When I saw the boxes, which housed the MC501 monoblocks I had a moment of despair, and wanted to turn around, pretending that they did not arrive to me. Because I need to carry them home, at third floor, using the stairs. This moment of weakness should be justified, as the boxes are really big. The amplifiers themselves, after unpacking from the internal box, turned out to be smaller than expected. This is because their shape is a bit out of proportion, at least when we compare with other Mac amplifiers or the P-7100 Accuphase . Those monoblocks are quite high, but short, and frankly speaking, they resemble in shape the tube power amplifiers from Manley, the Neo-Classic 250. Those tube monsters (250W per channel) can also be compared to the MC501 in terms of weight – those are incredibly densely packed amplifiers, which one person can carry only with great effort and endangering his or hers backbone. And they do look like that at all.

Like I already mentioned, the MC501 are power amplifiers, monoblocks, from the ‘500’ series of McIntosh, together with the C500P/T/C preamplifier and the SACD player MCD500. Their design incorporates a glass front (or actually three smaller ones – this is called 3D design by the company) instead of the commonly used aluminum, which houses also a big, blue VU meter. Also characteristic is the layout of other elements behind the fascia – we don’t see classic top and side covers, there are metal cups shielding the power transformer and autoformer inside, accompanied by a set of heat sinks. We can see a reflection of the amplifier’s balanced architecture, as each branch received its own heat sink.
The sockets were also placed unlike other amplifiers, as they were placed on the horizontal part of the chassis, extended to the back of the unit. This amplifier is a true power plant, as it is capable of outputting 500W (rated value) to any load. This because one of McIntosh patents applied in its design, an autoformer was employed, a kind of output transformer, used to adapt the power stage output to the loudspeaker impedance. It is also worth mentioning, that the MC501 releases this power with very low distortion, about 0.005%. Low THD is also a characteristic of all products coming from this American manufacturer, as even their first products, the power amplifier 50W-1 had distortion below 1% at full power of 50W, something, that not all amplifiers can achieve even nowadays. After this first success the company scored more good products and THD went to 0.1% and lower – something the competition cannot reach for years.
The MC501 is not a very recent construction, it was introduced to the market in 2003, but in case of McIntosh this has absolutely no meaning…

Discs used for testing: Compact Disc

• Laurie Allyn, Paradise, Mode Records/Muzak, MZCS-1124, CD.
• Lucy Ann, Lucky Lucy Ann, Mode Records/Muzak, MZCS-1121, CD.
• Herb Ellis, Man With The Guitar,Dot Records/Universal Music Japan, UCCU-5287, CD.
• King Crimson, Larks’ Tounges in Aspic, Discipline Global Mobile/WHD Entertainment, IECP-30006, HQCD/HDCD.
• Tsuyoshi Yamamoto Trio, What a Wonderful Trio!, First Impression Music, FIM DXD 079, silver-CD.
• Depeche Mode, Piece, Mute, CDBONG41, SP CD.
• The Doors, The Doors, Elektra Records/Warner Music Japan, WPCR-12716, CD.
• Thom Yorke, The Eraser, XL Records/Warner Music Japan, WPCB-10001, CD; review HERE.
• Yoko Ono, Open Your Box, Astralwerks, ASW 88710, CCD.

Super Audio CD

• Groove Note. True Audiophile. The Best of Groove Note, Groove Note, GRV1036-3, SACD/CD; review HERE.
• Milt Jackson Sextet, Invitation, Riverside/Mobile Fidelity, UDSACD 2031, No. 01828, SACD/CD.
• Manuel de Falla, The Three Cornered Hat, Ansermet, Decca/Esoteric, ESSD-90016, SACD/CD.
• Mozart, Piano Contertos No.20&No.27, Curzon/Britten, Decca/Esoteric, ESSD-90014, SACD/CD.
• Depeche Mode, Exciter, Mute, DMCD10, SACD/CD+DVD.
• Dead Can Dance, Toward The Within, 4AD/Warner Music Japan, WPCB-10077, SACD/CD; review HERE.
• Henry Purcell, Fantasias for the Viols, Hespèrion XX, Jordi Savall, Alia Vox. Heritage, AVSA 9859, SACD/CD; review HERE.
• J.S. Bach, Matthew Passion (ver. 1742), Dunedin Consort&Players, Linn Records, CKD 313, 3 x SACD/CD; review HERE.

