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The main function of an amplifier is to control the level of the signals received from the oscillators
and the filters. Amplifiers may be Voltage Controlled Amplifiers (VCAs) or, as in the OB-12, Digitally
Controlled Amplifiers (DCAs).
VCAs consist of operational or differential amplifiers, while in the case of DCAs, since all it takes
to amplify a digital wave is to multiply its numerical width values by a given factor, amplification is
carried out by applying a width modulation to the oscillators. However, it is preferable to the keep
the two blocks (oscillator and amplifier) conceptually separate, for the sake of clarity.
As for the filter, an ADSR envelope (described in point 8.4) can be used to check the level of the
signal for amplification over time.
We will therefore now take a look at the display pages relating to programming of the amplifier
parameters. From the EDIT TIMBRE MENU page, select option 6-AMPLIFIER:
containing the following controls:
ATTACK
([ATTACK] of the AMPLIFIER section)
level once a note has been played. The values available range from 0 (no ATTACK time) to
100 (maximum ATTACK time).
DECAY 1
([DECAY] of the AMPLIFIER section)
(or DECAY 2 level, if present) from the maximum level. The range of values is from 0 (no
DECAY time (to 100 (maximum DECAY time).
SUSTAIN
([SUSTAIN] of the AMPLIFIER section)
maintains until the key is released (unless the SUSTAIN TIME is shorter than this period). The
range of values is from 0 (no signal after the DECAY) to 100 (maximum signal level, until the
key is released).
RELEASE
([RELEASE] of the AMPLIFIER section)
annulled after the key is released, in a range of values from 0 (no signal on release of the key)
to 100 (maximum signal release time).
You can now select the ADV-ENV folder to access the second page for programming of the
envelope applied to the amplifier:
Featuring the following parameters:
DELAY: sets a delay time from when a key is pressed to when the signal level starts to be
: sets the time the signal takes to reach its maximum
: regulates the time taken to reach the SUSTAIN level
: sets the SUSTAIN level, or the level the signal
: sets the time taken for the signal level to be
179
OB 12
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