"Jim Thompson" wrote in
message ...

I have been "backstage" for at least 40 years. Back then I recall
big-ass chokes with a moveable core to change the inductance.

...Jim Thompson

Bingo - That's what I remember in one of the older stages I worked once.
Nothing to do with mag-amps or saturable cores. Now the question is if that
dimmer system had a trade name? I doubt that they called it a 'big-ass
choke..."

Every time I see a moveable core arc welder (to adjust welding current) I
think of that old and scary dimmer cage.

Regards,
Oppie