Moog Music SUB PHATTY - Manual (Page 17)

17
FILTER CONTROLS CONT.
The depth of the envelope’s effect on the cutoff frequency also depends a lot on the CUTOFF setting.
If the setting is very high and you adjust the EG AMOUNT to raise it further, then the envelope will have
little effect. The lower the cutoff frequency, then the more the envelope will be able to modulate it. On
the other hand, if the setting is very low and you adjust the
EG AMOUNT to lower it further by turning
the knob counterclockwise, again, the envelope will have little effect.
KB AMOUNT: Use this knob to specify how much the filter cutoff tracks the keyboard; that is, how
much the keyboard pitch affects the filter’s lowpass frequency. With
KB AMOUNT turned up halfway,
the filter cutoff will follow the keyboard pitch at a 1:1 ratio centered around middle C (MIDI note 60).
KB AMOUNT at maximum sets a 2:1 ratio for filter keyboard tracking.
ENVELOPES
OVERVIEW
When you make any sound, it may take
a moment for that sound to reach its
maximum amplitude and brightness.
This initial moment is called the sound’s
attack. An attack may be gradual (like
a cymbal roll), abrupt (like a cymbal
crash), or anything in between. The
attack often tells us more about how
an instrument is played than any other
characteristic. Likewise, when the
sound ends, it may take a moment to
die away completely, or it may stop
suddenly. This final drop in amplitude
and brightness is called its release. The
attack and release, along with variations
in amplitude and timbre that occur
between the attack and release, make
up the sound’s envelope.
The Sub Phatty shapes electronic sounds using two envelope generators (abbreviated EG). One
envelope affects the Sub Phatty’s filter, which controls timbre, and the other affects its amplifier, which
controls amplitude. When you press a key on the keyboard, it sends a signal that tells the envelope
generator to begin the attack. In voltage-controlled synthesizers like the Sub Phatty, this signal is called a
gate. The gate ends when you release the key, telling the envelope generator to begin the release.
Each of the Sub Phatty’s envelope generators has four stages: attack, decay, sustain, and release
(abbreviated ADSR). Just as attack is the time it takes a level to peak, the decay is the time it takes
to fall to a steady level, called the sustain. The sustain level is held until the note ends. At that point,
the signal returns to zero at a rate determined by the release setting. Whereas the attack, decay, and
release stages are specified as lengths of time, sustain is a control-signal level.