DOEPFER / A-110-4 Thru Zero Quad VCO

Variations

Module made by Doepfer, a German synthesizer manufacturer. Oscillator capable of generating very pure sine/cosine waves with minimal overtones and distortion.

The A-110-4 Thru Zero Quadrature VCO is an oscillator module. Quadrature" refers to this connection, which outputs sine and cosine waves simultaneously. Thru Zero" means that negative frequencies are generated. However, this is misleading, as negative frequencies do not exist. Negative simply means that this connection stops the sine/cosine wave when the linear CV reaches 0V, and then reverses the sine/cosine wave when the linear CV advances in the opposite direction.

This module has two sections: linear and exponential. The exponential section consists of an XTune control, a 1V/Oct input, and an XFM input and attenuator for XFM. The exponential CV is the sum of these three voltages. The linear section consists of the LFrq control, the LFM input, and the attenuator for the LFM. The linear CV is the sum of these two voltages. Dual color LEDs indicate the polarity of the linear control voltage (red = positive / yellow = negative).

The main advantage of the A-110-4 over other through-zero VCOs is its sine/cosine core. Sine/cosine waves are not generated from other waveforms (e.g. sawtooth or triangular), and the A-110-4 can generate very pure sine/cosine waves with minimal harmonics and distortion.

■Width: 8HP
■Depth: 60mm
■Current consumption
+12V : 90mA
-12V : 30mA