Ryan Coleman explains why the $9,400 pair of
McIntosh MC501 solid-state monoblock amplifiers
is his ultimate interim solution

October, 2006
McIntosh MC501 Monoblock Power Amplifier Specifications:

RMS Power Output: 500W minimum sine wave continuous average power output from 20Hz to 20kHz
Dynamic Headroom: 1.8dB
Wide Band Damping Factor: 100 @8Ω
Signal-to-noise Ratio: 97dB balanced and unbalanced (124dB below rated output)
Frequency Response: 20Hz to 20kHz (+0, -0.25dB), 10Hz to 100kHz (+0, -3dB)
Input Impedance: 10kΩ (RCA), 20kΩ (XLR)
Input Sensitivity: 2.1V (RCA), 4.2V (XLR)
Total Harmonic Distortion: 0.005% maximum at any level from 250mW to rated power output
Intermodulation Distortion: SMPTE 0.005% maximum if instantaneous peak output does not exceed twice the
output rating
Power Guard®: Clipping is prevented and THD does not exceed 2% with up to 14dB overdrive at 1kHz
Dimensions: 17.5 W x 9.43 H x 14.81 D (inch)
Weight: 91.5lb each
MSRP: $9,400 per pair
McIntosh Laboratory
2 Chambers Street
Binghamton, NY 13903
Tel. 800-538-6576
Fax: 607-724-0549

URL: http://www.mcintoshlabs.com
Email: feedback@mcintoshlabs.com
INTRO

Is there a more well-known company in audio than McIntosh? Sure, Wilson Audio, Krell and Quad are the
stuff of legends, but those companies are for hard-core audiophiles; the masses think hi-fi means Bose
(egads!) or, if they’re a bit more knowledgeable, will think of McIntosh as the defining brand of “hi-fi.”
However, it’s a disservice for McIntosh to be grouped in with Bose and somehow excluded from
consideration by the audio snobbery, where “serious” audiophiles think McIntosh is the stuff of doctors,
lawyers, and well-to-do unsophisticates whose hearing doesn’t match their pocketbooks.

I cannot speak to older McIntosh components, but the sonic reputation is one where McIntosh has a “house”
sound, a prospect that evidently most audiophiles find objectionable. Oh the horrors! The company has a
“house” sound! Hmm, that means McIntosh falls in the same category with, oh, every other high-end audio
company that’s ever existed, as every company has a “house” sound. So why the polarity in opinion of
McIntosh, and why do some audiophiles go on hating McIntosh? Its not like it’s a fly-by-night operation, as
its been in operation out of New York since 1949, and its electronics have a reputation for being as
dependable as the lunar cycle, not to mention having the best resale value in the industry. What gives,
everybody? Do you really think this company’s products sound that inferior to the others in the market?

I’ve seen in the other rags that McIntosh has had a bit of a renaissance as of late, with new products or
reissues that specifically target the audiophile community. The subject of this review, the McIntosh MC501,
a 500 wpc monoblock amplifier, is one such design.



BACKGROUND
The MC501s are about 18” wide by 10” high by 15” deep, and they weigh in at a very distressing 90+ lbs.
Now, I am a stout man and can normally move around amplifiers without a care for my back, but the lack of
equipment handles on these chasses make moving the MC501s a strenuous and delicate process---for
both the amps and my back. Evidently, the company opted for aesthetics over ease of handling.

Despite my discomfort in wielding these beasts, all I have to do is see those sexy blue meters and I find I
agree with their priorities. God, these things are sexy! There is serious pride-of-ownership here. Each
monoblock puts out 500 wpc into 8, 4, or 2 ohms, as there are separate speaker binding posts in the back
for each. Simply match your speakers’ impedance to the appropriate set of binding posts and you’ve got
enough power on tap to power any loudspeaker, and you will need as much power as possible and
possibly more than you think if you want realistic dynamics.

While the amps have input connections for both RCA and XLR interconnects, the amplifier is fully balanced,
so one would expect improved sonics via a lower noise floor from using XLRs, which I use. Input
impedance range from 10k (RCA) to 20k (balanced), so matching the MC501s to a passive preamp
seems like a non-starter, and I venture to guess that some weak-willed tube preamps would also struggle.
Now, one part of the amp deserves special consideration: the Autoformers. The Autoformers are
transformers in the output stage that load-match the amplifier to the load (speaker) that it will be connected
to (thus the 3 sets of speaker binding posts). From a purist’s perspective, this is highly objectionable; as
Lew Conrad of Conrad Johnson fame is known to say, “there is no perfect part”, and adding a big honking
transformer in between your amp and your speaker would seem like a great way to lose detail and subtlety
in the presentation. You’re not just listening to the gain stage, you’re also listening to another transformer.
So, why did McIntosh make this design choice? I can only assume that the answer is two sides to the same
coin: heat & reliability. The Autoformer takes the load off of the transistors in the output stage, so they can
run nice & cool. From an engineering perspective, heat causes failures (also known as “thermal
breakdown”), so it would appear McIntosh is building their amps to minimize service issues, thus the
reputation for reliability. The downside, from an audiophile’s perspective, is that hot amps sound better;
solid-state amps biased in class A have inner detail, subtlety, delicacy and a liquidity to the midrange that
their cool running class AB/ B/ D cousins cannot match. So McIntosh, in a clear break with their competitors
in the audiophile marketplace, made a choice: reduced heat and increased reliability being preferred to
absolute fidelity. But, was this tradeoff even present in listening impressions?



