Vibrating/rattling QSC

[george_wright]

I have a QSC RMX2450. It's all alone in a Gator two-space rack, with rear rack-ears installed. The amp rack sits on top of an Acme B4 and under a Gator six-space rack with other electronic toys in it.
 
Any notes on the B or E string at any appreciable volume cause the face plate of the QSC to vibrate loudly. I can eliminate the rattle by pressing on the face-plate between the on/off switch and the fan exhaust grille.
 
I've ruled out vibrating latches---it's the amp faceplate.
 
A layer of bubble-wrap between the amp rack and the cab raises the volume level necessary to cause the vibration, but this isn't a practical fix. The vibration still occurs at anything above bedroom practice volume.
 
So.... Two questions.
 
First, is this common with QSC RMX's, or do I have a lemon?
 
Second, are PLX and PLX2 models (which, as far as I can tell from pictures, have a much beefier face plate) less likely to vibrate in the face plate?
 
(Cross-posted to talkbass.)  TIA

[jacko]

George.
My PLX faceplate doesn't rattle but, when I first got it there was a rattle from inside. I eventually traced it to the fittings that held the circuit board in place - it was as if the board was made from a slightly thinner material if you get what I mean. I've 'fixed' this by putting blobs of epoxy on the board/fitting which has removed all rattles.
 
Graeme

[george_wright]

Thanks, Graeme.  I'll unmount the amp from the rack over the weekend and check it out.

[David Houck]

At one point I had a rattle with my PLX.  However, I no longer put my amp on top of my speaker cabs, and thus no longer have a rattle.