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Crossover Polarity and Inductor?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=82693
Printed Date: June 15, 2024 at 10:17 PM


Topic: Crossover Polarity and Inductor?

Posted By: silentblackhat
Subject: Crossover Polarity and Inductor?
Date Posted: September 10, 2006 at 1:50 PM

I am wanting to build a third order crossover network.  What i am confused about is does it matter if the capacitor is polarized or not? The reason why i am asking is that a while ago when i first started getting into car audio, i got some bass blockers but wanted to learn to make my own so some instructions said to get a non-polarized capacitor. So, if it doesnt matter if its non polarized or not, if i get a polarized cap, im guessing the + side connected to the + lead of the amp, then the inductor and the + side of the 2nd cap connects to the "-"
 side of that cap and then the "-" of the 2nd cap conencts to the + of the speaker terminal. and ofcourse the otherside of the inductor connects to the "-" amp lead.

Also, is it possible to create ur own inductors? I am looking to make one that is about 1.2mH.  I saw a formula that on Howstuffworks.com says:

H = (4 * Pi * #Turns * #Turns * coil Area * mu) / (coil Length * 10,000,000)

The area and length of the coil are in meters. The term mu is the permeability of the core. Air has a permeability of 1, while steel might have a permeability of 2,000.

I am wondering if that is correct and how i would make one? if i got the right cylinder, would i just wrap the couil of copper wire around that? also if i did, could it be a wire that has a thin jacket over it so it wont short on anything in the car? an

any help is greatly appreciated




Replies:

Posted By: DYohn
Date Posted: September 10, 2006 at 3:51 PM
You need non-polarized caps because audio is AC, not DC.  Yes, it is possible to use two polarized caps connected in parallel and reversed polarity from one another, but it usually results in degraded sound quality.  Yes, you can wind your own inductors, people do it all the time.  Me, I find it is usually easier to buy pre-made inductors, and if I need a specialized size to buy larger than I need and unwind to the value I need.  Do a Google for "hand-wound inductors," there are some good resources on line.

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Posted By: silentblackhat
Date Posted: September 10, 2006 at 10:19 PM

ok lets say i need a 50µf capacitor.  would i get two 50µf capacitors and then hook them in parallel with reversed polarity or would i need two 25µf caps hooked in parallel with reversed polarity?  I really dont care about the sound quality. I am just using the crossover for a loudspeaker(the Radioshack 25watt 8-ohm loudspeaker) thats hooked upto an amp that i have a microphone hooked up to so it doenst matter if it sounds really great or not since it will only play someone talking.

thanks for all of the help so far, its helped a lot






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