LISTENING IMPRESSIONS

Ultimately, the midrange is the starting point, whether we want to admit it or not. It’s where our ears are at
their most sensitive, regardless of what our listening priorities are. The MC501s strike me as being tuned
for this area above all other considerations, and they did a darn good job at it. There’s a liquidity and
wholeness to the midrange that is often found in tube amps, but rarely in SS amps. The MC501s get it. I don’
t doubt most casual listeners who are looking for a ‘high-end’ amp will pull out the plastic and buy on that
basis alone (along with some other considerations that I describe later). And you know what? They’re never
going to get tired of this midrange. It’s not as juicy or sexy or euphonic as a SET or a tube amp, but you get
none of the hassles or limitations of those more temperamental cousins.
What is interesting is that the MC501s achieve this goal,
despite some shortcomings in clarity. Now, I’ve read more
than enough boring, cliché-ridden reviews where someone
writes about how inserting some component reminds them “of
an open window”. Not me though, I don’t roll that way! If I ever
say the phrase “open window” in one of my reviews, I promise
to put the Paris Hilton CD on “repeat” for 1 week as
punishment to myself. Instead, the clarity of the MC501s
remind me of trying to look out a window from a distance of 50
feet, and you can barely tell that the window adjacent to it is
just a wee little bit clearer, and it is only upon walking up to the
windows that you realize one pane has a screen, and one
does not. The MC501s have a lack of absolute clarity that
reminds me of that screen; the lack of clarity is barely there. In
no way does this compromise the musical performance, but it
is there, and those looking for perfection in amplification will
notice this lack of absolute clarity and find it a problem.

I believe that the lack of total clarity is simply one side of the
coin; the other side is some treble attenuation. While all the
treble information is there, it is attenuated ever so slightly. It's
funny; I find myself thinking I'm getting all the treble info, but
when I think about the sparkle that exists in live music (or with the plasma tweeter of the Accapella
speakers), I know these amps don’t have it. But given how most rock & roll CDs are too hot in their mix
anyways, I do not find this effect to be that objectionable on most music I listen to; and with the Wilson Watt
Puppy 6s the 501s are driving, the issue of treble extension has remained insignificant.

Another great way to think about this aspect to the MC501s: think about the way the early releases of Neil
Young sound---they’re horribly bright and threadbare, exasperating the already nasal qualities to Neil’s
voice. Now, the MC501s humanize Neil Young a bit more on my system by not giving the unvarnished truth.
Sometimes, less is more.

Now, let’s put the two together: lack of absolute clarity & minute treble attenuation. What do you get? I’ll bet
$5 that it’s the sonic result of the Autoformers. When you put a giant transformer between the output stage
and the speaker, this is what you expect, and this is what you get. And this, I can only surmise, is the
McIntosh "house sound". Is that such a problem? For some it will be, but its tough for me to be so critical
when it didn’t detract from my enjoyment of music, and it may have possibly enhanced it: while the lack of
total clarity was only barely noticeable, the treble attenuation is a nice complement to the hot high frequency
performance of my Wilson Watt Puppy 6s, and the liquidity in the midrange helps compensate for a slightly
disjointed crossover in the Wilson Watt. And with most systems that rely on digital source playback and
aren’t nearly as coherent as the Wilsons (after all, the Watt Puppy 6s are world class; I’m just doing my job
criticizing them), the MC501s will be a terrific match. But I think that much better amps could be found to
match to speakers like Merlins or Magnepans that are already highly coherent with a pure, soft treble region.

Moving on, one of the most fun aspects to the Wilson speakers is the incredible bass transients &
dynamics that they possess. The MC501s definitely grab hold of the woofers and will rattle walls and rock
the house. After all, it puts out 500 watts, and we’re not talking about those crappy Best Buy watts either. I’m
talking about steel-toed boots, diesel-power, bone-crunching watts. And the MC501s have serious power
and control, though I’d be remiss if I didn’t say I’ve heard slightly more control in the rump with other amps --
all of them high power solid state, of course.
quicker on the attack and escalation of the distinct event, which I’ll hereafter refer to as “speed”. This was a
problem with lesser tube preamps I had on hand that didn’t like the low input impedance of the MC501s, but
this problem improved mightily when I dropped in the Einstein preamp, which is as dynamic as a gunshot.
The MC501s aren’t the fastest amps out there (OTLs are), but they’re hardly last in the race either. Its just a
bit surprising, given the power ratings, but any reduction in total dynamic expression or speed as a result of
the MC501s is hardly a problem in my rig, given the exceptionally complimentary performance of the
Einstein preamplifier and the Wilson speakers in these regards.

