Help Somethigns terribly wrong with my Nats!

[Raptor550]

OK, I probly did something super stupid yes, but keep the teaseing down - at least untill I fix the problem.

The Nats started to sound super scratchy, at first I thoguht it was my amp, or my computors sound card but no. I pulled out the Denon CD changer, same problem. Hooked up a second decent AMP, again same thing.

It sounds like a blown speaker. :E

I ran some test tones and it appears like the Woofers are crossing over and the tweeter is NOT! I played a few high notes (1-5khz) with a pillow over the tweeter, and a few low notes (70-900hz) with a toilet paper roll from the tweeter to my ear and my other ear plugged. Scientific? I know. But I do not know what would cause this, if some bare wire was touching I could see both getting full feed, but just the tweeter?
1. did I blow both my tweeters? Or are they just putting out low end garbage? 2. Is there a part of the circut that could be crossed that wouldent affect the woofers?
3. If the Nats are proporly wired, how loud do you have to play them to blow a tweeter? I would assume louder than my amp can put out but I dont know.

I still am new at speaker building and so maybe I cant hear what 6 & 10 db dow is with the tweeter. I changed rooms maybe I am hearing a ground loop or something crappy and stupid but I think that a low chance.

[Brian Walter]

I think you need to do some more testing. If you think the tweeter might be blown, why did you play high notes with the tweeter covered by a pillow? I would suggest playing the high notes with the woofer covered and tell us how the tweeter sounds then. That would be a better test of the tweeter than playing low notes through the tweeter with a toilet paper tube to your ear.

I would also like to point out that its easier to blow a tweeter with not enough amp power than with too much. Obviously if you crank them both up all the way, the more powerfull amp will certainly blow the tweeter easier, but in normal use, the smaller amp is more likely to clip and clipping is a leading cause of tweeter damage. My understanding is that when an amplifier starts to clip, you get full peak power delivered to the tweeter which could easily be way more than they were designed to handle. There is or at least was a good article about this on the RANE website. You might want to Google it and check it out.

But in conclusion, you really need to do a little more testing so we have more information to help you out. Even with your testing you did do, you really only told what you did, not what you actually heard when you tested.

Brian Walter

[Rolex]

Pull the tweeter out of the cabinet to do some testing on it. Or try disconnecting the midbass drivers and focusing on just the tweeter.

It is extremely unlikely that you would ever fry a tweeter with too much power. It's a amplifier that starts to clip and causes distortion that will blow your tweeter.

[Raptor550]

Well I covered the tweeter first because I thought it might have been the woofers createing the sound.

I was playing with an amp I just got (not my main) so im not oo familiar with it, it might have been doing clippng. Its an old pioneer sa-7500, I only ever turned it up halfway (which was plenty loud). Its rates @ 60 watts RMS per channel. My regular amp is a vintage kenwood ka-7100. I thoguht it would have to be turned up closer to its max before I had to worry about clipping.

As for the sound? I'll try to describe it. It kinda sounds like distortion or something muddled and slightly scratchy 300k-900k similar to the stuff the rs180 puts out at 2.5k+, but I dont think the woofers are responcible. I'm going to do some more testing aftr work its going to be hard to pry the tweeters and woofers out, they are a very snug fit and they are welded directly to the wire because I thought they were finished. *grumbless*

Would bad house wireing put a spike or surge into my speakers and cause this? The house is pretty old, and when the air conditioner turns on the lights dim more than a little, and its shut off my computor a few times. Im just throughing things out their.

[ThomasW]

I only ever turned it up halfway (which was plenty loud).

Given the 'taper' on most volume controls, the 12:00 position = full output

[---k---]

Are the crossovers still mounted on cardboard??? I'm guessing something came loose and a broken connection.