How do you design a zobel

AllenB · 19th September 2009, 03:08 AM

My front mains are peaky above 1kHz and the crossover only has an inductor. I think I can improve things by adding a zobel network across the woofer out terminals of the crossover but I need a formula I can use. I don't want to measure the impedance, I'd rater do trial and error but I need the formula to put me in the right starting place.

tinitus · 19th September 2009, 03:57 AM

how big is your inductor
what kind of woofer
what kind of tweeter
are there no cap on tweeter

MJL21193 · 19th September 2009, 04:07 AM

A Zobel reduces the rising impedance of the woofer...you need to have the DC resistance (measure with a meter) and the Le (electrical inductive equivalent of the driver)( from the T/S specs.

Then it's: Rz = Re x 1.25
Cz = Le / Rz^2

Where Rz is the zobel R, Cz is the zobel C.

AllenB · 19th September 2009, 04:07 AM

how big is your inductor....don't know. By looking I'd guess no bigger than 150mH
what kind of woofer....6 inch kevlar cone
what kind of tweeter....1 inch silk dome. Rolls off below 2k.
are there no cap on tweeter....4.5uF and small value adjustable resistor.

Oh, and there is no available value for Le.

MJL21193 · 19th September 2009, 04:15 AM

Quote:

Originally Posted by AllenB

Oh, and there is no available value for Le.

Given the lack of available information and your obvious aversion to effort, you'd best forget about a zobel.

AllenB · 19th September 2009, 04:26 AM

To be honest, I'm not even sure whether the full zobel would be a good thing. The crossover was obviously designed to be an improvement on the raw drivers and if I go full zobel I'll also have to re-do the inductor, then I'll need to re-do the tweeter. I'd rather buy better speakers.

I do appreciate your help. I measured re as 3.8 ohms so I'll try a 4.7 ohm resistor.

19th September 2009, 03:08 AM	#1
AllenB diyAudio Member Join Date: Oct 2008	How do you design a zobel My front mains are peaky above 1kHz and the crossover only has an inductor. I think I can improve things by adding a zobel network across the woofer out terminals of the crossover but I need a formula I can use. I don't want to measure the impedance, I'd rater do trial and error but I need the formula to put me in the right starting place.

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19th September 2009, 03:57 AM	#2
tinitus diyAudio Moderator Join Date: Nov 2005	how big is your inductor what kind of woofer what kind of tweeter are there no cap on tweeter

19th September 2009, 04:07 AM	#3
MJL21193 Account disabled at member's request Join Date: Mar 2007	A Zobel reduces the rising impedance of the woofer...you need to have the DC resistance (measure with a meter) and the Le (electrical inductive equivalent of the driver)( from the T/S specs. Then it's: Rz = Re x 1.25 Cz = Le / Rz^2 Where Rz is the zobel R, Cz is the zobel C.

19th September 2009, 04:26 AM	#6
AllenB diyAudio Member Join Date: Oct 2008	To be honest, I'm not even sure whether the full zobel would be a good thing. The crossover was obviously designed to be an improvement on the raw drivers and if I go full zobel I'll also have to re-do the inductor, then I'll need to re-do the tweeter. I'd rather buy better speakers. I do appreciate your help. I measured re as 3.8 ohms so I'll try a 4.7 ohm resistor.