Output resistor for OT protection/ Garnet "Herzog" style line-out?

[Carlsoti]

I'm in the process of hammering out the details of HiFi to brownface Princeton 6G2 conversion. The base is a vintage Qual-Kit 2200, which ran a pair of 6V6 in UL, with a pair of 12AX7s up front. Both PT and OT test as good. I plan on taping off the UL leads and running it as a conventional PP output.

I'll be adding a 3-position switch to select ohms for the single output jack. I'd like to add a resistor to a shorting jack for protection against being run without a load.
If I lean towards the Herzog mod, I've got to get something with some weight to it, I think. I figured that a 25W chassis mounted resistor with thermal compound would give ample overhead.

If I just wanted to add an OT protection resistor WITHOUT adding a line-out tapped off of it, could I safely use a higher value resistor @ lower wattage? How high can I go before I have to be worried about fly-back voltages toasting the little OT from impedance mismatch?

Any info or direction would be greatly appreciated.
 

[sluckey]

The easiest thing to do is just connect the switch lug to the ground (sleeve lug). Fender style.

[tubeswell]

220R to 470R 5W should provide sufficient protection against accidental open load, without affecting the reflected speaker load too much.

[sluckey]

220R to 470R 5W should provide sufficient protection against accidental open load, without affecting the reflected speaker load too much.

This is probably a better idea if you connect the resistor so it is always in the circuit. This provides protection even if the speaker cable gets disconnected from the speaker cab.