Oberheim OB 12 Operating Manual - page 64
OB 12
Z-Domain Synthesizer
8.8 EDIT KEYBOARD MODE
184
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CUTOFF RATIO: sets the cut-off frequency of the filter referred to above, in relation to the
frequency of the signal leaving the LFO, specified with the RATE parameter. The values
which can be selected are the following:
-1/2: filter cut-off frequency half an octave lower than that of LFO2.
0: filter cut-off frequency equal to that of LFO2.
1/2: filter cut-off frequency half an octave higher than that of LFO2.
1: filter cut-off frequency one octave higher than that of LFO2.
1+1/2: filter cut-off frequency 1.5 times higher than that that of LFO2.
2: filter cut-off frequency two octaves higher than that of LFO2.
3: filter cut-off frequency three octaves higher than that of LFO2.
OFF: filter disabled.
The purpose of the KEYBOARD MODE section is to set the modes of the keyboard and its
transposition. This allows use of the Portamento and Unison function, set the keyboard in
monophonic mode (with addition of Legato) or polyphonic mode, and regulate the transposition
of the oscillators (and thus of the notes played on the keyboard). From the EDIT TIMBRE MENU
video page, select the 8-MODE field and the display will show the following editing page:
containing the following parameters:
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PORTAM.STATUS
(Portamento Status, [PORTAMENTO])
: enables or disables the Portamento
function. Portamento allows you to make changes in pitch between a note and the one played
after it within a given period of time and not simultaneously with the pressure on the key, so
that the intermediate tones are produced.
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PORTAM.TIME
(Portamento Time, [TIME])
: sets the time of the Portamento, meaning the continuous
change in pitch between a note and the one played after it.
For a clearer understanding of this function, look at the illustration below: