It’s the best way to nuke “bad
vibrations” in your studio
People screaming about the importance of acoustics were voices in the
wild not that long ago. But as more studios shift into homes and
garages that were never designed with acoustics in mind, more people are
asking the question, “Why does my music sound fine in my
studio but horrible when I play it elsewhere?” and the answer is . . .
Savvy studio owners hire professionals to do the design work for them.
This process, while not necessarily cheap, is often the best
investment any studio owner can make; acoustic treatment will be the one
piece of “gear” that you’ll use on every recording and every
mix. A pro knows exactly where placing bass traps, absorption,
diffusion, and the like will do the most good—and has the tools to
any necessary tweaking. (For expert advice from top studio designers,
see our “Studio Makeover” feature.)
But what if, for financial reasons or just because you want to learn,
you decide to treat your studio space yourself? Fortunately,
companies that make acoustic products are more than happy to educate you
about how it all works, in the hopes you’ll buy their products.
(See the sidebar for recommendations on some good internet resources,
including a few product lines from top studio
designers such as Hanson Hsu [Delta H designs], Carl Tatz [Auralex], and
Chris Pelonis [Pelonis Sound]) Meanwhile, here are the terms
and concepts you need to know before you start your journey to seek out
and destroy nasties like flutter echoes, cancellations, standing
waves, acoustic coupling, and more.
Fig. 1. Primacoustic sells turnkey packages as well as individual products. The London 12 Room Kit is a live-end, dead-end (LEDE) room design; it includes 22 panels in a choice of three colors, and is designed for rooms that measure approximately 120 square feet.
|Fig. 2. This shot shows RealTraps’ Diffusor Modules, MiniTraps in the wall/ceiling corners, and Corner MondoTraps and Fat MondoTraps in the wall/wall corners.
Absorption Untreated rooms have several problems, but the most
common involves sound waves bouncing around inside the room.
On their journey they combine and cancel each other out, causing
peaks and nulls—in other words, your room is a gigantic parametric
equalizer with thousands of bands, all adjusted by a gang of
Absorption absorbs sound, so absorptive treatment would seem to
diminish most sound that bounces off walls. However, problems are
often most pronounced at low frequencies, which require specialized
solutions, usually in the form of bass traps. This is because in smaller
rooms, the wavelength of a bass sound’s single cycle might be longer
than the room itself, and cannot be controlled by thin foam panels
and other wall treatments; typically, separate absorbers control
midrange/high frequencies and low frequencies (see Figure 1).
Fiberglass material designed for acoustics (covered with fabric for
both aesthetics and to contain the fiberglass) is a popular absorptive
material, as is acoustic foam.
If you can afford to reduce your room size somewhat, creating a
second sheetrock wall offset at least a couple inches inward from an
existing wall can also help control reflections. Sheetrock has some
“give” so it absorbs sound, and the airspace between the two walls
also helps. This approach also tends to keep sound within the room
by decoupling vibrations from the “public-facing” walls. For similar
reasons, absorptive panels are also offset inward from the wall somewhat.
Diffusion Absorption won’t stop all reflections, so diffusion
helps make those reflections less objectionable. When rooms have
parallel surfaces, buildups happen at frequencies that relate to
room resonances. If non-parallel walls aren’t an option, diffusers
mounted on walls scatter the sound in multiple directions to defeat
these resonances. Diffusors on non-parallel surfaces are even better.
Between absorption to reduce reflections and diffusion to create more
desirable reflection characteristics, you can cover most of a room’s
inherent problems (see Figure 2).
Effective diffusion can reduce leakage if one instrument is
reflecting off the wall into a mic for another instrument. Scattering
the sound waves can reduce the amount of ambient sound hitting
|Fig. 3. Acoustic Sciences offers Full-Round, Half-Round, and Quarter-Round Tube Traps. The Full Round version rotates to present sides that provide absorption or diffusion; the Half-Round and Quarter Round versions combine absorptive and diffusive properties.
||Fig. 4. This plug-in GUI from ARC version 2 shows room response before (orange line) and after (white line) correction.
Acoustic Sciences’ portable, cylindrical TubeTraps (see Figure
3) represent an interesting combination of absorption and diffusion
for midrange/high frequencies. On the Full-
Round model, half of the cylinder is reflective
for diffracting/diffusing sound, while the
other half is absorptive; the way you orient
the TubeTraps around a performer can help
control the acoustics within that environment.
