McIntosh C22 MK V AC / MC 275 AC pre-amplifier Review

The McIntosh C22 MK V AC and MC275 AC are by no means the most expensive models from McIntosh. But they are definitely among the most beautiful – both visually and sonically: A pre-amplifier combo to fall in love with.

If you can blame McIntosh for something, then perhaps the almost unmanageable number of amp models that are largely assembled by hand by around 150 employees in Binghamton, New York State. I counted 20 different power amplifiers alone. Even if, as a stereo fanatic, you can easily sift through the multi-channel models, for example, and even if you discard something very sophisticated like the 300-gram mono MC2KW, you are still faced with a bewildering variety. Which in the next step will finally be supplemented by one of eleven preliminary stages. If you want to make it easier for yourself, you can take an integrated amplifier – but there are ten offers waiting for you, one nicer than the other.

The exact device does not matter to the pride of ownership. As soon as the more than 70-year-old company logo is emblazoned on the front panel and the familiar play of colors of black, chrome, deep green and turquoise illuminates the room, the banal purchase of entertainment electronics becomes something bigger, almost metaphysical. I say this as a tester who has sat in front of hundreds of great amplifiers, sometimes significantly more expensive than this US combo: McIntosh has its own magic. There are many brands that perfectly fulfill their technical task. But only one that’s been doing it consistently for over 70 years just like McIntosh. After a few weeks with the MC275 and the C22, I can understand very well why the path to McIntosh is one of no return for many music fans: From a hi-fi point of view, the stuff makes you very happy and extremely satisfied. It is an absolute pleasure

What is special about the McIntosh MC275 V AC

When you switch on the C22 MkV preamp and the MC275 MkVI power amp – which can be done with a single push of a button thanks to the PowerLink control voltage – you get a little bit of a Woodstock feeling. Not only because both amplify completely with tubes and their design unmistakably points back to the 1960s. But because the PA of the epochal rock festival in the summer of 1969 actually consisted entirely of McIntosh amps. Numerous copies of the 350-watt tube mono MC3500, which was recently reissued in a new version, were sweating in the racks. But also – if you believe those involved at the time – a number of MC275 MkI, i.e. direct ancestors of today’s power amplifier of the same name, in our test combination. The great Tim de Paravicini once said that the basically unchanged “Unity Coupled” output stage circuit was the only foreign design

Together with the C22 MkV preamp, the MC275 MkVI forms a classic, beautiful team, optically retro, but technically modernized wherever sound, reliability and safety benefit. The basic circuitry and functionality has not changed: the preamp and power amp work completely analog, which includes two complete phono sections in the preamp, one for MM and one for MC systems.

And, of course, the power amp draws on classic McIntosh DNA in the form of the Unity-Coupled output stage. Introduced by McIntosh in the 1950s, Unity Coupling promised drastically lower distortion and greater bandwidth, but placed high demands on the design and quality of the output transformers. What McIntosh solved with in-house, artfully wound bifilar transformers just as elegantly as the equally demanding control of this output stage. So it’s no coincidence that there are no fewer than seven double triodes lined up on the upper deck of the MC275 to animate a pair of KT88 beam tetrodes to work on each channel.

Of course, they can also be made to play with less preparatory work – which countless other tube amps demonstrate. But usually not with the combination of low distortion, high power output and low output resistance, as the MC275 manages. Thanks to truly huge output transformers and a power supply that is no less impressive, McIntosh gets a generous 2 x 75 watts out of the end tubes – or even twice that when the MC275 is running as a mono block. The two channels are then not bridged, but switched in parallel, which is why not only is the power doubled in mono, but the output resistance is also halved, which is advantageous when dealing with difficult loudspeakers. And without unduly stressing the vacuum pistons and driving them to wear:

Today’s 275s are potentially even more reliable – a result of modern materials and processes: High-voltage-resistant capacitors last longer today and are significantly more compact. Modern components are more temperature-stable, so they keep their values ​​constant better under load. At best, the listener’s consciousness drifts today, but not the operating points of his amplifiers. The expensive output transformers that are so important to the sound and that once burned out when there was a defect in the tube are not only better today, but also more resilient because enameled wire with today’s coatings is simply more resistant. In the worst casean electronic protection circuit that monitors output currents and power tubes also takes effect. If any parameter ever goes out of control, the MC275 will automatically shut down and even indicate which tube is in trouble. To do this, she uses the LED lighting of the input tubes, which then changes from green to red next to the affected KT88. The third color on the program is amber orange – but only briefly and less alarmingly: it signals the warm-up and stabilization phase after switching on.

