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Old 1st January 2007, 03:39 AM   #1
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Default crossover question Measure at 2500?

Do I need to know the impedence at 2500 to build a crossover, or do I just go by them factory nominal rating?

Thanks Ben
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Old 1st January 2007, 12:26 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

Neither. Build a documented and tested design.

/sreten.
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Old 1st January 2007, 01:11 PM   #3
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Been there done that. I have a bunch of Polk drivers that i want to build a speaker for. They are rated at 8 ohms, but I know the the imp changes with frequency. I have read Weems book on speaker building, and have seen different calculators on the net. They all assume that speakers are 4 or 8 ohms. I know frequency changes resistance so if the woofers go up to 12 ohms at 2500 do I need to build a crossover at 12 ohms or 8?

Thanks much Ben
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Old 1st January 2007, 02:00 PM   #4
sreten is offline sreten  United Kingdom
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Hi,

Its far more complicated than that. Possibly start here :

http://www.rjbaudio.com/Audiofiles/FRDtools.html

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Old 1st January 2007, 02:27 PM   #5
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I realize that building a crossover isn't a simple first shot kinda deal. I would just like an idea where to start. The seas tweeters I have selected are 6 ohms and dip to 5 ohms at 2500. There are plenty of calculators out there where you plug in the ohms of the speakers, crossover point, and what type of crossover you want to use. So my ? is pretty simple do I say 6 or 5 ohms?
Thanks for the link. Here is the site that I have been using for reference.

http://www.lalena.com/Audio/

Thanks Again Ben
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Old 1st January 2007, 02:32 PM   #6
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You need to measure the impedance rise with Speaker Workshop, Arta, or similar, and calculate a Zobel network to flatten the impedance curve.
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Old 1st January 2007, 03:18 PM   #7
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Thanks much. I do have speaker workshop, and I do plan on plotting out the woofers because Polk gives no specs with there woofers. They just sell replacement parts. Not a DIY supplier.
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