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I am attempting to design a low-pass filter for a subwoofer, as the audio amplifier that is connected to it does not filter any of the sound coming in, and it is getting pumped full of high frequency sound. I have settled on a Butterworth LC filter, and want a crossover frequency of around 200Hz. I have determined that I want a capacitor somewhere in the range of 140-160 uF and an inductor in the range of 4.5-6.5 mF to hit that frequency, and from a circuit standpoint, it seems to make sense. Source: this website

Here is where I hit a difficulty. I am aware that I don't want an inductor with very much DC resistance and is rated for a high current throughput (possibly in excess of 5A). I don't know which to choose.

I also am at a loss for the capacitor to choose, as I need one which is two-way (able to handle AC), but I am not sure for the other requirements of it. If anyone can clarify these points for me, and give suggestions as to the actual parts to use, I would be forever grateful. It is also worth noting that I am on somewhat of a budget, so please try to recommend affordable products, even if they have lower performance.

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  • $\begingroup$ "a capacitor able to handle AC" well, that's what capacitors do. $\endgroup$ – Marcus Müller Jul 6 '18 at 11:54
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    $\begingroup$ I'll be honest, and from experience, I'd say this question would probably work far better on electronics.stackexchange.com than here, not only because it's kind of only borderline about signal processing, but also because the low-level analog hardware audio guys are active over there, more than here. (not saying that we don't have great audio signal engineers here, but LC filters ... feels more electronic-y than signal process-y) $\endgroup$ – Marcus Müller Jul 6 '18 at 11:56
  • $\begingroup$ Haha, I did post it there, and they sent me over here. As for the AC business, it is true that capacitors can handle varying signals, but some of them have a specific polarity that will wreck the capacitor if current is pushed through the wrong way. electronics.stackexchange.com/questions/327664/… $\endgroup$ – RJP Jul 6 '18 at 11:59
  • $\begingroup$ @ReedPetersen I've addressed the matter of polarization in my answer, you probably missed it. Also about the inductor. And I don't see anywhere an answer or comment pointing you to dsp.ee, maybe I missed it? $\endgroup$ – a concerned citizen Jul 7 '18 at 6:42

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