Class A amps or Class D??: Which sounds better??

Amplifier performance and synergy depends on the other components, and cables in a system. I have read alot about the advantages of Class A.amps Though an older amp design, do class A amps necessarily sound better than Class D digital amps like Nu-Force, Bel Canto, and Wyred4Sound?? These class D amps supposedly run more efficiently, with less heat and noise and are smaller in size.

I have a friend who has a Musical Fidelity A3CR power amp and a Bel canto pre-amp, and a pair of Spendor floorstanders. The MF amp is at least 10 years old, and no longer made. I have listened to the amp in his system, and it does sound very good. Most noteably is its across the board smoothness. However, I think its performance is system dependent, and might be a liability in other systems. Would like to hear comments and opinions about these two amp "designs", and if one sounds better than the other, OR JUST DIFFERENT.

BTW, I am not sure that owning a 10 year old amp like the MF A3CR is a good idea, despite its class A rating, and a few positive consumer reviews I have seen. Thank you
I am one who replaced a MF A3CR for a W4S ST-500 and am very happy with the result.
Not a bad word to say about the MF, a very nice piece of gear, but W4S is, in my experience, in a different (superior) class altogether.
Most notably is that when I made the change the rest of the system stayed the same, thus I was able to truly compare the difference made by the power amp upgrade alone.
MF was smooth and warm, whereas W4S is more detailed and neutral, not to mention more powerful and authoritative. The smoothness is there as well. The speakers do what it wants, not the other way around. And there's much more detail to be heard.
You may have a different opinion, but in my case it was a clear and noticeable upgrade, NOT a lateral move.
Class A has been preferred over all other classes by the the majority of listeners over a very long run and seems likely to be preferred in the fututre.
It really doesn't make much sense to discuss amplifiers apart from the speakers with which they will be paired. Different speakers have different amplification needs, and may have been designed with certain types of amplifiers in mind, as well as being voiced with specific types of amplifiers. Some speakers will need huge wattage (not easy or cheap for Class A), and others will not. Some speakers will benefit from a very high damping factor (a strength of a Class D amp usually), but others may feel overdamped with high damping factor amps.

And I will also point you to Atma-Sphere's paper on the Power vs. Voltage Paradigms:
Many audiophiles grew up listening to Class A/B amplification so the type of changes to live instrument sound it produces is judged preferable to the type of changes the newer Class D amps produce. Based on the age demographics of the audiophile community alone, there is going to be an aesthetic bias towards established technologies, which shows up in board discussions all the time.

It's a type of aesthetic "lock-in."
If you're having to accommodate your speakers you're limiting the potential of your system imo. I love the comment "the speakers do what it wants, not the other way around". They are after all, the weakest link. The amp on the other hand is the heart of the system. Worst thing you can do is punish it.
That aspect of design alone does not determine the sound. So I think it is hard to generalize.

I have heard very good Class A, A/B and D.

I replaced a MF A3CR with my current Bel Canto Ref1000ms and much prefer the BCs. In some systems, the A3CR might be preferred. It all depends on overall synergies and balance.

Biggest difference between A3Cr and BC Class Ds in my case is A3CR is a touch hotter through the upper midrange perhaps and much lower power for my power hungry speakers, though they sounded fine.

There was a big difference in the bass with BCs being much more articulate and dimensional which I would attribute at least partially to very high damping factor compared to A3CR.
The new Rogue Medusa hybrid thing sounds pretty damn good...class D plus a tube or two in there.
Jult52 and Csontos both make excellent and insightful observations.
I would like to hear the new Rogue hybrid.
Thanks to all who responded so far.

To Wolf Garica, the Rogue Medusa (200RMS) is $3995; the Hydra is $2995....and as Sinbad's cabin boy says in the mythical tale:...."beyond the beyond".

What about NuForce class D; there is a model 8.5V3 stereo amp which is "supposed" to be a scaled down version of 9V3 monoblocks. Or, do all these class D amps sound the same??.

Also, there is an Odyssey Khartago SE Extreme (with Kismet upgrades) for sale on AG (Kismet upgrades are not indicated or explained on the Odyssey website) which makes me a bit skidish about the offering. The Khartago operates as a class A/AB amp, if I'm correct
Class D is evolving and if you do a search on the Hypex NCores you will find a significant number of owners who have dropped their high-end amps for the NCores. Several big-name Class A amps that are often mentioned in these forums have fallen to the new NCores.
Sunnyjim: Odyssey's web page is not up to date or comprehensive (my old Dual Mono was never on the site), but this would not make me hesitate. If you are interested, you might give Klaus a call; he generously supports second (and third) owners of his gear. I think all of Klaus' amps are A/B.

In the world of musical instrument amps class D has made huge inroads for bass players and also keyboards, because they are a lot lighter.

