PoppaDom Posted March 5, 2009 Posted March 5, 2009 I have a Yamaha P4500 amplifier that has a wee problem. When audio passes through it, the amplifier appears to sing in time with the LF content which is leading me to think it might be to do with current passing through the output stages? I haven't opened it up yes but it does it on both channels; Audio seems to pass completely normally and without problem. Thought I would see if anyone has any ideas / that must be's before I open her up.... Dom
noiseman Posted March 5, 2009 Posted March 5, 2009 I have a Crown macrotech that does the same thing.If it's not causing a problem don't worry about it.
PoppaDom Posted March 5, 2009 Author Posted March 5, 2009 The problem I have is that the amplifier is used in a rehearsal rack and can be heard in the room... Anyone else with any ideas? Dom
KevinE Posted March 5, 2009 Posted March 5, 2009 Get a different amp! Many amps produce their own music.
PoppaDom Posted March 5, 2009 Author Posted March 5, 2009 So in a rack with 4 others one starts the sing and the best advice the forum can give is get another.... No-one have any idea what causes this? Dom
revbobuk Posted March 5, 2009 Posted March 5, 2009 I'm a little out of touch with amp design, and there are others who are much more likely to know, but a couple of places to check would be: The tightness of the bolt running through the toroid - magnetostriction is one way of transforming current to sound. The old response to the question 'How tight should I do up the transformer bolts?' - 'Tighten them up till they break, then slacken them off half a turn' If LF signals are loading the PSU to any extent, they just might be affecting fan speeds, and causing some singing noises there. Clean the fans, try running without the fans for a few minutes (no more) and see if the singing stops. Check that any physical damping (gluey stuff) restraining components on the boards is still in place. Just a few suggestions. And a general purpose clean and de-fluff.
RustyBrooks Posted March 7, 2009 Posted March 7, 2009 Have you tried kicking it? Used to work with some battered c-audio amps that did it from time to time, and some poor over abused yammy amps that also got very hot...
fatfrog Posted March 7, 2009 Posted March 7, 2009 I had a similar occurrence to this a few years back with a yamaha p3500s. It turned out that there was a small short in one of the cables to the speakers. Once corrected the singing went away. To be honest I have to say the singing was quite disturbing at first, I really didn't think that this could happen. Alan
KevinE Posted March 7, 2009 Posted March 7, 2009 best advice the forum can give is get another Yes. If the amps and speakers are all working ok, its probably magnetostriction in one of the transformers or on the output heatsinks..ie the current through some component is making it act like a tiny loudspeaker. It's not a fault, many amps do this and I spend alot of time in amp rooms in nightclubs and bars for a living. It happens especially when they're pushed very hard and the rack is positioned so that the singing isn't masked by the main PA.
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