Miata Mailing List: December 1996, Message #155
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   From: (none)

Subject: RE: Rattle & Hum... 

   Date: (none)



Jae has the typical problem with buzzing speaker protectors.





   Jae, there are some plastic membranes that cover the speakers to protect 

them from moisture.  Like all things, they have a ntaural frequency at which 

they vibrate most.  It's a resonance thing.  There is a small range of 

frequencies where the membrane vibrates greatly.  Mazda should have designed 

the natural frequency to be at some inaudible frequency (say, 50 KHz) but 

they didn't.  I can't see how Mazda's Noise, Vibration, & Harshness people 

let the buzz get past them.  We're talking about a little bit of plastic.  

Not some expensive drivetrain component.

   Until recently, I had a '90 Miata and the buzz was on my short list of 

things to fix.  I was going to find my Vibrations textbook and see if adding 

mass to the membrane would shift the natural frequency out of the audible 

range.  If adding mass helps, I would put some glue on the membrane.  Heavy 

stuff like silicone.  Not much would needed.  The weather protection is 

maintained and the buzz would be gone.





But then, what about harmonics?  Ack!  Where's that textbook!



Mike Lowe (mikelowe@phoenix.net)

Houston Region SCCA -- Texas A&M SCC -- Miata Club of America

White '96 Miata R   CS 93

Homepage:  http://www.phoenix.net/~mikelowe





p.s.  My '96 Miata's speakers produce so little bass I don't have the buzz 

at all.  The speakers suck and they blow but they sure don't buzz.  I'm 

calling Clearwater soon.