They are new 3 way speakers, NHT Classic 3. At first listen, they had plenty of details in high; after 5 days "break-in" period, details in top high is obviously not there (not recessed, not tamed down, they are not there). There were power outage during "break-in" period. I am afraid that sudden power spike could have produced sound spike destroying the tweeter. If they are two way speakers, it's easy to tell. They are three way, so they still have high even tweeter broke, but just no top high.
These are new speakers, new sound to my ears, thus why I have hard time to tell. I guess only way to test is to run test sound files, anyone has them?

http://www.hydrogenaudio.org/forums/index....showtopic=23120

SigJenny is a FREE audio generator program. But, be very careful! You can easily burn-out a tweeter with a signal generator (if it's not blown already). It only takes a few watts to burn-up a tweeter, and you might not hear anything because the test-tone can be above the tweeter's range, or above your hearing range.

I also found a sample of Pink Noise. This is safer than pure test tones. I assume you can find some white noise (more high-frequency content) at the same web site.

Another option is a Test CD.

If the speaker grill is removable, you can just play some music and put your hand over the tweeter. You should hear a difference if the tweeter is working. You can try the same experiment with pink or white noise (Or, with interstation FM hiss, if you can turn-off the interstation muting on your FM receiver.)

If you suspect that only one speaker has a blown tweeter, you can play pink or white nose and compare the two channels.


I would not expect a short-duration spike to blow-out a tweeter. It usually takes sustained high-frequency high-power to do damage. A power-spike is more likely to damage the electronics than the speaker. But, there could have been something else in in your "burn in" protocol that damaged it.

Thank you very much. I think "Pink Noise" will do, I wish they label file by frequency - need to dig deep for that.
I did have a test CD, but where is it??
My "break-in" is nothing special, turn on the tv while I was out - no fancy earth shaking thing, just plain good old tv sound.

A TV audio signal can contain a significant amount of the horizontal frequency, which is 15.734 kHz for NTSC and 15.625 kHz for PAL

Put a cardboard tube (the big ones for kitchen paper tissues, not the short ones for toilet paper) at your ear and point it to the tweeter you want to check. If you hear the high frequencies then the tweeter's still alive, if there's only the low and mid frequencies from the other drivers then you have to buy (a) new tweeter(s).

When using the paperboard tube this way it works like a lowpass filter, so you don't really need special test sounds. In case the tweeters are not completely dead, but you have a hunch that they may still be damaged, you can combine the hearing tube and a high frequency test file for a better test experience.

Of course, any material will do, but those paper tubes are available in every household. For convenience just make sure it's not too short.