From: dpierce@cartchunk.org   
      
   Paul G. wrote:   
     >    There is a remote chance it is a "fusible resistor",   
      
   The farthest reaches of the universe are not as remote as the   
   chance this is a fusible resistor.   
      
   > I've replaced these things on older TV sets.   
      
   This is not an old TV set. It's a speaker. Fusible   
   resistors were placed in older TVs as a prevention   
   against potential fire hazards incase other components   
   failed, NOT to protect the TV.   
      
   > They are used extensively in the electronics industry,   
      
   Not in speakers, they are not.   
      
   > especially where temporary large surge currents   
   > are tolerated.   
      
   Lordy, what are you people smoking?   
      
   let's assume the fusing current is equivalent to 15 watts   
   dissipation, twice the rated value. 15 watts dissipated   
   in .47 ohms means it has to sustain 5.6 amps. That same   
   5.6 amps through an 8 ohms voice coil is 255 satts.   
      
   Any voice coil in that speaker would have blown trying to   
   dissipate 255 watts LONG before the resistor even knew   
   what was happening.   
      
   > If that were the case, you would be required to replace   
   > it with a similiar resistor of the same power rating.   
    > 0.47 ohms is a popular value for a fusible resistor.   
      
   Good lord, IT IS NOT A FUSIBLE RESISTOR!   
      
   > They DO have a compartively long time to blow compared to a fuse,   
   > since the resistor must heat up to the point where the fusible element   
   > breaks.   
      
   And in that sense they are USELESS for protecting voice   
   coils, since the thermal time constant of most voice   
   coils is VERY short by comparison.   
      
   > In that respect they would be useful in a speaker, since you   
   > could allow large transients, and the resistor would open up before   
   > the voice coil would be damaged.   
      
   B*llsh*t, in a word. a couple of milliseconds at 5.5 amps,   
   and a tweeter voice coil is smoke.   
      
   Try dumping 5.5 amps into a woofer voice coil near resonance:   
   the voice coil could be completely mashed aginst the back plate   
   of the magnet within a fraction of a second.   
      
   Every single scenario that has a fusible resistor in there   
   results in a destroyed loudspeaker BEFORE the fusible   
   resistor acts.   
      
   Why persist in such speculative nonsense?   
      
   >    They were not meant as a consumer replacable item, since the trauma   
   > that caused the resistor to blow usually indicated some circuit   
   > problem or gross abuse.   
   >    My guess is that such a low value of resistance would not have much   
   > effect on the audio performance (being swamped out by the voice coil   
   > resistance), and might give more credence to its function as a slow   
   > fuse.   
      
   Wrong, completely, totally wrong.   
      
   As a series element to a driver, it would provide almost   
   exactly 0.5 dB of broad-band attentuation. just what you   
   might need for equalizing efficiencies of drivers. As a   
   series element in the shunt reactance in a 2nd- or 3rd-   
   order high- or low-pass crossover, it's just the kind of   
   thing you need to significantly modify the response in   
   the transition region to tailor the response of a network.   
      
   There are ALL sorts of actual and real uses for such a   
   resistor in a network that have NOTHING to do with what   
   you're talking about. And as a "protection" element, it's   
   provably useless.   
      
   >    If it is a fusible resistor, it is probably chosen for a specific   
   > thermal time constant. It would not be wise to replace it with an   
   > ordinary resistor, or fusible one of unknown characteristic.   
      
   The guy posted the designation as stated on the crossover:   
   IT'S A FREAKIN' RESISTOR. It is NOT a fusible resistor.   
      
      
      
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   +         Dick Pierce            |   
   + Professional Audio Development |   
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