Just curious what others do for tweeter protection in active crossover speakers?
My speakers have a ScanSpeak Revelator R2904/7000 tweeter, and at around $350 each, I'm not eager to replace them due to some problem with an amp or active crossover, or even just a mistake by ME.
They crossover at 2500hz.
The typical thought is to put a capacitor in line. The speaker has an Re of 3 ohms, so at 2500hz a cap would be 21uf. But that's a filter that has a 3db down point at 2500hz and is 45 degrees out of phase, so to keep it from interacting and causing issues it really needs to be lower. An octave lower gets it mostly out of the way, but puts the crossover so low (1250) that maybe it's useless. At 6db/octave and increasing phase shift, there really isn't any way to have it completely protective and transparent.
You can go to a 2nd order filter, which does a better job at protection, but has double the phase shift.
I guess I can go to fuses, but they also have issues. Not to mention I have to figure out the current limits on the tweeter and to trust the fuse it has to blow fast and also work as advertised.
There just doesn't seem to be a really good solution. I guess the good news is my tweeters are pretty robust, handling 210w long term so maybe a fuse could be sized effectively. If my math is right, that's sqrt of 210/3, which is about 8.4. So maybe a 5a fuse would offer sufficient protection?
Any comments or help would be appreciated.
My speakers have a ScanSpeak Revelator R2904/7000 tweeter, and at around $350 each, I'm not eager to replace them due to some problem with an amp or active crossover, or even just a mistake by ME.
They crossover at 2500hz.
The typical thought is to put a capacitor in line. The speaker has an Re of 3 ohms, so at 2500hz a cap would be 21uf. But that's a filter that has a 3db down point at 2500hz and is 45 degrees out of phase, so to keep it from interacting and causing issues it really needs to be lower. An octave lower gets it mostly out of the way, but puts the crossover so low (1250) that maybe it's useless. At 6db/octave and increasing phase shift, there really isn't any way to have it completely protective and transparent.
You can go to a 2nd order filter, which does a better job at protection, but has double the phase shift.
I guess I can go to fuses, but they also have issues. Not to mention I have to figure out the current limits on the tweeter and to trust the fuse it has to blow fast and also work as advertised.
There just doesn't seem to be a really good solution. I guess the good news is my tweeters are pretty robust, handling 210w long term so maybe a fuse could be sized effectively. If my math is right, that's sqrt of 210/3, which is about 8.4. So maybe a 5a fuse would offer sufficient protection?
Any comments or help would be appreciated.