Doepfer A-114 Vintage Edition, Dual Ring Modulator@+Module A-114 contains two separate ring modulators. A ring modulator outputs the product (multiplication X * Y) of the input signals X and Y. The difference to a VCA is that both input voltages can be positive and/ or negative while the product still has the correct algebraic sign on the output (4-quadrant multiplication). The VCA, on the other hand, allows only positive voltages for the control input (2-quadrant multiplication). The ring modulation is thus an amplitude modulation for both positive and negative input voltages. Ordinary amplitude modulation will output the original carrier frequency fC as well as the two side bands (fC - fM, fC + fM) for each of the spectral components of the carrier and modulation signals. Ring modulation however doesn't supply the carrier frequency. A ring modulator is used, for example, for producing bell-like sounds or for speech alienation., Vintage edition with black front panel, Black front panel, Width: 4HP/ 20.0 mm, Depth: 40 mm (measured from the back of the front panel), Power Requirements: +40 mA (+ 12V)/ -30 mA (-12V)