Equalization is the term used
to describe the process of changing the balance between high
and low frequencies. Equalizers allow us to selectively boost
and/or cut specific frequencies or bands of frequencies. With
regard to equalization of the instruments you are recording,
you must first assign the range of each instrument into its
own frequency so that it won't interfere with any of the other
instrument frequency ranges.
There are many types of equalizers and they get used in many
different ways by different people. In general, "Parametric
Equalizers" allow for very specific effect with adjustable
Q and frequency control for each frequency band.
"Graphic Equalizers" feature as many as 31 individual
sliders centered on fixed frequencies and tube equalizers
utilize vacuum tubes in their circuits as opposed to transistors
("solid state") and are often preferred for their
All mixers provide some kind of EQ, switchable on or off,
in the signal path. These days, semi-pro consoles usually
feature a couple of overlapping bands of semi-parametric EQ
on the low-mids(200-2K) and hi-mids(1.5K-7K), and one EQ each
for the low(100 hz) and high(10K) bands with shelving switches
and low-frequency roll-off. Professional consoles offer fully-
parametric designs and more overall flexibility, as you might
expect. Since we can't all afford Neve VR consoles at home,
another option for small studios is outboard equalizers. Get
a couple of good ones and insert them into the signal path
and print through them to tape. This will definitely take
your sounds up a notch without totally blowing your college
I've also received questions inquiring about dynamics. The
term, "dynamics" refers to whether a sound is "soft"
or "loud". The ability of a recording medium to
reproduce the difference between soft and loud is called its
"Dynamic Range". Vinyl records and cassette tapes
have a limited dynamic range of about 20 db, while modern
CD's and Digital Audio Tape (DAT) are capable of full dynamic
range- that's 100 db! The limiting factor of how much of that
range you get to actually hear is determined by the speakers,
amplifiers and the room you're listening in.
We've all heard terms like "bright", "dull",
"deep" and "thin" used to describe music.
Two major factors complicate this affair. The first is that
we all hear the same thing differently; one person's "bright"
is another person's "dull". The second is the accuracy
or lack thereof, of our sound source, i.e. the speakers and
amplifiers. Technically, the audible frequency range for human
hearing is 20 Hertz(Hz) on the low end and 20 Kilohertz(Khz)
on the high end. Most people's hearing range falls between
40Hz and 16 Khz and in fact, the specified frequency range
of FM radio is 50Hz to 15Khz. A typical car radio, boom box
or home stereo has two EQ knobs on it. The "Low"
and "High" knobs are usually centered at 100 Hz
and 10 Khz respectively with a broad "fixed Q".
"Q" refers to the range of frequencies affected
by the boost or cut and is expressed in octaves. Their effect
is not subtle but for consumer applications this is simple,
convenient and usually sufficient. The loudness button is
simply a low frequency boost that compensates for the apparent
lack of low frequencies at low listening levels. While the
human voice is the most dynamic, all of these instruments
present a similar problem to the engineer. How can we preserve
the performance, that is the soft and loud of it, and get
it accurately on tape? With these instruments, we usually
have to use a microphone.
The two main types of microphones are "dynamic",
which have no active electronics involved in amplifying the
input signal, and "condenser", which require either
batteries or "phantom power" to power their electronics.
Both types have a thin membrane, called the diaphragm, that
vibrates and that physical vibration is translated into an
In general, condenser mikes are brighter and have a broader
frequency response, but they are more fragile. That's why
you usually see an SM57, a general purpose dynamic mike, in
the lead singer's hands at a concert. They can withstand a
lot of abuse. Classic condenser microphones like the Neumann
U-47 and AKG C-12 use vacuum tube electronics and are treasured
for their unique sound. They are rather large and have diaphragms
2 inches in diameter.
Ribbon microphones are another vintage design that incorporate
a thin rectangular strip as its diaphragm, hence the name.
PZM designs are a relatively new invention. They work on
a completely different principle and don't look anything like
traditional microphones. The signal created by the microphone
is very small and it is the microphone pre-amp that increases
this level to what is known as "line-level" for
interfacing with the mixing board. This is yet another link
in the chain with its opportunity to affect the sound, and
Everyone has his favorite microphones and pre-amps for different
situations and most do color the sound. The important thing
is whether you like that color and if it's appropriate for
the particular situation at hand. Here again, we run into
the concept of "flat frequency response" and again
it is relatively meaningless. Most microphones are not "flat"
and some are better suited for certain jobs than others. As
always, you need a reference, and in this regard, frequency
response charts and the like can be useful.
Andy Cahan is a veteran of the music industry.
As a recording engineer and record producer, Cahan has worked
with such artists as Ringo Starr, Harry Nilsson, Flo &
Eddie and Eric Carman.