EVER WONDER WHY YOUR MIXES—WHICH SOUND SO GOOD IN YOUR HOME
studio—sound like muddy swill when you play them back somewhere else? Where’s the
beef? What happened to the definition in the high end? Why did that big stereo image
collapse into sounding like it’s inside the cardboard box your studio monitors came in?
The Problem
The answer is that no matter how painstaking
your recording process, and no matter how great
your mics, preamps, converters, synths, and
monitor speakers, the mix can only be as good as
the decisions you make based on what you hear.
In turn, what you hear is affected by what your
room does to the sound.
Unless your space was purpose-built for acoustic
accuracy, that’s usually not good. Decisions
that sound right enough in your studio—say,
how much low end you put in the bass track or
how widely you panned that stereo synth—won’t
necessarily translate well to car stereos, headphones,
and other environments.
The sonic culprits are many, and without
turning this into an acoustics lecture, there
are two approaches to the problem. You can
pre-emptively tweak what’s coming out of
your speakers to compensate for how your
room is about to mess it up, and/or you can
address the room physically. The former is
room correction: technology that analyzes
the “as-is” frequency spectrum in your space,
then applies corrective EQ. The latter is room
treatment, and can involve bass traps, acoustic
foam, diffusers, speaker isolation pads, and
other such materials.
Most real-world creative spaces are problematic
enough that some combination of both is
ideal. In this issue, we’ll examine digital room
correction systems from IK Multimedia, KRK,
and JBL. Next month, we’ll look at strategies for
using the broad range of room treatment panels
and products on the market.
IK Multimedia
Advanced Room
Correction (ARC)
$349.99 list | $199.99 street | ikmultimedia.com
 |
| IK ARC’s measurement mic and room analysis screen. |
Like all solutions in this roundup, IK’s ARC includes
an omnidirectional condenser mic for sampling
your room and standalone room analysis software.
What sets ARC apart is that other than the mic, it
uses no dedicated hardware. You insert a plug-in on
the master stereo output of your DAW, and based
on the room analysis, it corrects the audio as you
mix. When done mixing, you turn the plug-in off
before bouncing to disk or summing to your stereo
medium of choice.
Calibrating ARC is simple. Plug into a mic input
on your interface and point the mic skyward
on a stand. After performing a few simple level
adjustments, you’re ready to sample your room.
Naturally, you want the mic to listen from
the same spot you do, but ARC 
aims for a broader
sweet spot. You start by placing the mic at
ear level, in the center of your optimum seated
position between your monitors, and then at
random spots nearby. Th e software sends audio
impulses from the left speaker, then from the
right. You must take at least a dozen samples
before you can store an analysis, but IK encourages
16 or more. I took 20 samples, loosely
describing a concentric, elliptical area around
my listening post on my first pass, and 30 on a
second, wider sweep.
The plug-in window shows color-coded contrast
between untreated audio, a target correction,
and the actual frequency response post-correction.
From this, it was easy to tell that my room
needed help with dips at 70 to 100Hz. ARC’s
corrections were less drastic on the left channel,
likely due to the placement of my manual-packed
bookshelf, which absorbed low-end distortions
caused by standing waves. A couple of spikes existed
around 200 and 220Hz, and again, this was
more pronounced in the right channel—which
made a strong case for moving my whole setup
leftward for better symmetry between channels.
Different EQ curve presets are mostly useful for
auditory perspective, but you can also use them to
roll off highs and mids in rooms that may overemphasize
those frequencies. As always, play some of
your favorite mixes through the plug-in to arrive at
a setting that works best for you. After A/B comparisons
on the same material, mixes through the second
analysis had more detail across the frequency
spectrum, more discrete imaging, a better-defined
low end, and clear transients—so clear, in fact, that
the annoyingly uniform picking transients on a
sampled guitar sent me back to my sample libraries
in search of a new instrument. That’s the kind of
thing I otherwise might not have caught until I’d
finished a mix and was listening outside my studio.
Because ARC relies on just two software
components and the provided mic, it’s the most
mobile compared to the KRK and JBL products,
which use proprietary interface and control surface
hardware in addition to a mic. Additionally,
you can save as many analysis files as you’d like,
which is ideal if you work in different rooms.
