Definitive Technology SM45 Bookshelf Speaker Review

Last updated on: 11-8-18
Bottom Line: significantly discounted due to now legacy status. Quoted response range is stellar but probably optimistic. Full range 2-way bookshelf speakers don’t make much sense anyhow – it’s better to just cross them over to a subwoofer to handle the bass. Better alternatives currently exist – see the end for such recommendations.
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Important Specs Overview

Speaker type: passive, 2-way, back ported
Continuous power handling: 45 W*
Peak power handling: 150 W
Impedance: 8 ohms
Sensitivity: not specified by manufacturer
Frequency response range: 35 – 30k Hz
Driver Size: 5.25 in
Unit weight: 13 lbs
Cabinet dimensions: 7 x 12 x 12 in (width x depth x height)
Warranty: 5 years

*When nominal/RMS power isn’t specified by manufacturer, we use an approximation of ~30% of the specified peak/dynamic power for comparison purposes.

Review And Discussion

Definitive Technology is a well regarded audio company that mostly makes higher end products, but they do produce some budget tier speakers, including the StudioMonitor series (purposeful one word), which includes three sized bookshelf speakers. The 5.25 inch driver SM45, reviewed herein, is the smallest of the bunch.

The SM45 has decent specs for a budget 2-way bookshelf speaker – 45 W of (approximated) continuous power handling will be plenty sufficient for near/mid-field listening, but will likely fall short in a full sized home theater setting.

The response range looks stellar on paper, but it’s a little suspect, especially without a standard 3 dB differential. Definitive technology is allegedly a little… optimistic we’ll say about their range specs, and it’s unlikely that a smaller 2-way bookshelf speaker can actually hit a floor of 35 Hz, or if it can, there’s probably a significant drop off in relative volume. That said, if such speakers can even get close to what they claim, it’s quite good for the price.

The other issue is that it doesn’t really make sense to invest in 2-way speakers that try to go super low on the bass when you can just get an external subwoofer, something which is truly designed for that. A 2-way bookshelf speaker is rather generally designed and best suited for focus on the mids/highs while diverting the work of the bass to a larger subwoofer.

The SudioMonitor bookshelf speakers feature a proprietary polymer blend woofer and an aluminum dome tweeter. These materials are generally more durable and consistent as opposed to silk or paper drivers, but have a propensity to sound thin and “shriek,” which might have consequences if you plan to position these closer in a desktop setting. Performance will depend on the room, and it’s likely these will sound their best after a break in period.

They look decent enough, pretty par for the course for budget bookshelf speakers. They’re relatively large and heavy, but not exorbitantly so. They also have the option of a removable foam grill cover with a sheen logo on the bottom. The cabinet is pretty standard black vinyl MDF. Definitive Technology offers a five year warranty on all its passive speakers, which is pretty top of the line.

Our Overall Take, As Compared To The Competition

The SM45s have become significantly discounted, we imagine due to their now legacy status since they’re not officially listed on DTs website anymore (this happens fairly often in the audio world). These have the best quoted response floor that we’ve seen for bookshelf speakers so cheap.

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… but, said again, take that with a grain of salt – it’s unlikely a single midrange driver can produce full bass at that range, and 2-way bookshelf speakers are just not designed for that. We’d rather see speakers that have more power and just cross them over to an external subwoofer. This usually boils down to a listening test, and the kinds of stuff you plan to play on your speaker.

Keep in mind these are passive speakers and thus need a receiver to power them. If you’re looking for something you can just plug right in, they’ll need to be powered. Many such options are available – see the links below for recommendations.

Relevant Links and Resources

The best overall budget bookshelf speakers