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Drum effect with Extruded foam base?

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  • Member since
    February 2007
  • From: Seattle, WA
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Drum effect with Extruded foam base?
Posted by Frisco-kid on Monday, December 6, 2021 10:48 AM

I plan to use extruded form sheet as my layout base; over open grid benchwork with cork roadbed. I used this method before, but some have mentioned the dreaded "drum-effect." I honestly never noticed it on my previous layout.

Is it something I should consider, and if so - how to ameliorate it?

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Posted by jmbraddock on Monday, December 6, 2021 12:58 PM

If you build your frame and cover it with 1/2" plywood befor the foam, you shouldn't have a drumming problem. The 1/2" plywood is thick enough that it absorbs instead of resonating any sound vibrations.

Joe

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Posted by Lakeshore Sub on Monday, December 6, 2021 3:07 PM

Frisco-kid

but some have mentioned the dreaded "drum-effect." I honestly never noticed it on my previous layout.


The second level of my layout is exclusively 2" foam attached to wooden cross members supported by various types of shelf brackets and secured with latex caulk.   I've never experienced "drumming" but my layout is a secondary main line with only 1 or 2 trains running at any given time, at relatively slow speeds. 

I would suspect if I has running multiple highspeed mainlines, withs lot of multi-unit consists, there would be substanitally more noise.  

It really may depend on what you plan on running.

Scott Sonntag

 

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Posted by selector on Monday, December 6, 2021 3:30 PM

Dual densities has a marked effect on vibration dampening.  Yes, your peripherally supported foam will act as a soundboard.  But, support it below with two thin 1X2 joists, and glue the foamboard to the tops of those joists with a thin layer of cheap acrylic caulking, and you'll find it quite a bit less noisy.  Maybe not half as much, but close to.

One other very critical problem: hardened ballast making glued contact with pretty much any supporting medium will be noisy.  So, going back to dual density, we use homasote, cork underlay, foam roadbed, even plywood or strips of drywall (you wouldn't believe how quiet drywall is).  But, if your glued ballast spills over that roadbed and makes hardened contact with the base...see above.

All this to say that if you isolate the hardened ballast and trackage from the main base, no matter what that base is, it will be quite quiet.  If you have a bridge over a river or chasm, note how quiet the trains are over that bridge.  Amazing.

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Posted by BATMAN on Monday, December 6, 2021 3:59 PM

I have found that what is on the floor beneath the layout is more important. I had the same 5' x 10' layout set up over a hardwood floor, porcelain floor, and carpet. There was a noticeable difference between the three.

Brent

"All of the world's problems are the result of the difference between how we think and how the world works."

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Posted by rrebell on Monday, December 6, 2021 5:19 PM

All out methods produce a drum effect, if it really bothers you you can seal the bottom with plastic but the effect has never bothered me.

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Posted by ndbprr on Tuesday, December 7, 2021 7:03 AM

I have wanted to try this for awhile.vinyl flooring uses an 1/4" foam underlayment thst comes in a roll. Thought I might cut that in strips and use it directly under the track after spraying it grey. 

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Posted by rrebell on Tuesday, December 7, 2021 10:08 AM

ndbprr

I have wanted to try this for awhile.vinyl flooring uses an 1/4" foam underlayment thst comes in a roll. Thought I might cut that in strips and use it directly under the track after spraying it grey. 

 

P:eople use cork for a reason, you can sand it smooth and carve in transitions, can't do that with the WS stuff.

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Posted by NVSRR on Tuesday, December 7, 2021 10:16 AM

ndbprr

I have wanted to try this for awhile.vinyl flooring uses an 1/4" foam underlayment thst comes in a roll. Thought I might cut that in strips and use it directly under the track after spraying it grey. 

 

 

after reading an article about it in MR some 11 or 12 years ago, I decided to try it.   Dead quiet even over foam and per strip cheaper than cork.  

shane

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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Posted by Pruitt on Tuesday, December 7, 2021 10:29 AM

I've never noticed any particular sound problems with foam...

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Posted by Doughless on Tuesday, December 7, 2021 10:29 AM

Drumming is caused by the trains vibrating the subroadbed, which is caused by a lack of mass or density.

If you made your subroadbed out of 2 inches of concrete instead of 2 inches of foam, there would be no drumming.

What ever you use, secure it well so it eliminates the little vibrations the best you can.

- Douglas

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Posted by rrebell on Tuesday, December 7, 2021 3:10 PM

How about sound deading foam shoved up inside the box, less than 50cents a sq ft.

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Posted by Nevin Wilson on Tuesday, December 7, 2021 4:29 PM

I've used WS foam roadbed over pink foam that was glued to a wood ladder-type framework.  I've seen no increase in noise at all. 

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Posted by IDRick on Wednesday, December 8, 2021 8:45 AM

BATMAN

I have found that what is on the floor beneath the layout is more important. I had the same 5' x 10' layout set up over a hardwood floor, porcelain floor, and carpet. There was a noticeable difference between the three.

 

Interesting observation, so how did the three flooring options rank from best to worst?  My guess is carpet is best and ceramic was worst...  Close?

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