here are three important tips for
aspiring sound engineers. so let's get
right to it!
number one:
signal flow...
learn about and understand signal flow.
said simply, signal flow is the path that
a signal takes from the stage to the
mixer,
through the mixer, into the various
outputs:
to the house speakers, the monitors,
recording feeds, a stream mix, etc.
you want to understand signal flow
because this is how you will understand
things like pre and post fader sends.
it's how you will be able to make
routing decisions when setting up a
console.
understanding how certain things
interact, both inside and outside of the
console.
and it will definitely help your
troubleshooting skills as well.
while signal flow in the big picture is
the entirety of the sound system, it's
important to look at the nuances of how
the signal is routed through your mixing
console.
we can see with this graphic that the
vocal goes from the stage to the console...
where it first hits the gain stage of
the
console. we then can send the vocal to
the house speakers, to the monitors, to a
stream feed, and of course do the same
with all of the channels to create our
mix or mixes.
understanding signalflow is how we
understand terms like pre-eq and post-eq
pre-fader and post-fader.
in the case of channel sends, these tap
point options work like this:
this is a very basic outline of the
signal path entering a console channel.
a pre-eq send would tap the signal
before the eq.
a post eq send would tap the signal
post eq...
after the eq.
with post eq, anything you would do on
the channel eq would also go to the post
eq send.
also you can see that these tap points
would be before the channel fader.
therefore they are pre fader.
we could also have the option to pick a
send point that is post fader.
therefore it would get its signal after
the channel fader.
so not only would it include everything
that comes into the channel fader,
like the eq, but it would also pick up
the channel fader moves itself.
in other words,
a post-fader send will track with the
channel fader changes.
that's why when you're doing monitors
from front of house you typically do not
want a post fader send.
you don't normally want your monitors
changing with your front of house
channel fader moves.
that brings us to tip number two:
eq with a purpose!
sound engineers don't just simply turn
the eq knobs until the source sounds
good.
we listen and evaluate and identify
areas that need to be addressed in the
frequency balance and then address them.
usually we're looking to use subtractive
eq principles first and foremost,
de-emphasizing problem frequency areas.
and that is particularly true with
system eq.
with channel eq you still want to listen
to remove things first but there can be
times when something needs lifted.
you need a basic idea of what each
frequency sounds like to know what to
reach for.
from left to right- bass to treble.
low to high.
having a working knowledge of the
frequency ranges of various instruments
is also pretty important.
then to put this knowledge to work you
need to understand some fundamental
terms like these:
high pass filter,
also called a low cut.
a high pass filter gently rolls off lows
to take away any unnecessary low end
from a source.
almost anything can benefit from a high
pass filter being applied.
then there's the low pass filter,
also known as a high cut.
a low pass filter gently rolls off
unnecessary high end from a source.
a low pass filter is typically not
applied to every channel since high end
doesn't have the same issues as the mud
created with excessive low end on
sources that don't need it, nor as
annoying as vocal plosives on a
channel without a high pass filter.
then there is a low shelf eq.
that is an eq filter that has a knee
frequency and then all frequencies below
that knee frequency are raised or
lowered equally.
it looks like a shelf.
a high shelf would be just the opposite-
a knee frequency with everything above
that knee frequency raised or lowered
equally.
ideally you'd want a shelf eq for
coloring the signal not for feedback
control.
for feedback control you generally want
tight fillers to surgically target a
frequency. that would be a place for a
parametric eq. a peq.
a parametric eq, with its variable
bandwidth setting, also known as the Q
setting, can be very useful for both
feedback control and musical uses of the
eq.
generally you want narrow for feedback
control...
wider for coloring the signal.
while a graphic eq a geq might seem to
be a great option because of all the
bands of eq, it's generally not the best
option because it doesn't allow for the
precision that a parametric eq brings to
the table.
but that said, for system and monitor eq,
some people still prefer it because they
are quicker with a graphic eq.
all this is why digital consoles offer a
distinct advantage when it comes to eq,
because they can offer so many options
to the operator without needing to carry
racks of outboard processing equipment.
that brings us to tip number three:
input gain!
all of these tips go hand in hand.
with signal flow the first point you
have control over at the console is the
input gain.
modern mixing consoles give us metering,
either pfl metering,
or individual channel meters. both let us
see the input levels to the console.
we don't have to guess about our input
levels or headroom because we can use
these meters to consistently set our
inputs for each channel, each and every
show.
but knowing signal flow, we can see that
anything we do with the input gain will
affect everything in the channel
following it.
this is extremely important to remember-
change the gain control and you change
the level of everything in that channel
that follows it.
monitors from front of house will change...
stream feeds will change... even that
channel in the house will change level
when you adjust the gain!
that's why we want to adjust the gain as
the first point in our sound check or
line check.
there's also a misconception that
there's some magic, perfect, or wrong gain
setting that will eliminate or cause
feedback.
that's simply not true.
volume and frequency levels cause
feedback and feedback doesn't care where
that volume comes from.
the misconception likely gets oxygen
because if you're three db away from
feedback, and turn the gain up 3 db,
then of course you'll get feedback.
and if you turn the gain down 3 db,
then the feedback will go away.
but it's not because of the gain setting
itself, as it might seem if you don't
take signal flow into consideration,
it's because the gain change affected
everything after the gain!
if the feedback was in the house pa and
you'd turned the house PA up 3db, then you
would still get that same feedback... yet
the gain control would stay in the same
place.
because the channel input level, the gain,
was not the problem.
if you have a flat tire and you put air
in all four tires, then you will fix the
flat tire, but at the expense of changing
three other things (in this case the air
in the other tires that were perfectly
fine all along).
it's the same principle!
just like the air pressure gauge tells
you what air pressure your tires need to be,
the channel gain needs to be what your
input meters tell you your input gain
needs to be.
the input gain is just optimizing the
signal into the console for headroom and
consistency with the other channels.
this video talks about mixing live
vocals. you might want to check that out
if you haven't already.
leave me any questions or comments below.
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