against numerous suggestions here I used 1/8" luan plywood for my roadbed
with some reinforcement underneath to add structure.
It's just plain loud when trains roll over it now with ballast and scenery
what is my best option to deaden the noise.
I am considering using "great stuff" foam insulation under it - any other
Foam underneath may or may not help. Try a small area first. In some
cases certain foams will add to the noise.
Something you might also try is that stuff they stuff pillows with.
It's sometimes used in sound enclosures.
If you used nails to fasten the track try and remove them as they just
transmit the noise. The type of glue you use matters. Matte medium works
good as it's somewhat rubbery and abates noise. White glue is bad. I know
you can't change this but remember for the future.
I suspect that the only way to 'fix the noise' is to rip up the track
and put the homabed on the Luan and put the track on top of the
homabed. Putting something *under* the Luan is not going to help much.
What is happening is that the (long) *rigid* Luan plywood strips are
acting like an instrument soundboards: as mechanical audio amplifiers.
The homasote / homabed is compress paper fibers and is a 'soft'
material that does not vibrate well (too 'mushy'). The sound waves
don't travel well. Think of what happens when you drop a stone into
think mud vs. a clear deep water pond. You get a nice set of ripples in
the clear water that will go all the way to the far shore, but in the
mud, the stone just goes plop and no ripples form. The homasote is
like the mud and the Luan is like the clear deep pond. As the train
moves along the track on the Luan, the whole piece of Luan vibrates and
amplifies the train's rolling sound.
Robert Heller -- 978-544-6933
Deepwoods Software -- Download the Model Railroad System
On Wed, 10 Dec 2008 16:23:40 GMT, tex shalter wrote:
He gave you an excellent suggestion:
Putting vibration absorbent material UNDER the lauan would not help - and
in facr might even make it worse. You need something like homosote or
rigid foam (for glued down track) to keep the vibration from reaching the
sounding board of the lauan or possibly heavier plywood below.
Not quite. There are two ways of damping unwanted train noise:
(A) Keep the vibrations from reaching the soundboard in the first
(B) Damping the soundboard so it won't amplify those vibrations even
if they *do* get there. (This is the "solid-body electric guitar
In the case of (A), you want to seat the track on something like
Homasote which damps vibrations by virtue of both it's density and
it's sound-absorbing qualities. This is the classic method, and it
works pretty well.
In the case of (B), you *can* add density and sound-absorbing
materials to the underside of the soundboard, and it will help *a
lot*. (Remember that any soundboard projects just as much sound energy
from it's bottom as it does from it's top. Because of the scenery Etc.
on top of the layout, it's not at *all* unusual to hear more sound
coming from *beneath* the layout than from on top.)
The problem with adding damping materials to the bottom of the layout
is that there are generally too many wires, switch machines, etcetera
down there that get in the way; and to get effective damping you've
got to cover nearly *all* of that bottom surface...or enclose it.
Lastly, (A) and (B) are not exclusive: if you want *real* quiet you
can -and should- use something like homasote roadbed and put it atop
really rigid benchwork that resists vibrating. If you want to go
completely nuts, you can glue acoustic foam -or old-fashoined paper-
mache egg flats- to any exposed portions of the underside of the
layout. *Then* enclose the bottom portion of the layout.
You might try what I've used with some success: glue that awful
foam-rubber-stuff carpet underpad under the plywood. Probably not easy
to do with an existing layout--you'll have to figure out how to keep the
stuff against the bottom of the layout until the glue sets
(staples???)--but it does a good job deadening sound. (Obviously easier
when layout is being built. You might consider it for the next part of
Washing one's hands of the conflict between the powerful and the
powerless means to side with the powerful, not to be neutral.
Well, it's not easy to reduce sound after the fact. there are no
guaranteed methods. Essentially, you need to do three things:
1) add mass to the roadbed/track, which will reduce the loudness,
because the limited sound energy from the trains will have more mass to
move, and can't move it as much. Hence the motion imparted to the air
(sound) will be less, too.
2) mess up the harmonics, so that there are no sound frequencies that
are amplified by matching the natural frequencies of the roadbed/track.
Gluing 1x2 chunks of wood underneath the roadbed will accomplish both
these purposes. Experiment with a few pieces of different lengths,
applied at random angles, glued flat and on edge.
