Installing Quadro effect
Specialists of the German Democratic Republic created the installation "Quadratec" creating pseudocategories sound effect. Schematic diagram of the setup is shown in the figure. The main signals are emitted heads Gr I Gr. The difference signal is radiated additional heads HR and HR included in antiphase. Resistors R6 and R7 serve to reduce the level of the signal applied to the additional head.
Capacitors C1 and C2 .limit the bandwidth of the signal. entering additional head and she is 500-5000 (8000) Hz.
Selection of operation mode (stereopony or pseudophedrine) is a push-button switch Q2. Switch v3 change the level of the signal on the secondary heads. In the left, under the scheme, the position of the switch B1 head HR and HR in addition to the difference signal to radiate a portion of the main signal, and in the right position - only the difference signal.
Radio fernsehen electronik (GDR). 1974. N19
RADIO N 6, 1975, c.60.