crossover question Measure at 2500?

ben62670 · 1st January 2007, 03:39 AM

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

sreten · 1st January 2007, 12:26 PM

Hi,

Neither. Build a documented and tested design.

/sreten.

ben62670 · 1st January 2007, 01:11 PM

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

sreten · 1st January 2007, 02:00 PM

Hi,

Its far more complicated than that. Possibly start here :

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

/sreten.

ben62670 · 1st January 2007, 02:27 PM

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

pinkmouse · 1st January 2007, 02:32 PM

You need to measure the impedance rise with Speaker Workshop, Arta, or similar, and calculate a Zobel network to flatten the impedance curve.

ben62670 · 1st January 2007, 03:18 PM

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.

1st January 2007, 03:39 AM	#1
ben62670 diyAudio Member Join Date: Dec 2006	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

1st January 2007, 02:32 PM	#6
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	You need to measure the impedance rise with Speaker Workshop, Arta, or similar, and calculate a Zobel network to flatten the impedance curve. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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1st January 2007, 12:26 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Neither. Build a documented and tested design. /sreten.

1st January 2007, 01:11 PM	#3
ben62670 diyAudio Member Join Date: Dec 2006	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

1st January 2007, 02:00 PM	#4
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Its far more complicated than that. Possibly start here : http://www.rjbaudio.com/Audiofiles/FRDtools.html /sreten.

1st January 2007, 02:27 PM	#5
ben62670 diyAudio Member Join Date: Dec 2006	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

1st January 2007, 03:18 PM	#7
ben62670 diyAudio Member Join Date: Dec 2006	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.