Also, make sure that the scenery is fastened solidly to the roadbed.
That way the mass of the scenery will be added to the roadbed, and and
its mixed up harmonics will help mess up the roadbed harmonics, too.
3) break up the sound transmission path between trains and roadbed as
much as possible. If you pinned the track down, pull all the pins. The
ballast will hold the track in place. Pulling the pins will reduce the
rigidity of the track to roadbed linkage, which also help reduce sound
transmission from the trains to the roadbed.
Foam insulation won't do as good a job. It works as sound dampener by
breaking up the sound transmission paths, so it works very well inside
hollow walls (for example.)
From my experience, carpet stapled to the underside of the train board
does SUBSTANTIALLY reduce the noise. Here was the situation: I build a
fairly large Lionel tinplate portable display layout for our club's
annual open house (to sort of "show the tinplate flag"). The first year
it was so LOUD that you could hardly talk over it. After the open house,
I had some old carpet lying around, so I stapled it to the underside of
all the layout pieces. Next year, no problem. Just a "nice" tinplate sound.
Henry Murray Consulting Service and
President, CEO, and General flunkie
of the Central Valley Terminal Railroad (HO)
Razor for human behavior: (with apologies to John of Occam)
Never attribute to malice, intention, or plan
that which can be explained by ignorance, incompetence or stupidity.
I don't see what the big deal is about the model train noise. My
friend's entire layout is built using 1/4 luan plywood on L-girders
and the noise doesn't seem to be objectionable. We don't even really
notice it. It is a fully finished layout with most of the track on
cork roadbed and mostly using extruded styrene insulation for scenery
base. Maybe the fact that it is N scale plays a role in this? I
wonder if Tex's layout is H0 (or larger) in the "plywood plains"
stage? I could see how a bare plywood layout would seem louder than
one with finished scenery. I suspect that scenery muffles the sound
quite a bit. I also suspect that Tex is not using 1/8" plywood (as he
stated) but 1/4".
I would start with a strip of plywood glued to the underside of the
road-bed in line with the tracks, going from support to support (kind of
like a bridge structure). Then I would add additional supports in as
many places as possible (random angles and positions are good ;-)
Basically the noise is amplified by (large) boards vibrating in
frequency with the train's vibrations. The stiffer your road-bed,
scenery and sub-structure get, the less free vibrating masses are left.
You will still have some noise, but much less...
I would rather add foam as a last resort to shrink the hollow spaces
beneath the layout. Compare an acoustic guitar: the strings are rather
silent, but with the hollow body beneath them, there is a "mechanical"
amplifier. It uses large flat boards surrounding a hollow space to
amplify the sound. If you fill the guitar with foam (whatever) it will
be quite silent.
So if your layout has an enclosed, thin-walled space below it - this
might act as amplifier - along with the rather well-amplifying road-bed.
So, first work on your road-bed and if that's not enough, just put the
boxes with your spare material below the layout to break up the space.
In some cases you'll want to put foam inside some cover boards or inside
a hollow beneath your scenery, but I doubt adding foam beneath the road
bed to be very efficient by itself ;-)
Here's a somewhat crazy one that might work. Cut your roadbed free from
the surrounding plywood and then secure it back in place with caulk or
foam insulation. This will minimize the amount of material that's
allowed to vibrate and should thusly quiet your trains.
Many model railroads do something similar but do it before they lay
track. They then butt the scenery material (foam or plaster) up to the
On Usenet, no one can hear you laugh. That's a good thing, though, as
some writers are incorrigible.
Not such problem I'm going to rip up good looking trackwork and scenery.
I'll try a few different suggestions ( for UNDER existing roadbed) in a few
different places and see what works best.
You need MASS affixed to the underside of your plywood.
In your situation I would use 3/4" MDF (cheap resin bonded furniture)
glued to the underside of your ply.
I guess you will have to "cookie cut" it to fit between cross-supports etc
- tight fitting would be best.
After 40 years of baseboard building I use 1/2" chipboard with 1/2" soft
board (presumably like Homasite) on a 3" x 1" ladder frame.
(spacing = electric drill with 1/4" drill bit)
I long ago figured that light weight isn't worth the effort or savings,
especially after a complex station yard developed waves after it was
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