"Eeyore" wrote in
message
Trevor Wilson wrote:

"Scott Dorsey" wrote
Trevor Wilson wrote:

**There are plenty of reasons NOT to go pure Class A
and very few to do so.

Other than size and heat?

**Cost, reliability and the fact that high bias Class
A/B is lower in distortion.

Lower ?

Yes, there are two problems with class A - both related to the fact that
with class A, the output stage always has far more current flowing in it.

(1) Power transistors tend to be less linear at high currents - the beta
falls off. Running an output stage class A approximately doubles the
current that the output stage has to handle. So, you move the operating
point way out on the output devices.

(2) Less SOA from the perspective of the load, because the output devices
are pulling so hard against each other.