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Class A Power Amp Degredation

Dear Forum Members,

I've read in several places that because class A amplifiers run hard all the time and most people don't cut them off, they wear our faster. Plus, because they remain on all the time they burn much more electricity and generate lots of heat, some more than others, at least that's what I'm told. I wonder what happens if I have to go away for a day or two?

I can't afford to purchase a brand new class A amp so I wonder if I should even consider the purchase of a used Mark Levinson, Pass Labs or other class A amp? The only amplifier I know of that can be switched between class A and A/B is the Plnius. I am told that this amp only run very hot when it's running in class A.

Here are my questions:

1. What should I look for in a used amplifier?
2. Do class A amps wear out faster than other amps?
3. Are there amplifiers that can match the musicality, sound staging, bass and sweet sounds of a class A amp? In other words are there any class A/B amps that have all of the quailities of the class A amps?
4. If I do decide to buy a class A amp how far back in years should I venture? Right now I am considering the Mark Levinson 27 or 27.5 or Pass Labs X150/250 and X150.5 and X250.5 amplifiers. It's been suggested that the Mark Levinson is more musical????? I just want to get the best amplifier to run my audio system.

I will be driving Magnapan 1.6 speakers which does require a fair amount of amps/power to drive them. Also I mostly listen to classical music, large/small scale choral works, contemporary and gospel music and all modern jazz. I love the human voice. I also love a huge sound stage with lots of depth perspective.

Any assistance and suggestions you can provide will be very welcomed. Thank you so much for taking of your time to respond to this plea for help.
rbwinterlink
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elevick
2,636 posts
 
1-If you are going away, definitely shut off the system. It may take an hour or two to get back up to where you will like it when getting home.

2-Having owned many class A amps, I'd state very confidently that they don't wear out faster as long as they are well ventilated. They do run very hot but are designed for that. The problem is that when a class A amp blows, it usually goes badly. Look at how many 20 year old class A amps are out there working perfectly...

3-The old standby on on Class A amps that is switchable from A to A/B is the Yamaha M series. If you are looking to just play, these are great. The M45 has around 150 wpc and the M60 through M85 have way more power.

Finally, I can't put Levinson and Pass in the same ballpark. The sound is drastically different. I love Pass and can't stand Levenson's "dryness" in comparison.

Keep in mind that most Class A amps are only in the A mode for the first 10-15 watts and then automatically switch to A/B. So loud listening will be in A/B anyway. Some amps are always in class A but those are usually rated in the same league as tube amps (20-60 watts). Don't be fooled by an amps rating of high power and class A, it's usually an either/or situation.
jaybo
4,478 posts
 
the theory that class a outperforms a/b and is debatable. buy the amp that will best serve your speakers, regardless of catagory.
atmasphere's avatar
atmasphere
11,803 posts
 
Elevick, a class A amplifier, by definition, is class A at full output. If not, it is called class AB. There is no exception to this definition- the amplifier is class A if the output device does not go into cutoff at full power.

It is true that class A amplifiers last just as long as any other type of amp. They do run hotter- trading efficiency for improved sound quality. Class A operation is the most desirable mode of operation if the best sound quality is your goal. All other classes of operation trade off greater power output (and less heat) for less sound quality. Unfortunately it is not so simple to say that all class A amps sound better than all other amps; that would only be true if that class A amplifier had all the other most desirable design attributes and was properly executed. What is the best of the other design attributes is controversial, but the class of operation is not.
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