Wanted: Dead . . . or Maybe Alive Before
you go too crazy with absorption, analyze your
needs. Absorption reduces a room’s reverb
time, which generally a good thing when
mixing and mastering, but may not be ideal for
tracking—Jon Bonham’s drum sound on Led
Zeppelin’s “When the Levee Breaks” proves
that room ambience can be a beautiful thing.
While that example may be a bit extreme, a
little “air” in a room can make guitar amps
come alive and add a little depth to vocals. For
a more “live” sound, diffusors become more
important than absorbers, as the reduction of
resonances gives a more “open” feel and less
high-frequency information is absorbed.
|Fig. 5. sE Electronics’ portable Reflexion Filter Pro reduces room ambience to achieve a “drier” vocal or instrument recording.
Some larger studios have LEDE (live end/
dead end) rooms that conform to a standard
design in which one end is live, and the other
dead. So you could, for example, set up drums
in the live end and guitar amps in the dead
end if you plan to add ambience to the guitars
during the mix. Even better, scope out your
studio to see if there are other options. A
nearby tiled bathroom can give a super-live
sound, while a large closet that’s filled with
clothes can serve as a vocal booth that’s ideal
for narration, where you typically record dry
and add ambience artificially.
Isolation In addition to room acoustics, “inroom”
acoustic considerations include leakage
and sound isolation. Acoustical coupling is a
common isolation issue with simple solutions:
For example, a “floating floor” for drums helps
minimize the transference of kick drums,
drum hits, impulse sounds from high-hat
stands, and the like from working their way
into the floor—and then to walls, other mic
stands, etc. Some studios also float bass and
guitar amps, which often sit on a floor and
couple sound into the room.
Minimizing leakage is usually done with
gobos—portable panels that absorb sound. For
example, when miking a bass amp, you can
surround it with gobos and place mics inside
the gobo “fort.” Taytrix’s StackIt Gobos are like
a Lego setup for gobos; you can stack them,
adjust them to different angles, or even enclose
a loud sound source such as a guitar amp.
Other isolation methods include isolation
shields, such as Primacoustic’s Crashguard,
which wraps around drum mics to keep
leakage away from cymbals. I’ve also become
dependent on their TriPads, which are
basically foam isolators for mic stand legs
that isolate the mic stand from the floor—if
you can’t float a floor at the source, at least
you can float a mic stand at the destination.
And IsoAcoustics makes speaker stands
designed to provide isolation for speakers,
which of course produce a lot of vibrations.
(If you have the resources, you might even
consider a prebuilt iso booth; see sidebar on
page 56 for tips.)
Getting Attached Don’t overlook the
importance of the way you attach absorption
panels or diffusors to the wall, as some
adhesives eat away at foam. Auralex has
several adhesive products, from Tubetak Pro
Liquid, designed for permanent mounting,
to TEMP•Tabs, which are designed to be
temporary and are ideal if you plan to move
your studio around (or want to live with
a particular treatment for a while before
committing to a permanent installation).
Quick Fixes I’m generally not a fan of quick
fixes, but when all else fails, these simple
options can make a huge difference.
|Fig. 6. Auralex’s MAX-Wall lets you set up a mixing or recording space without having to attach anything to the walls—renters, take note.
• Primacoustic Recoil Stabilizers These
mount under speakers, providing isolation
and stabilizing speaker motion. It seems like
snake oil, but after extensive testing (because
frankly, I didn’t see how the “miracle cure”
claims could be true), there’s no doubt it
makes a major, audible difference in terms of
bass, imaging, and an overall “tighter” sound.
• Bright Star Audio Isonodes These reject
vibration—put them under your portable hard
drive, tube amps, units with transformers,
and the like to quiet them down and minimize
IK Multimedia ARC (Advanced Room
Correction) System This is one of
the best-kept secrets for those who want
better mixes: It’s a system for DAWs that
combines a measurement microphone and
measurement software, but the unique
element is a correction plug-in (Figure 4
on page 55) that compensates for room
issues. You can mix and record with the
plug-in inserted in the master bus, so
your mixes are targeted to acoustics with
a flat response. When it’s time to render
to a stereo mix for duplication or other
environments, bounce without the plug-in . .
