- Published in issue 12/1990 on page 0
Although sales of gramophone record may have slumped, there are millions of peopte who still treasu re their record collection. Many record players unfortunately exhibit two undesired side effects: rumble (noise caused by the motor and the tu rntable) and other low-frequency spurious stgnals. The active high-pass Chebyshev filter presented here was designed to suppress those noises. The filter has a 0.1 dB ripple characteristic and a cut-oft point of 18 Hz. A note for designers: a passive filter with the same characteristics was tried: a si xth order Sessel filter; which was soon rejected when it was found that inductors of 600 H were needed!