Recording - September 2013 - 48

By Matt Seile

Home-based recording, by its very nature, means that you’re working
within the preexisting architectural elements inside your home or apartment to make and capture your music. The traditional problem is that the
designers and builders of your place didn’t exactly have acoustic purity in
mind when they built it. And so there are some common challenges, especially the taming of low-frequency buildup, that we all face when trying to
retrofit corrective strategies to produce decent-sounding recordings.
There are a ton of products on the market which aim at helping you curb
some of these issues, with spot treatments. They’re not a broadband
approach, they only work where they’ve been placed, and—let’s face it—
we’re often guessing where to put the stuff.
On the upside, traditional drywall walls have one thing going for them:
they’re essentially diaphramatic absorbers that work on the low-end frequencies. Intentional oversimplification: As sound energy hits the walls,
the sound waves either pass through the walls into the spaces behind, or
(frequency dependent) they get reflected back into your space. But the
entire wall is really only going to respond to a single frequency, the resonant frequency of that particular thickness of drywall board.
How to overcome the challenge
One knee-jerk reaction that some folks like recommend is to simply
reskin the existing walls with even more drywall. The second layer adds
mass, and with a different thickness of the added panel (say, a 3/8" drywall layer over an existing 1/2" or 5/8" layer), you gain a second frequency where the new panel will resonate. And it’s a darned good strategy, truth be told; it does result in better sounding rooms. But there is a
way to take things to the next level, by applying a second product
between the original and the new drywall layers.
Homasote 440 (www.homasote.com/Products/440-Soundbarrier.aspx) is
a fibrous material that comes in 4' x 8' sheets at a street price of about $35
per sheet. It’s a compressed wood pulp product that’s easy to work with using
hand or power tools. It holds drywall screws very well and is pretty polite stuff
to work with; it’s easy to lift, very easy to cut cleanly, and doesn’t shed.
Now, Homasote 440 is not going to be found at your average chain home
improvement store; it’s a construction material that’s usually used in full-on
building construction projects, and is most likely to be found at businesses that
cater to folks building houses from scratch! Call around to old-fashioned and
traditional building and lumber yards for a supplier, or search for one at
www.homasote.com/WhereToBuy/. It gets used all the time in the commercial construction trade, so finding it shouldn’t be terribly difficult. Mercifully, it
doesn’t weigh a ton, but plan on needing a pickup truck to get it home.
Application
The first thing to do is to use a stud finder ($20 at any home improvement center) and locate your studs in the wall. Go ahead and draw on the
existing walls to call out all of the stud locations—you’ll be covering them
up anyway, and you don’t want to miss!

RECORDING September 2013

Homasote 440 panels
But instead of simply adding a second drywall
layer, you’ll want to add a piece of Homasote 440
atop every other stud bay (a “bay” is the gap
between any two studs). I would cover each bay
that dead-ends into corners, creating a mass-loaded
corner inside the wall to help tame the low-frequency issues that like to hang out in the corners, especially on the wall where your gear (and monitors!)
live. Then stagger your every-other-bay strategy
down the wall length from there.
By covering every other bay, you’re creating alternating resonant and reflective zones in your walls. One
bay will sport a sandwich of drywall/Homasote/drywall. This provides lots of mass, with three different resonant and reflective sets of characteristics. Then the
alternating bays will sport drywall/air gap/drywall layers. So in those bays the two layers of drywall aren’t
coupled together and it provides a tougher challenge
for the sound energy to penetrate and get back out of.
A good thing!
Installation couldn’t really be any simpler. Cut your
Homasote into 171/2" wide strips by the entire height
of your wall. I happen to own a woodworking shop

http://www.homasote.com/Products/440-Soundbarrier.aspx http://www.homasote.com/WhereToBuy/

Recording - September 2013

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