2. amps-preamps
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Cabinet resonance problem with Marantz MM9340 amplifier

The MM9340 amp is a four channel Class D amplifier producing 275W into 8 Ohms and 400W into 4 Ohms. I am using it to drive four subwoofers, which it can drive with ease. The problem is, the cabinet resonates seriously and appears to be in beat with the music. It does not appear to be airborne related nor is it originating from the stand. The resonance appears to generate from within the amp itself. Has anyone experienced a similar problem such as this? Any suggested solutions?

128x128spatialking
fiesta75
1,378 posts
 

Contact Marantz and have them fix it for free. This is unacceptable.

erik_squires
16,331 posts
 

It is quite possible the amps are generating an intense magnetic field.

Can you feel it on the cabinet?

spatialking's avatar
spatialking OP
610 posts
 

@fiesta75 - Well, I can call them, but it is out of warranty, so it would be at my expense.  At 80 lbs, freight & insurance won't be cheap.  The thing is, I am sure they will say "It meets specs, nothing wrong with it".  There is nothing in the specifications that the cabinet is resonance free.  And, it does work perfectly, other than vibrating.

@erik_squires - I can definitely feel it, the cabinet vibrates like crazy.  It is a steel chassis, so internal magnetics can be the cause.   That was my thinking about using a thick plexiglass cover.   

fiesta75
1,378 posts
 

I've used spray on 3M rubberized undercoat, P/N 03584 on the inside of a CD player cover with success. Good luck.

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