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So I have some older a/d/s/ PX tweeters which I don't know the impedence of, whether they're nominal 8 or 4 ohm tweeters. For the rears I have Diamond audio tweets (also no clue on specs) I have an a/d/s/ 860mx which I am going to go active on and I know my amp is notorious for pops at startup, and throwing DC in catastrophic failure... yes I've fried 4 of 8 channels on the amp and 6 of 8 speakers before... it is dangerous.

So I need a blocking tweeter cap. And found this nifty calculator :

http://www.the12volt.com/caraudio/crosscalc.asp

So you pick your crossover frequency, and divide by 2, so say I want to cross over at like 2250hz, my cap on my tweet would be like 1000hz (roughly 1 octave lower right? divide by half to get 1/2 octave in hz?)

So if I have an 8 ohm tweeter, that would give me my 1000hz with 20uF cap. But if I have a 4 ohm tweeter, that would give me my crossover at 2000hz, which is definetly going to run into my active crossover at 2250hz roughly (12db/octave).

What do you do if you aren't sure? Can I go to a lower cap crossover without having issues with sound quality? how close do you need to be?


I was just going to use the parts express metallized polypropylene caps.. i.e. here :

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=027-436

5$ a piece, not sure they're worth the Solen Cap price of 8$ a piece, but I dunno...

Is there a way to calculate the tweeter impedence with just a multimeter? I thought not since you'd have to measure it over the entire spectrum...

I did a search, but didn't quite get the answer I was looking for...

Any help would be appreciated, Best, Bill
 
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