The physical layout of the MC275 is idiosyncratic. There’s no distinct front or back, and no matter how you position the chassis, cables and switches pop out in unexpected, not always practical places. If the power amp is standing sideways, you can see its beautiful name relief, carved out of solid metal in the old steampunk style. Behind them are the pre-tubes, then the end tubes and at the back the three powerful transformers. All audio connections, mono, standby and input switches are then on the left side of the case, while the IEC mains socket, fuse and the switch for the energy-saving auto standby are on the right flank.

All the technical data – from power to intermodulation distortion – are also printed there in black on the stainless steel. So there is quite a lot going on, on and around this amp. But that’s OK and that’s a good thing. In the engine compartment of a 1960s sports car, not everything is packed in plastic Tupperware like it is today. Whereby there is no angle from which the power amplifier does not look great. Its upper deck is now made of polished stainless steel (it was originally made of chrome-plated sheet steel, which could rust over the decades), the chassis, transformers and tube protective cage are unspectacular, but painted clean black. What’s missing are the iconic blue gauges. They first appeared on a McIntosh power amp in 1967 and would have on the 275,

The control and connection panel on the – formally – left side wall is already well populated. The upper half, which is angled backwards for easy access, carries a total of eight extremely solid connection terminals, which owners with weak fingers can also tighten and loosen with a 15 mm socket or open-end wrench. But then please don’t overdo it, because note: The audiophile’s strength becomes enormous when he creates with the lever. Of course, bananas also fit in from above, which are also more practical, at least for finding the clamps with the best sound. In addition to the common ground, there are transformer taps for 4, 8 and 16 ohm loudspeakers for each channel, in mono operation the allocation shifts to 2, 4 and 8Ω as described above, which also makes sense in view of the fact that the true watt eaters mostly modern ones,

On the lower, vertical part of the stainless steel wall there are two small jack sockets for the trigger voltage for remote switching on the far left, followed by the mono switch and the input selector, which selects between XLR and cinch socket pairs. The balanced input bypasses the first tube gain stage and is therefore 6dB quieter than RCA. If you have misplaced the manual in 25 years, you can also read it on the right side wall: From 1.7 volts via cinch, input sensitivity increases,i.e. the input voltage required for full modulation is then just 3.4 volts. With the C22 as the source, we liked the unbalanced connection better in a direct comparison anyway. In the case of very long connections, however, it can sometimes turn out the other way around, if only because “Balanced” is superior in terms of litter security.

The McIntosh C22 Mk V AC Preamp

The fact that the C22 MkV does not normally sound any better via XLR than via RCA becomes clear when you look at the block diagram of the preamplifier: the C22 basically works asymmetrically, for XLR an additional (semiconductor) amplifier must balance the tube signal. You don’t have to leaf through any service manual for this information either, just look at the device cover: In the best McIntosh tradition, the signal path through the device is sketched there. And not just in any way, but in gold on black behind a real glass pane in A5 landscape format. That has style. Especially because in the lower third of the glass window, well protected and yet perfectly staged, the six tubes that play the active main role in the preamplifier’s signal path glow. They are all double triodes, five times 12AX7 as well as a low-impedance 12AT7 as output driver. Of the five 12AX7, only one is for the line stage. All others are dedicated to the two phono stages of the C22.

Now at the latest it becomes clear: Even with the McIntosh preamps there are clear user profiles, and ultimately the initially confusing selection is no longer so confusing. For example, the C22 MK V AC has my name on it: a purely analog preamp with two fully configurable phono inputs, specialized in MM and MC pickups. And one whose roots, like those of the power amplifier, go back to the early sixties.

Visually, the similarity to the C22 archetype is striking. The six tubes also existed in the MkI, albeit with more varied tasks, which no civilian preamplifier has to master today, no matter how hard it tries. For example, tape inputs with variable equalization for tape machines without their own electronics. Stop things like that. Now there are two phono inputs, run separately until the signal reaches full line level and has also passed through the RIAA equalization. That sounds like a waste when all but the very first gain step could be the same in MM and MC. But in this way both inputs can be specialized for their respective task. In addition, the signal is completely strengthened and equalized in this way, even before it encounters the first switching contact.

However, there is no danger from this either, not even in the long term: all switching processes, from the input selection to the tone controls, the mono switch to the resistance and capacitance adjustment of the phono inputs, run via hermetically sealed, long-term stable and extremely contact-safe reed relays, which are Indicate opening and closing with their characteristic, soft ticking. The volume and balance control, which uses an integrated resistance network component, works completely silently and without any noticeable steps. Unlike the C22 examples of past decades, the current MkV controls its functions digitally with an ARM processor including an updateable operating system – with the paradoxical effect that the entire handling feels particularly analogue.