But to say that they sound better is another thing! Even with the highly inaccurate speakers that are common with music amplifiers, the lack of authority that class D brings to the party is obvious- a good tube amp, class A or AB, can deal a swift blow to class D.

Not surprisingly, in the world of high end audio I hear exactly the same thing. Can't say so much about a class A transistor amp, but if you are talking tubes, it almost seems like there is no contest- the tubes will easily rule the day.

1) the tube and class D amps must be compared on a speaker that is comfortable for both amplifiers.
2) speaker cables are kept short.
Hi Athmosphere:

Your caveat #1 negates your point, largely. If its non-OTL
tube amp then if power is needed I HEAR distortions I can't tolerate. So for easily driven speakers when low power is needed I also prefer tube.

For OTL, the power is not a big problem, absense of the output transformer make it (almost) dissapear. The problems with OTL are two fold: they have difficulties to drive low impedance speakers and require high degree of maintance. Otherwise, I am OTL lover and as you know I work with Jud Barber of Joule-Electra because of it !!!!

Regarding your caveat #2, I can't comment because we at Spectron Audio have proprietary speaker cable, we call
"Remote Sense" which negatate effects of imperfect real-life long speaker cables.

All The Best

>>07-22-12: Csontos
The amp on the other hand is the heart of the system.<<

That is incorrect.

It all starts with the speakers; they are the most important component in every system.
To many variables to give an accurate answer. Lets just give our thanks to the gentleman who keep improving our amps and enjoy the music. They are both winners when put in their proper place. Do we really need a winner? Enjoy
My personal preference is for Class A, having just switched from D to A. Despite the much lower rated power, I found the Class A amp to have greater definition, control and musicality.
["07-23-12: Atmasphere
But to say that they sound better is another thing! Even with the highly inaccurate speakers that are common with music amplifiers, the lack of authority that class D brings to the party is obvious- a good tube amp, class A or AB, can deal a swift blow to class D.'}

Your opinion regarding class D, while somewhat shallow, is understandable.

I've been playing Upright and Slab Bass professionally since 1965. Playing in the rhythm section means you have the largest gear to deal with. I own and have owned a great deal of instrument amplification over the years. It boils down to having the right tool for the job. Often I need to transport my fiddle, amplifier and cabinet, in one trip to and from the car. A 90 pound Ampeg SVT head is out of the question.

My Acoustic Image Focus 2R has two preamp sections, effects, and puts out 600 watts at 6 pounds. With my 12" shallow wedge monitor it's a one trip combination. Combined with my Bag End 4-10" it eats my 1970 Ampeg SVT/8-10" for lunch. It goes lower and louder with much more tonal flexibility. With a Slab Bass and the 4-10" it's one trip to the car. The Ampeg and the Mesa 400 are collecting dust and value as time passes. The Ampeg SVT is still very popular yet it's the silliest bass amp ever made.

I also have some very powerful QSC amplifiers. They have switching power supplies but even they get congested when pushed. Class D doesn't, its like the cabinets are plugged directly into the AC receptacle. I'm not aware of any class A solid state instrument amplifiers.

I love listening to the relaxed presentation of my tube amps in my main system. In my little studio I have a much different goal, I need to hear everything. I'm driving my Avalon Monitors with a pair of DIY Hypex nCores 400s which recently replaced a big well known solid state amp. The improvement in reveling transparency with the nCores and the Monitors is stunning.

I've owned a few switching amplifiers, IMO the nCore design is by far the biggest single step forward in class D technology. Then again its still class D.
Class 'D' is for car stereo. Not good enough for in-home use, IME.
I'd love to hear the NCore class D amps. I had a Hypex based class D amp as well as the lower powered Red Dragon M100 monoblocks and I just found I enjoyed Class A and Class AB amps more. The Class D amps I had seemed to lack definition and the music in my system wasn't as open or airy. I believe it is just preference and the synergy with one's equipment in their system.
"..lack of authority that class D brings to the party is obvious "

What about vehicles with internal combusion engines ???
Once I drove Yugo and its was horrible !!!!!!! Friend recommended Ferrari but I said "Thanks but no, I know how they drive!"

The "authority" is a function of well designed power supplies be it for class D or class XYZ with BIG, BAD, headroom (and NO distortions, pleeeease!)

I piblished article on the topic in Enjoy The Sound:

If interested in the topic - please read, I wrote it as educational tool for non-engineers music lovers.

All The Best,
"It boils down to having the right tool for the job."

Thank you for that answer that "hits the nail on the head".

What hammer works best? Screwdriver? Amplifier?

Audio is not so complicated anymore as some make it out to be. The basic problems have been solved for years.

Now it is exactly more about choosing the right tool for the job than ever because, guess what, there are many very good ones out there and they are all different! Go figure!

