Erin's review of McIntosh MC462 power amplifier

[Oddball]

Definitely not an engineer or expert, but long time user, now mostly focused on HT. Couple of points.

95dB is not really that loud for peaks. Some peaks last longer than the others. If you listen at 85dB reference level HT material, your peaks could actually hit 105dB, especially if you run your speakers as large.

I have always wondered if the test signals actually capture the whole story, especially with any given speaker load at low frequency. If you have a 30hz peak (or even better more peaks below 100hz) that is 105dB, how would you fit that in the charts? If one had the REW compression charts for that signal from both amps perhaps that could shed some more light to what's happening?

 

[kyuu]

95dB is not really that loud for peaks. Some peaks last longer than the others. If you listen at 85dB reference level HT material, your peaks could actually hit 105dB, especially if you run your speakers as large.

Right, but I don't believe Erin was testing at 95dB peaks, he was testing at 95dB average SPL. Unless I misunderstood?

 

[Soniclife]

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

The 888 are well behaved in the audible range.

 

[kyuu]

The 888 are well behaved in the audible range.

They seem to be between 6 and 10 ohms for most of the audible range. That might actually support that the autoformer is making a difference, as the McIntosh would be able to put out more power at those higher impedances than the March Audio I believe.

 

[Oddball]

Right, but I don't believe Erin was testing at 95dB peaks, he was testing at 95dB average SPL. Unless I misunderstood?

Will need to watch the whole thing and take a look at his review as well.

Music does not really have set dB range as soundtracks do. For 95dB soundtrack level, that would be +10 reference volume, with peaks of 115dB for mains and 125dB for subs.

My system is not too shabby, but could definitely not deliver these levels even if Macs and all components were sprinkled with wholly audio water. For that SPL one would need to look into pro audio solutions and an army of subs.

 

[Old_School_Brad]

Right, but I don't believe Erin was testing at 95dB peaks, he was testing at 95dB average SPL. Unless I misunderstood?

95 dBA average is definitely loud. With some material, the peaks can easily exceed +20 dB unweighted, putting the speakers at risk of non-linear behaviour and the amplifier on the verge of clipping and audible distortion.

 

[A Surfer]

Really makes little practical sense to test at that volume, IMO. And while 80% suggests something is there, it isn't 90% which it should be.

Additionally, this needs to be replicated by him several times. Although not statistically likely, it absolutely could be chance, hence the need for replication.

Increase the trials and retain this discrimination rate and that would catch my attention more than a one off result like this.

 

[WisEd]

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.

A very good example of McIntosh resale. I had a 3 y/o MX123 AV preamp I had no use for anymore. I sold it for 7k within a week on adiogon. Thats an almost 80% retained value after 3 years! No other manufacturer's resale value is even close. Most home audio is worth 50% when you open up the box!

 

[WisEd]

95 dBA average is definitely loud. With some material, the peaks can easily exceed +20 dB unweighted, putting the speakers at risk of non-linear behaviour and the amplifier on the verge of clipping and audible distortion.

It depends what you listen to and the level of distortion. Most speakers are not rated for distortion but usually will have around 1% distortion at rated SPL. Many will rapidly degrade beyond that 1 watt rating. This creates stridency and listening fatigue. Speakers with low distortion feel a lot more comfortable at significantly higher levels. The other factor is what you listen to. A classical, jazz or vocal composition can have peaks at well at 100db due to its dynamic range yet it will be a lot less uncomfortable or damaging to your ears than the relentlessly screeching guitars and vocals of an acid rock band at a much lower volume.

 

[SIY]

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.

The data presented are grossly incomplete, and it's a mis-interpretation of statistics for him to say, "[He] could pick it out 80% of the time."

 

[WisEd]

95 dBA average is definitely loud. With some material, the peaks can easily exceed +20 dB unweighted, putting the speakers at risk of non-linear behaviour and the amplifier on the verge of clipping and audible distortion.

