BEC Posted October 15, 2006 Share Posted October 15, 2006 I think most of the time a fuse is just not quick enough to protect a tweeter. It might protect from continuous over power, but for a transient, probably just not quick enough. Specs on fast blow fuses usually read something like "opens when 137 percent of rating is applied for 2 minutes or 200 percent for 30 seconds". Some verbage like that. A zener should react quicker than any fuse. A polyswitch is pretty fast also, but introduces some resistance in the circuit. Bob Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted October 16, 2006 Share Posted October 16, 2006 Fritz, If the zeners break down at 5.8V, that means at an extreme overload you will have a square wave into the tweeter of 5.8 V peak + and -. That is quivalent to 5.8V DC. (E*E)/R = (5.8 * 5.8) / 8 = 4.21 Watts. That is the absolute worat case the tweeter can ever see. Will that blow a K77? Al K. Quote Link to comment Share on other sites More sharing options...
tidmack Posted October 16, 2006 Author Share Posted October 16, 2006 Hardhead, Wow, I came back and saw my thread started one heck of a discussion. My conclusion isn't nearly as exciting though. I'm going to have my AA's in the 1979s rebuilt. I'm not interested in doing it myself. As far as the 1984s, I think I'll eventually sell them. To make them sound the way I want them to will cost more than I'm willing to spend and deals on LaScalas do come up from time to time. Thanks everyone for their help! Jeff Jeff-- No one has answered your real question yet. As I noted above, I believe your K-55-M squawker and K-77-M tweeter are simply too loud (efficient) for the Type "AA" crossover. The way to find out for sure if that really is the problem is to swap the "-M" tweeter and squawker with the Alnico ones as I previously suggested. If that is, in fact, the problem, Al Klappenberger's ALK crossover networks have a way to adjust the volume of both the squawker and the tweeter to put their outputs in line with the woofer. You can kill two birds with one stone that way: get a fantastic crossover and fix the tweeter-squawker output problem. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 16, 2006 Share Posted October 16, 2006 Al Klappenberger Accroding to EV's data, 4.21 watts is within the 5 watts continuos rating and well below the 50 watt peak (10ms) rating of the voce coil. You and Bob have me wondering. So this week, I'm going to do some tests using some AA networks and a few t-35's I could spare if they blow. I am off thursday and wensday this week. If you have any specific voltages and frequency ranges you want me to test with let me know. Else, I will be testing two fold, direct hits within the crossover range of the tweeter, and some mid band and low band signals to determine how much low and mid band juice these tweeters and zeners are actually seeing. Quote Link to comment Share on other sites More sharing options...
BEC Posted October 16, 2006 Share Posted October 16, 2006 SF, Watch about getting any low frequencies through the tweeter filter. 1/2 watt at 3 khz will turn the voice coil into a slinky. Bob Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 16, 2006 Share Posted October 16, 2006 Bob I'm goingt to setup an AA xover with all the drivers on them. Send signals to the xover at different frequencies and voltage levels. Both above and below the tweeter xover point. The zeners should be able do what ever they can do. I hope 1/2 at 3khz, while connected to a properly loaded AA xover will not "slinky" the tweeter, since most of that should go to the k-55, if it does, "slinky" then we need a better tweeter protection scheme, polyswitches, fuses, etc. Quote Link to comment Share on other sites More sharing options...
BEC Posted October 16, 2006 Share Posted October 16, 2006 SF, You should not be able to get that much through the caps and inductor in the tweeter circuit with those parts working right. But if it does get through there, the zeners, fuses or polyswitches would not help for that. That is what happens to the AL crossovers because of poor solder joints in the tweeter filter. Bob Quote Link to comment Share on other sites More sharing options...
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