do hartkes not clip??

EVERY amp can clip.

Some amps have a built-in limiter that prevents the amp from clipping, and the clip led just shows that the limiter is kicking in.

 

I'm not familiar with Hartke amps, but the clip light on many amps indicates a different thing than the limiter/compressor light. When the latter is triggered (usually selectable by the user), its light goes on, thus indicating signal processing activity. In contrast, when the power amp stage of a head clips, it has nothing to do with a limiter circuit: it shows that the output waveshape is starting to distort greatly compared to the input waveform. And if an amp doesn't have a clip light, it simply means that it has no way to tell you it's clipping - you'd have to listen to the telltale sound of clipping to know.
- Mike

 

Oops, Mike, you're right of course.

I messed up on that post, sorry.