ATC SCM45A Pro Review: More Bass, More Slam

The ATC SCM45A gives us much of what we value in the SCM25A Mk2, with more bass and even more slam. It also brings more weight, more cabinet volume and a higher price. These are the monitors we ultimately chose for the room with our API console.

Why we chose them

Our enthusiasm for the SCM25A Mk2 centers on its extraordinary midrange presentation. The SCM45A feels closely related in character, while adding the bass and impact that made it our choice for this room. We kept the SCM25A Mk2 pair in our B room, so both models remain part of our studio.

The distinction is straightforward in our experience: the SCM45A offers more of the low-end weight and physical impact we wanted. That does not make the smaller monitor obsolete. It gives the two systems different roles in our studio.

What changes

The SCM45A is an active three-way design with two 6.5-inch bass drivers, a 3-inch soft-dome midrange driver and a 1-inch ATC dual-suspension tweeter. Its Class A/B amplifier pack supplies 150 W to the bass section, 60 W to the midrange and 25 W to the tweeter. The two bass drivers share the bass amplifier section.

ATC specifies a 42 Hz low-frequency cutoff at −6 dB, compared with 47 Hz for the SCM25A Mk2. Those figures describe the manufacturers’ stated limits; our impression of greater slam comes from using the monitors.

Like the smaller ATC, the SCM45A accepts balanced analog audio through a rear-panel XLR. Adjustment is limited to input sensitivity and bass boost. It keeps the same straightforward approach to connectivity rather than adding digital inputs or onboard room correction.

The practical cost

The extra capability comes with a larger footprint. Each cabinet measures 353 × 600 × 375 mm before allowing for the rear handles, and weighs about 36 kg, or 79 lb. The size and weight are real considerations when planning positions and support.

There is also more money involved. We regard the SCM45A as a step up in scale and impact, with the corresponding demands on the room, installation and budget.

Our verdict

The SCM45A became our choice alongside the API because it combines the ATC qualities we already valued with more bass and more slam. The SCM25A Mk2 remains an excellent monitor in our B room. For the room where we wanted the larger presentation, the SCM45A was the right choice.

Technical references: ATC SCM45A Pro product information and technical data sheet. Listening impressions and studio-use details are our own.