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rotated from the center to the left it I)roduces only about a 1 db. gain in the left channel while
attenuating the right channel by 60 db.
A system without this provision would produce excessive
apparent volume changes as a sound source was panned from one side to the other.
MASTER GAIN
The master gain control_s on the right end of the panel control the overall gain
of the respective outputs without altering the percentage of each input present.
These controls
have a 30 db operating range and are not designed to turn the output signal off completely.
OUTPUTS
The output jacks on the right edge of the panel provide a low impedance source for
driving extemal amplifiers or additional processing modules.
Anyone using the 4711 Mixer for other than synthesizer work will already have a good idea of what
they hope to do and the means of accomplishing it.
It is sufficient to say here that mixers are
required in the amateur or professional production of slide and film shows to mix together
background music with narration or in adding sound effects of various kinds to the program
material.
The ultimate mixers for these purposes have built in, adjustable equalizing (eq.)
networks and such niceties as echo send busses and Que buttons to allow the user to listen to each
channel individually.
All of these features are great to have but add significantly to the cost of the
console.
Synthesists are in a little different position.
To them a mixer is another processing module and
its ultimate usefulness will depend to a large extent on the creativity of the user.
To get you
started here are some examples.
PANNING
One of the current fads in a lot of Rock and Roll music is to mix the master tape so that various
instruments seem [o jump or glide from one side of the room to the other.
Using this technique
a single instrument can seem to be two instruments as when a lead guitarist plays a riff with one
setting of tone controls on the left and then switches tone control settings to play a second line
on the right.
As will be explained shortly this can also be done with a synthesizer set to produce
two entirely different voices.
Drums also work well at this and it is currently common practice
to mike each drum or small group of drums individually for placement later in the final mix.
Slowly panning a tom-tom or snare drum from left to right..( or around the room in quad) produces
striking effects.
Figure 8
To observe panning in action set up the simple voice shown in figure 8 .
Route the output of the
VCA into channel 1 of the 4711 and set the level control for that chamel and the left and right
master gains to '`max. " Oscillator and function generator parameters are not important here, set
them to something that pleases you and while playing the keyboard with one hand run the channel 1
pan pot from left to right to cause the sound Of the synthesizer to glide from one end of the room to
the other.
Two amplifiers are nice here but a stereo hi-fi amplifier can be used equally well.
10
VOICE twHENG
Popular groups famous for their synthesizer work rarely use a single oscillator waveform in
building a sound.
Different waveforms from the same oscillator can be mixed together to produce
new sounds or the output of two oscillators can be mixed to produce striking effects.
Mixing the
outputs of two oscillators produces much more life-like effects than mixing two outputs of the same
oscillator because no matter how precise and stable an oscillator is it will never be entirely identical
with another oscillator even Of the same type.
It is these slight differences that produce the very
slow time varying timbral changes in the sound of a natural instrument as well as a synthesizer.
(Some oscillators can be locked together with "synch. " inputs but this is not relevant to this dis-
cussion).
Figure 9
Figurey snows a voice that has been described as a ''berserk electronic trumpet" and its main
feature is the mixing of the outputs of two oscillators*.
The ADSR is set for moderately fast
attack and decay, about 3/4 sustain and moderately long release.
The AR controlling the VCA
is set for moderately fast attack and decay.
Note in particular in this cormection that the two
input charmels that are being used should be panned fully to the left so that none of their signal
appears in the right channel.
This leaves half of the 4711 unused and by panning the two remaining
inputs fully right they can be used as an independent mixer.
''SUBPATCHING"
While modular synthesizers are without question more versatile than equip-
ment with ''normalized" controls, the extensive patching required limits their use in live performance
work.
There is really no way to get around this inconvenience completely but a mixer can help by
allowing two or more voices to be set up in advance and selected with a single knob.
In principle this is a simple concept but in practice it can place great demands on the imagination of
the user.
Figure 10 shows a patch that RIchard Bugg used on the PAIA "Epsilon Bcotis" demonstra-
tion record.
The first voice is the manually swept VCO with a triangle output and this voice is
E;elected by bringing up the level on input channel #1 of the mixer.
The second voice is the pulse
width modulated VCO under keyboard control and is selected by bringing ap the level of charmel #2
of the mixer.
The balanced modulator here is used simply as a VCA and note that with this patch
a keyboard key must be held down even if the manually swept triangle is the selected voice.
____---------------------------.---------------______
*
PAIA 2720-2 VCO's can be used in this connection but lack the necessary stability to keep in
tune with one another for long periods of time.
Better choices would be PAIA 2720-2A and 4720.
in
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