EML SynKey Owner's Manual page 17

Fig. 6
3. Set the MODE control to HP (high pass)
and repeat the same exercise. Here, as you
rotate the TUNE control, the higher
overtones remain at the same strength while
the fundamental pitch and lower overtones
are successively diminished in strength. In
high pass mode, with the TUNE at 7, you'll
have a very thin sound, depending on pitch
range.
4. You have performed the preceeding with
the RESONANCE control set to 1. Now
return the MODE to LP (low pass), set
RESONANCE to 3 and rotate the TUNE
control back and forth. Set RESONANCE
successively to 4, 5, 6, & 7 and rotate TUNE
repeatedly.
Now in addition to diminishing certain
overtones, the filter is emphasizing the
overtones to which it is tuned. At higher
resonance you can readily distinguish the
individual overtones.
5. With RESONANCE set to 5 or 6, set the
ROOT WAVEFORM control to square (fU )
and rotate the filter TUNE. Return to the
sawtooth ( /\) and repeat. The difference
you hear is due to the fact that sawtooth has
both even and odd harmonics; while the
square wave has only odd. Each of the
waveforms depicted on the ROOT WAVE
FORM control has a different overtone
structure and will provide somewhat different
results after being modified by the filter.
The filter provides much to think about and
many possibilities. Practice, with various
settings of the TUNE, RESONANCE, and
MODE while playing simple pieces.
6. Return all controls to positions indicated in
Figure 4, except set RESONANCE to 5 and
ENVELOPE in the FILTER CONTROL section
to 5. Thus far you have been using static
timbres — now we are going to change
timbre with time.
Play a few notes and notice that the timbre
changes during the note. The position of the
ENVELOPE dial in the FILTER CONTROL
section determines the amount of timbre
change; while ATTACK, DECAY, and
SUSTAIN levels of the FILTER ENVELOPE
determine just how the timbre changes with
time. This effect is commonly called "envelope
sweep" or "filter sweep". What you are doing
is using the FILTER ENVELOPE voltage to
change the tuning of the filter electronically
rather than by rotating the TUNE control.
It is similar to changing loudness with
AMPLIFIER ENVELOPE.
7. Experiment — slowly — with various
settings of the filter TUNE, RESONANCE,
and MODE controls, the ENVELOPE control,
and the ATTACK, DECAY, and SUSTAIN
controls of the FILTER ENVELOPE.
8. Reset all controls to positions shown in
Figure 4, except RESONANCE at 5. Now
rotate the MOD. OSC. control in the FILTER
CONTROL section clockwise. You are now
using the modulation oscillator to "sweep"
the filter. The modulation oscillator is now
effectively changing the filter tune.
9. With MOD. OSC. in the FILTER CONTROL
set to 5 or so, go to the MODULATION
OSCILLATOR itself and manipulate the
SPEED and SHAPE controls. You will be able
to affect the rate of timbre change and how it
changes with time. Notice when the SPEED
is set high, the ear cannot distinguish how
the timbre changes with time. The ear simply
hears a new timbre. Experiment!
B. Ring Modulation — Ring modulation is a
process which generates non-harmonic
partials. Overtones are harmonic partials.
Their frequencies are integer multiples of the
fundamental pitch, hence the tone having
harmonic partials will be bright, but have
a well defined pitch. A source with non-
harmonic partials will tend to sound discord
ant. Bells, cymbals and chimes are examples
of instruments rich in non-harmonic partials.
They are often described as being clangorous.
The ear will regard tones with non-harmonic
partials as having a "different" timbre.
1. Set the SynKey's controls as shown in
Figure 5. Play a little tune, then depress the
RING push button.
2. Push m2 and release R while playing.
Repeat the process of depressing the next
semitone button and releasing the previous
one. You will find a wide variety of timbres
(not all will sound pleasant).
3. Experiment with various filter settings, filter
control settings and root waveforms while
using ring modulation.
C. Pulse Width Modulation — Pulse width
modulation creates a chorus effect — the
sound of a number of instruments playing
together. This is accomplished electronically
by using the FILTER ENVELOPE to control
the width of a pulse produced by the
VOLTAGE CONTROLLED OSCILLATOR. This
results in the phase of the oscillator signal
changing in time much like the phase
variations of a chorus of instruments.
Set up the SynKey according to figure 6.
Depress a key and notice the chorus effect.
Experiment with different settings of
AMPLIFIER ENVELOPE and FILTER
ENVELOPE ATTACK, DECAY, and SUSTAIN.
The amount of chorus effect can be
decreased by moving the ROOT
WAVEFORM control clockwise until it is
vertical where the effect will disappear.