TK ACOUSTIC LAB
LOUDSPEAKERJOURNAL

ATC

SCM45A Pro

Active Studio MonitorDome Midrange

A three-way active monitor placing dual 164mm LF, 75mm soft-dome MF and 25mm HF drivers with 150W/60W/25W Class A/B amplification in a symmetrical horizontal enclosure.

Drivers
2 × 164mm LF + 75mm MF + 25mm HF
Frequency range
42Hz–25kHz (-6dB)
Amplification
150W + 60W + 25W Class A/B
Official page
Published in the Journal Product release
Official view of the ATC SCM45A Pro showing its dual LF drivers and central MF/HF section
Image: ATC

Product Overview

The SCM45A Pro is a mid-sized three-way active studio monitor introduced by ATC in 2015. Two 164mm carbon-paper-cone LF drivers flank a central 75mm soft-dome MF and 25mm dual-suspension HF driver, with two bass-reflex ports on the front baffle. It is intended for near- to mid-field monitoring, LCR and surround applications.

The three bands are individually driven by 150W, 60W and 25W discrete MOSFET Class A/B amplifiers, with fourth-order active crossovers at 380Hz and 3.5kHz. There is no digital input or room-correction DSP; the control set comprises balanced analogue XLR input, input sensitivity and 40Hz LF boost.

Specifications

System
Three-way active front-ported studio monitor
Drivers
LF: 2 × 164mm carbon-paper cones; MF: 75mm soft dome; HF: 25mm dual-suspension soft dome
Frequency range
42Hz–25kHz (-6dB, free-standing)
Amplitude linearity
70Hz–17kHz (±2dB)
Nominal dispersion
±80° horizontal and ±10° vertical, coherent
Maximum continuous SPL
112dB per pair at 1m
Amplification
LF: 150W; MF: 60W; HF: 25W; discrete MOSFET Class A/B
Crossovers
380Hz and 3.5kHz, fourth-order critically damped with phase compensation
Audio input
Balanced XLR, input impedance above 10 kilohms, 1Vrms reference sensitivity
Adjustments
0 to -6dB input sensitivity and 0 to +3dB LF boost at 40Hz, continuously variable
Dimensions
353 × 600 × 375mm (H × W × D, excluding handles)
Weight
36kg per monitor

Design & Technology

75mm soft-dome MF driver

Official image of the 75mm soft-dome MF driver used in the ATC SCM45A Pro
Image: ATC

The 75mm soft-dome MF driver covers 380Hz to 3.5kHz and defines the SCM45A Pro's reference listening axis. A large dedicated dome spans the range from the low crossover to the HF handover. ATC specifies placing this MF dome at or slightly above ear height.

Dual 164mm LF drivers

The two 164mm LF drivers receive the same signal and share the range below 380Hz. Compared with the SCM25A Pro, ATC states that doubling the LF radiating area reduces the excursion required from each driver at a given SPL while extending bass and increasing output capability. Two front ports remain unobstructed when the monitor is soffit mounted.

25mm dual-suspension HF driver

The 25mm SH25-76S soft-dome HF driver supports the voice coil and dome with upper and lower suspensions. ATC describes this as a means of reducing unwanted rocking of the moving assembly, and the SCM45A Pro was the company's first three-way professional monitor to use this HF driver.

235W of discrete three-channel Class A/B amplification

Internal amplification comprises 150W for LF, 60W for MF and 25W for HF using discrete MOSFET Class A/B circuits. The signal is divided at line level before each driver is powered directly. Fixing amplifier and driver combinations within the product allows gain, protection and crossover conditions to be set for each band.

Fourth-order active crossover without DSP

Crossovers at 380Hz and 3.5kHz use fourth-order critically damped filters with phase compensation. The sole input is analogue XLR, with no digital signal processing or network calibration in the signal path. User adjustment is limited to input sensitivity and 40Hz LF boost.

Symmetrical horizontal baffle

The two LF drivers are arranged symmetrically around the central MF/HF section, so there are no mirror-imaged left and right versions. The same model can serve as L, C or R and may be used on stands behind a console, on a meter bridge or soffit mounted. The central MF dome is the acoustic reference axis.

Near-field, mid-field and surround use

ATC positions the SCM45A Pro for critical near-field monitoring, LCR use in medium control rooms and surround channels in larger rooms. At 36kg per enclosure, it is intended for a suitable stand away from reflective work surfaces or for a properly designed soffit installation rather than casual desktop placement.

Sources

  1. 01
    ATCSCM45A Pro

    Manufacturer product page · Accessed August 15, 2026

  2. 02
    ATCSCM45A Pro Technical Data Sheet

    Official datasheet · Accessed August 15, 2026

  3. 03
    ATCATC Launches SCM45A Pro High-Performance Three-Way Active Loudspeaker

    Manufacturer press release · Accessed August 15, 2026

  4. 04
    ATCSCM45A Pro Supplementary Sheet

    Official manual · Accessed August 15, 2026