polarized or non polarized capacitor?
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=120670
Printed Date: May 13, 2025 at 6:46 PM
Topic: polarized or non polarized capacitor?
Posted By: jetmech_jt8
Subject: polarized or non polarized capacitor?
Date Posted: March 11, 2010 at 10:25 PM
I'd like to add a cap to cut the low end to my dash speakers. Something around 1000Hz high pass. I'd like to know If Im supposed to be using a Polarized or non polarized cap?
Thanks
Replies:
Posted By: smtgolf
Date Posted: March 11, 2010 at 10:41 PM
Non Polarized if you want to use it as a filter.
Watch the voltage rating on any cap you select. You need something with a minimum 50v rating to make sure it won't fail on you. Some places are sketchy about that.
Posted By: smtgolf
Date Posted: March 11, 2010 at 10:45 PM
Forgot to mention:
Make sure you know the impedance on those things. It will change which cap you get to filter at 1000 Hz. 2 ohm speakers need a 80uf cap. 4 ohm need a 40uf cap. Check the passive crossover charts 4 ohm chart
Posted By: i am an idiot
Date Posted: March 11, 2010 at 11:03 PM
Depending on your amp, you may be better off purchasing 100 volt caps. I have sen many 50 volt caps explode. I have never seen a 100 volt cap fail in an automotive system.
Posted By: smtgolf
Date Posted: March 11, 2010 at 11:14 PM
How much power were you pushing through those 50v caps when they blew? Just curious. I've used 50v caps before but not in any really high power situations (i.e. under 200 watts).
Posted By: haemphyst
Date Posted: March 11, 2010 at 11:36 PM
You can also use polarized 80 microfarad caps, wired in series, and out of phase, i.e. the two positive leads connected together, with the negatives making the connections between the amp and speaker.
Doing this, you 1: double the voltage capacity, 2: create a non-polarized cap, and 3: halve the capacitance.
A possible solution for you that MIGHT be slightly less expendy.
------------- It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: jetmech_jt8
Date Posted: March 12, 2010 at 8:40 AM
Great site. Thanks for the help
Posted By: i am an idiot
Date Posted: March 12, 2010 at 9:29 AM
The 50 volt caps were not in my system. We have the most abusive customers in the world. Most of the ones I saw were built onto a 2 or 3 way speakers.
Posted By: smtgolf
Date Posted: March 12, 2010 at 9:43 AM
I am.....: That's what I was curious about. I see 50v caps wired onto speakers for cheap x-overs. I admit I've used a few in-line for cheap tweet filters. Wondered about those things failing vs. 100v caps.
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