I want to take the opportunity to ask if you tested and used PTCs and PolySwitch ® before for protection of the HF drivers. What was your impression of them?

Should I point for PTC amperage and triggering at half the wattage RMS or (half) the max. handling watts of the driver. I can use the initial resistance values (at 20º, before tripping) and enter them in SPICE, say .31 min and .48 max (for RXEF065 Polyswitch coupled with a 45Wrms driver) in series, averaging between .25 and .75 Ohms (for RXEF050 and RXEF075).

Is the time to trip, 4/5 seconds too much for the driver to handle, just in case?

From your perspective when installed in the X-over circuit do they (PTCs) alter the sound quality in any way? From your point of view the use of a fuse (series with the PTC) or a lamp (in parallel) ‘a la Eminence’ is a good idea? What is the best protection set-up?

(>custom-built aerospace lamps as positive temperature coefficient series varistors: Eminence PX SERIES pro x-overs)

Best Regards