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Figure 4-2 Phase Cancellation Effect
Distance
to Mic2
Distance
to Mic1
Sound
Cancelled
=
3.5 USING THE PAD
An input pad is nothing more than a resistive
attenuator that drops the level coming from the
input. Its purpose is to give you a way of prevent-
ing overload of the preamp when incoming signals
become excessive.
In the Channel, we provided a pad of 20dB. That
means when the pad is on, the net gain of the
preamp is 20dB lower. There are times that the input
may be overloaded even with the GAIN control set all
the way down. For example, a bass player with active
pickups and an agressive playing style might peak the
instrument input. Or a microphone on a kick drum
or snare drum could do it. Engage the pad and 20dB
of headroom will be provided allowing you to better
control the input signal.
3.6 USING LOW CUT
In the rearl world, mics pick up all sorts of unwanted
low frequencies such as handling noise, wind rumble,
or lectern thumps. We designed into the Channel a
very effective way of cutting out these low frequen-
cies. Switching on the LOW CUT FILTER rolls off all fre-
quencies below 70Hz at 12dB per octave but places
a slight compensation around 120Hz to improve the
low end phase distortion and perception of remain-
ing bass.
Figure 3-6 LO CUT
3. USING THE PHASE ROTATOR
The Channel’s phase rotator is designed to help
reduce high assymmetric peaks that often occur with
audio waves. By reducing the amplitude of assym-
metric peaks, and making the wave more symmetri-
cal, the voice can ride louder through compressors
and limiters. This is accomplished by displacing the
time relationship of even harmonics to their funda-
mentals. Thus, it is called a “Phase Rotator”.
Some words of advice:
When doing voice work while
wearing headphones, the Phase Rotator will affect
how you hear yourself even though it is not affecting
the actual sound of your voice. That’s because the
body-conducted sound mixes with the sound from
the “headphones”. When the two sounds are out of
phase, there will be partial to full cancellation at vari-
ous frequencies. Just as you experience the effect of
switching polarity, turning on the phase rotator will
have a pronounced effect.
You should evaluate the
phase rotator by auditioning recorded tracks made
with and without the rotator effect.
It should also be noted that the effecs of the Phase
Rotator are program dependant and results should
be evaluated with any new signal.
3.8 USING THE COMPRESSOR
The Channel’s compressor is probably the simplest
one to use that you will ever see. Nevertheless, it
is more sophisticated than compressors with many
more controls. The Easyrider compression automati-
cally adapts to audio waves in a manner that greatly
reduces any pumping effect while it tightens the
average level very flatteringly.
There is only one obvious control: RELEASE. How-
ever, the mic pre’s GAIN control doubles as the com-
pression drive adjustment. To get more compression
depth, run up more gain. The RELEASE control allows
you to chose the aggressiveness of the compression.
For thick and loud, go faster. For more natural and
“open”, go slower.
The gain reduction is displayed on the Channel’s 10
segment bargraph meter. You may need to boost the
output level to compensate for the gain reduction of
the signal.
Aphex Channel
