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MultiWay Conventional loudspeakers with crossovers 

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8th January 2005, 07:50 PM  #1 
diyAudio Member
Join Date: Jun 2003
Location: Canada

Need formula for contour network!! Anybody?
I need to design a contour network for a woofer and have been desperately looking for a formula. I found one at www.lalena.com but he is not sure if it's correct. Any information would be great..
sardonx
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9th January 2005, 12:06 AM  #2  
diyAudio Member
Join Date: Jan 2004
Location: Canada

Loudspeaker Design Cookbook by Vance Dickason  I have the sixth edition from 2000. Beginning at p. 147, there are descriptions of circuits for:
Quote:
dooper 

9th January 2005, 01:09 AM  #3 
diyAudio Member
Join Date: Jun 2003
Location: Canada

Dooper,
I'm interested in situation A. It's for the SS 7 inch revelator. The response starts to rise at 800hz and tops out at 1800 with a total rise of about 4db.
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9th January 2005, 02:11 AM  #4 
diyAudio Member
Join Date: Jan 2004
Location: Canada

1. L (in henries) = 0.15916 / f  in this case f = 400 Hz.
2. "R is selected so the combined impedance of the total circuit equals the amount of maximumneeded attenuation (or average if the rise is not welldefined), where: Z = (RX) / ((R ^ 2 + X ^ 2) ^ 0.5) Z = total circuit impedance X = component reactance at frequency of maximum attenuation" For an inductor, X = 2 * pi * F * L. Dickason suggests R = 5 ohms would result in 4.8 dB attenuation. The book has more info, formulas, and examples. It's well worth the money EDIT: The formulas on the Web page you posted appear to be the same as the ones in Dickason's LDC. Cheers, dooper 
9th January 2005, 01:41 PM  #5 
diyAudio Member
Join Date: Oct 2003
Location: North Georgia

Sardonx,
I used the 7" revelator in my previous system and as I recall, for the circuit you are asking about, L was .2 and R 23 ohms. I am not certain about either value...optimum reponse on your baffle may require different values anyhow. I also used a very subtle series RLC trap across the VC tuned to the ~800Hz impedance glitch in the rev. I don't remember those values at all, but the overall result of the two networks was much flatter reponse. You're on the right track...keep going. Paul 4way dipoles 
9th January 2005, 08:27 PM  #6 
diyAudio Member
Join Date: Jun 2003
Location: Canada

Thang you v much guys.
Paul, I came up with the same value of L too. As for the resistor I will experiment with it. I still haven't ordered the revelators but i know they will sound good. Slit paper rules. sardonx
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