Recording - November 2015 - 51

4. Take measurements; identify peaks and dips.
To equalize your monitor system, you have to figure out what's
there to be equalized. Take a few measurements with a mic at
various points at and around the listening position, and print
them out on paper.
There are a lot of methods to do this and a lot of products out
there for the job. If I were endorsing products, I'd suggest Metric
Halo SpectraFoo and the Josephson Series Five microphones.
The Josephson microphones come with accurate calibration so
you can see what is actually going on. If you have an uncalibrated measurement mic, you can never be sure if a peak is the
microphone or the room. To be honest, microphone problems
below 250 Hz are rare, but you'll still want to know about high
frequency problems before you even start this process.
Some people have recommended the Behringer ECM8000
measurement mics, but the problem with those is that there are at
least two microphones sold under the same name and model.
One has a transformer in it, and the other one doesn't! If you have
the one without the transformer, it's probably just fine for this sort
of measurement since you don't need to trust it above 250 Hz. If
you have the one with the transformer, trade it for one without.
There are plenty of different pieces of software out there for
doing swept sine or impulse response measurements, and I don't
think it's really all that important which one you use. This is a
well-established procedure; Helmholtz was doing swept-sine
measurements 130 years ago. The measurements are fairly
easy; the hard part is interpreting them.
Note that when you have measurements in the listening area,
they don't necessarily correspond in any way to the response
outside of the listening area. So you can easily get a situation

where it sounds good at the mix position but there's no low end
at the producer's couch ten feet back. When this happens, it's
time to go back to Step 1, because that's the kind of room problem that equalization can't fix. On the other hand, at least the
monitors sound good at the mix position, which is probably
more than you could have said before.
At some point you have to define how important it is that playback sounds good in different places. The wider the area in
which you want stuff to sound good, the less effective equalization will be at hiding the room problems.
5. Identify the peaks that can be corrected safely...
Now, once you have a few printouts of the response at various
places in the listening area, look at how they are the same and
how they are different. If you see a peak that exists on one of the
printouts and not the other ones, you must ignore it. You can't do
anything about peaks that change with listening position.
See any big dips? There's nothing you can do about those
either-don't even try to fix dips with EQ! You can boost a frequency with an equalizer, but you only wind up putting more
stress on your amplifier and speaker and getting yourself that
much closer to clipping. If you have the microphone in just the
right place, you'll find some of those dips are so deep that all
the amplifier power in the world won't fix them. If they are really bad, go back to Step 1, but if they are a few dB here and
there, you have no choice but to leave them alone.
Now... the peaks that are left, the ones that are in the same
place on all the printouts? Those are the ones you can do something about with EQ. Pick the biggest two or three, and note
their center frequency and the width (i.e. how far off the center

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