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The Doepfer A-185-2 is designed to be a precision control voltage adder/buffer. This 'precision; means that the amplification of the inputs without attenuators is exactly 1.00, and is perfect for adding control voltages for controlling the pitch of VCOs. To achieve the 0.1% accuracy of added voltages, the A-185-2 uses summing resistors that are matched to 0.1%. The module features four CV inputs. One of these inputs is attenuable, whilst the other three are not. Each input is normalled to +1V, so if no plug is patched into the input, it contributes 1V to the sum appearing at the output. The input that features an attenuator can be used for common modulations for all VCOs that are connected to the module's output. The Lev.1 control is used for adjusting the depth of the modulation, whilst the first switch selects the polarity of said modulation. If no signal is connected to the first socket, then the attenuator will work as a fine tuning control knob, as a voltage in the range of 0V to +1V (right switch position), or 0V to -1V (left switch position) is added to the CV output.
The inputs without attenuation capabilities are designed to add CVs coming from sources such as sequencers, MIDI-CD interfaces, ribbon controllers, keyboards, and any other CV source that follows the 1V/Oct standard. Each input features a 3-position toggle switch, allowing you to select if the corresponding voltage is added, subtracted, or if the corresponding input has no effect. If there is nothing patched into the corresponding input, then the switch will work like an octave switch for the lower three sections, as the default 1V are added or subtracted to the output voltage according to the switch position. The first switch can be used to add a variable voltage to the sum output. The variable voltage is adjusted using the Lev.1 control, and the know then works as a form of fine tuning control. The module is also equipped with four outputs. Three of these are non-inverting outputs, whilst one of them is an inverting output. An internal jumper can be used to connect the non-inverted or inverted output to the CV line of an A-100 bus. That way, the module can be used to control several voltage-controlled oscillators that are connected to the same bus board as the A-185-2.
There is a pin header with three pines, labelled JP5, near the bus cable connector of the A-185-2. If no jumper is installed, then there is no connection between the outputs of the A-185-2 and the CV line of the A-100 bus. When there is a jumper in the lower position, the normal CV output of the module is connected to the CV line of the A-100 bus. When the jumper is in the upper position, the inverted CV output of the A-185-2 is connected to the CV line of the A-100 bus.
- Width: 6HP/30mm
- Depth: 50mm (Measured from the rear side of the front panel)