Of course some may like certain tools and build their solutions that way. No problem. Its all good! There is no better or best technology. IT ALL DEPENDS! Who'da Thunkit?

One needs to think twice before categorically dismissing certain technologies that they may not prefer because there may be others out there that know better and credibility is lost.
I've been playing Upright and Slab Bass professionally since 1965. Playing in the rhythm section means you have the largest gear to deal with. I own and have owned a great deal of instrument amplification over the years. It boils down to having the right tool for the job. Often I need to transport my fiddle, amplifier and cabinet, in one trip to and from the car. A 90 pound Ampeg SVT head is out of the question.

I too play string bass, and in my band I play keyboards. Our bass player uses a 400-watt vacuum-tube Peavey, I have moved the amp many times and am well aware of its weight! We did a comparison between it and the 500-watt Orange class D amplifier; despite having 100 watts less power there was no contest- the Peavey smoked the class D amp easily and I have seen it do that a lot.

But I understand fully the issues of weight and heat! If we are to compare apples to apples, I recommend that the class D amp have the same power as the class A amp it is compared to. I think anyone will see at that point the difference in authority. However, class D represents the cheapest power available, and IME what that means is to have good success with the class D, it needs to have a lot more power- IME about 2-3x more at least.

Class D amps are highly power efficient, as the output section switches on and off and so does not spend much time in the linear region. This keeps heat down, and the requirement for large heatsinks and power supplies.

If you play organ pedal tones on your system at lifelike levels, this is the sort of signal that will tax a class D amp as it will heat up and where its sonic weaknesses will be manifest. IOW, something that makes serious on-going power requirements of the amp. With a class A amp this is no problem but a class D amp of the same power will get into trouble and its easy to hear.

My recommendation for those who doubt me is to do the comparison- but in doing so make sure that both amps make the same power.

I have seen Class D as the rising star in high end audio for the last 10-12 years and we've been listening to them ever since they first appeared. I think the technology still has a way to go- if you look at price/performance curves you will see what I mean.

In the meantime, the best I can make out is that to make class D work, it is better to have the amplifier be a lot more powerful than you have expectation of needing. That way you are not taxing it an it can show itself off better. But if you are talking apples to apples its a different matter.

I do not agree that my 1st caveat is somehow contradictory to my prior points in my post above. An 8 ohm speaker is sufficient for demonstration. Now with regards to 'difficult' loads, there is a reason that such speakers are said to be difficult. Its not just that some amps won't be able do drive them- its a lot more than that. Its a simple fact that you can see in the specs of any amplifier- class D included- the lower the impedance and the harder to drive the speaker is, the more distortion. In transistor amplifiers and class D, this means you will hear more odd-ordered harmonics, which the ear translates as harshness. So while an amplifier may be able to drive a 'difficult' load, this is not the same as saying it is sounding its best. So my caveat is perfectly acceptable.
Strength of Class D is when lots of power is needed in a small and perhaps affordable low maintenance package.

Class D may or may not be a good option in other cases, however those will be weaker cases for Class D ie cases where the unique aspects of Class D do not matter as much.

What the best option is largely depends on the playing field. Each approach is sound and can sound very good on its home field, less so playing away games on the others, so one can always set pre-conditions that favor one solution versus another. What happens and is needed in real life is all that matters in the end.
I'd suggest that rather than just comparing Class D amps with Class A amps of the same power levels, compare them at the same price points, or for those that need to regularly transport their amps, the same sizes and weights, or any combinations there in.
Blah blah, and, of course, blah. Isn't this question (at least the subjective qualitative opinions part) like asking, "What's better...6 cylinder cars or 8 cylinder cars?" If the only thing defining an amp is its operating class, the world is too simple and I want off.
I suggest we get the quantum physics people on this and get the real skinny because I cannot trust my ears. However in china we do trust.
What is being written about the new N-Core technology sounds like a real game-changer. Pricey stuff though...Class D just got a whole lot better (than class A..? Well, that's what's being said by some industry leaders) up folks.
I think tubes are more fun than any newfangled the Class D modules glow and burn your fingers when you check the bias? No. I rest my case.
Class D is fine for sub-woofers...lots of power but no finess...Class A has little power but lots of finess
Which is really better, it is like comparing apples to oranges and ultimately depends on what type of music you generally listen to, personal tastes and power requirements. I have heard excellent sound quality from both. Just because Class D is an ideal application for subwoofers because of its efficient power delivery doesn't mean it cannot be engineered and refined to support an excellent two channel system. Please take the time to research both and hear for yourself the differences and then you will see where alot of audiphiles have been.
OK, how many of you looked up price/performance curves I mentioned?

I don't mind you going off on me, but look at the curves. Class D is about 12-15 years old. Class A is about 80 years old.

