2. amps-preamps
  3. 183302-13196

CLASS A POWER RATINGS

In well designed SS class A power amps I was told that although power could increase to double in class AB mode from speaker demands of  8 ohms to 4 ohms, class A suffered to be cut in half.

For example a class A denominated amp rated at 50 watts class A into 8 ohms would double to 100 watts class AB  into a 4 ohm load but only have 25 watts of class A power before switching to class AB.

But I've noticed of late claims of manufacturers stating their amps double their class A power as impedance demands are halved.

So is the explanation that technology has advanced ?

rost
wolf_garcia
6,626 posts
 

What's with the unventilated rooms? If my listening space got warm from my XA-25 or my tube amp I'd question the oxygen levels...I've got a Vermont Castings Intrepid behind my listening spot and I'm still never too warm (tall ceilings...but still). And AC flows in in the summer...

richdirector's avatar
richdirector
266 posts
 

I live in Scotland so just open the window a crack in the summer if my luxman starts to heat the room enough.... Which it never does 

sngreen
36 posts
 

This is a very good thread, but just to clarify; Class A is a single-ended amplifier. Push-pull is class A/B (even though it is often described as class A). Do I understand it correctly?

charles1dad's avatar
charles1dad
10,234 posts
 

@sngreen 

By default SET/SEP  is 100% pure class A operation. But as has been pointed out above,  you can have pure class A push pull amplifiers that do not utilize any class B operation.

Charles

clearthinker's avatar
clearthinker
1,582 posts
 

@yyzsantabarbara 

I read the specs.  The amp runs in Class B and has a circuit that senses when there is a peak in the programme.  It then puts the amp into Class A before the moment of the peak, so it can be fully reproduced.

OK read that again please.

That is of course impossible.

Without a time machine.

Krell called it an 'anticipator' circuit.  But of course it cannot anticipate.

If you want Class A, like I do, the Krells to buy are the pure Class A KRS200s like mine.  Class A, the whole Class A and nothing but Class A.

More to discover