Audio low pass filter (crossover)?

Looking at a crossover inside a speaker box, I see some inductor coils and capacitors. As  understand, it seems capacitors are high pass components, and inductors are the low pass components.

What is the formula converting frequency in Hz into inductance of the inductor coil and/ or value of the capacitor. (I would be looking for a crossover around 30 - 40 Hz)

To me, it seems logical to put this crossover not in the speaker box, but in front of the amplifiers, so the remaining audio spectrum can selectively amplified, which should result in some more power...  True?

(I see some recommendations for active crossovers, but the theory is way over my head).


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usbg3rd5 years ago
hi if u r trying to use a band pass filter to enhance your bass or something like that don't use IT WILL REDUCE POWER on the other hand now how to do so

use this ic
TDA1524 it is a preamplifier that will not only give u an option to enhance the certain frequencies like a band pass but also maintain the power so that the amplifier amplifies it as it does to a normal signal
in case u are looking for a schematics u can check this link
https://www.instructables.com/id/32W-Stereo-Audio-Amplifier/

i have made u can see in the video output is awesome :)

incase of any issue u can mail me at dinitrogenoxide@ymail.com
It depends on the response of the filter you are trying to make. Low frequency passive networks are harder to make because of the component values needed.

An active design is a lot neater.....

This site had a nice calculator for passive ones though.
www.bcae1.com/xoorder.htm

Is this for your subwoofer ?

Steve
BobS (author)  steveastrouk7 years ago
I found an extension for 'Foobar' which sorts various frequencies to the sound ports of the 5.1 or 7.1 sound cards. To make an 'infra-sound' sub, I need to find a fan with metal blades. Unfortunately, still not found. Can only go to the city recycling center when I have something to BRING... So still unable to test it...
BobS (author)  steveastrouk7 years ago
Right now in the research phase. Hopefully I'll find enough parts during spring cleaning season (broken sub, fan) to start building before summer! By that time, I might even understand active crossover design....
I HAVE a redundant passive crossover for a Sub, if you get stuck
;-)
Steve
NachoMahma7 years ago
> What is the formula converting frequency in Hz into inductance of the inductor coil and/ or value of the capacitor.
.  Search for "LC filter calculator" or "crossover calculator" (w/o the quotes)
.
> it seems logical to put this crossover not in the speaker box, but in front of the amplifiers,
.  That's precisely what a bi-ampped system does, but it requires more amplifiers.
Yes, an "active sub" is a useful thing to have.