Hi All, I'm trying to troubleshoot a set of 4 Mackie SRM350 speakers that have been installed in a dance studio. They were mounted high up near the ceiling and were left on permanently. After a couple of years they have started making a loud high pitched whistling noise all the time. When they were taken down for repair and switched on to test (after being off for several days) they sounded fine - clean clear audio - but after being on for about 20 minutes a static noise / fizzing / high pitched tone starts which slowly increases in frequency over several minutes until it settles to the high pitched whistling noise. The noise will increase in level as the input gain is turned up, but does not disappear with the input gain all the way off. The speakers still reproduce music as before but the noise over the top makes it unlistenable.
Has anyone come across this or similar before? It appears to be a heat related issue - if the speakers are switched off and restarted soon after, the noise is back straight away, but if left a while the noise takes time to appear - and it's the same for all 4 speakers, which have had identical usage from new - they have always been used together in the same installation. Any ideas where to look first would be most welcome.
Has anyone come across this or similar before? It appears to be a heat related issue - if the speakers are switched off and restarted soon after, the noise is back straight away, but if left a while the noise takes time to appear - and it's the same for all 4 speakers, which have had identical usage from new - they have always been used together in the same installation. Any ideas where to look first would be most welcome.