Erin's review of McIntosh MC462 power amplifier

[Symphoniac]

Just saw Erin's review of the MC462 power amp. Notably, he conducted an ABX test against the March Audio P501 and was able to tell the difference 80% of the time when played at high volume, roughly 95db, but not when played at low volume. His subjective description of the difference was that the McIntosh sounded "less congested, less strained". Is this one of the first blind tests that show an audible difference in solid state amplifiers when playing within their power limits? He used the Mofi 888s for the test, so not a terribly burdensome load, and at least on paper, the P501 (500W at 4ohm, 950W at 2ohm) can hold its own against the MC463 in power output, so I think we can say that both amps were still playing within their limits even at 95db in-room. It's very interesting that Erin was able to pick out the McIntosh 80% of the time!

 

[kyuu]

It's interesting, but not terribly convincing in my book. For one, what does "less congested, less strained" even mean, exactly? Two, if it was a definite difference, why was he unable to pick it out 20% of the time? Three, I'm unclear how many rounds of testing he did at the higher volume level. If it was, say 10 times, then the fact that it wasn't precisely 50/50 is not indicative of much. We'd need a lot more sample points to reliably filter out simple chance.

That said, 95dB at 10 feet is freaking loud and, with a roughly 85dB sensitivity on those Mofis, probably was using a considerable amount of power on any dynamic passages. It's certainly possible that the March Audio was running out gas where the McIntosh had a little bit more to give at certain points. Hard to be sure without more information.

Given that nobody should be listening at those volumes, and he was completely unable to tell them apart at normal volumes, I would say it's not much of argument for the McIntosh in any case even if he was actually hearing a difference. Unless you want to fill an outdoor venue with loud music, I suppose, but I don't think the McIntosh is the right tool for that job.

 

[fredoamigo]

If one listens in "normal" conditions and recommended 85db spl is the normality, but in realistic listening, or for classical music 95 db spl will be reached much more often than one thinks. but in this very precise case (with the McIntosh ), I would tend to give more weight to a blind listening.

 

[IngMishael]

the speaker used, the 888 is basically an 8 Ohm load for most of the spectrum of frequency so the March Audio never gets to use the reserves that kick in with speakers with lower than 4 ohm impedance.

using a low impedance speaker that dips to below 4 Ohm will have actually evened the power on taps difference he was hearing... well that is my layman understanding of why he was getting differences enough to notice in an ABx 80% of the time.

Basically, use it on a something like a KEF R7 Meta with minimum impedance of around 3.2 Ohms and the difference will disappear most likely.

Just my uneducated two cents. but the difference noted by Erin as he said isn't a frequency response difference, more of a perceived performance difference

 

[Blumlein 88]

One of those cases where I'd like for Erin to do a series amplifier test.

I remember reading about someone who worked for ASC in pro amps at the time. He did lots of blind tests. He said anytime his testees turned volume above 80 db average SPL the result were useless. That listening panels who had 75 db average levels could find some differences, but once it was turned up everyone's results went to crap. Your ear does begin to shut its self down to lower sensitivity and then distort itself above 75 db SPL. So especially odd that higher volume worked better than lower volume. And with transformers who knows? Does the bandwidth of the autoformers change with level?

 

[Audio Science Pal]

Just saw Erin's review of the MC462 power amp. Notably, he conducted an ABX test against the March Audio P501 and was able to tell the difference 80% of the time when played at high volume, roughly 95db, but not when played at low volume. His subjective description of the difference was that the McIntosh sounded "less congested, less strained". Is this one of the first blind tests that show an audible difference in solid state amplifiers when playing within their power limits? He used the Mofi 888s for the test, so not a terribly burdensome load, and at least on paper, the P501 (500W at 4ohm, 950W at 2ohm) can hold its own against the MC463 in power output, so I think we can say that both amps were still playing within their limits even at 95db in-room. It's very interesting that Erin was able to pick out the McIntosh 80% of the time!

The big Mac looks good.

 

[RoA]

The big Mac looks good.

Absolutely, feast your ears, feast your eyes and you can be proud of something you own. Plus it will be serviceable in years to come. You are paying for history and quality.

 

[fredoamigo]

Absolutely, feast your ears, feast your eyes and you can be proud of something you own. Plus it will be serviceable in years to come. You are paying for history and quality.

