what happens to tube amp if powered on without cabinet. how and why

[g1]

so now it's a question of whether it's better to replace it with the exact same type of jack, and let the same thing happen again, or to replace it with a regular 1/4 mono jack and strap a safety resistor across the OT secondary.

i'm leaning toward the safety resistor.

How about both? All the benefits with none of the drawbacks of a single method.

[Leo_Gnardo]

How about both? All the benefits with none of the drawbacks of a single method.

No problem! Another plan is to use stereo type output jacks SWCR 12B for instance and wire the ring to your output tubes' cathode circuit so no current unless speaker cable's plugged in. Seen it done in CAE amps and by a few modders. Done it myself on occasion. Works a charm. This may have been mentioned before so please excuuuuuse me if it has. Spent too many years in the Department of Redundancy Department.

[Gingertube]

' I prefer to put "voltage tether" resistors (say 330K to 470K) from each OT anode lead to 0V'
Ian, that's an interesting idea, what are the guidelines for the spec on such resistors, eg limiting element voltage and power rating?
Thanks - Pete

Pete,
Pobably use 2 off resistors in series to get the peak voltage withstand. Yes, the anode can swing to 2 x B+ voltage.
Power dissipated is V squared on R - say approx 700 to 800 milliwatts.
Use a couple of 2 watt metal films in series at each anode. Carbon Composition do have excellent pulse voltage withstand but it is about the only thing going for them.

Cheers,
Ian