Anthem MCA 325 3-Channel Power Amplifier

The Anthem MCA 325 is a 3-channel power amplifier from the Canadian manufacturer's MCA Gen 2 series, sitting alongside the 2-channel MCA 225 and the 5-channel MCA 525. All three share the same core circuit topology and construction, differing only in channel count. The MCA 325 delivers 225 watts per channel into 8Ω, scaling to 400 watts into 4Ω and 600 watts into 2Ω, making it a natural partner for the Anthem AVM 70 or AVM 90 processors and MRX series receivers in a three-channel front-stage configuration.

Power Supply and Output Stage

At the heart of the MCA 325 is a custom low-noise, high-power toroidal transformer paired with high-quality filter capacitors and advanced power supply regulators. Each channel employs eight high-current bipolar output transistors, distributing the load across multiple devices to reduce stress on individual components. Oversized aluminium heatsinks dissipate heat efficiently, and the completely redesigned circuit layout minimises internal cabling for a more direct signal path.

Advanced Load Monitoring (ALM)

Anthem's proprietary ALM technology continuously monitors internal temperature, current, and voltage across all channels. If a fault condition is detected on one channel, the affected channel is temporarily muted while the remaining channels continue to operate uninterrupted. Once the fault clears, full operation resumes automatically. This approach eliminates the need for signal-path fuses, which can introduce resistance and degrade audio quality.

Performance

The MCA 325 achieves a signal-to-noise ratio of 120 dB (IEC-A weighted, referenced to 225 W), with total harmonic distortion measuring just 0.001% at 1 kHz and 100 watts. Intermodulation distortion is equally low at 0.0005% (ITU-R) and 0.002% (SMPTE). Frequency response extends from 20 Hz to 20 kHz within ±0.1 dB into 8Ω and 4Ω loads, widening only slightly to ±0.2 dB into 2Ω. Power bandwidth reaches 90 kHz at −3 dB, and the damping factor of 300 from 20 Hz to 1 kHz ensures tight low-frequency control. The slew rate of 30 V/μs contributes to the amplifier's enhanced power bandwidth.

Connectivity and Control

Each channel accepts both single-ended (RCA) and balanced (XLR) inputs, with input impedances of 10 kΩ and 15 kΩ respectively. Input sensitivity is 1.5 Vrms for full rated power into 8Ω. Speaker connections are made via custom-designed audiophile-grade dual binding posts. A 3.5 mm relay trigger input provides automated power-on via a connected processor or receiver, alongside manual and signal-sensing activation modes. Standby power consumption is just 1.4 watts.

Construction

The MCA 325 is designed and crafted in Canada. The low-flux toroidal transformer is selected to minimise stray magnetic radiation, and the conservatively rated power supply ensures stable operation during sustained high-output passages. The detachable IEC power cord allows use of an aftermarket mains cable if desired.