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question about switching, Class D, and Class A

I've been reading about Class D amps (which I believe is the same thing as a switching amp). From my reading it looks like class D amps are clearly inferior to class A. So I've pretty much ruled them out. How do you know if the amp is Class D? I don't find it in the specs for, say, the McIntosh MA6300 which I've heard is a "switching" amp. I heard switching amps are Class D.

The thing is in the past I've owned amps where Class A could be switched on and off. In Class A mode the amp ran much hotter. I mostly didn't use it because I didn't think the improvement in sound was worth all the extra heat.

Now I'm thinking about buying a new int. amp. My top two contenders are McIntosh integrateds and a Krell 400Xi. I understand the Krell is class A all the time and can get quite hot. Is this true? Also I was thinking about a Mchintosh MA6300 which I think might be class D. I needed something with a smaller footprint was why I was considering the MA6300 over the MA6500. I've listened to a lot of different manufacturers and the McIntosh sounded really good to me so I'm leaning that way.

What is y'alls thoughts on this whole class D/switching amp business vs. buying something else that going to generate a lot of heat? Is there something in-between?

regards, David
wireless200
7 responses Add your response
muralman1
1,527 posts
 
Just to be contrary, :) I sold my class A running amp for a class D, and never looked back. Then again, I have a class A preamp by the same builder I have never heard the better of.
audiooracle
387 posts
 

First of all the Krell integrated is NOT Class A, a pure Class A integrated costs much more to build than $2500!

Also the sound of the Krell in not particularly warm.

Class D is generally a type of amplifier which has a switching power supply and can be either a digital amplifier or an analog amplifier, the difference is weather the signal is converted to digital and then modulated or not.

As a Nuforce dealer, which are analog switching amplifier, the sound is excellent, and you should not rule out an amplifier because it is or is not a class A or switching amplifier.

It comes down to system matching and preference.
photon46
1,076 posts
 
Repeat after me: DO NOT BELIEVE EVERYTHING YOU READ!! Sorry to shout, but I cannot emphasize how likely it will be that you will be led down a path to audio misery if you base your buying decisions on opinions in audio rags. The often referenced roundtable discusssion about class d amps in TAS was populated by industry personalities with strong biases and agendas IMO. Not that having biases and agendas is unusual or wrong, you just have to know where someone's coming from. Maybe at the most exhalted level of uber-components class d amps give it up to cost no object competitiors, but how many of us are in that buying segment? Class d, properly implemented, is a viable, energy efficient, cost effective engineering tool for an audio designer.
audiooracle
387 posts
 

Just a bit on the merits of Class D, our system at HE 2007 was given great marks by a number of reviewers and by many people who attended the show! See Stereotimes show review.

Our entire reference system cost what many rooms were using just for the electronics!

We were using the latest Nuforce Ref 9SE V2 to drive the Usher BE 10 loudspeakers.

The sound was crystal clear with excellent bass control and a clear well defined sound stage. The system was well balanced with wonderful low level detail.

All in all the system rocked and the Nuforce Ref 9 amps with the new P9 preamp cost $8,150.00 combined.

Class D is controversial and many people still prefer the warmth and presence you get in linear amplifiers, but the writing is on the wall look how many companies have moved into class D: Rowland, Bel Canto, Kharma, ARC, Rotel and their are many more.

Class A linear amplifers do have some wonderful attributes but with energy prices skyrocketing and Class D being so practical it seems that Class D is here to stay.
vicdamone
850 posts
 
Wireless, as you can see there are plenty of folks who have managed to implement their many versions of class D amplifiers with success and I'll take a liberty here and say in some cases their success have been startling. It's also important to ask yourself why so many established manufactures are embracing this technology.

There are many great amplifiers out there and the class they've been pigeon holed into maybe more of a misleading hindrance than a tool when it comes to choosing a product. Even the gap between vacuum tube designs has narrowed considerably.

For me the excitement of this hobby comes from the first hand experience of using a product regardless of its pedigree and design and realizing I like the way it sounds. Be fair to yourself and keep the audition door open to everything.

Vic
atmasphere's avatar
atmasphere
11,625 posts
 
David, class A is the purest form of amplification, be it tube or transistor, known to man. All other forms are compromises that have nothing to do with sound quality, and everything to do with heat.

If you choose your system based on the heat it makes, it will not sound anything like one that is based on choice for ultimate sound quality. Making good sounds is what the system is for :)

Comparison between the two is the sort of thing that you can hear in five seconds flat. Its not subtle.
ar_t
165 posts
 
Ignore the mags, and trust your ears.

Some folks like LPs...some like CDs. Same is true for amps. I moved towards building Class D amps because Class A amps are too hot to use in Texas during the summer months.

Which is around 8 months of the year........

(A true Class A amp burns up 8 times its rated output power....just sitting there.)

Anyway, I'm not going to tell you that switching amps are the greatest thing ever. Nor would I say the same about Class A. We have built and sold lots of both over the years. There are lots of good expamples of switching amps out there for you to audition. The only way you will know is to try one.
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