In terms of technology class A is considered mature, with are all sort of variations and embodiments (SET, push-pull transistor, etc). Class D OTHO is still developing. Hence my comments about it being a rising star. Sounds like the N-Core might be part of the next step in its development, I am sure time will tell- let's see what we are talking about in 2 years.

If you don't have confidence that it will still be the ticket in 2 years then you have an innate understanding of price/performance curves and how a technology matures.

I have confidence in sticking to my observations so far. I don't have confidence that those observations will still be the thing 2 years from now- the technology is changing that fast. From a business point of view this means I have to keep an eye on it; class D has certainly challenged conventional transistor art, such that many companies have already 'switched' over :)
I think a bottom line in this discussion is the "bottom line." From what I've seen, Class D modules can be VERY inexpensive relative to what they potentially can offer, and, weirdly, some of the manufacturers are trying to sell things and make a profit. A little tweaking here and there with added tubes or Serious High End Brand Name, and "open the vault comes da cash!"
"If we are to compare apples to apples, I recommend that the class D amp have the same power as the class A amp it is compared to. I think anyone will see at that point the difference in authority."

Brilliant! Brilliant idea. I am all for it ! My single question is: MOM, WHAT IS POWER?

If its continius (rms) power as most of manufacturers show in their specs then in my honest opinion its useless and misleading "digit".

If instead of bench test signal, we will use real life music then most speakers will require, most of the time - may be 10% of continius power. May be less.

A small percentage of time music is played is "filled" with loud sound (orchestral creshendo?) which to reproduce WITHOUT (!!!!) additional distortion you need 10 - 100 times more (peak) power then continus.

Compare two amplifiers with identical peak voltage, peak current, level of distortions, BW and....duration i.e. not 10 msec. Most class A amplifiers will do it with ease! Most class D amplifiers? .... try and see

All The Best,

The new class D: read about it here
Hi 2chnleben:

"The new class D: read about it here... "

I have read it and I understand that NCore is new amplifier on the market (excellent!) but how it is "new class.."? What is so different in itsdesign which make it "new class D" ?

Shell I sell now my Spectrons or....wait a bit ?

Thank you
Wait a bit. Think about price/performance curves. Unless you like buying new amps every six months.
" Think about price/performance curves"

Atmasphere, if your comment was addressed to me ...I was just teasing with every so often "THE class D amplifier of the DAY" attitude.

If I would change my current amps, I would install central air (if possible in 100 years old townhouse) and buy OTL - yours of that of Jud Barber of JOule-Ekectra....well and than had to change my speakers (B&W 802D).... probably not, sorry. There is no reason really to change my Spectrons - I invested bazzilions in various upgardes and...verrrrry happy with my sound. As a matter of fact I LUV IT (to put it modestly)


B&W 802s don't really work with tubes anyway...
Atmasphere is right that Class D amp technology is likely still evolving along the technology maturity curve, certainly it is newer than other types relatively speaking. But it has been around a while and has reached a fairly mature state at this point I would say, at least based on my experience so far. I did consider waiting about 2 years back when I splurged on my current Class Ds, but hey tthey seemed like the best solution available for me at the time so I decided to take the plunge. You only live once TTBOMK. One can never be certain what lies ahead.
Class A has little power but lots of finess
Stringreen, my Clayton M300 amps provide 300wpc into 8ohms and 600wpc into 4ohms - all in Class A. In the tubed world, Ralph and others also offer pretty high powered Class A amps. High powered Class A amps require large, high quality power supplies not typically found in Class AB or Class D amps. I am not saying there are no better sounding amps than those that run in Class A (because I don't know, plus the Class AB Jones PA-M300 amps are said to sound great) but there are reasons that really good Class A amps sound really good.
I think there's a lot to be said for system matching.

I have heard the Thiel CS3.7s powered by Bel Canto REF1000s, and then REF1000Ms (upgraded kit to the base 1000s), Plinius SA-Reference and Electrocompaniet.

For the price of the REF1000Ms, I think they punched way above their weight class. Once I improved the power to the REF1000Ms (ASI Liveline fed through Sound Application RLS 240 conditioner), the margin was very close especially when I switched from the Bel Canto Pre3 to an ARC Reference 5SE pre.

The price was like a factor of 1x (for Bel Canto), 2x and 3x.
As I recently posted elsewhere, speculation about the sound of something that the speculator hasn't ACTUALLY heard is merely speculative speculating and those opinions are worthless as information except to the speculator, who may have found some comfort from having merely vented a thought, so there's that.
That was brilliant, wolfy. In a Professor Irwin Corey sort of way.
I took Corey's class at Yale...he was brilliant, albeit somewhat smelly.
Not sure why we can't get along. Haha. I changed out a good a/b amp to class D and have no regrets. Love the sound. Still feel the top end is way more important I like the combo of great d/a with tube pre amp and class d on bottom.