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Post by micmacmo on Nov 25, 2013 17:56:27 GMT
Here's a shot in the dark. My friend was having problems with one of his Paradigm speakers. Being the devil-may-care guy that he is, he pulled the crossover out of the enclosure and hooked the cones directly to the amp. So now the speaker produces sound, just not good sound. Being the have-soldering-iron-will-try-to-fix-anything kind of guy that I am, I thought I'd investigate repairing the crossover. Is the challenge as simply replacing the two capacitors? If so, any suggestions on where to source such beasts? What is the white ceramic(?) bar at the bottom of the photo and does it bear replacing? Thanks in advance.
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solderdude
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Post by solderdude on Nov 25, 2013 19:07:07 GMT
Connecting the woofer without a XO filter is no problem. The tweeter is another story and may burn out pretty quickly as the voicecoil can only handle a few Watt at most. The white ceramic bar at the bottom is a 11W / 22 Ohm resistor The tweeter was probably connected on the red wire (+ = phase) and black wire (- = common) it is a 12dB/octave filter with no compensation network (may not be needed) The woofer is connected with the yellow wire (+ = phase) and black wire (- = common) The - connections are probably connected on the drive units. The woofer filter = 6dB/octave and the resistor + 12uF capacitor is a compensation network to counter the rising impedance of the woofer voicecoil. Even if that resistor was defective there would still be sound. None of the parts appear to be defective at first glance. I think there is a bad contact on the speaker terminals. For the woofer filter to become defective the inductor would have to be fried which does not seem to be the case. For the tweeter the 6uF capacitor would need to be defective and that would show (it would have been blown) I think there is nothing wrong with the filter. Measure in Ohm setting over both inductors... they should measure close to 0 Ohm. Measure the resistance between the LS terminals and the parts connected to it. Should you want to 'upgrade' the filter with a better capacitor for the tweeter you can replace it with a 5.6uF film-type capacitor or this one: www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-6-mfd/The 12uF capacitor in the woofer is not in the audiopath, should you want to upgrade it anyway use a 10uF filmtype or 2x 5.6uF in parallel or this one: www.madisoundspeakerstore.com/xxp-poly-cap-250vdc/bennic-poly-12-mfd/. original: www.madisoundspeakerstore.com/electrolytic-cap-100vdc/bennic-12-mfd-electrolytic-caps/These caps are expensive and IF you go and replace them you should do so for BOTH speakers. You can buy these parts from specialised on-line DIY speaker websites or the usual electronics part stores.
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Post by micmacmo on Nov 25, 2013 21:40:29 GMT
Thanks for the reply, Frans. I check all the various electrical paths. If an inductor was part of the path, the resistance was around 0.7 ohm. If the resistor was part of the path, the resistance was just over 22 ohm. And if a capacitor was part of the path, the resistance measured OL. So there's nothing obviously wrong with those measurements, is there? The jacks into and out of the crossover both were fine. Is there a way to test the capacitors?
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solderdude
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Post by solderdude on Nov 25, 2013 22:19:57 GMT
The best test would be to connect everything again (and hope he did not fry the tweeter with his experiment)
a way to test if they do act as capacitors is by connecting a meter in Ohm setting and watch if the meter reacts shortly and then shows open circuit and then reverse the test wires. The meter should register an short 'voltage' go through '0' Ohm and quickly to open circuit again.
As the capacitors are effectively in parallel now you would have to unsolder one of them if you want to test them individually.
I am quite certain they are O.K. though.
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Post by micmacmo on Nov 26, 2013 0:27:49 GMT
I'll make a point of talking to him about that tweeter! (I checked in the local online classifieds and see that he can get a replacement pair of used Paradigm 7SE for $150, so all is not lost.)
Thanks, Frans.
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solderdude
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Post by solderdude on Nov 26, 2013 6:09:37 GMT
If he did not play the speakers very loud and he can still hear sound coming from it his tweeter might still be O.K.
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Post by cornelis on May 24, 2023 15:38:04 GMT
I have a similar problem with a mission 717 crossover, the core looks as it is melted, can I fix that
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solderdude
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Post by solderdude on May 25, 2023 12:37:19 GMT
Can you post a picture ?
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