Inductor value?

B.VDBOS · 7th March 2004, 09:56 PM

Hi, I've just had a look at the pasive crossover for my 3 way speakers and I found an Iron core inductor for the woofer

I want to replace this with an air cor inductor to see if it makes an improvement, maby my bass will stop dissapearing at high volumes

Does anybody know a way of measuring an inductor to find its value? I dont know the crossover points of the speakers or any thing like that.

I have a multimeter and a p.c baced frequency generator if that helps?

Any advice would be a help

Billy.

sobazz · 7th March 2004, 10:29 PM

You could use your computer - if you have a sound card capable of recording the same signal on line in as is played on line out without internal feedback. Speaker Workshop here enables you to measure passive components. Depending on the values of the components (the higher the values the greater the relative deviation) and how precise your calibration of the software is useable. Certainly good enough for crossover components, since the values typically are very low.

There are some PC based scopes. They might be able to do the same. I don't know.

Good hunt!

Bill Fitzpatrick · 7th March 2004, 10:34 PM

Plug the frequency generator into a pre-amp connected to a power amp.

Wire a film capacitor (about 5mfd, 5%) in series with the inductor and a 10 watt wirewound resistor (about 20 ohms or so). Connect this network across the amps speaker terminal.

Attach the multi-meter across the resistor. With the volume set fairly low, adjust the frequency of the generator so that the reading of the multimeter is maximum. This will find the LC resonant frequency.

Then:

L = ((159235/F)^2)/C

Where L is in microhenries, F is in KHz and C is in picofarads.

7th March 2004, 09:56 PM	#1
B.VDBOS diyAudio Member Join Date: Aug 2003 Location: Auckland, New Zealand	Inductor value? Hi, I've just had a look at the pasive crossover for my 3 way speakers and I found an Iron core inductor for the woofer I want to replace this with an air cor inductor to see if it makes an improvement, maby my bass will stop dissapearing at high volumes Does anybody know a way of measuring an inductor to find its value? I dont know the crossover points of the speakers or any thing like that. I have a multimeter and a p.c baced frequency generator if that helps? Any advice would be a help Billy.

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7th March 2004, 10:29 PM	#2
sobazz diyAudio Member Join Date: Apr 2003 Location: Jutland	You could use your computer - if you have a sound card capable of recording the same signal on line in as is played on line out without internal feedback. Speaker Workshop here enables you to measure passive components. Depending on the values of the components (the higher the values the greater the relative deviation) and how precise your calibration of the software is useable. Certainly good enough for crossover components, since the values typically are very low. There are some PC based scopes. They might be able to do the same. I don't know. Good hunt!

7th March 2004, 10:34 PM	#3
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	Plug the frequency generator into a pre-amp connected to a power amp. Wire a film capacitor (about 5mfd, 5%) in series with the inductor and a 10 watt wirewound resistor (about 20 ohms or so). Connect this network across the amps speaker terminal. Attach the multi-meter across the resistor. With the volume set fairly low, adjust the frequency of the generator so that the reading of the multimeter is maximum. This will find the LC resonant frequency. Then: L = ((159235/F)^2)/C Where L is in microhenries, F is in KHz and C is in picofarads.

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