McIntosh C22 (1963–1968)

Name: McIntosh C22
Brand: McIntosh

Six tubes, seven line inputs, and a warm-up delay that keeps the speakers silent until the 12AX7s are ready - the preamp McIntosh built as the front end for the MC275.

Overview

The C22 is heavy, and McIntosh built it to sit under an MC275 for the next sixty years. It is a stereo vacuum tube preamplifier that McIntosh Laboratory produced from 1963 to 1968, and it was the company's flagship tube preamp of that era. The circuit is all tube, one 12AT7 and five 12AX7A valves, pure analog. No op-amps, no digital logic. Between the phono cartridge and the output stage there is nothing but glass and wire.

According to available documentation, the C22 is a control unit rather than a switch box. It has seven line-level RCA inputs and two balanced XLR line inputs, plus a single phono MM input. That covers a tuner, two tape decks, an auxiliary source, and a turntable without reaching around the back. Line gain to the tape output is 0 dB, so the record-out path is unity. What comes in goes out uncolored, which helps if you're dubbing. Phono gain to the preamp output runs 55 dB, enough for a typical moving-magnet cartridge to drive a power amp directly. Total harmonic distortion is rated at less than 0.2% at 10 volts output and less than 0.02% at 3 volts output. Those figures were respectable for tube gear of the period and still hold up when the unit is properly serviced.

The chassis measures 445 by 152 by 415 millimeters. That's deeper than most preamps of the era, so you plan your rack around it instead of squeezing it into whatever shelf is left. It was positioned as the companion to high-end McIntosh amplifiers such as the MC275, and it was the top of the company's tube preamplifier lineup during its production run. Owners report a warm, engaging vintage sound, and collectors keep calling the build quality "legendary."

One thing to flag up front: the C22 name has been reused. McIntosh later revived the model number for the C22 Mk V, a modern vacuum tube preamplifier. It shares the 12AT7-plus-five-12AX7A tube complement and the C22 name, but it comes from a completely different generation of design. When someone says "C22" in a forum thread, ask which one. The original is the one with the 1963-1968 production run, and it's the one this page covers.

Key Features

12AT7 and Five 12AX7A Valves

The signal path runs through the 12AX7A, the high-mu dual triode that defined tube preamp design across the 1950s and '60s. McIntosh used five of them alongside a single 12AT7. The high gain of the 12AX7A lets the phono circuit reach 55 dB without stacking extra stages, and fewer stages means less noise, which matters to anyone who has chased hum in a phono stage. The tubes also explain why the C22 needs a warm-up before it sounds right. McIntosh planned for that.

Automatic Turn-On Delay

Most tube preamps of the era let you hear the amplifier settle in: the soft thump as the tubes come up, the hum that fades over the first thirty seconds. The C22 doesn't do that. An automatic turn-on delay mutes the output until the tubes are warmed up, which cuts startup noise. It's a small feature on paper. It helps most with a high-efficiency speaker system, where every transient is audible.

PEC Devices for Tone, Loudness, and Filters

The tone controls, loudness compensation, and filter circuits are managed in part by PEC (Packaged Electronic Circuit) devices. These are the encapsulated modules McIntosh used across its preamp line, and they cut both ways. They kept the circuit compact and consistent, with the tone and filter behavior calibrated at the factory rather than left to component drift. But replacement PEC devices are no longer available, and that's a real constraint on restoration. If a PEC module fails, a technician has to rebuild the function from discrete parts or find a donor unit.

Rumble Filter and Separate High/Low Filters

The C22 has a rumble filter and separate high and low filters, which gives three independent ways to shape what reaches the power amp. The rumble filter is the one to know about. Owners report a known operational flaw: the rumble filter cuts off one channel when engaged. That isn't a case of "it was always broken." It's a failure mode that develops, and it's fixable. If a seller says "the rumble filter is a little weird," this is probably what they mean.

Power Supply: 210µF, Three Twist-Lock Cans, 310/290/268V Rails

The original power supply design includes 210µF of effective filtering and contains three twist-lock capacitor cans, with reference voltages at 310V, 290V, and 268V respectively. That's three separate rails, each with its own filtering, which is a serious supply for a preamp. It also makes restoration a project. Original twist-lock cans are no longer available, so a rebuild means either restuffing the original cans with modern capacitors or mounting replacements underneath and leaving the originals in place for appearance. Either approach works. Neither is a five-minute job.

Historical Context

The C22 was McIntosh Laboratory's flagship tube preamplifier before the C2200, which marked the company's first entirely new tube preamp design since the C22. It wasn't a mid-range model that happened to sell well. It was the top of the tube preamp line, and it held that spot through its entire 1963-1968 production run. It was positioned as the companion to high-end McIntosh amplifiers such as the MC275, and the pairing was deliberate - the preamp and the power amp were designed to be bought together.

When the C2200 arrived, it was McIntosh's return to a clean-sheet tube preamp design after decades of solid-state development. Contemporary advertising of the period shows the C22 marketed alongside the MC225, MC240, and MC275 power amplifiers and the MR71 tuner, a full McIntosh system with the preamp as the control center. Audio (March 1965, p.47).

Collectibility & Value

The C22 is considered highly collectible and is likely the most sought-after vintage McIntosh preamplifier. Recent eBay listings for original-production units have run $4,214 for a 1963 example with a wood cabinet and $4,280 for another 1963 original. Those are asking prices rather than settled sales, but they're consistent with how the market sees the model.

Buying one is a commitment, and the maintenance list is the reason. Degraded performance from aging capacitors is the headline issue, particularly in the power supply, where the original twist-lock cans are no longer available. Replacement PEC devices are also unavailable, which makes repairs to the tone and filter circuits difficult when something goes wrong. The rumble filter cutting off one channel when engaged is a known operational flaw reported by owners, so test it before purchase. Rebuilds typically involve replacing diodes, upgrading power supply capacitors, and rewiring the rumble filter circuit with shielded cable. None of that is exotic work for a competent technician, but it's not a weekend project either. Done right, you have a $4,000 preamp that sounds like one. Skipped, it sounds tired.

One caution for shoppers: the C22 name appears on several generations of McIntosh gear, and the model number alone doesn't tell you which one you're looking at. A factory-sealed C22 Mk V and a 1963 original share a name and a tube complement and almost nothing else. Check the production era before you bid.