McIntosh MC275 - Black

Description

The MC275: From 1961 to Today, McIntosh's Most Iconic Tube Amplifier

Introduced in 1961, the MC275 quickly became a reference amplifier for driving the power-hungry loudspeakers of its era with high power and remarkably low distortion. It was discontinued in 1971 as the transistor era took over, but the story didn't end there: McIntosh brought it back in 1993 as a commemorative edition posthumously honoring McIntosh co-founder and longtime president Gordon Gow. The reintroduced version won unanimous praise from the international audio press and earned its permanent place in the catalog. Now in its sixth generation, the MC275 preserves the musical qualities that built its reputation while incorporating subtle refinements from each successive revision. It is hard to imagine McIntosh without the MC275.

Unity Coupled Circuit: The Widest Bandwidth McIntosh Output Transformer Ever Used on the MC275

The MC275 is built around the Unity Coupled Circuit output transformer — the technology McIntosh patented in 1949, and the foundation of the brand's tube amplification craft. This unique architecture connects both the cathodes and plates of the output tubes to the hand-wound output transformer, allowing full rated power to be delivered across all common speaker impedances. This sixth generation carries the widest bandwidth version of the McIntosh output transformer ever used on the MC275: measurably tauter bass control and a thermally quieter circuit design — the two most notable improvements over previous generations. Rated total harmonic distortion 0.5% max from 250 mW to rated output over the 20 Hz – 20 kHz band (≤ 0.25% at 1 kHz), 105 dB signal-to-noise below rated output, 1.2 dB dynamic headroom, damping factor greater than 22, frequency response +0/-0.5 dB from 20 Hz to 20 kHz (+0/-3 dB from 10 Hz to 100 kHz).

75 W × 2 Stereo (4/8/16 ohms) or 150 W Monoblock (2/4/8 ohms) — Side Switch

The MC275 can be used in either stereo mode or mono parallel mode via a switch on the side of the unit. In stereo mode, it delivers 75 W per channel into 4, 8, or 16 ohm speakers — the high-impedance tap is 16 ohms (not 2 ohms as on other McIntosh amplifiers), which is useful with certain high-impedance vintage speakers. In mono parallel mode, the two internal channels are combined to feed a single speaker with 150 W into 2, 4, or 8 ohm loads. This flexibility lets a listener start with a single MC275 in stereo, then add a second MC275 later to form a pair of 150 W monoblocks — a natural upgrade path to a reference-tier all-tube stereo chain. Connect each speaker to the tap that matches its nominal impedance rating to get full rated power through the Unity Coupled Circuit transformer.

Output Stage: Four KT88s and Seven Small Signal Tubes With LED Status Indicators

The MC275's power stage uses four KT88 output tubes laid out visibly on the top chassis. The Input, Voltage, and Driver stages use seven small signal tubes: four 12AT7 and three 12AX7A. Under each of these seven small tubes, McIntosh installed a multicolor status LED. At start-up, the LEDs sequentially glow amber during tube warm-up, then all turn green when the amplifier is ready to play. Should an output tube fail — a rare event — the LED(s) under the affected channel turn red to flag the issue immediately: instant visual diagnostics that simplify servicing.

Sentry Monitor™ Protection and Solid Cinch™ Speaker Binding Posts

The MC275 carries the McIntosh Sentry Monitor™ protection circuit — a fuse-less short-circuit protection that disengages the output stage before current exceeds safe operating levels, then automatically resets once conditions return to normal. No fuse in the signal path, no associated sonic degradation. The patented McIntosh Solid Cinch™ gold-plated speaker binding posts accept bare wire, banana plugs, or spade lugs, and clamp down firmly by hand to guarantee an optimal electrical contact that doesn't loosen over time.

Balanced XLR and Unbalanced RCA Inputs, Power Control Ports

The MC275 provides one balanced XLR input and one unbalanced RCA input, selectable via a side-panel switch — the XLR input is particularly useful for long cable runs from a distant preamplifier, since it actively rejects common-mode noise induced along the signal path. 3.5 mm Power Control input and output ports enable synchronized power-on and power-off with other McIntosh components in the chain — preamplifier, CD player, turntable, or network streamer — for one-remote-press system operation.

Where the MC275 Sits in the McIntosh Tube Amplifier Lineup

The MC275 is the iconic stereo tube amplifier in the McIntosh catalog. Above it: the MC1502 (150 W x 2 tubes, also with Unity Coupled Circuit and Solid Cinch™), and the three McIntosh tube monoblock amplifiers — MC2301 (300 W Quad Balanced tube monoblock), MC3500 Mk II (350 W monoblock), and MC901 (hybrid 300 W tube + 600 W solid-state for bi-amping a single loudspeaker). On the solid-state side: MC152 (150 W x 2), MC312 (300 W x 2), MC462 (450 W x 2), and the monoblocks MC611, MC451, MC830, MC1.25KW, and MC2.1KW. The MC275 speaks specifically to the listener who wants the McIntosh tube signature in its most historic form — KT88 tone, timeless design, 1961 heritage — while benefiting from the measurable progress delivered by the sixth generation.

Common Questions

Which speaker binding post (2, 4, 8, or 16 ohms) should I use?

It depends on the operating mode. In stereo mode (75 W x 2), the available impedance taps are 4, 8, and 16 ohms — note that there is no 2-ohm tap in stereo, but there is a 16-ohm tap that is useful with certain high-impedance vintage loudspeakers. In mono parallel mode (150 W × 1), the available taps are 2, 4, and 8 ohms. In both cases, connect each speaker to the tap that matches the nominal impedance rated by the manufacturer. Thanks to the Unity Coupled Circuit transformer, the MC275 delivers its full rated power on each of these taps with no compromise.

How does mono parallel mode work?

The MC275 has a stereo/mono switch on its side panel. In mono parallel mode, the two internal channels of a single MC275 are combined to drive a single loudspeaker at 150 W (up from 75 W per channel in stereo). To build a complete monoblock system, you need two MC275s: each configured in mono mode and connected to a single loudspeaker (one for the left channel, one for the right), for a pair of 150 W monoblocks with increased dynamics and speaker control. A natural upgrade path for the listener who starts with a single MC275 in stereo.

What do the LED colors under the small tubes mean?

The seven small signal tubes (4 × 12AT7 + 3 x 12AX7A) are each illuminated from below by a multicolor LED. At start-up, the LEDs sequentially glow amber during tube warm-up; they turn green when the amplifier is ready to play. Should an output tube fail — a rare event — the LED(s) under the affected channel turn red to flag the issue immediately: instant visual diagnostics that simplify servicing. LED brightness can be dimmed remotely from a compatible McIntosh preamplifier through the Power Control link.

Which McIntosh preamplifier is recommended with the MC275?

McIntosh explicitly recommends the C2800 reference vacuum tube preamplifier or the C8 vacuum tube preamplifier (with integrated MM/MC phono stage) — in both cases, a coherent all-tube chain in style and signature. Additional McIntosh partners: the MCD85 or MCD600 SACD/CD player, the MT10 turntable, the MR89 AM/FM tuner, the MEN220 room correction system, the MPC1500 power controller, and the ML1 Mk II or XR100 loudspeakers for a fully McIntosh system. The 3.5 mm Power Control link between preamp and MC275 provides synchronized power-on and power-off across the chain.

What's in the Box

McIntosh MC275 2-Channel Vacuum Tube Power Amplifier

Four KT88 power tubes (installed)

Four 12AT7 tubes (installed)

Three 12AX7A tubes (installed)

Removable tube protective cage

AC power cord

Power Control cable (3.5 mm)

Owner's manual