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 Wrote:
My understanding is a class A /AB amplifier will have a switch to differentiate between the two classes. The switch changes the amplifier's quiescent current. My amplifiers have a switch on the front panel in class A for 30 watts output, @ 8 Ohms the quiescent current is 250 watts and in class AB for 200 watts output, @ 8 Ohms the quiescent current is 80 watts. In my audio system my amps are always in class A mode. I hope that answered the OP question. 😎 Mike |
I've got a Pass 250.8 amp that runs 25 watts in pure class A and then transitions into class AB and can generate 250 RMS into 8 ohms. It idles in Class A and sucks 400 watts of juice from the wall when not reproducing music- just turned on. It's about 110 pounds and when on is hot- not warm- hot- and will heat my dedicated room to 73 degrees after being on for a couple of hours. The power meter on the front which shows when it starts to move from Class A into AB mode never budges and I play it loud into a pair of Wilson Sasha 2. It's an incredible amp, super musical and dynamic and great bass. I've never been able to get it to come close to moving into AB, the first 25 Class A watts will drive the speakers louder than you can stand! |
