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The Doepfer A-147-2 VCDLFO features a voltage controlled LFO with Triangle, Sine, Sawtooth, and Rectangle waveforms. The LFO also features a Reset/Sync input. The Triangle/Sine and Rectangle are displayed by means of dual colour LEDs, whilst the Sawtooth uses a uni-colour LED. The output levels are roughly -4V to +4v for the Triangle, Sine, and Rectangle waves, and the Sawtooth level is roughly 0V to +8V. You are given the ability to switch the CV control between Attenuator and Polarizer mode using the handy 'CV Mode' switch. When in Polarizer mode, the CV inputs affect the frequency in the reverse manner when the CV control is set to the left of the centre position. When set to the central position, CV has no effect, whilst positioning it to the right of the centre will cause it to work like a normal attenuator. The frequency without external CV ranges from 0.005Hz (roughly 3 minutes per period) to 200Hz. With external CV, the maximum frequency is roughly 1kHz. You can also enable an 'ultra-low- mode using an internal jumper. When the jumper is set, a fixed voltage is connected to the switching contact of the LFO CV socket. When the CV control is in Polarizer mode, extremely low frequencies are possible.
The A-147-2 is also equipped with a linear VCA that can be switched between normal VCA modes, and voltage-controlled Polarizer VCA modes using the 'VCA Mode' switch. In normal mode, amplification of +1 is achieved using a +5V CV. In Polarizer mode, the amplification ranges from roughly -0.5 with 0V CVs to +0.5 with a +5V CV. With around +2.5V CV the signal is suppressed. The VCA can also be treated as a DC-coupled ring modulator in this mode. The VCA is equipped with 3 available sockets - In (the signal input), Out (the signal output), and CV (the control voltage input). The Triangle output of the LFO is normalled to the VCA's signal input by means of the switching contact of the VCA In socket. If another LFO waveform (or any other signal) should be processed by the VCA, the corresponding signal must be patched to the VCA In socket. The VCA is also able to be used independently from the LFO and the Delay CV. In this case, the VCA's sockets (In, Out, and CV) must be patched accordingly. The VCA can also be used as a waveshaper for the LFO signals.
The VCDLFO also features a third and final sub-unit, which is a simple voltage-controlled envelope generator with a single parameter labeled Delay (or Attack). This sub-unit generates a linear increasing voltage that starts from 0V after each Delay reset until it reaches roughly +5V. Then the voltage remains at +5V until the next Delay reset occurs. The gradient is controlled by the manual Delay parameter control and the Delay CV input. The waveform is linear, whilst the control scale is exponential. The output voltage is displayed by a uni-colour LED and is available at the Delay Out socket. The manual Delay control ranges from roughly 5ms set fully clockwise, up to 2 minutes when fully counter-clockwise. This range can be extended using an external voltage applied to the Delay CV socket. A rising CV results in a shortened delay time. The Delay output voltage ranges from roughly 0V to +5V. The rising edge of the gate, clock, or trigger signal applied to the Delay Reset sockets resets the delay output voltage to 0V. Delay Out is normalled to the VCA CV input by means of the switching contact of the VCA CV socket, and sonsequently controls the Triangle level provided that no other patch is made. The Delay sub-unit can also be used independently from the LFO and VCA, such as using it as a voltage-controlled waveshaper, or for other applications where a linear increasing signal with voltage controlled steepness is required.
- Triangle/Sine/Rectangle Output Level: -4V to +4V (Symmetrical)
- Sawtooth Output Level: 0V to +8V (Positive Only)
- Frequency Range (Without External CV: 0.005Hz (Roughly 3 Minutes) to 200Hz
- Frequency Range (In Ultra Low Mode Or External CV): Roughly 1 Hour to Roughly 1kHz
- VCA CV/Amplification:
- 0V to +5V For Amplification 0 to +1 (In VCA Mode)
- 0V to +5V For Amplification -0.5 to +0.5 (In Polarizer Mode)
- Delay Range: Roughly 5ms to Roughly 2 Minutes