. very clever. Recently upgraded to Version 2
(with upgrade pricing for Version 1 owners),
ARC works well because it doesn’t do pinpoint
EQ for just one sweet spot, but the
measurement process takes the entire room into
account for broader, more forgiving correction.
It even lets you create alternate references like
TVs, club P.A. systems, radios, and the like so you
can mix to a specific target playback medium.
• JBL MSC-1 This monitor system
controller incorporates their RMC (Room
Mode Correction) process. As a controller,
it can switch among three input source and
two sets of speakers (including subwoofer
management); it includes EQ, mute, sub on-off,
and level. Like ARC, the RMC process requires
using the included reference mic, but it
corrects mostly low frequencies where errors
tend to be most egregious.
• sE Electronics Reflexion Filter This
is primarily for vocalists and narrators, as it
provides an “acoustic shield” (Figure 5 on
page 38) that blocks your voice from reaching
the walls and creating echoes, but also shields
against those reflections returning back into
the microphone. It’s a highly effective concept.
• Instant Recording Space Can’t do
permanent acoustic treatment? Check out
Auralex’s MAX-Wall (Figure 6).
Super Silencers: Prefab Vocal Booths
The following tip is excerpted from The Studio Builder’s Handbook
by Bobby Owsinski and Dennis Moody. For more information on this
informative guide for improving the sound of your home studio on
any budget, visit Alfred Music Publishing online at Alfred.com.
Sometimes the only thing that’s needed is a really quiet place to
record vocals or voiceovers. You can build that space yourself,
but if you’re in an apartment, condo, or some space that you plan
on leaving someday, it’s best to be as portable as possible. That’s
where a prefab vocal booth comes in.
The beauty of a prefab vocal booth is that not only is it portable,
but it’s capable of giving you great isolation as well. Most of them
are easy to float, so it can become a room-within-a-room, and
the acoustics are controlled, so it’s not too dead. They’re so quiet,
some night owls in big cities like New York even use them to sleep
in during the day. So what’s not to like?
If you’ve ever spent more than 15 minutes in a totally isolated
area, you know that the heat soon becomes oppressive, which
means that some sort of climate control is required, and that’s
where the expense comes in. While most manufacturers of vocal
booths have an option for HVAC, the whole idea becomes a lot
more costly and complicated once that factor is introduced. Most
vocal booths will have a heat exchanger that will keep the heat
down, but still may be too hot for extended sessions.
Another issue with prefab vocal booths is that they provide
excellent isolation at mid and high frequencies, and only good
isolation at low frequencies. If you’re only concerned about
recording vocals or narration, this will never be a problem, but if
the booth is large
enough for drums,
you have to take that
factor into account.
One of the best
reasons to purchase
a prefab vocal booth
rather than attempt
to build one yourself
is that building a
small room that
actually sounds good is far from trivial. You may end up with a
worse-sounding space than when you started if you try it yourself
and do it incorrectly. Manufacturers of portable booths spend a
lot of time perfecting the acoustics of the space, so the products
are pretty good right out of the box. Many manufacturers also
make enclosures for guitar amplifiers so you can crank till your
heart’s content without affecting your neighbors. While these
work pretty well, remember that an enclosed space could cause
your combo amp to overheat unless it has ventilation, which
might compromise the isolation that you’re getting in the first
place. Non-ventilated enclosures should work well with speaker
cabinets, though. Just like with premade acoustic components,
be sure to check out the shipping and packaging costs before
you order, as they can be prohibitively expensive. Vendors for
vocal booths, drum booths, and speaker enclosures include
acousticalsolutions.com, soundsuckers.com, vocalbooth.com,
clearsonic.com, whisperroom.com, and realtraps.com.
Creative Insanity Designs
Delta H Design deltahdesign.com
Ghost Acoustics ghostacoustics.co.uk
GIK Acoustics gikacoustics.com
IK Multimedia ikmultimedia.com
Pelonis Sound & Acoustics
Pro Acoustics proacoustics.com
RPG Diffusor Systems rpginc.com
sE Electronics seelectronics.com
on the Web
John L. Sayers:
Ethan Winer’s acoustics forum on