Now, I just spent time trying to describe parts of the whole musical experience, but much like a gourmet
meal, music is more than the sum of its parts. To put it all together, let me say this: It's pretty easy to boogie
to these amps, no matter what type of music you’re listening to. They’re fun to listen to, they never poop out
or sound hard & aggressive, and its easy to overlook their shortcomings. I think I like them for the same
reason people flip out for SETs: the midrange is where it needs to be. Granted, its not nearly as good as a
SET, mind you; I’m just stressing the fact that the midrange is where this listener is sensitive, and its
definitely voiced in the right direction. I’ve heard lots of SS amps that are off in this critical region more than
the MC501s, and that’s why I wouldn’t own them -- they sound aggressive and unmusical.

If you want the live experience, you have to get dynamics right, but if you want to enjoy the experience, you’
ve got to get the midrange right. And the MC501s got both in sufficient quantities to keep this reviewer
grooving. For a SS amp, that’s quite an accomplishment. Now, I’ve heard a few SS amps that can do it,
and usually they’re super-expensive and they run as hot as a firecracker; the MC501 is the first amp I’ve
found that can do it, runs cool and comes in at a somewhat affordable price.



OTHER CONSIDERATIONS
As someone who is focused on tuning his system to
recreate the live experience in the home, I must say the
MC501s throw an excellent soundstage, complete with
terrific width, depth and focus. Performers are easily found
playing on their space in a well- defined stage. Depth is
presented as a they-are-here experience, in stark contrast to
the you-are-there experience that one gets when sitting mid-
hall. Horns also have the they-are-here perspective, but
horns are far more pronounced in this perspective than the
MC501s.

If you read my review on the Einstein “The Tube”
preamplifier, you’d know that my priorities are such that I’m
looking to recreate the live experience in the home, and that
transients & dynamics are the biggest impediment to doing
so. The MC501s strike me as being highly competent in the
“jump” factor, and they most certainly bring the event home
and alive, but they strike me as being slightly soft relative to
the best SS & OTL amps out there. Other amps are a bit
Usually, the sonic performance is the end of the story in a review. But I think that’d be a disservice to the
MC501s, as they have a story about them that other products in the market cannot tell.

Anyone who purchases the MC501s is entering a relationship with a company that’s been in business for
over 55 years. Now, how many other companies can match that for “factory support?” Not that you’ll need it;
as mentioned earlier, McIntosh has a reputation for reliability, and I wouldn’t be surprised if the MC501s will
run 20+ years without a hiccup. As I mentioned in my review of the Einstein Tube preamplifier, the
engineering principle of “thermal breakdown” is always a concern in electronics; the hotter they run, the
shorter the mean time to failure. Well, the MC501s don’t have that problem designed into them, no doubt a
result of the Autoformer providing load-matching services between the amplifier and the speaker. There is
no heat, which is a Godsend to our readers who have small rooms in a warm climate and are none too fond
of listening in underwear (well, I do listen in my underwear; I’m just saying that I don’t want to listen in my
skivvies because of the heat).

And let’s face it: those big blue meters on the front panels are Miles-Davis-cool; there is a serious aesthetic
value here--just ask your wife / significant other when you plug them in for the first time. Finally, if you’re like
me, though you may not plan on selling a component when you buy it, you do at least think about what you’d
get back out of your purchase. Well, to my knowledge, there’s no brand that has better resale values than
McIntosh.   




CONCLUSION

So, is this an amplifier to like, to respect, to love? I guess the answer to that is: It depends on your
perspective and on your system. I could as easily envision systems that would fare wonderfully with the 501s
as I could see some listeners finding the 501s objectionable for the same reasons I discussed above. From
a pure sonic standpoint, it’s got competition that will exceed it in some areas (treble extension, clarity,
“speed”) and not in others (liquidity, staging, midrange tone).While it has sonic shortcomings, they’re small
in the absolute sense. But that’s what we’re searching for, right? I’m obliged to point them out, though most
people won’t ever complain about the MC501. As always, system matching matters such that there is no
universal right answer, so a demo will be appropriate. McIntosh has an extensive dealer network, so
arranging a demo shouldn’t be much trouble, other than lugging the heavy boxes around.

All that being said, I think that the “total package” that this amplifier offers is its defining characteristic. It has
some advantages that other products in the market don’t match, and can never match. What company has
been in business longer than McIntosh? What products have a better reputation for reliability? What
products have a better resale value? What products have a higher Wife Acceptance Factor? And what
speaker can this amp not drive? And let’s not forget, its easy to enjoy music with these things. It is for these
reasons that the MC501s represent the lowest risk audio purchase one can make.

Me, I’m searching for absolute fidelity, and I know these amps are not it. And while I look forward to the day
I’ll get something I like better, in the meantime I have and will continue to enjoy every minute with the big
Macs. For many people, this will be the last amplifier they ever buy. For readers like me, the McIntosh 501
will stay as an interim solution before I move on to something slightly better and far more expensive.
Also read Ryan Coleman's review of:

Einstein "The Tube"
preamplifier
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