Elektron Analog Four MKII, User Manual

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14. MORE ON OSCILLATORS, FILTERS, AND ENVELOPES
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LP2 This 12 dB/octave lowpass mode attenuates frequencies above the cutoff frequency with twelve
decibels per octave, similarly to most other classic 2-pole VCFs. The amount of resonance determines
how much the frequencies around the cutoff frequency will be boosted. The sound of this filter is
cleaner than the ladder filter, and their different sonic characters are both worth trying out. If com-
bined, they can add up to an extraordinarily steep 6-pole filter.
LP1 This unorthodox 6 dB/octave lowpass mode has a less steep attenuation slope above the cutoff
frequency than the LP2 mode. More high-frequency content will thus be retained, making the filtering
less aggressive. The slope is gentle like a 1-pole filter – which normally cannot have resonance – but
works in essence like a 2-pole filter with a resonance peak. The amount of resonance determines how
much the frequencies around the cutoff frequency will be boosted. The LP1 mode is useful for equaliz-
er duties without resonance, or for adding a resonance with just a hint of lowpass softness.
BP The bandpass filter gradually attenuates frequencies above and below the cutoff frequency with a
slope of 6 dB/octave. The resonance setting controls how much the frequencies around the cutoff fre-
quency will be boosted. The bandpass filter is good for isolating a sound in the frequency spectrum,
making it easier to blend with other sounds in a mix.
HP1 This unusual 6 dB/octave highpass filter attenuates frequencies below the cutoff frequency with a
less steep slope than the HP2 mode. The amount of resonance determines how much the frequencies
around the cutoff point will be boosted. Besides ordinary highpass filter effects, the HP1 mode without
resonance is useful for removing some of the bass of a sound, which in turn is helpful when you want
to avoid a muddy mix.
HP2 This is a classic 12 dB/octave highpass filter, attenuating frequencies below the cutoff frequen-
cy. The filter slope is steeper compared to the highpass 1 filter, thus filtering out more low-frequency
content. The amount of resonance determines how much the frequencies around the cutoff point will
be boosted. A highpass filter is suitable when creating lead sounds or hi-hats.
BS The band-stop filter, also known as a band-reject or notch filter, works as an inverted bandpass
filter. Signals around the cutoff frequency will be attenuated the most, while frequencies above and
below the cutoff frequency gradually will become less and less affected. The higher the resonance,
the narrower the filter notch will be. This means that in contrast to the other filter modes, the effect of
the resonance parameter is greatest at a low setting, giving a wider notch. This filter shape is useful
for both basic equalizer duties and unique filter effects. For example: sweeping the cutoff frequency
with an LFO gives a phaser-sounding filter effect. Controlling it with an envelope while at the same
time using the ladder filter gives a more complex filter sound. Static filter settings can give a some-
what acoustic resonant quality to sounds, especially transient-heavy ones.
PK The peak filter passes all the sound, boosting frequencies around the cutoff frequency. The higher
the resonance, the more they will be boosted. A peak filter comes in handy when you want to highlight
a certain characteristic of a sound, by for example adding more low end or more mid end. It can be
used either statically, as the peak of a parametric equalizer, or dynamically, controlled by for example
an LFO or envelope.
14.3 ENVELOPES
The amplitude envelopes and the assignable envelopes offer 12 different shapes, consisting of six basic
shapes each with two different trigging behaviors. The envelope shape graphics indicates how the envelope
will affect the modulation destination. The left portion of the graphics shows how the envelope behaves
when it is rising, i.e. the attack phase, and to the right the falling behavior is shown, i.e. decay and release.
The rise and fall can each be either linear or exponential, useful in different applications as described below.
A dot to the left of the visual representation of the envelope indicates that the envelope will restart from
level zero each time it is trigged. Envelope shapes without a dot mean the envelope will start from the level
it had when being trigged.
0–1 Linear attack and decay/release. An envelope shape suitable for controlling the filters if linear attack/
decay/release sweeps are desired. When used as an amplitude envelope the decay and release phase
appears to drop quicker towards the end, making it most useful for sounds that should fade out without a
tail.
2–3 This can be considered the standard envelope shape. Decay and release fall quicker in the beginning
of their phase, behaving more snappy and – just like acoustic sounds tend to do – leaving a tail instead of
ending abruptly. This envelope shape is useful for creating distinct sounds, for example, kick drums and
basses, but also lengthier sounds like pads.
4–5
Exponential attack, linear decay/release. This shape makes the envelope rise quicker and quicker.
This envelope is suitable when for example creating sounds appearing to be played in reverse or for
sounds requiring a sudden attack.