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Yamaha NS-C444 troubleshooting

N

norwid

New Member
Hi,
I just bought a Yamaha NS-C444 off Marketplace for very little money because the previous owner said that the tweeter was blown. He said that dialogues when watching movies got quieter and quieter with time until he replaced the speaker.
After taking it home and trying it, the tweeter is working. I did a sweep test from 20 to 20kH and I can see a clear drop in loudness (in the curve) when I reach about 2500hz. When using the speaker to watch TV or a movie, the dialogues feel really muffled.
I opened the speaker to have a peak inside but everything seems good visually. Unfortunately, this is kind of where my knowledge stops. My very limited knowledge would say there is something wrong in the crossover. Could it still be the tweeter that is faulty? What should be my next step?
Thanks!
 

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It is possible that the capacitors in the crossover have drifted in value, or are simply bad. I'd replace them - you can either use new electrolytics, which will probably produce the sound intended by the designers and will be cheap, or you can use film caps, which will almost certainly give a bit brighter sound, which you may like or not, and which can cost either somewhat more than electrolytics, or astonishingly more, depending on what you get - there are always people on the internet who tell you the capacitor that costs vastly more than the entire speaker sold for originally is absolutely worth it. Ignore them.
 
Thank you for your answer. I discussed with a colleague at work, whom I didn't know was into hifi systems, and he suggested to test the resistance of the tweeter by disconnecting it from the speaker and I got an infinite value. So I guess I now know that tweeter is definitely not working.
 
But then my question is: is it possible that the woofers produce sound until 10000ish hz during the sweep test?
 
It appears from looking at the crossover than the woofer is rolled of at the crossover frequency, but it may still be audible - the coil progressively diminishes the output as the frequency goes up, but it is still there, and if the woofer has some peaks in the upper region, as many do, they might be quite audible when the greater output of the tweeter doesn't mask them.
 
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