Both phono inputs can be assigned in parallel and adapted to the system used. Owners do not have to bend unworthy behind the rack or even unscrew the noble preamplifier. Rather, the fine adjustment takes place directly on the front panel: An aluminum rotary knob in the classic McIntosh style with a silver checkered rim and black anodized center offers the MM driver seven capacitance values ​​between 50 and 350 picofarads. The MC pilot can choose between seven resistances ranging from 25 ohms to one kilohm. Enough leeway to correctly terminate each pickup and fine-tune it to the listening taste.

Both phono inputs work supremely noise-free. Even with really quiet systems, such as a Denon DL-103R in the FX512 twelve-inch arm on my Funk Super Deck Grande, the inherent noise of the electronics remains far behind the groove noise and is not noticeable even when the record is turned up with the volume turned up. If MC inputs have so little noise, either input transformers are at work or, as here, an MC-optimized, very low-noise transistor amplification stage, which sensitively and yet firmly raises the sensitive currents from the moving micro-coils out of insignificance.

Not to forget: the phono inputs sound outstanding. So good that an external phono preamp really doesn’t make any sense here. That would be idiotic, too, because the C22 in its current form is already a full-fledged phono preamp. Just as all good preamps were once primarily phono preamps – simply because LPs were the only true primary medium for listening to music.

Of course, the C22 also has line inputs, five of them in cinch and symmetrical XLR format. Plus four output stereo pairs, all level controlled. In this way, even more complicated chains, such as those with bi-amping and subwoofer(s), can be conveniently wired. There’s a headphone output with a powerful dedicated amplifier that sounds excellent and can handle tricky high-end listeners like my Audeze and quad magnetostats. The McIntosh specialty HXD can be switched on, a crossfeed process that is intended to turn the headphone-typical in-head localization into a sound with spatial depth and a loudspeaker-like stage. It doesn’t do that for me, instead focusing the music in the middle and eliminating stereo detail. Like everything headphone-related, HXD is likely to look very different on an individual basis, depending on your ears and headphone model. And so the same effect that caused perplexity under my Audeze sound helmet could only produce true personal listening ecstasy with Gerd X.’s Great Grado or Steffi Y.’s top-class Sennheiser.

As a real Mac, the C22 also comes with classic tools that other preamps often lack: bass and treble controls, for example, each with a ±10dB control range in precise 2dB increments, which can of course be switched off. And a volume control with a clear LED status display that can be seen from afar and a lightning-fast response: You don’t have to turn the crank like you would on the steering wheel of an old coach to briefly lower the level: The electronic control reacts directly like an analog potentiometer, but more evenly and with a softer sound turning sensation. A short press on the input selection button mutes the signal. If you give the volume wheel a nudge, it temporarily becomes a balance control. And of course a system remote control is included that can also control other McIntosh devices – thanks to data ports on the rear of the C22 even if they are in the IR shadow,

It is actually unimaginable that someone would set up their Macs invisibly and therefore need the control lines with such gems, but it should happen occasionally in their home country. In my listening room, the preamp and power amp were within sight and reach right in front of me on a Tabula Rasa lowboard. There they are: Operating the C22 by hand means additional aesthetic pleasure. In addition, tone controls, balance and phono adjustment do not obey infrared dictates anyway.

hearing test

In terms of sound, the McIntoshs achieve what only really good amplifier combos can: that the large amount of material and circuitry of almost a hundredweight of electronics, even compared to the highest quality integrated amplifiers, sounds like an abbreviation for the music signal, a ballast shedding and free dancing of the notes. If a fine digital player like the Rega Saturn Mk3 feeds the line input of the C22 Mk V AC, the MC275 finally produces an enormously spacious, finely defined and lively sound image.

The fact that this is a complete tube chain is only noticeable in a positive sense: This freedom, speed and immediacy typically characterizes puristic, often little or no negative feedback and often also underpowered tube amps. The sound of the MC275 is amazingly reminiscent of such particularly straight-forward designs, but without their disadvantages: it delivers performance almost to the limit, even with loudspeakers that do not fall into the “tube-friendly” category. It shows practically no – at least for tube conditions only extremely small – reactions to the impedance curve of the box. And it still plays very friendly and low-distortion even when it is close to its performance limit. It’s not some one-off feature that justifies the MC275’s price.