SOUND

This listening test of the MC501 was preceded by a longer contact with the integrated amplifier MA7000, which turned out to be a very sublime product. It was characterized with phenomenal bass, cleanness of all frequency sub-ranges and lack of aggression. Now because McIntosh is a company based on solid engineering knowledge, every product is designed based on previous experience and achievements. This is the reason, that we easily can draw parallels between the individual models, common dividers and planes. So plugging in the MC501 into my system I did not get surprised or enlightened. Its sound reminded me much of the MA7000. At least that was my first impression. And yet, disc after disc, hour after hour, it became clear, that although the basic character of sound is similar, the foundation identical, yet we deal with something more refined and sublime here, than we did with the integrated. Interestingly, those were not zero/one changes, no exchange of paradigm, but rather stepping a few more meters down, in many points a soft change from good and very good to very good and fantastic, respectively.

This is still the same character of the sound we deal with, similar to other products of that company. So this is still an incredibly clean and clear sound, completely free from brightening and sharpness. Now I am sure, that when you experience a McIntosh based system play too bright, then it is a problem with some other device, and not Mac. I am sure about that. Another characteristic of the MC501 is a splendid tonal balance. Because I could compare with my Luxman M-800A (60W in class A), Accuphase P-7100 (class AB) and Jota Sentry Art Audio (SET, 20W), the thing I am speaking about was shown really nice: the American monoblocks were best balanced from the pool, I could not find any point, any range, where something would be boosted, underlined or withdrawn – from upper treble to lowest bass. Maybe, analyzing it deeper, it could be said, that the upper treble is a bit withdrawn, but only when compared with the Jota and Luxman, which are outstanding in this aspect. What is important, that this neutrality was not associated with lack of saturation. This could be attributed to the Accuphase A-60 (the A-65 not), or, with a little of ill will to the Krell EVO402, but never to Mac. This way of perception is, most probably, the result of some kind of softening of the attack, something natural, imitating real events, and not being a real softening. The mentioned Manley Neo-Classic 250 and the Accu P-7100 sound in a softer way, crossing a bit the line of neutrality, while the MC501 are able to balance everything just right. This was audible with discs like The Eraser Thom Yorke and Open Your Box Yoko Ono, built with synthesizers and electronic sounds. Those discs sounded as if they would receive comfortable environment, as if the musicians would sit comfortably in front of their computers’ monitors.

During the listening sessions my attention was drawn to an incredible “freedom” and ease the Macs have in reproducing everything found on the disc, without a trace of “holding something back”, compression. And this all is not only in terms of dynamics, it was also there with the MA7000 and the Accu P-7100, but about something more, something that is the result of how this unconstrained dynamic influences the rest of the transmission. And this is a different thing. Sitting in front of the monoblocks, with every coming hour, I became more and more convinced, that those are a perfect tool for reviewers. For “normal” people also, but the job of a reviewer requires the usage of different tools than usual. To make one thing clear: those are not the last word in terms of resolution of midrange and treble, SET tube go further in those aspects.

