Dave A Posted March 16, 2020 Author Share Posted March 16, 2020 That is different than the ones I have. On the polyswitch I would not worry about what to use other than use the same thing Klipsch did. Some guys advocate for changing them out when you are in there and they are certainly cheap enough to do so. Like much of Klipsch and in particular the pro gear documentation on why things were done is poor. Quote Link to comment Share on other sites More sharing options...
WMcD Posted March 16, 2020 Share Posted March 16, 2020 I agree with Glens about protecting the amp. I'm not smart enough to figure it out. One of our moderators long ago pointed out that we often have a high pass (or low pass) second order filter in the cross over. If the speaker burns out, it forms a series RL across the amp. Thus at some freq there is a dead short to ground and potentially the inductor (probably) fails if the amp doesn't fail first. This may account for gross failure of crossovers. The tech doing a post mordem will see the crossover in a burned out condition and announce that the crossover failed and then failed the amp and or driver. Actually the driver failed first. Then there was a cascade of failures. An open polyswitch could do the same unless there is resistor in parallel. At least that is my read. WMcD 1 Quote Link to comment Share on other sites More sharing options...
FMnoise Posted March 16, 2020 Share Posted March 16, 2020 (edited) PTC Resistors: https://www.lautsprechershop.de/hifi/ptc_en.htm Size it based on the power the tweeter 'sees' from the crossover (attenuated). Edited March 16, 2020 by FMnoise 1 Quote Link to comment Share on other sites More sharing options...
risingjay Posted March 17, 2020 Share Posted March 17, 2020 Dave what year were your 904's made? Quote Link to comment Share on other sites More sharing options...
Dave A Posted March 17, 2020 Author Share Posted March 17, 2020 3 minutes ago, risingjay said: Dave what year were your 904's made? I am guessing 1999. Some of the speakers out of the pile had dates marked on horns and they were all bought and installed in one place at the same time. There are serial numbers but I have not tried to find out when they were used. Quote Link to comment Share on other sites More sharing options...
risingjay Posted March 17, 2020 Share Posted March 17, 2020 Wierd. Mine were made in 99 as well and it seems like there are multiple crossovers for the 904's. Quote Link to comment Share on other sites More sharing options...
Dave A Posted March 17, 2020 Author Share Posted March 17, 2020 Here is something to consider. How many options were out there then. For example could crossovers be ordered for behind screen or side fill or arena usage? Did some come with THX limits and others not? Were they made for the 510 or 402 horns? You can't find answers to all this anywhere I have looked. The Hunter suggestion if you are really curious is a good one since he might have records or know of the decisions made. 1 Quote Link to comment Share on other sites More sharing options...
Alexander Posted March 17, 2020 Share Posted March 17, 2020 10 hours ago, FMnoise said: PTC Resistors: https://www.lautsprechershop.de/hifi/ptc_en.htm Size it based on the power the tweeter 'sees' from the crossover (attenuated). perfect, thanks Quote Link to comment Share on other sites More sharing options...
risingjay Posted March 17, 2020 Share Posted March 17, 2020 Will ask. I'll get better pic's of the crossovers then. Might not be till this weekend. Thanks Dave. Quote Link to comment Share on other sites More sharing options...
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