Postavio sam istu temu na drugom forumu i neko mi je odgovorio sledece :
For 1.5"~ 1.75" coils I would use the RXEF 090, and for 1.75"~2" coils the RXEF 110 (these values are for 8 ohm drivers.
For 16 ohm drivers use the RXEF 065 and RXEF 075.
Do not use RUE series devices, they can only interrupt 30V (RXEF are 72V devices).
For a 1" coil device in 8 ohms the RXEF 050 and RXEF 065 for the 1.25" coil in 8 ohms.
The RXEF series PTC devices take up to 10 seconds to trip at 200% of rated holding current, ie: the 050 holds at 0.5A and takes between 10 seconds and 30 seconds to trip at 1A.
Using lightbulbs and resistors in parallel changes things a bit, in general you would want to go down one value on the PTC (ie: from a 050 to an 040, from an 110 to an 090) for a device with a parallel resistor, and add a resistor in series with lightbulbs (the series resistor plus lightbulb to then be wired in parallel with the PTC).
Lightbulbs suitable for protection :
Resistor values to go in series with the lightbulbs (and then the combo to go in parallel with the PTC device).
5R 10W + 1A lightbulb for 040/050 devices
3R3 15W + 1.5A lightbulb for 065/075 devices
2R2 25W + 2A lightbulb for 090/110 devices
If you're NOT going to use a lightbulb across the PTC you must parallel it with a suitable resistor, 50W 25W. If there is no load on the crossover (after the PTC opens up), the network can burn up. If there is an L-pad that still loads the network after the PTC opens up (PTC between pad and driver), you won't need this extra resistor.
While the listed bulbs are all 12.8V, they will handle 18V~20V for fairly long times (in music). Combined with the typical 10dB or so pads in passive crossover networks they will not blow (even with short bursts of feedback) with amps up to about 600W/4R. If you're using bigger amps than this you really should be using an active crossover system/bigger speakers.
A relay based protector may be better than using a PTC, but is more expensive/compex. Most of the time I use just the 211-2 or 1156 lightbulbs (as appropriate) with no PTC/relay.
KAKVI su to RXEF PTC otpornici i da li mogu da se nadju kod nas
size does matter(to my back, and to my wife)