With the new album “Now Is” by Rival Consoles, I was able to reach the point where the lustily fat mastered electro basslines softened up a bit. But that only happens in everyday listening if you deliberately provoke it. What inspires anew every time and at every volume is the juicy, full, physical playing style of this amplifier combo, from which all styles of music benefit equally. Despite all the magnificent breadth and transparency, the sound always has something warm, almost creamy. That does not reduce the transparency, but really only promotes the naturalness.

This is particularly evident with the phono inputs. For example, “Promises” by Floating Points, Pharoah Sanders and the London Symphony Orchestra needs all the transparency you can get: an LP-long jazz meditation for diverse keyboards, orchestra and of course Sanders’ saxophone, deep in the acoustics of the huge Air Lyndhurst Hall Studios looks inside. With the Macs, this has an almost provocative breadth and with occasional tutti accents a fabulously finely structured ending. The myriads of small, large and tiny stimuli that reach the microphones in such a setting seem like the long march over hundreds of meters of cable, digital and analog processing steps, paint master (Chris Bellman at Bernie Grundman Mastering), Pressing process (Pallas) on blue mottled vinyl and finally having miraculously shortened the scanning with a 1960s radio pickup. As if a wormhole had opened up on the back wall of the venerable Air Studio, leading directly into my 1970s family home.

Denon DL-103, McIntosh C22 and MC275 came onto the market in Japan and the USA at almost the same time. How they played together back then – if at all – I don’t know. In any case, today anyone who wants to push the sonorous, hearty McIntosh sound to the extreme will find a perfect partner in the R version of the MC classic. The system sounds a bit fuller on the C22 than on other top phono stages, but also grippier, emotionally more gripping and always with this wonderfully creamy midrange. A gnarly, full-fledged-healthy bass drives the whole thing along. And it’s not just powerful, but above all dynamic and lively.

So you don’t need audiophile masterpieces to literally nail music fans in front of the system. The Söderberg sisters Johanna and Klara from First Aid Kit manage this with their new album “Palomino” despite a rather compact pop production. Because they are great songwriters and sing beautifully. But also because the Macs lovingly lift their voices out of the mix and project them even closer to the listening position than is otherwise possible. If you are not smitten, you have a soul made of steel – or very darkly tuned boxes that cannot get out of the quark without a high-frequency bonus on the amplifier side.

Of course, the DL103R is quite lively in the presence and brilliance range, but it is a bit limited at the top end. In order not to wrongly infer the sound of the preamplifier from the sound of the system, I have therefore also listened with very modern systems that are sufficiently broadband even for bats and dogs – such as the Rega Ania Pro or the even more opulent Lyra Delos. The openness and transparency of the C22 makes such comparisons appear crystal clear and always offers a wider framework than even top pickups are able to fill. This applies to headphones as well as to the power amplifier and good speakers.

Conclusion McIntosh C22 MK V AC and MC275 AC

The C22 and MC275 form a wonderfully subtle and at the same time grippingly dynamic amplifier combination that sounds dewy, cutting-edge and ultra-modern despite the optical retro appeal. And thanks to outstanding workmanship and future-proof construction, it will continue to do so for many years to come. Music fans with a focus on vinyl have also exhausted the topic of phono preamps with the purchase of the C22. This also puts the price of the station wagon in a friendlier light. Especially since you can then shelve the subject of amplifiers for a very, very long time or forever.

McIntosh MC275 AC

Technical concept: tube power amp

Perfomance: 2 x 75 watts (4, 8, 16 ohms)

Inputs: 1 x XLR, 1 x RCA, triggers

used tubes:      4x KT 88, 4x 12AT7, 3x AX7A

Special feature: Can be bridged to 1 x 150 watts

Dimensions (W x H x D: 41.9 x 19.0 x 46.5 cm

Weight:           30.5 kilos

With a power amplifier that has been in the program for so long, the question naturally arises as to whether it has to be the current version. Answer: yes. Visually, not much has changed, but technically all the more so. The MkVI has better transformers, a higher operating voltage, therefore lower distortion than any previous version. In addition, thanks to the intelligent protective circuit, it is even more reliable.

The technical data

McIntosh C22 MkVAC

Technical concept: tube preamp

Tube assembly: 5x12AX7, 1x12AT7

Analog inputs: 2 x XLR, 3 x RCA, 2 x phono (RCA)

Outputs: 2 x XLR, 2 x RCA

Phono MM customizable:        50 to 350pF in 50pF steps; 47k ohms

Phono MC customizable 25, 50, 100, 200, 500 or 1,000 ohms; 100pF

Dimensions (W x H x D): 44.5 x 15.3 x 45.7 cm

Weight:    11.3 kilos