Klipschguy Posted August 3, 2022 Share Posted August 3, 2022 One of the forum members recommended a fuse to protect the tweeters against an unexpected surge, such as accidentally unplugging an input cord with the volume up. Klipsch recommends a 1 amp fast blow fuse. Does anyone know what the recommended voltage rating would be? I found a fuse holder that looks like it should work well. Quote Link to comment Share on other sites More sharing options...
Edgar Posted August 3, 2022 Share Posted August 3, 2022 To send 1 Amp through 8 Ohms only requires 8 Volts. Use any 1A fuse that you can find; it will be fine. 1 Quote Link to comment Share on other sites More sharing options...
Racer X Posted August 3, 2022 Share Posted August 3, 2022 My experience with fuses is 1 amp 250V is not sufficient for my listening on LaScala or Heresy, and I do not think I listen loudly at all. Currently use 1.5 amps speaker and 2 amps tube fuses and seldom have a problem, only popped once when my new tubes were settling in, I've heard this is common as loose particles burn off within new tubes. Fuses are available in 1, 1.25, 1.5, 1.75, 2 amps and onward, so very easy to find the sweet spot for your application. Always best to have a number on hand, no one likes to have a listen cut short by loss of a fuse. 1 1 Quote Link to comment Share on other sites More sharing options...
Edgar Posted August 3, 2022 Share Posted August 3, 2022 Understand that @Racer X is making recommendations on the current capacity, not the voltage rating. It is a compromise between how loud you want to listen and how much risk of tweeter damage you're willing to take. 1 Quote Link to comment Share on other sites More sharing options...
Racer X Posted August 3, 2022 Share Posted August 3, 2022 Yes, exactly. Never paid much attention to voltage rating, but it seems most fuses commonly available are rated for 250 V. Perhaps more importantly, use fast blow for most applications, slo-blo for the power line fuse. Quote Link to comment Share on other sites More sharing options...
billybob Posted August 3, 2022 Share Posted August 3, 2022 Yes, just inline fuse for tweeter only. 1 Quote Link to comment Share on other sites More sharing options...
Klipschguy Posted August 3, 2022 Author Share Posted August 3, 2022 Thank you for the replys. If 25 watts into 8 ohms gives about 14 volts and 1.8 amps, I assume varying output of the alternating current would probably still not blow a 1A fuse? 1 Quote Link to comment Share on other sites More sharing options...
Edgar Posted August 3, 2022 Share Posted August 3, 2022 25 Watts RMS AC is exactly equivalent to 25 Watts DC, in terms of average voltage, average current, amount that a voice coil heats-up, etc. Quote Link to comment Share on other sites More sharing options...
billybob Posted August 3, 2022 Share Posted August 3, 2022 Looks like would be fine according to @Edgar... If blows using a fast blow 1 amp, you have 1/4 amp stepup fuses to find out, according to @racerx. 1 Quote Link to comment Share on other sites More sharing options...
Klipschguy Posted August 3, 2022 Author Share Posted August 3, 2022 9 minutes ago, Edgar said: 25 Watts RMS AC is exactly equivalent to 25 Watts DC, in terms of average voltage, average current, amount that a voice coil heats-up, etc. Empirically speaking, it seems like DC will fry a voice coil MUCH quicker than AC, but as a student of science and engineering (many years ago) what you are saying rings true. 1 Quote Link to comment Share on other sites More sharing options...
Edgar Posted August 3, 2022 Share Posted August 3, 2022 5 minutes ago, Klipschguy said: Empirically speaking, it seems like DC will fry a voice coil MUCH quicker than AC, but as a student of science and engineering (many years ago) what you are saying rings true. Don't forget that the DC resistance of a voice coil is generally lower than the AC impedance. 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted August 3, 2022 Share Posted August 3, 2022 There is a saying...that a $25 semiconductor will blow to protect a $0.05 fuse.......In my experience the same is true of the K77 tweeter voice coil. We are talking about a K77? A fuse will not suffice. Quote Link to comment Share on other sites More sharing options...
babadono Posted August 3, 2022 Share Posted August 3, 2022 IOWs get a real tweeter 1 Quote Link to comment Share on other sites More sharing options...
Klipschguy Posted August 3, 2022 Author Share Posted August 3, 2022 2 minutes ago, babadono said: There is a saying...that a $25 semiconductor will blow to protect a $0.05 fuse.......In my experience the same is true of the K77 tweeter voice coil. We are talking about a K77? A fuse will not suffice. K77, yes with AA network Quote Link to comment Share on other sites More sharing options...
babadono Posted August 3, 2022 Share Posted August 3, 2022 So it has the Zeners? Quote Link to comment Share on other sites More sharing options...
geoff. Posted August 3, 2022 Share Posted August 3, 2022 Ok, there was something else I thought I had read in a post on here from the past. Something about cascading failures in a speaker or crossover possibly causing serious damage to the amp? I know from personal experience all I have ever done is fried the tweeter, or had the amp’s protection shut it down. But is there a risk to the amp if part of the equation is removed by an open circuit across the tweeter leg of the crossover? Quote Link to comment Share on other sites More sharing options...
Klipschguy Posted August 3, 2022 Author Share Posted August 3, 2022 8 minutes ago, babadono said: So it has the Zeners? Yes, which did protect my tweeters from the 1.21 gigawatts they received during a scientific experiment. 1 Quote Link to comment Share on other sites More sharing options...
Edgar Posted August 3, 2022 Share Posted August 3, 2022 2 minutes ago, Klipschguy said: Yes, which did protect my tweeters from the 1.21 gigawatts they received during a scientific experiment. On a somewhat related topic, my house once took a 1.21 GW lightning strike. The only piece of stereo equipment that survived was the UPS / surge protector. 2 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted August 3, 2022 Share Posted August 3, 2022 All righty then...you're good to go or no? If you still want to add a fuse it won't hurt...I did it on my LaScalas long ago. But as others have posted you may need a wee bit more than 1 amp fast blow. 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted August 3, 2022 Share Posted August 3, 2022 15 minutes ago, geoff. said: But is there a risk to the amp if part of the equation is removed by an open circuit across the tweeter leg of the crossover? Some esoteric tube amp .....maybe. But SS naw. Quote Link to comment Share on other sites More sharing options...
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