In addition to their timeless and instantly recognizable look, the main advantage of MC intosch is that they can be resold at a very good price and very quickly...and when you invest so much money, this is not negligible and must be taken into account.

 

[Old_School_Brad]

I will revisit his review to maybe answer some of the questions I have. But in the mean time; because of the pretty loud session, could one rule out speaker compression effects?

 

[TonyJZX]

this is an old video but i'm say the gist of it boils down to...

Can you ABX a top end class a/b vs a top end class d?

i'm probably of the opinion that certain numbers of people can.

 

[MaxwellsEq]

Is this a difference between a regulated power supply and non-regulated (I know nothing about the MC462 - but assume it may not have a regulated PSU)? If there is a difference, it will be measurable. Perhaps the pulse recovery test may show this up.

 

[kyuu]

Is this a difference between a regulated power supply and non-regulated (I know nothing about the MC462 - but assume it may not have a regulated PSU)? If there is a difference, it will be measurable. Perhaps the pulse recovery test may show this up.

I haven't seen anything regarding if the McIntosh uses a linear power supply or not. However, on the review for the March Audio P502, which I'd think is largely identical to the P501 asides from the number of channels, we can see that it does have a good amount of burst power available beyond the continuous rating.

The McIntosh does have what they are calling an "autoformer" that supposedly allows it to put out full power regardless of the speaker's impedance. Also, the McIntosh has a limiter that prevents clipping, which looking again at the P502 review it doesn't appear the March Audio has. Either of those could possibly result in a difference at those extreme volume levels perhaps?

 

[kemmler3D]

Erin's generally quite credible and the test conditions are plausible for hearing amp distortion, I don't think this is the craziest thing I've seen claimed. I wouldn't say I'm certain he "passed" the A/B test but I think if you looked at the distortion / power graphs you could find a plausible explanation for this in there.

what does "less congested, less strained" even mean, exactly?

In this context, I'd say almost definitely having to do with HD and maybe IMD in the mids and lower treble.

this is an old video but i'm say the gist of it boils down to...

It was posted 2 days ago?

 

[kyuu]

Erin's generally quite credible and the test conditions are plausible for hearing amp distortion, I don't think this is the craziest thing I've seen claimed. I wouldn't say I'm certain he "passed" the A/B test but I think if you looked at the distortion / power graphs you could find a plausible explanation for this in there.

Hmm.

McIntosh:

March Audio:

Unfortunately we don't have as nice a THD+N vs. power graph for the March Audio P502 (standing in for the P501), but just going by these it's hard for me to see where the March Audio's distortions would rise to an audible level where the McIntosh's wouldn't.

 

[MaxwellsEq]

we can see that it does have a good amount of burst power available beyond the continuous rating

Interesting, thanks!. The thing I'm particularly interested in is recovery after bursts. In previous decades, power amplifiers were hit with a burst signal then the recovery was captured on a scope, some amplifiers recovered quickly, whereas others took more cycles to become stable again. It was this I wondered about regarding audibility.

 

[kemmler3D]

Hmm.

McIntosh:
View attachment 404487View attachment 404488

March Audio:

Unfortunately we don't have as nice a THD+N vs. power graph for the March Audio P502 (standing in for the P501), but just going by these it's hard for me to see where the March Audio's distortions would rise to an audible level where the McIntosh's wouldn't.

Hmm, I have to agree with you there, but the IMD graphs are only at 5w and although nothing looks audible to me here, the MC looks a bit smoother on that chart especially in the mids.

Presumably Erin was pushing them a lot harder than 5w, so we can speculate (perhaps tenuously) that the grass could grow high enough to hear at high power.

 

[Soniclife]

Marchaudio P501 Mono Block Power Amplifier Review

(Photo from Marchaudio) I saw some of ASR members request about review this Amp. And for my personal curiosity I asked to Company to lend one for review. After I finished measurement, I asked company how to return. But the Company gave me right to dispose of it. Disclaimer This is a review and...

www.audiosciencereview.com

The Mac has 300W more into 8 ohms, at high output you need to know if that came into play, good amps are only meant to sound the same until they run out of power.

 

[Blumlein 88]

I might suspect the auto-former is audible at power. These only give constant power at constant impedance. Speakers are not constant impedance.

 

[Audio Science Pal]

this is an old video

It was posted 2 days ago?

There is an explanation in the video.

 

[TonyJZX]

mandela effect

i remember the stuff that erin likes because there's not much of it out there