These observations are from years of job-related exposure, I work for a large
Building Materials Wholesaler. The observations are not meant to advertise or
promote the items mentioned ...it is simply to aid all you phone contest ops
who are trying to make your shack more soundproof...ok, maybe CW guys can
benefit, too.
STC, or Sound Transmission Class, is an architectural rating for how well a
building material stops sound travel....ask your building material suipplier
for comparison numbers when you go to buy.
The act of insulation whether it be for noise or temperature is accomplished
with fiberglass batts by virtue of the fact that they contain trapped air.
Fiberglass insulation is soft and puffy, and sound travels best along hard
surfaces.
Haven't you ever noticed that when you are singing the "I own 40 meters" song
during your SS shower break on Sunday? Surely you doo-wopped in the ceramic
tiled high school boys restroom (or for KU2Q, the girls room).
Sound moves into and out of your shack by virtue of the air containing the
noise hitting one side of the wall and causing a simalar vibration to appear
on the far side of the wall - which is in essence a regenerator of that
noise....oh my god, it's a repeater, squelch!
Serious soundproofing like that used in commercial settings will include
closely spaced parallel walls which are not even physically attached to each
other so that those sound waves can't reappear on the other side. I
understand this is what W3ZZ is rumored to use at his CQ-Tape recording
studios.
A type of soundproofing for walls that is economical is 4x8 sheets of fibre
products such as Soundstop, by Celotex. Soundstop is low density sugar cane
fibre that has been pressed into 1/2" thick sheets. It has very little
structural strength - don't try and pick up from one end, it will snap like a
cheap Cracker (settle down, AA4GA). Its strength is just about enuff to hold
itself together and usually it is not painted or prefinished. The sheets are
mounted onto the wall studs and then the drywall is mounted over it.
Since the hard drywall is not directly touching the hard studs, but instead
is touching the loosely packed cane fibre the sound waves from the back side
of the drywall which would normally then pass onto the studs now have to
first travel through the loosely packed fibre board. The route through the
fibre board is not particularly condusive to reproduction of the sound wave
on the far side so by the time it gets to the stud you are ahead.
This product is usually used on bathroom walls so you don't have to hear the
flushing of a toilet or other bathroom sounds...for fanciers of XE quisine
the soundstop can even be placed on both sides of the walls studs to get
twice the poor sound transmission......rrrrrrrrip.
Another sound deadening board is Homasote. It is a gray recycled wood fibre
product (mostly old NJ newspapers and lottery tickets) and is much denser
than Soundstop/similar products. The basic Homasote product is normally used
on the floor as a carpet underlayment. It is very helpful in lowering the
sound of teenagers upstairs pacing up and down the hall while waiting for the
'phone to ring. Because it is more dense than the cane fibre boards it is
able to be used in floors, cane fibre boards are much too loosely packed to
stand up to something like a womans high heel, even a petite woman! Homasote
can also be used in a wall but is not as effective as a low density fibre
board. For those with the deep pockets, Homasote manufacturers their product
in 4 X 8 sheets with a 1/16" cork veneer - a Giant Cork Board!, -or- wrapped
in Burlap....very deep pockets can look into the "Designwall" colored burlap
wrapped boards. Homosote is excellent for holding thumbtacks.
Once a very popular method of lowering noise levels, but not in step with
current Inreior Designer's desires is the act of putting 12" X 12" ceiling
tiles on walls. The ancient offices I work in use it. A chair rail, dividing
the lowest 3 foot of wall from the upper three foot is a popular design
technique that allows you to put something hard (toungue and groove 1X6
lumber?) on the lower half of the wall and then use ceiling tile on the upper
half. This way when you jump out of the chair as you make your Clean Sweep,
or beat out K1AR to an exotic DX mult you won't have to worry about the
runnaway chair denting up the wall (not too much, anyhow).
Ceiling tiles, on the ceiling or wall, help lower sound transmission by two
methods. Fissuring, those irregular grooves in the tile, are a sound
deadener....tiles are either Directional Fissured (they all run the same way)
or Non-Directionally Fissured (with random direction grooves). Pin holes in a
tile take it one step further in sound reduction. The next time you are at
work and look up at the ceiling tile over your head you might ponder the face
of it, odds are very good it has grooves and pinholes....now get back to
work.
An added advantage to putting ceiling tile on the wall of your shack is that
it also accepts push pins well, and you can be cheap and show off your AC4YN
and other QSL cards without vinyl hangers. Or, show off your growing
collection of Contest Certificates without them having to be framed....you
could even pin up your Dr Bafoofnik hat (circa Dayton '96) - only if you are
cheap, of course!
One more thing you might wanna consider for your shack is a solid core door
as opposed to the typical interior hollow core door....this goes against
everything above, in that it is a hard versus a trapped air or hollow
structure. The fact though is that hollow core doors typically use two very
thin skins of plywood or hardboard less than an 1/8" in thickness seperated
by some 1 3/8" pieces of carboard on edge. The hollow core door is a great
reproducer of sound - seemingly acting like a cone on a speaker! The skin is
so thin it goes along with the soundwaves - easily regenerating the sound
onto the far side.
The lumber yard may not have this type of door in stock as most interior
doors are 1 3/8" thick and most solid core doors are for exterior use and
usually are 1 3/4" thick ....but they ARE available! If your shack is in the
formative stages save yourself the some headache and order a prehung solid
core dore....I recommend making the door as wide as possible, 36" (3/0) is
great for hauling in your new mondo 4CX10000 Lousianna Propagation Creating
Final's power supply....or a 36" deep desk!
So, if you wanna build a quieter shack, use a solid core door and ceiling
tile that is pinholed and fissured....perhaps even on the walls or parts of
the walls....some sound deadening in the walls from a Soundstop like product
also will help, and if your shack is in the basement, well....you sure as
hell ain't here in Florida!
73,
Jim zx k1zx@contesting.com
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