Doepfer A-143-4 Quad LFO/VCO Eurorack Module

Module A-143-4 is a fourfold voltage controlled low frequency oscillator (LFO). As the frequency range includes moderate audio frequencies it can be used as a four-fold VCO too.

• four independent VCLFOs/VCOs with triangle core
• frequency range switches: low (bottom position) = LFO mode, high (top position) = VCO mode
• two frequency control CV inputs for each unit
• CV1 without attenuator (~ 1V/oct)
• CV2 with attenuator
• manual frequency control
• internal jumpers for the frequency range of the manual frequency controls:
• jumper not installed: ~ +/- 1 octave range (mainly for VCO applications)
• jumper installed: ~ +/- 5 octaves range (mainly for VCLFO applications)
• Sync inputs:
• combined Reset/Direction inputs for unit #1 - #3
• separate Reset and Direction inputs for unit #4 (normalled sockets, i.e. Reset is connected to Direction if the Direction socket is unused)
• up/both/down direction switch for unit #4, for technical details concerning the Reset and Direction function please refer to the sketch below
• triangle and rectangle outputs for each unit
• typ. output voltage range -5V ... +5V for both outputs (i.e. about 10 Vpp, symmetrical with reference to 0 V)
• red/yellow LED displays for the triangle outputs (red = negative output voltage, yellow = positive output voltage)
• common control section with two CV inputs and manual control (these inputs and controls affect the frequency of all four units)
• sum outputs for triangle and rectangle with red/yellow LED displays
• optional ultra-low frequency mode: for this a negative voltage can be applied via a jumper internally to the CV2 input of each unit and the common section (i.e. a negative voltage is normalled to the socket CV2 in question). Then the CV2 attenuator control works as a negative frequeny control (i.e. turning up this control lowers the frequency). Herewith LFO periodes up to about one hour (or even more) are possible.
• optional CV bus access via jumper (i.e. the module can pick up the CV from the A-100 bus, e.g. generated by a Midi/CV or USB/CV interface A-190-x or a bus access module A-185-1/2), if the jumper is installed the bus CV affects all four units as the bus CV is added to the CV generated by the common control section
• typ. frequency range: < 0.001 Hz (~ one hour, LFO mode with ultra-low option) ... 15 kHz (VCO mode with installed frequency range jumpers for the manual frequency controls)
• heat-up time: ~ 15 minutes (required to heat-up the main circuit by the affixed oven)