True! But, it all depends on the gear. I have occassionally listened to my gear at a tested 105 dB avg, essentially rock concert level. Neither my McIntosh MC 462 amp, nor my BW 803, broke a sweat. The amp was barely running at 70% capacity. I certainly don't do that with any regularity, but whats the use of a Porsce 911 thats never driven faster than 70 mph!

 

[WisEd]

The data presented are grossly incomplete, and it's a mis-interpretation of statistics for him to say, "[He] could pick it out 80% of the time."

Agreed. The fact is that unless an amp is driven to some sort of distortion due to inadequate power capacity they should sound identical. However its easier with a tube map vs a transistor amp since the tube amp always distorts by odrders of magnitude. Very good transistor amps have levels of distortion in the .00x range while tube ampare lucky to have10 to 100 times that amount which of course is a pleasing and sought after quality since that distortion is second and third order harmonics (AKA warmth).

 

[WisEd]

Agreed. The fact is that unless an amp is driven to some sort of distortion due to inadequate power capacity they should sound identical. However its easier with a tube map vs a transistor amp since the tube amp always distorts by odrders of magnitude. Very good transistor amps have levels of distortion in the .00x range while tube ampare lucky to have10 to 100 times that amount. Which, of course, ifor tube afficiomados is a pleasing and sought after quality since that distortion is second and third order harmonics (AKA warmth).

 

[Old_School_Brad]

It depends what you listen to and the level of distortion. Most speakers are not rated for distortion but usually will have around 1% distortion at rated SPL. Many will rapidly degrade beyond that 1 watt rating. This creates stridency and listening fatigue. Speakers with low distortion feel a lot more comfortable at significantly higher levels. The other factor is what you listen to. A classical, jazz or vocal composition can have peaks at well at 100db due to its dynamic range yet it will be a lot less uncomfortable or damaging to your ears than the relentlessly screeching guitars and vocals of an acid rock band at a much lower volume.

Even if you're in a large venue with massive line-array speakers and subwoofer clusters, or listening to a horn speaker in your living room at an average of 95 dBA -it’s going to be very loud, no matter the distortion level.

You're generally right in your point, but 95 dBA average will undeniably be perceived as very loud regardless of how clean the signal is.

As for genre, I illustrated my point by referencing both the dBA average and the C-weighted peak levels.

 

[WisEd]

Even if you're in a large venue with massive line-array speakers and subwoofer clusters, or listening to a horn speaker in your living room at an average of 95 dBA -it’s going to be very loud, no matter the distortion level.

You're generally right in your point, but 95 dBA average will undeniably be perceived as very loud regardless of how clean the signal is.

As for genre, I illustrated my point by referencing both the dBA average and the C-weighted peak levels.

You are absolutely correct it is very loud, but the perception of loudness with less distorted sound is lower simply because it causes less fatigue. If you listen to white noise at 105 dB it will drive you absolutely nuts almost immediately. On the other hand, a classical composition at the same level allows for accomodation of the ear (by means of the stapedius muscle) which reduces the feeling of loudness. In effect, its the ear's dampener. Of course, a longer the exposure will overwhelm accomodation too. For example the level of pain is 130 which is obviously a lot louder than 105.

 

[Old_School_Brad]

You are absolutely correct it is very loud, but the perception of loudness with less distorted sound is lower simply because it causes less fatigue. If you listen to white noise at 105 dB it will drive you absolutely nuts almost immediately. On the other hand, a classical composition at the same level allows for accomodation of the ear (by means of the stapedius muscle) which reduces the feeling of loudness. In effect, its the ear's dampener. Of course, a longer the exposure will overwhelm accomodation too. For example the level of pain is 130 which is obviously a lot louder than 105.

I was simply highlighting that 95 dBA average is very loud -regardless of distortion. That was my only point, and it was made in context with the discussion about Erin’s listening levels in comment #26.

I don’t have anything further to add to the conversation.

 

[Slave IV]

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.

Just sharing an interesting story about McIntosh amps used for outdoor venues.