Just as we went to press, we learned IK was
about to release a new version, ARC System 2.
Though we haven’t tested it yet, we know it increases
the number of EQ bands fourfold (tightening the
bandwidth of each to 10Hz, compared to the current
40Hz) and promises to require fewer measurements
to produce an accurate analysis.
KRK ERGO
$799 list | $499 street | krksys.com
 |
KRK’s system stores its room profiles
in the hardware. The only software is a control panel for its audio interface functions—there’s no plug-in or graphical EQ curves to deal with. |
ERGO stands for Enhanced Room Geometry
Optimization. Home studios tend to be squares or
rectangles, and sound waves bounce off parallel
walls, boosting or reducing reflected frequencies.
Because of the nature of low frequency
waveforms, which need more physical space to
develop than higher ones, they can lose focus,
especially in small rooms.
ERGO operates on the premise that the most
troublesome frequencies dwell from 20 to 500Hz.
KRK claims that their room correction is “almost
insensitive to broadband background noise.” The
fact that I achieved virtually the same calibration
results during a period of heavy outdoor traffic
and during quiet, early morning hours tends to
bear their claim out, making ERGO ideal if you
don’t have a space that’s sonically isloated from
the outside world. ERGO works well with any
studio monitors, not just those made by KRK.
KRK includes a proprietary measurement
mic (it uses 15 volts for phantom power, not
the usual 48) as well as a 24-bit/96kHz FireWire
400 audio interface and a four-pin adapter to fit
the port many laptops use. (USB would be a better
call for a future version, given trends in consumer
electronics.) ERGO saves its room analysis
data in the hardware unit, and you’re limited
to analysis for each of two monitor systems. You
can always overwrite the memory if you need to
record in a different room, but as the analysis
can take nearly half an hour, it would be handy
to be able to store more data files offline. It
would also be a plus if, like the other packages,
ERGO produced a visual graph of its findings.
ERGO gathers its data starting with the
engineer’s ear-level perspective. You then do a
number of sweeps of your room from random
vantage points, until the system acquires what
KRK calls “room knowledge.” Whereas ARC required
a close, elliptical pattern of measurement
spots, KRK encourages mic placement anywhere.
The result is a pair of data files: one representing
the near-field position, and another with a much
broader sweet spot. A button switches between
the tight focus, the broader image, and bypass.
The broad (called Global) image is useful if you
have clients in the room, but I’d stick with the
focused one for a critical mix.
The dedicated hardware lets ERGO double as
a monitor control module; you can hook up either
a 2.1 system or two stereo pairs. If your recording
needs are relatively simple, you can use it as your
main audio interface: You get a couple of line-level
1/4" inputs, and that’s about it. You can also can
pipe your main interface through the ERGO’s
S/PDIF digital audio input and enjoy its room correction
capabilities. The system has balanced 1/4"
line outputs for your active monitors or studio
power amp. I’d have preferred XLR outs as well, but
still, this is one clean, sweet-sounding interface.
As promised, the bottom end of my mixes went
from boomy to tight, with more focused bass;
punchier, balanced kick drums; and even improved
definition for pad parts and drones dwelling in the
lower frequencies. Mixes translated nicely between
studio, home hi-fi system, and car stereo.
JBL MSC1
$375 list | $299 street | jblpro.com
 |
| The JBL hardware (left) and software console (right), showing a graph of the author’s room response. |
MSC stands for Monitor System Controller, and
indeed, JBL’s offering is both a room corrector
and a monitor volume control/switcher that can
handle two pairs of speakers, a subwoofer, and
three input sources: two on 1/4" balanced ins and
one (such as an iPod) on unbalanced RCA jacks.
For our purposes, the relevant acronym is RMC:
Room Mode Correction. MSC1 aims to isolate
any issues typically in the low frequency range of
your room, and applies customized filters based
on its findings. Of the three packages, the JBL
system’s room analysis process is inarguably the
most detailed—and the most complicated. JBL
supplies a proprietary calibration mic and the
requisite cabling.
