I bought a cheap computer Sub to repurpose it as a selfmade gaming vest. The circuit has 2 amplifiers on it, one for the normal unfiltered sound that goes to the 2 speakers, and then the output of this one is filtered and sent to a second amplifier for the subwoofer. The filtering is not great... I tried with a wave generator and got clear, loud sound up to 11.000 hz... I would like to add a low pass filter that has a cutoff frequency of 200Hz on the input of the second amplifier. I found a 1uF capacitor at home, and after googeling around i somehow came up that with that capacitor I would need a resistor of 820Ohm to have a cutoff frequency of roughly 195 Hz.

Is that correct? Wouldn't that resistor in series lower drastically the input volume to the amplifier?

  • \$\begingroup\$ RC filter calculator \$\endgroup\$ Dec 28, 2019 at 20:18
  • \$\begingroup\$ yep, already checked that.. so a 1uF capacitor and a 820 ohm resistor should give 195 hz cutoff frequency.. but what about the volume? \$\endgroup\$ Dec 28, 2019 at 20:19
  • \$\begingroup\$ @sharkyenergy um, what about the volume? That designer tool gives you a bode plot. \$\endgroup\$ Dec 28, 2019 at 20:28
  • \$\begingroup\$ @MarcusMüller, sorry, i am a mechanic and read about RC filters the first time 2 hours ago.. what is a bode plot? the signal going to the amplifier has an amplitude of about 20 mv... what worries me, is that adding the resistor will reduce the tension so much that i cannot hear anything... \$\endgroup\$ Dec 28, 2019 at 21:08
  • \$\begingroup\$ i just tried with a 10uF and a 82 ohm resistor.. according to the simulator it should cut the frequencies above 200 hz.. what it did was lowering drastically the output on all frequencies... as soon as i removed the capacitor it worked normally again.. \$\endgroup\$ Dec 28, 2019 at 21:21


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Browse other questions tagged or ask your own question.