McIntosh MC 427 Amplifier Review

[GXAlan]

Impressive!

But expected. . McIntosh in the Clarion era was SOTA. Clarion was so focused on precision that they introduced the water jet glass front panels of the home unit.

Yes, McIntosh sells expensive coffee table books and wall clocks, but I still think that the McIntosh is a reliable choice for performance when cost is taken out of the equation.

They sold a MPM4000 which is a power meter which fits in a single DIN slot.

 

[Sokel]

Yep,this one did it!
I love the THD+N vs level across frequencies.
Following the really good performance of their SS hi-fi siblings despite the compromises of the small fit,etc.

I suspect that used ones will get a raise in price

Thanks Amir!

 

[MJG]

Audiotec Fischer claims state of the art in car audio. Would love to see how one of their DSP/amp combo units measures.

 

[DHT 845]

Wow, nice amp for home audio with external power supply. Also I believe nice amp for DIY active subwoofers.

 

[jjmanda]

As a long time car audio enthusiast, it's great to see some reviews here.

@amirm Thank you!

 

[pma]

Why is there a 60Hz bump in the SINAD dashboard for one of the channels?

My guess is the setup or wiring layout. 60 Hz individual line says it is picked-up from somewhere, into some loop. If it was power supply issue, you would see 120 Hz + further line frequency multiples.

 

[jjmanda]

It seems the amplifier was made and sold betwen 1995 to 1997. The date codes on the Philips NE5532s pictured above (@JSmith ) are 1996, so I don't doubt the years made.

View attachment 332000

from Roger Russell's site:
View attachment 332001

So ~27 years old and still going strong.

Awesome @amirm.

I feel like a lot of the old stuff from back then were very good quality. There was some crap, but some very good.

I still have gear from back in the 90's. I'm running a 1997 model Alpine head unit that is still going strong.

 

[Waxx]

That is a good amp. And solid state McIntosh always sounded relative clean. I hate the styling and the marketing of that brand, but at least the technical side (even with the tube amps) is done more or less like it should, and with this amp it's not different.

 

[JayGilb]

Wow - time to start collecting car batteries and dump my home system.

Amir thanks for another review.

 

[CedarX]

Fortunately in use the amp ran very cool, barely getting warm and I don't think the fans ever came on.

With less than 50% efficiency, it won’t run very cool for long. I suppose the fans will come on eventually.

 

[pma]

With less than 50% efficiency, it won’t run very cool for long. I suppose the fans will come on eventually.

Could you please explain those 50%. Well designed class AB amplifier will have about 70% efficiency.

 

[Michael Fidler]

Looks like a positive and negative rail generating SMPS with a class B linear amplifier. Very nice performance. Definitely a 'blameless' design.

The only way I can think of improving this would be to use a class-G topology to improve the efficiency at normal listening levels (easy to generate rails at 30% or so of the normal ones with such an SMPS by tapping the transformer).

 

[CedarX]

Could you please explain those 50%. Well designed class AB amplifier will have about 70% efficiency.

The 46% measured by Amir is relative to drawn power. The internal DC-DC boost converter may not be the most efficient either, compounded with the class AB amp relatively low efficiency. Not necessarily a problem in a car except for the heat if the amp is hidden and not well vented.

 

[BR52]

Could you please explain those 50%. Well designed class AB amplifier will have about 70% efficiency.

At full power, it can be, but with partial power, class A becomes more dominant. It's
like an offset. Depends how much Class A you allow by design.

 

[nebunebu]

Quite impressive! Especially since this isn't their main segments.
Isn't this the first McIntosh tested at ASR? What a great start.

 

[Deleted member 48726]

Yeah, that's what I thought too. Is it fair to say then the battery powered SINAD would be better than what the dashboard shows?

Not necessarily. It depends on the cars' charging system, (generator, rectifier).

 

[Deleted member 48726]

The issue is how much spare current your stock alternator has and how many of these you deploy. If listening at lower levels is should be fine.

Most car generators are over 90 A capacity today. But back in the day it was a party trick to get the headlights to dim to the beat of the sub. A 1F capacitor was often used as close to the amp as possible if you would like to have permanent light on the road ahead.

 

[JakeK]

Of course it does and then some. But better have good supply of current seeing how almost 40 amps were drawn.

Yeah that's going to need some thick power cable direct from the battery. I imagine many cars would need an upgraded alternator to be able to power this beast!

 

[MediumRare]

So now we can add one data point showing the Mac measured performance is indeed "high end" and not just hype. Let’s see more.

 

[Multicore]

Noise performance is excellent for a car amplifier:

Might it be even better in a car? I'm thinking of the 60 Hz noise spike in the dashboard.