Усилители мощности моно — McIntosh MC3500

The MC3500 Mk II is a mono tube amplifier by McIntosh Laboratory, announced in November 2021 at a suggested price of USD 15,000 and shipping to the US and Canada from December 2021. It reimagines the original MC3500 built from 1968 to 1971, the amplifier that powered the sound system at Woodstock, and McIntosh describes the new version as a conservatively rated monoblock inspired by that design. Two units are required for stereo.

Key specs that matter

Rated power is 350 W for 2, 4 or 8 ohm loads, and dynamic headroom reaches 2.4 dB. THD stays at 0.3% maximum from 250 mW to rated power and below 0.20% at 1 W. Noise sits 120 dB below rated output, and damping exceeds 25 across the band. Response stays within 0.5 dB from 20 Hz to 20 kHz and within 3 dB from 10 Hz to 70 kHz. Input sensitivity is 3.8 V via XLR and 1.9 V via RCA, input impedance is 22 kohm and gain is 29 dB. The amplifier measures 45.7 cm wide, 30 cm high and 57.5 cm deep and weighs 54.9 kg.

Engineering and use context

Eight EL509S output tubes do the heavy lifting. These are high-power sweep tubes with a sturdy cathode, whereas the 1968 original used 6LQ6 sweep tubes. The fully balanced driver section uses three 12AX7A tubes as the differential input amplifier, a buffer and driver, and a voltage amplifier, while one 12AT7 buffers and drives the output tubes. A Unity Coupled Circuit output transformer delivers full power to each of its three load taps. Power Guard Screen Grid Sensor technology works against clipping in the tube stage, and Sentry Monitor regulates output current. A cage of 12-gauge stainless steel wire behind the power and output transformers protects the tubes. The machined aluminium front panel has a bead blast finish with gold anodizing and holds a centre-mounted DualView meter with watts, decibels and warm-up time scales, larger than the offset meter of the original. The chassis base is polished stainless steel, U-shaped siderails with black rubber bumpers replicate the road-ready details of the 1968 version and ergonomic handles are fitted.

Pairing

A balanced XLR input and an unbalanced RCA input accept a preamplifier. Balanced and unbalanced outputs pass the signal on, which suits multi-amp configurations where further amplifiers are fed from the same source. Loudspeaker wires connect through McIntosh Solid Cinch posts with gold plating, and the transformer taps suit loudspeakers of different nominal impedance.

Alternatives

The McIntosh MC1.25KW is a solid-state monoblock rated at 1,200 W with 0.005% distortion and Autoformer output.