Loudspeakers - Speakers emitting high frequency....

[Thefoxygranpa]

Thank you all for all the replies!

Yesterday I had a guy who I bought this system from come down and take a look. This was his third time coming to my theatre, yet he said he could never hear the sound I was describing.

This time however he actually got up on the ladder and took a closer listen, and alas he heard my noise! The reason he didn't hear before is because it was upwards of 17kHz and his quick listen in my room didn't catch the noise. We tried a power conditioner until we finally ruled out that it was a power issue.

Now as for why they didn't catch that while it was in the shop....well I can guess that those techs have lost hearing at that range . My dealer personally called the shop and told them it was a bad amp, and they should put a frequency measure..er[whats the term for this?!] up to the speaker.

Well, thanks all for the replies....hopefully I'll have a working speaker before the end of the month

[maxkelley]

I think that'd be an RTA.

Yeah, high-pitched noises are fun. I know my home stereo receiver emits a buzz when the input stage is muted (switching sources, mute mode, etc) for the first 10 minutes or so as the amp warms up, then it's fine. Sounds like something similar to what you have going on, but inverted so that it doesn't happen until it's warmed up.

Good luck on successful repairs.

[Chris15]

I actually would think you would be talking about a spectrum analyser...

Most techs worth their salt would soak test a product for a good 24 hours before returning it to pick up things that get unhappy under extended use...

[SHARYNF]

The problem with this is that the likely hood of a repair shop setting up a microphone with a spectrum analizer and recording the output for 24 hours is pretty remote. As I mentioned above there is a SLIGHT possiblity that the power system at the shop vs in the venue could be different, one derived from a 3 phase system, the other from a standard split phase system, and a system component (likely to be power filter capacitor) in the one speaker is starting to go. So IMO it certainly is possible that the shop just turned it on waited a few minutes and then reported no problem found, it is also possible that the different environment could have triggered the problem in a failing component.

Sharyn

[museav]

I'd put my money on the busy shop that didn't test it long enough to trigger what seems to likely be a thermal problem. Or the ambient noise levels in the shop are so high that they couldn't hear it.

[Thefoxygranpa]

According to my invoice they had the speaker on for two days continuous and played music through it for that time....

I'm guessing what museav said.....the noise at the shop was higher than what this speaker was making.

Thanks again!

[SHARYNF]

As I mentioned before, before shipping it back, take it home, plug it in and see if you can duplicate the problem, if you can, then the resolution is easy, if you cannot, then it might be more difficult for the shop to determine the problem (they might just replace the caps anyway which might fix the problem)

Chances are it is the speaker but there is still a chance that there is an "environment" factor in the equation that you might want to still check for.
Sharyn