المشاركة الأصلية كتبت بواسطة MEENA
Long time a go I have been implementing this project I could't remeber the exact circuit and technology of 30 years ago quite differ than now
Any way the idea is to make preamplifier then split the audio input to three diffrent frequencies Lo Mediam and Hi, let say Lo from 20Hz to 3.5Khz by using Lo filter then the medium frequency by using mid range filter of rang 3.75kHz to 8.5Khz and the last Hi filter from 8.75Khz and up
the out put of each filter need to be rectified and converted to DC the level of the DC voltage directly proportional to the center frequency of each filter stage
(plus/minus delta fo) and apply the voltage to a linear valve that change the opening of the valve according to the frequency
I am expecting a new technology that have more sophisticated solution may be my old idea will help you
I used at that time a filter called Twin T by usinf LM741 op amplifier.