Tweeter distortion on NS10

Just bought a pair of NS10M Studio monitors in cosmetically perfect condition. As soon as I got them I tried a 1Khz sine into both speakers to check if they were working correctly and found out that in one of them the twitter starts distorting at very low levels. By distorting I mean that the sine pretty much turns into a square wave.

Is the twitter blown? Can it be something else? I always thought that a blown twitter was a completely dead twitter, not half dead.
Is this repairable? I dont have a problem going DIY with it. I really dont want to have to deal with the seller  :'(


Any ideas? Thanks!

Maybe a crossover issue???

edit...... I would double check by swapping speaker cables etc before asking the seller to make it right...... Which they should by covering the cost of whatever..... Those tweeters are definitely capable of taking a poo....I think I still have some blown ones in my attic from years ago just because...maybe the technology will come around for me to repair them.....
Then I'd only need some other NS-10s to go with them..... :-[

But don't touch a screw until you get something from the seller.....I know the Bay is very clear about this and will not be able to help at all if you mess with anything...... And if it isn't the Bay, then IDK....

Good Luck!

tomas1808 said:

Just bought a pair of NS10M Studio monitors in cosmetically perfect condition. As soon as I got them I tried a 1Khz sine into both speakers to check if they were working correctly and found out that in one of them the twitter starts distorting at very low levels. By distorting I mean that the sine pretty much turns into a square wave.

Is the twitter blown? Can it be something else? I always thought that a blown twitter was a completely dead twitter, not half dead.
Is this repairable? I dont have a problem going DIY with it. I really dont want to have to deal with the seller  :'(


Any ideas? Thanks!

Click to expand...

1 kHz is an octave below the crossover frequency of 2 kHz.  In a 12 dB per octave crossover it will be down 12 dB.

Some things to try

- Is the tweeter tight in the speaker box (air leaks can sound like distortion, also bolt rattles).
- Try swapping the tweeter from the known good speaker to the bad one, this will rule out crossover issues.
- Move the tweeter from the bad speaker to the good one, this will confirm a bad driver.
- Check that there is no debris stuck to the tweeter diaphragm (I've seen this cause buzzing).

Thanks for the ideas. I did swap channels and unfortunately the problem follows the speaker. 

Cant see any debris on the diaphragm.

Interesting, didn't know the crossover was at 2Khz. Maybe it's the woofer? I'll try doing a sweep with my wave generator to see how it responds.

This thread gives me a bit of hope: https://groupdiy.com/index.php?topic=47986.0

I will talk with the seller before doing anything invasive though.

Thanks!

Edit: Here is a spectrograph showing the extra harmonics. It was recorded with a phone hence all the artifacts (aliasing) and noise. You cant see the scale but the harmonics start right at 2Khz, as expected. 

NS10s were notorious for blowing tweeters IIRC.

I just checked and the cost for replacement tweeters is crazy...

Perhaps that's why they were sold  (as is I assume).

JR