Also my Luxman shows a better differentiation of cymbals and vocal factures. Those were not big differences, audible on high resolution, clean loudspeakers, but it is hi-end, and everything must be taken into account here. If I would be fighting to get those mentioned elements, then I would choose the Jota Sentry Art Audio, or Ancient Audio Silver Mono Grand, the latter being the best monoblocks I ewer hears, regardless the price. But music is an amalgamate of many different elements, and we cannot choose one element – I mean, there is no sense of picking one, and evaluating everything from its perspective. This means – I am confusing you a bit, but those are not straight forward things – it can be done, and in reality many audiophiles – music lovers do that, but this is not the right direction. At least, this is my private opinion. I think, that it is better for the music to combine the audio gear elements the right way, and although we may have our priorities, we should restrain them, and they should not play the most important role. This is why the MC501 seems a very attractive proposition for me – the play everything in an incredibly even and balanced way. Like I say – we can do more in the area of micro information, this is slightly smoothed in the Mac, but we cannot do it keeping all the rest.

And this is related – we cannot escape it – with the units sheer power. Power spoils, and absolute power spoils in an absolute way, and we can experience that listening to amplifiers like Accuphase P-7100, Krell EVO402 or the MC501. Already with the Krell, when I played Pasodoble Lars Danielssona & Leszek Możdżer (review HERE), I was aware, that I am dealing with a new quality, that sound needs power just to make us forget about it, so that we do not have to worry. SET tube amplifiers, having only 10-20W of output power, tend to clip early, and although they do it in a soft way, they have no chance of playing with full frequency range and dynamics (I also mentioned that – I think, that high efficiency loudspeakers, while being easy to drive, have big problems in achieving a flat frequency response). Physics does not allow that. But it is worth to remember, that power on its own, let me phrase it that way, is also useless and does more harm than good, this is something what I can experience again and again, when I am responsible for the sound of some stage performers – 500W on the stage is nothing, this is just a starting point. If power would solve all problems, then those monster should rule our homes. But this is not the case. Why? Letting the audiophile phobia for professional units, that would be a failure, I can tell that based on my experience. Its high power is not associated with refinement, saturation, or even the basic requirements of hi-end. That is why Mac’s power is so incredible. It allows everything to play with comfort. When something on a disc is made in some way, then we do not have any doubt, that it is like it is, nothing is underlined or masked. It just is as it should be. There is no brightening, because the amplifiers are not asked to work outside their comfort zone. Even my Luxman, being a phenomenal amplifier, compared to the Krell and McIntosh, showed that somewhere, on the lower bass, and bass-midrange edge, that it compresses something delicately, pushes some part of the frequency spectrum in front of the rest.

Like I say – MC501 is not an ideal amplifier, because an ideal would combine the resolution, timbre, etc, of the midrange and treble of a SET tube (e.g. Silver Grand Mono) with the ease of handle bass and dynamics of the McIntosh. But there are no such things. This is why, if I’d choose a tool for me to work, which would also be satisfying in my private life, then Mac would top the list, with two-three other products. Its sound stage is wide and fairly deep, and the elements in counter phase, engulfing the listener, are reproduced phenomenally! For 100% this is helped by the separation of both channels, and is not hampered by the extraordinary coherence of all sub-ranges, in amplitude and time. The stage depth is not especially outstanding, this not its specialty, and we should just accept that. Small heat sinks, and the fact, that they do not get very hot, suggest that the power stage was tuned in deep AB class. The usage of autoformers is helping in that aspect, because the output transistors are not stretched and work well within the safety zone of their parameters. Also the topology is helping, but I think the first reason is more important. This makes the resolution not so unbelievable, class A amplifiers, and SET tubes in particular, are better in that aspect. But, as usual, we have to make a choice, even in top hi-end, and the MC501 monoblocks are for sure inside that category.