The USB port is only for talking to the included
MSC software—unlike the KRK ERGO,
the JBL is not an audio interface itself. For that
reason, room analysis requires a specific wiring
setup whose oddest routing is from the headphone
out on your audio interface to the RCA ins
on the MSC1 box—this is the only path taken by
the test tones used for room analysis. We get it—
JBL is being inclusive of audio interfaces (and
internal sound cards) that may have only stereo
main outs plus a headphone jack. You don’t have
to leave it this way when mixing through RMC,
only when performing the analysis itself.
Setting out to do just this, I heard fluctuating
low-level noise, which sent me around the room
chasing the cause. Not surprisingly, the wiggle
factor of the cabling I’d cobbled together for the
required routing (1/4"-to-1/8" adaptor plug in
the headphone jack of my MOTU 896 interface,
then 1/8"-to-stereo-RCA Y cable) was to blame.
The measurement mic also connects to the MSC1
via a 1/8" jack. Balanced I/O and pro connectors
for the test tone path and mic would add cost,
but would resolve such issues.
The MSC1 software uses animated diagrams
to walk you through the multiple setup stages.
The first of these is a preliminary calibration
of your system, including your audio interface.
This involved reconfiguring audio I/O in order
to analyze the inner workings of my MOTU 896.
The process was a bit fiddly, but fortunately, you
don’t have to repeat this part of it unless you
change audio interfaces. Once completed, you set
up gain-staging between your interface, mic input,
and speaker output. Only then are you ready
to “shoot the room.” There are a few variables,
including the mic input gain knob on your interface;
the MSC1 itself provides a large volume
knob and and input trim.
Now, set the mic at ear level, click the start
button, and get out of the way quickly and
quietly—I had five seconds before my speakers
produced a raft of organ-like tones. Th e MSC1
performs just one sweep consisting of a series
of tones from left and right monitors. This
takes about ten minutes per side, but unlike the
other products, doesn’t involve moving the mic
around the room.
The MSC1 software won’t complete the calibration
without peace and quiet; even a little
noise returns you to the gain-staging phase. My
studio has a window facing a well-traveled street,
which necessitated moving my test sessions to
late evening. When things were perfectly quiet I
tried again, but gain-staging that made the software
happy still took some time to get right.
I found the now familiar low-end problems
in the 70-to-100Hz range; my room is what
it is. The results were similar to my measurement
with the other systems, with the MSC1’s
added benefit of sweepable EQ for lows and
highs. (For midrange to upper frequencies,
you get a plus or minus 3dB shelving EQ ranging
from 2.5 to 17kHz.)
Conclusions
None of the products we’ve auditioned are magic
fixes; you’lll still have to EQ, compress, adjust levels,
pan … you know, mix. Room correction simply
helps you make better decisions. If you’ve followed
the room analysis procedures to the letter, any
of the above products will dramatically reduce
bass issues and frequency response problems
endemic to tight spaces with parallel walls. The
EQ-based nature of room correction, though, may
not resolve other issues such as flutter, ringing,
or coupling between your monitors and the desk
they’re on. We’ll discuss physical room treatment
next month, as well as integrating the digital and
physical approaches. See you then!
Focusrite VRM
To quote The Shining, one way to
“correct” a room is to eliminate it. That
may not be the primary purpose of
Focusrite’s VRM (Virtual Reference
Monitor) Box, but it’s cerainly a benefi t
of this nifty little D-to-A converter/
headphone amp/speaker simulator.
You can place any of 15 pairs of virtual
speakers (including KRK, ADAM, and
Yamaha NS-10) in one of three spaces
(studio, living room, or bedroom),
and immediately hear the effects on
your mix. Whatever lab-coat geekery
Focusrite put into the modeling pays
off: I experienced fewer stereo placement
issues that I normally do when
mixing on headphones. For our purposes
here, the simulations’ accuracy
is less important than their diversity:
The more of them you get your mix
sounding good through, the better
it will translate outside your studio.
Obviously, you want accurate headphones.
I’ve been using Audio-Technica
ATH-M5Os with good results.
Stephen Fortner