From: joej1959@gmail.com   
      
   On Friday, October 7, 2022 at 7:27:45 AM UTC-7, legg wrote:   
   > On Sun, 25 Sep 2022 19:40:36 -0700, Jeff Liebermann     
   > wrote:   
   > >On Sun, 25 Sep 2022 11:23:10 -0700 (PDT), Joe Jaramillo    
   > > wrote:    
   > >    
   > >>I have the same problem on a C 430. I’ll be playing either quiet or loud   
   and then a hear A rumbling noise that kind of trails off for a bit and then   
   comes back. Did you ever find out what the root cause was?    
   > >    
   > >There's an important clue in the text:    
   > >"It goes away when you plug headphones"    
   > >    
   > >My guess(tm) is it's some form of microphonics. That's where the    
   > >speakers cause some electribuc component to vibrate, which then causes    
   > >audible noises in the speakers. If the gain and phase of the    
   > >amplifier is correct, it will produce low frequency feedback, which is    
   > >the rumbling noise you hear. If the noise was a high pitched squeal,    
   > >then it would be high frequency feedback.    
   > >    
   > >In your case, you have a "C 430". That might be a Yamaha NX-C430    
   > >speaker system. The system does not have any built in amplifier(s),    
   > >so there's nothing wrong with the speakers. I suggest you remove your    
   > >speakers from the amplifier or receiver case, and the microphonics    
   > >will likely be reduced or stop.   
   > You might check boards for degrading adhesive employed in tack-on or    
   > harness security, in this case - after the volume control section.    
   >    
   > RL   
   > >    
   > >Incidentally, you're only 19 years too late to catch the original    
   > >posters.    
   > >    
   > >>On Wednesday, March 12, 2003 at 9:56:01 AM UTC-8, Michael and Janet Inman   
   wrote:    
   > >>> I have a Yamaha CLP-411 Clavinova that is about five years old. It has    
   > >>> developed an occasional rumbling sound that comes from both speakers.    
   > >>> It only lasts a few seconds at a time, is unbelievable loud, very low in    
   > >>> pitch, and sounds just like wind noise on a microphone. Seems to happen   
   at    
   > >>> random times although more common when someone is playing it. Volume    
   > >>> control position has no effect on the noise volume but does sometimes   
   seem    
   > >>> to affect the timbre of the noise. It goes away when you plug headphones   
   in    
   > >>> (you don't hear it in the headphones).    
   > >>> Without the benefit of a service manual/schematic, I have tried to trace   
   the    
   > >>> analog audio signal with an oscilloscope to at least determine from   
   which    
   > >>> stage the noise is coming. I'm suspecting it's originating in the power   
   amp    
   > >>> section - the amps are IC "bricks", one for each channel but since it's   
   in    
   > >>> both speakers equally I'm thinking it's not them. Due to the sheer   
   volume    
   > >>> of the noise it actually loads the power supply to a point where signals   
   at    
   > >>> all stages are affected. I did change the filter cap in the dc supply.   
   No    
   > >>> improvement.    
   > >>> I did read some newsgroup accounts of noise in the Clavinovas being due   
   to    
   > >>> dirty contacts in the volume control... I'm picking up some contact   
   cleaner    
   > >>> today and will try that but I'm not too optimistic about it.    
   > >>> Any experience with this problem or guidance much appreciated.    
   > >>> Mike   
      
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