Audio filter

Thread Starter


Joined Oct 31, 2011
I would like to make an audio filter.. let me explain.

In electronic music, there is a common effect of filtering out the high frequencies of the music, using a potentiometer to change the cutoff of the filter. Such filters are on synths and mixers.

I would like to build one for use with mp3 players. The purpose may sound silly, that's fine.. I want to talk about concept.

I learned in school about active filters. I figure that I can take a low-pass filter design and then choose a frequency that I would want such a cutoff filter to start at (I have to think about this more carefully) and then maybe choose a potentiometer value (say 10k), then use the formula C = 1/(2∏*f*R) to find which capacitor value I should use.

Is my theory straight so far?

I was wondering about the output impedance of my mp3 player. I think I have to make sure to have input resistors of the right value or else I could over-load the mp3 player and possibly damage it. Can anyone tell me more about this? How might I find the impedance of a given source?

Anyways, the plan for the device would be to have a 1/8" input and output. I will use a powered amplified speaker plugged in to the output for sound.