Oberheim OB 12, Руководство по эксплуатации

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OB 12
Z-Domain Synthesizer
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Naturally, the above diagrams are only an example of the waveform leaving the filter, since as we
have seen, the waveforms generated by the two oscillators are much more complex.
The OB-12 makes available two filters, with total configuration with regard to their type (low pass,
band pass and high pass) and parameters of use.
As can be seen, the two filters can be set as:
•
LOW PASS (LP): high pass filter which attenuates all the frequencies above the cut-off
frequency. This attenuating action will affect all the harmonics above those present at the cut-
off frequency, thus giving the sound a darker and/or softer timbre.
•
HIGH PASS (HP): high pass filter which attenuates all the frequencies below the cut-off
frequency. Therefore, all the harmonics below those which coincide with the cut-off frequency
are attenuated; the resulting sound will be sharper and brighter.
•
BAND PASS (BP): band pass filter which attenuates all the frequencies not present in a band
having its centre at the cut-off frequency.
•
FLAT (no LED on): in this case the filter is not enabled and does not operate in any frequency
area.
In addition to this, the user can set the envelope of the two filters, meaning how the filter cut-off
frequency will change, thus regulating the timbre of the sound in relation to time.
An envelope generator supplies a time curve as output in real time. This is used to pilot the three
main components of a synthesizer described previously, within the synthesis chain.
Generally the filter and amplifier are controlled (as in the OB-12) by an ADSR envelope, ADSR
being the acronym of Attack, Decay, Sustain and Release.