[Phil Allison[_4_]]

Scott Dorsey wrote:

Notice how much softer the tube amp goes =
into distortion than the solid state does.


90% of that has to do with the output transformer rather than any of
the gain stages.


** Nothing magical about transformers, just the fact there IS one included inside the feedback loop. This limits how much feedback the designer can use before the amp becomes unstable at high frequencies to much less than with typical transformerless designs.


You can build a solid state amp with an output transformer
(like McIntosh did in the seventies) and get similarly soft clipping
behaviour.



** Some 100V line amplifiers have a transformer included in the output stage using a topology not too different from a tube amp with a single positive supply rail ( often 24VDC) connected to a CT on the primary.

The secondary may have 8ohm ( used for NFB) plus 50, 70 and 100V windings for the distributed speaker system.

Normally clipping is softish.


...... Phil