DESCRIPTION

MC501 is the name of power amplifiers, monoblocks by the company McIntosh. Its predecessor was the stereophonic power amplifier MC500 manufactured in the years 1994-1999. Fortunately, I had various opportunities to listen to it in many configurations, because at that that time I was employed by the first distributor of the McIntosh brand products in Poland, the company Audioholic. The new version cannot be bridged, like the older version could (we got then a combined power of 1000W), because those are monoblocks, but this is probably a good move. The devices are tall and incredibly heavy, although not overly deep. The fascia is made from three glass elements, placed in a way, that the middle one is protruding towards the listener. It houses the big VU meter in the typical blue color. John Atkinson shows in his measurements (Paul Bolin, McIntosh MC501, „Stereophile”, Vol.27, No.8, August 2004, S. 68-77), that it is not very precise, because when the needle in the tested unit showed 50W the actual power outputted was 30W. But the real power turned out to be much higher than the one quoted in company materials – 500W – and measured 720W at 1% THD! Above the display there is a red LED called ‘Power Guard’. This is an indicator that light up when a protection circuitry kicks in – this happens, when the amplifier generates too much distortion. A similar protection scheme is used by NAD, where it is called ‘Soft Clipping’. The side panels are black, when we disregard the green descriptions of the turn knobs. The left knob controls the way the VU meter behaves, including switching it off, and the right one serves as an on-off button, with a center notch, that allows the unit to be controlled by the preamplifier (but we need to connect the two by means of a mini-jack cable).
Like I mentioned, the devices are not especially deep. On the main chassis, from polished steel, there are big cups, holding the mains transformer and autoformer, and to their back end two small heat sinks are mounted. There are two of them, because in reality the MC501 is composed of two, balanced, amplifiers (four channels in total), working in bridged mode – the company calls this solution ‘quad-amp’. The connectors are mounted in a not so typical way – on the horizontal part of the chassis – there is an RCA and XLR input, switched by means of a small switch placed conveniently nearby. Next to those we see three pairs of loudspeaker terminals (2, 4 & 8Ω) using fantastic, probably most expensive, WBT sockets. However those are fairly close together, what prevented secure bolting of my Tara Labs Omega spades. There is of course a IEC power socket and mini-jack sockets for linking the unit with the preamplifier. For testing i used the Acrolink 7N-PC7100 power cables. I tested the amplifier in a few combinations. The first one, in my reference system, the device was connected to the preamplifier Leben RS-28CS by RCA Wireworld Gold Eclipse 52 cable, and the player was connected to the preamp with Acrolink 7N-DA6300 Mexcel. In the balanced system i used the Velum NF-G SE Blues to attach the monoblocks, and the XLR Acrolink 7N-DA6000 Mexcel for the player connection.

The insides of the amplifier is divided into two sections, similar to the integrated amplifier MA7000: one section is the power stage, bolted directly to the heat sinks, which shields them from one side, and the transformer cups act as shelds on the other side. Each PCB (there are two of them) we find six transistors, in parallel setting, working in push-pull. Yes, I know that this are monoblocks, but McIntosh employed the ‘quad-amp’, what means, that we have in reality four stereo, balanced amplifiers working in bridged mode. The second section of the amplifier is accessible when we remove the bottom panel, just like in a tube amplifier. The XLR input (gold plated) and the RCA input (not gold plated) are soldered to a small PCB, where the RCA signal is made symmetrical in a simple NE5532 chip. So I recommend the usage of the balanced input. From here we go to the power section with unshielded cables. Here we will also find a worked out power supply, with big capacitors, McIntosh logo all over them, manufactured by the company Cornell Dubillier in US, their products are also used by other companies, like Manley or VTL. The input section has a separate power supply. It is also worth to mention, that the loudspeaker wires are attached to the loudspeaker terminals with gold plated connectors. I tell you about that, because most manufacturers use nickel plated ones, which makes terminal plating with gold useless.

Technical data (according to manufacturer):
Output power: 500 W/8, 4 and 2Ω (20-20 000Hz)
THD: 0.005% (full power)
Frequency response:
(+0, -0.5 dB) 20Hz-20 000Hz
(+0, -3 dB) 10Hz-100 000Hz
Input sensitivity (for 500W): 2.1V (RCA), 4.2V (XLR)
S/N: -97dB
Distortion: < 0.005%
Damping factor: 100
Input impedance: 10kΩ (RCA), 20kΩ (XLR)
Dimensions (WxHxD): 228.6 x 444.5 x 376.2 mm
Weight (piece): 41.6 kg