From: joej1959@gmail.com   
      
   On Sunday, September 25, 2022 at 11:23:12 AM UTC-7, 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?   
   > 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   
   Incidentally it also happens with headphones so I’m a bit flummoxed.  Oh and   
   btw I have a CLP-440.  Next stop Yamaha…   
      
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