Mackie lm3204 User Manual

grinding distortion.

Somewhere between the noise and the

clipping is an optimum level for your signal:
high enough above the noise floor to render
the hiss inaudible, and far enough below the
distortion point to allow range for loud peaks
of music to pass without clipping. This safe
operating zone might be called operating level
or nominal level or zero or perhaps line level.
The range between your operating level and
clipping is called headroom, which defines
just how tall your signal can be without hav-
ing to duck for the rafters.

Your mission as a designated Master of the

Levels is to get the low level signals up to line
level as soon as possible and to keep them
there as much as possible, but not to turn them
up too much.

On a Mackie mixer, the easy way to do this

is to set all the level controls in your path to
the “U” marks screened onto the panels. Set
the Balance control to the center and press
the channel Solo button. This will display the
channel level on the Left and Right meters.
Then adjust the channel Gain or the Mic trim
until you have a good level on the meters. The
“U” stands for unity gain, which basically
means level in = level out. Now, with mic in-
puts that’s not exactly the case, but ignore
that and set your faders at “U”. That will get
you in the safe zone.

Pay close attention to the meters. A meter

is an aid, a window looking onto part of the
dynamic range of your signal, and it will tell
you if your level is in the ballpark, so to speak.

Try to keep your signals in the middle

range of the meters, for the most part. If the
signal is always very low, you may not be get-
ting the best signal-to-noise ratio you can.
If the meter LEDs are always solidly lit from
bottom to top, you are likely distorting both
the console and your recording tape regularly.
Keep the signal in the middle, with occasional
peaks into the yellow. Remember, the top
yellow LED of the meter represents a level of
+10dBu, and the LM-3204 doesn’t clip until
+22dBu. Even when “banging” the yellow
LEDs hard, you still have around 12dB of
headroom for your peaks. The Left and Right
meters have a red LED segment to show
imminent clipping at +20dBu.

Many of you reading this

manual have a lot of experi-
ence in using mixers and
mixing consoles. For you
battle-scarred pros, Section 2

and the Block Diagram will probably be all that
you need to look at.

For those of you who are either new to using

mixers or just like to read even larger quantities
of our glib prose, we’ve provided this short sec-
tion. It discusses the basic concepts and
procedures used in recording, mixing and sound
reinforcement work. If you can make some
sense of it, you can check out your application
and patching in Section 4 and start plugging
things in.

Here is a primer covering a few important

ideas you should be on good terms with before
you sit down to a mixer.

Microphones have low output levels. Line

level devices have high output levels. One of the
functions of a mixer is to amplify or attenuate
these signal levels properly. Since it’s easy to de-
grade the signal by not handling levels well, and
since it’s your hand on the knobs, you should be
sure you know how much gain to apply and
where to apply it.

combination of cable
adapters you may have at
hand, never connect the
output of a power ampli-

Every electronic circuit produces noise or

hiss or hash or buzz, and any noise present on
the input of an electronic circuit will be faith-
fully passed through. Turn it up high enough,
and you will hear the noise.

Every electronic circuit also has a point of

overload, a clip point, where the voltage simply
cannot rise any higher, no matter what the input
signal and your fader move would like. This
overload, or clipping, will show up as tooth-