Tag Archives: class A amplifiers

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

More Class A audio amplifier stuff. Not including sliding bias amps, generally, they are the best sounding of all audio amps!!

If you’ve been keeping up with my rant on amplifier classes you’ll recall that in yesterday’s post I explained class AB operation.

One of the takeaways from that explanation would be that without an input signal, a Class AB amplifier constantly draws a small amount of power out of the wall—enough to warm its heatsinks. Not until there is an input signal does the amplifier start to draw much power.

Remember back to the beginning post on efficiency where I pointed out that in a Class AB amplifier, for 100 watts delivered to the loudspeaker another 100 watts would be converted to heat? The net result of that is an increase in heat for every watt delivered to the speaker. More power delivered to the speaker equals more heat generated by the amplifier. Makes perfect sense, right? The harder the amp works the hotter it gets.

Class A amplifiers are the opposite.

In a Class A amplifier, the more watts delivered to the speaker the cooler the amplifier gets! In fact, the point of a Class A amplifier’s maximum power output happens also to be the point of maximum efficiency.

Weird, right?

A 100 watt Class A amplifier with no input signal draws 200 watts out of the AC wall receptacle. All 200 watts are converted to heat. That same 100 watt class A amplifier delivering 100 watts of audio power to the speaker still consumes the exact same 200 watts from the AC wall socket, only this time, half of the 200 watts consumed goes to heat while the other half goes to making music.

Thus, Class A amps are strange beasts indeed.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

New categories

While life is certainly easier when we’re able to put things in predefined boxes, those same box labels sometimes hold us back because it gives us permission to form opinions without direct experience.

I was reading some of the opinions on our M1200 Beta Tester’s comment section and couldn’t help but notice the tendency of people to categorize their likes and dislikes. “I love the sound of class A amplifiers.” “I like vacuum tubes but prefer solid-state amplifiers.” “Class D amps never get things right.”

It’s normal to box ourselves in, and always a joy to read someone’s revelation of a product achieving the status of being in “a league unto itself.”

This new “league” a few of the M1200 testers have remarked upon is, of course, yet another predefined box – a separate category that does not fit the standard mold. It’s what creatives hope for when launching a new concept or design.

Over the next few weeks, we will be delivering M1200 amplifier pairs to our beta testing group and they will be posting their observations on the forums.

If you’re interested in what league they are placing this new amplifier in, you can go here to read their observations.

Stay safe.