Noisy after ballasting

[flatlander]

I just finished ballasting track on my 4X8 Display layout. The HO scale track is laid on Cork which is on plywood. After ballasting and gluing, it got very loud when I run Locomotives. Especially Athearn Blue boxes.
Can I insulate under the plywood to quiet it down or what? I put it in my office when we are not at a train show and now its too loud to operate.
I will post a picture of it too.

 

[Armchair]

Noise

Several Questions. What thickness plywood, how supported underneath, does the plywood vibrate? Since some locos are louder it may be resonance between train and plywood. You might try gluing blocks of 3/4" wood or additional supports or even drywall underneath to reduce the resonance. Armchair

 

[diburning]

How is the track secured to the wood? Nails, tacks, etc makes for a more rigid mount and transfers vibrations. If you glued the track down with liquid nails or something, it provides some vibration reduction so that it doesn't vibrate everything under it.

 

[kenw]

the problem is the ballast that is glued down and you've created a very nice sound conductor thru the ballast to the plywood. It's common and unless you are willing to pull it all up, it's best just to live with it. You've 'acoustically' bypassed the cork roadbed in this situation. I know, mine does the same thing.

The corrective action is to lay a cork mat under the cork roadbed to prevent the ballast from transferring the sound to the plywood. But even that isn't 100%. The plywood acts as a nice sounding board and amplifies a lot of the sound that reaches it. Once you cover the topside of the plywood with scenery it will decrease the sound somewhat.

 

[Outback]

With regard to the problem and the above post...

I have the same problem after ballasting and I have a layer of buffalo board (similar material to ceiling tile but in 4x8 sheets) between the cork roadbed (cork as in the type used for bulletin boards and not prefab cork roadbed) and the plywood that acts as my ground base. Trackwork seemed quiet before ballasting. Benchwork is supported by 2x2 on long sides and open on ends - no cross bracing as width is max 16 inches, buffalo base is glued to plywood, cork roadbed is siliconed to base, track spiked to hold contours then ballasted w/ white glue mixture. Spikes could be removed but havent tried that yet. I agree in that I think the noise amplification has something to do with the hardening of the glue mixture.... how on earth can one avoid that and still have solidly ballasted track? Seems like we are at an impasse.

D