
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1 Stars
I finally decided to get a new sound system after my old one died of old age. After much listening, I decided on a 2.1 channel Denon receiver, 2 DefTech SM 45s and a Prosub 1000. I have played in amateur orchestras (violin), sang in amateur choirs (basso!), and worked in a high-end audio store in the 60s-70s. I listen to live music, and fell in love with BIG pipe organs in the mid 70s. Therefore, my requirements for a music system were severe: musical honesty that would not add to or subtract from the source in any type of music, from one solo acoustic instrument to Mahler's Symphony #8. Full tonal range, from 16Hz organ pipes to triangles, full dynamic range in my listening room, without any exaggeration or ommission, and all at a price I could afford (not much!). When I started, I doubted I could fulfill the last requirement, and that I would have to compromise. Was I wrong! I auditioned several high-end speakers (Mirage, B&W, Paradigm and DefTechs). The DefTechs fullfilled my requirements and my dreams. They are transparent to the music. When I play organ music, the full tonal range is reproduced at all volumes in the natural timbre of the instrument; in other words, it sounds and feels, like an organ. Orchestral recordings show details and inner voices I missed before, in a sound stage that has more breadth and depth than the distance between the speakers, yet the instruments can be located aurally as in a live performance. The SM45s have a tremendous sound stage and musically natural sound. Instruments sound like themselves - very natural timbre. They also reveal inner detail in very complex passsages that some other speakers. The ProSub 1000 blends seamlessly with them. adding the bottom they lack for an impressive impact. Together they make a very full range, compact, and truly musical speaker system. Often, I forget I am listening to speakers - I am listening to MUSIC! And even though I usually listen at quite loud levels (my listening room is not very large), I have not yet managed to overdrive them, which is outstanding in itself, considering the volume of some of those bass drum rolls and pipe organ pedal notes! Kudos to Definitive Technology for combining top-end sound at a very affordable price!
August 25, 2012
Originally posted at
Definitive Technology
Excellent loudspeaker, forget the size/price.
I've used these in the garage for a year on an old receiver. However I decided to give 'em a listen in the living room on the "good" receiver (Denon 3808ci) and some new DVD audio, and compared them to my Vienna Acoustics Bachs. After a couple hours switching back and forth I have to give a very-well-deserved nod to Definitive for making a nicely voiced, gutsy and articulate loudspeaker at such a modest pricepoint. The Definitives aren't as "sweet" and don't create quite the presence of soundstage as the VAs, but they do present more punch and clarity, and are just as musically pleasing. My paycheck, and consequently my equipment prove that I'm only a wanna-be audiophile, but if their bookshelfs are this good it compels me to consider the higher end products from Definitive.
March 9, 2015
Originally posted at
Definitive Technology
The Best
I have had these for about 3 yrs. They blow away my old JBL G300's & some real nice Quads I tried. I have also tried the Def 55's & 65's. The 45's are my Fav. by far-- more defined bass.

I would buy another pair if they came in a white ash. Maybe the front baffle could come in a few other colors as well.....

The are Very attractive and the build is quite solid.
May 28, 2016
Originally posted at
Definitive Technology
Always the best speakers from Def Tech
Bought SM45 several years ago. We have used SM45 as the bookshelf speakers in our office to stream Pandora. The sound quality is just the best, crystal clear, smooth, sweet. Love it.
The only complain is the cost of all Def Tech speakers as they are expensive. Of course, you get what you pay for!
December 9, 2017
Originally posted at
Definitive Technology


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