Ultrasonic Oscillation

Italian, It sounds to me like your amplifier has too little power and you are pushing it too hard. That is why tweeters fail! Its not because of a malfunction.

So you either need a more powerful amplifier or more efficient speakers.

Hi Atmasphere, thank you for your response. I appreciate it very much. And a consideration that I had not considered. I have used my GMA Europas(4 ohm/88db/7-120W @ 8 ohm amp)for years with both an Odyssey Stratos amp at 150W @ 8 ohm and a Denon POA 1500 at 150W @ 4 ohm. I don't play my sytem at loud volumes. The GMA's are known as an easy load and are known to be driven with low power amps from what I have read here over the years. That really is what is vexing, until this year system played fine. Even the Snell's that are a more difficult load are pushed by tube systems of a lesser power then the amps above from what I have read also. This weekend I'll be taking the system to my daughter's house to see if the problem persists there no matter how dumb that may sound. No stone unturned. Again, thanks much. Dave

One other thing to look at is corrosion on the ground contacts of your RCA connectors. That can toast tweeters too.

Not sure why I read this old thread but I did. A very interesting read, and now I'm curious as to how the situation resolved. ???

Yeah, we ought to have an unsolved mysteries category, it would be interested to see what the outcome turned out to be. I liked the one with the system hum that baffled the OP for quite a while and was finally traced/linked to the dc cabinet lights in the kitchen being on.