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Module A-185-2 is a precision control voltage
adder/buffer. Precision means that the amplification of the inputs without
attenuators is exactly 1.00 and is suitable to add control voltages for the pitch
control of VCOs (e.g. from keyboard + sequencer 1 + sequencer 2). Summing
resistors matched to 0.1% are used to obtain an accuracy of 0.1% for the added
voltages.
The module is equipped with four CV inputs: one
with attenuator and three without attenuator. Each input is normalled to +1 V
(i.e. if no plug is inserted the input contributes 1 V to the sum appearing at
the output). The input with attenuator can be used for common modulations (e.g.
from an LFO, ADSR, Theremin, Pitch-Bender) for all VCOs connected to the output.
The inputs without attenuators are planned to add control voltages coming out
of keyboards, sequencers, Midi-to-CV interfaces, ribbon controllers or
other CV sources that follow the 1V/oct standard. For example the CV of a
keyboard can be used to transpose the CV coming from a sequencer, or the CV of a
slow sequencer can be used to transpose the CV from a fast sequencer.
Each input is equipped with a three-position
switch that determines if the corresponding voltage is added (right position),
subtracted (left position) or if the input has no effect (center position). If
no plug is inserted the corresponding switch works as an octave switch as the
default 1 V are added or subtracted to the output voltage according to the
switch position.
The module is equipped with 4 outputs: three
non-invertíng and one inverting ouput. An internal jumper
can be used to connect the non-inverted or inverted output to the CV line of the A-100 bus. That way the
module can used to control several VCOs that are connected to the same bus board
as the A-185-2 (same functionality as A-185-1).
Remark for A-185-2 users: There is a pin
header with three pins (labelled JP5) near the bus cable connector. If no
jumper is installed there is no connection between the outputs of the A-185-2
and the CV line of the A-100 bus. In the lower position the normal CV output of
the A-185-2 is connected to the CV line of the A-100 bus. In the upper position
the inverted CV output of the A-185-2 is connected to the CV line of the A-100
bus.
Attention: The module comes with an installed jumper, i.e. one
has to remove the jumper if e.g. an A-190 or A-185-1 is already connected to the
CV line of the same bus board! If the A-185-2 should be used as CV source
for the A-100 bus the CV connection of another CV source (e.g. A-185-1 or
A-190) has to be removed. Otherwise a short circuit is made between the outputs
of the CV transmitters !
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