Dave A Posted December 23, 2019 Share Posted December 23, 2019 OK this is on a "KPT-904M-B, P/N 116427" crossover for the KPT-904. There is a polyswitch and the label on it reads XX 50V X 110 JX3L-T Taiwan This crossover is different than the only one I can find on the forum and has an additional 25W200ohm resistor and this Polyswitch added to the tweeter circuit. How do I find out what the value of the polyswitch is and yes I have searched using all the data on the OEM polyswitch to no avail. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted January 6, 2020 Share Posted January 6, 2020 Do you even need it? Quote Link to comment Share on other sites More sharing options...
mark1101 Posted January 6, 2020 Share Posted January 6, 2020 Ask Hunter. Quote Link to comment Share on other sites More sharing options...
JohnA Posted January 6, 2020 Share Posted January 6, 2020 Is it damaged? Why replace it at all? Quote Link to comment Share on other sites More sharing options...
Deang Posted January 6, 2020 Share Posted January 6, 2020 https://www.parts-express.com/te-connectivity-raychem-rxef050-050a-polyswitch-speaker-protector--071-254?gclid=CjwKCAiA0svwBRBhEiwAHqKjFjY8gc_99_VWp1Z3AIjP1ihpbh8g6MmOKUYWG6FOace24-pt2y-s8RoCIokQAvD_BwE Quote Link to comment Share on other sites More sharing options...
avguytx Posted January 6, 2020 Share Posted January 6, 2020 I hate those things. Got rid of them in most any of the speakers I've owned. Polk SDA's always had them and, after they are tripped enough, they do so easier the next times. But, they are a protection circuit and have been used for years in home and car audio crossovers. Quote Link to comment Share on other sites More sharing options...
Dave A Posted January 6, 2020 Author Share Posted January 6, 2020 They are on the OEM 904 crossovers. My intent is to build more rather than buy new ones as the price I was quoted was $200 per from Klipsch parts. This is not to replace a bad part. I think they might be needed here as the tweeter is rated 100 watts and the bass bin 800. These seem to be in most Klipsch pro gear and I am not smart enough about electronics to know how important these are. Turns out the x110 is the important number. Thanks Dean as always for your links. Quote Link to comment Share on other sites More sharing options...
glens Posted January 6, 2020 Share Posted January 6, 2020 If the end result is intended, or may even be used, for pro use, then by all means replace them with new. As was stated, actually having been used will affect their performance, same as with any overcurrent protection device (i.e. a 15 amp breaker in your service panel). Quote Link to comment Share on other sites More sharing options...
Dave A Posted January 7, 2020 Author Share Posted January 7, 2020 3 hours ago, glens said: If the end result is intended, or may even be used, for pro use, then by all means replace them with new. As was stated, actually having been used will affect their performance, same as with any overcurrent protection device (i.e. a 15 amp breaker in your service panel). They are cheap enough and that is probably a good idea. Quote Link to comment Share on other sites More sharing options...
FMnoise Posted March 15, 2020 Share Posted March 15, 2020 Dave: That looks like a 1.10 Amp polyswitch, not a 0.5 A. They are rated for current and usually paired with a resistor in parallel. Here is a link to where you can purchase one. https://www.parts-express.com/te-connectivity-raychem-rxef110-110a-polyswitch-speaker-protector--071-262 Quote Link to comment Share on other sites More sharing options...
risingjay Posted March 15, 2020 Share Posted March 15, 2020 @Dave A I only have one KPT-904M-B crossover and it doesn't have the polyswitch. Quote Link to comment Share on other sites More sharing options...
Dave A Posted March 15, 2020 Author Share Posted March 15, 2020 1 hour ago, FMnoise said: Dave: That looks like a 1.10 Amp polyswitch, not a 0.5 A. They are rated for current and usually paired with a resistor in parallel. Here is a link to where you can purchase one. https://www.parts-express.com/te-connectivity-raychem-rxef110-110a-polyswitch-speaker-protector--071-262 I did end up getting some of those a while back. Quote Link to comment Share on other sites More sharing options...
Dave A Posted March 15, 2020 Author Share Posted March 15, 2020 12 minutes ago, risingjay said: @Dave A I only have one KPT-904M-B crossover and it doesn't have the polyswitch. That is nothing like the little PC board mine are on. Is that an OEM board? Quote Link to comment Share on other sites More sharing options...
OO1 Posted March 15, 2020 Share Posted March 15, 2020 - Quote Link to comment Share on other sites More sharing options...
Dave A Posted March 15, 2020 Author Share Posted March 15, 2020 Far less. Quote Link to comment Share on other sites More sharing options...
OO1 Posted March 16, 2020 Share Posted March 16, 2020 - Quote Link to comment Share on other sites More sharing options...
Alexander Posted March 16, 2020 Share Posted March 16, 2020 Just curios. How would we determent (calculate) the resistor/polyswitch values one would use to add to an existing tweeter circuit? Say you were to be building an a or aa xo using a k77 from scratch? But I would rather know how to calculate the values rather than be given them for the above example. Quote Link to comment Share on other sites More sharing options...
Dave A Posted March 16, 2020 Author Share Posted March 16, 2020 I have no idea and the only time I use them is to duplicate a crossover from Klipsch or rebuild one from Klipsch. Quote Link to comment Share on other sites More sharing options...
risingjay Posted March 16, 2020 Share Posted March 16, 2020 @Dave A Not sure if it's OEM since we bought the KPT-904's used, but the pic I posted above has a sticker on it marked KPT-904M-B. The pic below (which we have 6 of) is just marked KPT-904M. I am currently building 3 new crossovers based on the one pic above (KPT-904M-B) and off the scematic. I ran REW on both crossovers and found the M-B "THAT I HAVE" is 9db hotter than the M "THAT I HAVE". But what confuses me is that on the schematic, there is no resistor, autotransformer or polyswitch. I prefer the M over the M-B crossover but because the graph is smoother, but my brother-in-law wants his 9db hotter on the HF since he might put a screen in front of the horns. Quote Link to comment Share on other sites More sharing options...
glens Posted March 16, 2020 Share Posted March 16, 2020 7 hours ago, Alexander said: Just curios. How would we determent (calculate) the resistor/polyswitch values one would use to add to an existing tweeter circuit? Say you were to be building an a or aa xo using a k77 from scratch? But I would rather know how to calculate the values rather than be given them for the above example. I don't think it's rocket science. Size the polyswitch to your needs, and the resistor is there to maintain a circuit (when the switch opens) after the crossover elements solely for the safety of the amplifier (assuming the driver hasn't blown). Quote Link to comment Share on other sites More sharing options...
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