PLEASE help me build an inductor

[guitar333]

I am trying to build an in inductor for my subwoofer to filter out the high and mids (when I hook my subwoofer up to my amplifer It basically acts like a midrange) and I do not want to buy a crossover, I would like to build one for the experience.........

anyways please tell me what materials I will need

I have a Rockford fosgate Punch Z 4-ohm 200w rms subwoofer (30Hz)

a Alpine 2x35w amp

So anyways what materials can I puchase from Radio Shack to make this work?

I am new to this....................

buy I chart I found by searching I need a 236uf non polarized capacitor and a 9 mH coil........right?

Where do I found a bobbin and how big? thanks

 

[Kanga]

If you have separate amps available for the subwoofer you would be much better off using a line level crossover. This way you have only very small value components to worry about, and you can change the XO frequency easily.

If not, you will probably be going for an iron-core inductor, unless you want to be carrying a lot of weight around.

What XO frequency and slope are you planning? For a sub a high slope is normally recommended (eg 24 dB/Oct, which is 4th order).
This means you will have two inductors and two capacitors
for a passive XO.

Mick

 

[guitar333]

well Im not too good with this stuff and I really want to build one (for experience)

I just want to filter out the highs and midrange so the subwoofer is only receiving bass, becaude right now my subwoofer sounds like a midrange.

I would like to wire it exactly like this:

but I dont know how to build the inductor

the sub is a 4ohm @ 30Hz

so where do i start from here on building an inductor

what parts will i need (preferably fromradio shack, here,

Using a calculator I figured this:
coil = 21.221 mHy
capacitor = 1326.33 ufd

Thanks

 

[JOE DIRT®]

guitar for the cost of going the passive route your going to be looking at atleast 100 dollars for half decent components....I would buy a 2 way active crossover unit.....the sound will be much better than going the passive route


Cheers!!The DIRT®

 

[Bill Fitzpatrick]

All things considered, you are better off buying an iron core inductor. Gathering the materials to wind your own will be a major pain - you won't find what you need at RatShack. Even were you to have the material, building the coil to the correct inductance value would be a second major pain.

In addition, the parts values you specified are probably textbook values that apply only to a resistive load and will not work exactly as intended with speaker loads. It might be close enough though, depending on how fussy you are.

But there are other considerations. If your woofer has only a single voice coil you're dead in the water because you could only hook it up to one channel.

If you have a dual voice coil woofer - or two woofers - and are determined to make your own crossover I suggest that you buy what you need from Parts Express or your local car audio installer.

I agree with Kanga that a first order filter will not be enough. Consider a second order at least.

$100 for the parts, as suggest by JoeDirt, is massive overkill for this project, IMO. But I do agree with Joe that bi-amping is the way to go if you have the funds available.