Recording - March 2015 - 24

Close mics
Good microphone technique is one of
the most important skills a recordist can
develop. For many years, it seemed like
such an arcane skill, like an experienced
engineer would somehow just know the
right spot to put the microphone. I thought
of it as more of an isolated phenomenon; it
took me a long time to realize that mic technique is as much about room acoustics as
almost anything else.
When placing a microphone, there are many things to consider. First is the ratio between the direct sound and the reflected sound. The closer the mic is to the sound source, the more
direct sound there will be, relative to the volume of the reflected
sound. In a good sounding room, this is purely an artistic concern, since the room sound will be pleasing and you can easily
put some beautiful space around a recording simply by moving
the microphone a bit further than you would in a bad room.
Second is proximity effect, which is a characteristic of directional microphones (cardioid, figure-8, etc.) where putting the mic in
close proximity to the sound source will boost the low end, in addition to getting louder overall. An obvious example of proximity
effect is the "Voice of God"
radio announcer sound, where
the audio talent is right up on
the microphone and the low
end is greatly exaggerated.
Getting the proximity effect right
for a recording can make the
mix easier, in the sense that less
EQ will be needed in the mix if
you tune the low end properly
with mic placement.
Third is using the null points of
the mics-angles in their polar
patterns where they reject
sound-to your advantage,
which is particularly important
when recording more than one
sound source. For instance, you
can arrange the mics and the
performers so that the null point
of one performer's mic is pointing toward the other performer, so it
rejects the sound and reduces bleed. This technique, combined with
absorption at nearby reflection points, can be astonishingly effective.
These first three factors are commonly understood even by
beginning engineers, but a fourth factor is less so. What if you
are recording in a bad room, with no acoustic treatment or bass
traps, and the the low end is wildly out of control with peaks and
nulls all over the place? And, what if your upright bass player is
set up in the same location as a nasty null at, say, 82 Hz, and
the song is in the key of E, which has a fundamental right at 82
Hz? Needless to say, the resulting recording will be suboptimal.
As a result, one of the best things you can do in terms of mic
technique happens before you even get the mic out of the
case-spend some time placing the instruments in the room.
Note that the less treatment there is in the room, the more important this step is, since a properly treated room will be much more
consistent from place to place.
For instance, if I am recording a drum kit, I will often take the
floor tom (since it is reasonably portable and produces abundant
low end) and move it around the room while hitting it and listening
for the low end response that I want. Once the floor tom sounds
good, I set it down, and the drum kit gets set up in that spot.

draped over a boom mic stand with the
boom arm placed parallel to the ground in
a T formation. Most thick blankets will
absorb high frequencies; the main question
with blankets is how low a frequency they
will absorb. Broadly speaking, the thicker
the blanket, the lower the effective absorption frequency.
Two of these arranged in a V shape will
help quite a bit, often in many of the essential midrange and treble frequencies. But
as always, the better the acoustic treatment, the better the
sound. There are also commercially available products that can
perform this task very well, such as the RealTraps Portable Vocal
Booth shown in the photo.

Portable treatment to bring your tracks into focus
If you don't have access to proper acoustic panels, you can still
improvise in a pinch. One of my favorite tricks is to use blankets,

James Lindenschmidt (lindenschmidt@recordingmag.com) is
the General Manager at RealTraps. You can find a lot of free
educational material about acoustics at www.realtraps.com.

RECORDING March 2015

Room mics add space to the focus
Once I have a nice, focused, dry sound with the close mics, I
then like to use room mics to capture the ambience of the space.
This is very common in modern drum recordings; capturing the
room sound and applying heavy compression to it, then tucking
the room mics under the basic drum mix, is by now a very well
established technique to get a great drum sound. I like to use this
technique for a wide variety of
other instruments, even singer/
songwriters singing and playing guitar at the same time.
Of course, artificial reverb
can be used to add a sense of
space, but I find it much more
interesting to use the room
mics. If you are lucky enough
to be in a great room, then
sometimes the room mics don't
need much. If the room isn't
great, then sometimes the
tracks require some EQ to get
them sounding good. A highpass and/or lowpass filter will
often be useful, and if the room
is untreated there will almost
certainly be narrow peaks that
should be notched out. You can
create a narrow EQ band with a very high Q, boost it significantly (18 dB or more), and sweep it slowly through the frequency range until you find the worst offending frequencies.
Then a cut at that frequency, with the amount and the bandwidth
tweaked, will often make a world of difference.
Of course, all the tools of the modern audio engineer can be
used to enhance these tracks. Compression can produce a more
exciting sound. You can also delay the room mic tracks, from
15-40 ms or so, to give even more space between the close dry
mics and the ambience; this is roughly equivalent to a predelay
control in a reverb unit. But my favorite technique to get the
room mics to really enhance the recording is volume automation. This way, you can control exactly how much room sound is
in the mix at different points. For quieter, more intimate parts of
the recording you would probably prefer less room sound. For
louder, bigger parts of the song you can increase the level of the
room mics for a bigger sound.
Mastery of these techniques will go a long way toward a better sense of space in your recordings. Even if you are in a poor
room, some care and attention to the recording technique can
produce great recordings, maximizing your flexibility during
mixdown.

http://www.realtraps.com

Recording - March 2015

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