On Thu, 04 Nov 2004 20:50:43 GMT, "Fleetie"
wrote:

"Wally" wrote
Keith G wrote:
OK, exactly why don't trannies (on valve amps) like it being run
without a load?

I think it has something to do with the xformer's secondary trying to drive
a very large impedance (ie, open circuit). I think this translates into
excessive current in the primary (but I could be wrong).

I'd have thought quite the reverse; usually, I'd have thought the
primary current would decrease when the load was removed from the
secondary.

Mind you, if there's feedback and so on happening round it all, goodness
only knows.

Flippin' 'eck, I thought you guys were supposed to be the experts on
valve amps! What happens is that you have a situation similar to that
in a car ignition system. A transient hits the primary, it gets
transformed massively in the secondary, and the energy has to go
somewhere when the magnetic field collapses, so the secondary arcs
over, damaging the insulation and destroying the tranny in quick time.
--

Stewart Pinkerton | Music is Art - Audio is Engineering