Peavey 600 - Page 2

600 M ixer
INPUT CIRCUITRY • It is absolutely
necessary for a mixer to be compatabie in most ap¬
plications and to have the capability of boing able
to control the sensitivity of the Input circuitry of
each channel. This requires an input attenuator,
(1) sometimes referred to as an Input pad. Some
mics and signal sources can be at such a level as to
overdrive or clip the input circuitry of a mixer.
An Input attenuator allows the operator to reduce
the input gain when input clipping occurs. Some
manufacturers put attenuators in their snake or
stage box to be able to control the sensitivity of
the mic or signal source. This is not the best ap¬
proach if you are sending your signals through ca¬
ble runs of any length. The more signal being car¬
ried by the mic cable the less susceptible Is the sig¬
nal to picking up hum or noise which allows for an
Improved signal to noise ratio. Many times it
would be Impossible to make an adjustment on
one of the attenuators If necessary during the per¬
formance. You shouldn't have to run up to the
stage and pick up the drummer's leg so you can ad¬
just a mic input!
In use, the operator must adjust the Input
attenuator in such a manner that input clipping Is
avoided- This can easily be done by setting up the
channel with the highest expected Input signal
level and adjusting the Input attenuator so that no
clipping or distortion Is heard from the speaker
system. After the mixer has been used several
times, the operator will have a very good idea
of the signal levels encountered and will be able to
set up the attenuators accordingly. The different
types of microphones will have different output
levels and different performers will get widely
varying levels from mics depending on the strength
□ f their voices and/or their basic “mic techniques".
The input attenuator should be operated
m the position yeilding the least attenuation re¬
quired to avoid clipping. Operation in this mode
allows maximum gain to be utilized in the Input
preamp where it Is most efficiently obtained. Ex¬
cessive Input padding sometimes makes necessary
higher settings of the channel gain controls and/or
master control thus yeilding a less than optimum
signal-to-noise ratio for any given situation.
It is important to realize that not all
"breakup" is caused by the mic signal overloading
the input stage of the mixer. If the performer's
mic technique includes very close and/or very loud
situations, tho Internal elements of the mic can
"bottom out" or distort just as a loudspeaker can
when it is overdriven. Quite a few of the mics now
used by performers lack the dynamic range re¬
quired to adequately handle the tremendous sound
pressure levels encountered in a very loud rock and
roll concert situation, it is vital for the profes¬
sional soundman and the musicians to be aware of
the limitations of the various links in the audio sys¬
tem in order to correctly diagnose and solve the
various problems encountered in a sound rein¬
forcement situation,
Overall, the input attenuator Is the first
control in the circuit and must be set up properly
in order for the remaining circuits to function pro¬
perly, “Common sense" and experience operating
the 600 Mixer on several jobs will allow the opera¬
tor to achieve superb results in virtually any mixing
situation. Our variable Input attenuator allows for
much more flexibility than some other manu-