Roadbed Construction (Homasote)

Model Railroader General Discussion (Model Railroader)
1

In the post at http://www.trains.com/TRC/CS/forums/1136666/ShowPost.aspx, the idea of dual density seemed to be the most promising option for keeping the layout quiet. Foam board seemed to be a poor choice by itself, but what about putting Homasote on top of the foam board and then cork roadbed? Would you want to add something on top of the Homasote? Would that reduce it’s effectiveness? I want to keep my layout lightweight, yet the layout I have now uses just foam and cork, and I would prefer it to be a little bit quieter.

My plan is a 1x2"benchwork, glue the two sheets of 2" foam on, cut the Homasote to track width and use caulk to attach it and the cork roadbed.

2

That’s certainly a viable option if sound is a real concern. It will add weight as the homasote is not light and it’s very messy to cut (homadust everywhere unless you have someone follow the saw with a shopvac!). Use matte medium for ballasting as it stays a little flexible and therefore will transfer less sound. Also remove all track nails/pins after ballasting so they won’t transfer through the layers.

3

Where do you get matte medium? A craft store like Hobby Lobby? Any tricks to it?

4

Matte Medium is actually an artist product. You can find it at any art supply store such as Micheals. I have found it at Jo Ann’s here in the Atlanta area.

5

Ok, being new, I have not read all the post on the forum yet, but I did read the link you posted ( and the link in that one as well ), and all of the posts, and one thing that struct me, is the fact that while some people offered observed data, no one asked the most important questions or came close to answering them althow if you look closly at the posts you will see that the observed data gives some insight to the nature of sound when it comes to trains ( prototype and model ).

When the questions and answeres are understood, then the proper steps can be taken to deal with the sound of our scale models ( if we deciede to ). Now before I get started, let me explain that while I am not a employied as a sound tech, I do audio and visual volenteer work for my church, and you can’t do that for long, without picking up a few things.

Important question #1:

What are the differances in sound between proto-typical trains and scale models.

Answer:

Other than the sound that the engines make it’s all about frequency. Proto-typical rails are more or less 60ft long ( if not welded ), and while model rails may be just as long ( in scale ), that does mean that the weight and density ( both factors in sound ) are even close it being in scale. Someone can check, for me, but I think it came out that 1 ton would scale out to 200 oz in N scale.

The bigger, heavier & denser materials used in proto-typical construction are more conductive to lower frequency sounds, while the ligher, smaller, less dense materials used in scale construction are more conductive to higher frequency sounds. IOW, our models go clicky-clakity russssh while a proto-typical goes clank-clunk rummmbbbblllle.

What this means, is that if we build out layout in a way that promotes the higher frequency sounds, it can get downright noisy if we do not pay attention to our construction methods and the materials t