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I have a Mackie SRM450 that's making a loud but short distorted, noise when turned on. After about a split second, the noise goes away and operates normally. I'm afraid this could eventually damage the speaker. Any hints on what the cause is?
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A bit more info would be useful to narrow down the problem.
Is this the old SRM450, or the newer (V2) version with the switching PSU and class D amp?
Does the noise come from the woofer, the horn, or both?
Is the problem present also without any input or volume control turned down?
What does the noise sound like? Is it a burst of distorted hum/rattle, a chirp/wail, or hiss? -
The noise is everything you described on both the horn and woofer. But it's short burst. It doesn't matter whether the volume is turned up or down. Still does the same. This is the old version SRM450. I probed the speaker output with my vom and seen a quick dc voltage spike. I've read somewhere that it could be one of the large filter caps going bad.Comment
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Interesting. Try to record a sample and polish it up a bit, you might make some money selling it to the techno/dance sceneThe noise is everything you described on both the horn and woofer.
Anyway, we now know that the power amps themselves are not the problem. The SRM450 does not have speaker protection/mute relays, so everything that happens on turn on / turn off will be sent to the speakers. This also means that the designers at Mackie are confident enough that their circuitry doesn't misbehave too badly when powered on / off. But if the power supply develops a problem, you'll most likely notice.
A loose solder joint, as Mr. Jazz P. Bass pointed out, is not unlikely - or a broken terminal.one of the large filter caps going badComment
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I replaced the caps and it seems to do the same thing. I made sure all the solder connections were intact. Could it be something else?Comment
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