Ferro cooled or not

soongsc · 8th May 2005, 04:55 AM

I have been playing around with some drivers testing the impedance charatersitics. I seem to see a trend that ferro fluid cooled drivers show some jaggedness (like noise) in the impedance graph, while those not ferro fluid cooled have impedance curves really clean.

I wonder what other people experience.

CMBYA · 8th May 2005, 08:14 PM

Have you tried warming them up first with a test tone, pink noise or even music? Ferrofluid has a tendancy to migrate toward any magnetic 'hot spot' inside the gap and therefore become distributed unevenly in a FF cooled driver. By warming them up I jsut mean 10-15 seconds of stimulation to distribute the FF. Try it both ways and see if it makes a difference.

soongsc · 9th May 2005, 01:23 AM

I normally test many times to mak sure I get consistent results, eachg test runs about 5 seconds, but do not intentinally warm them up. The ferro ones normally come up with impedance curves that look like they were created using a zig-zag stich.

CMBYA · 10th May 2005, 06:31 AM

I suppose there is some fluid dynamics taking place in the gap that may cause that. At certain frequincies It may be more difficult for the ferrofluid to get out of the the way of the former as it moves up and down. Is there any way you could post a curve? I think I know what you mean by the curves looking zig-zag but I want to see if I am thinking of the same thing that you are describing. I am going to look into some of the drivers at my work and see if ther is a correlation between ferrofluid and the jaggedness of curves.

soongsc · 10th May 2005, 07:59 AM

This is a non ferro.

soongsc · 10th May 2005, 08:02 AM

This a ferro.

8th May 2005, 04:55 AM	#1
soongsc diyAudio Member Join Date: Mar 2005 Location: Taiwan	Ferro cooled or not I have been playing around with some drivers testing the impedance charatersitics. I seem to see a trend that ferro fluid cooled drivers show some jaggedness (like noise) in the impedance graph, while those not ferro fluid cooled have impedance curves really clean. I wonder what other people experience. __________________ Hear the real thing!

9th May 2005, 01:23 AM	#3
soongsc diyAudio Member Join Date: Mar 2005 Location: Taiwan	I normally test many times to mak sure I get consistent results, eachg test runs about 5 seconds, but do not intentinally warm them up. The ferro ones normally come up with impedance curves that look like they were created using a zig-zag stich. __________________ Hear the real thing!

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8th May 2005, 08:14 PM	#2
CMBYA diyAudio Member Join Date: May 2005 Location: Philadelphia, PA	Have you tried warming them up first with a test tone, pink noise or even music? Ferrofluid has a tendancy to migrate toward any magnetic 'hot spot' inside the gap and therefore become distributed unevenly in a FF cooled driver. By warming them up I jsut mean 10-15 seconds of stimulation to distribute the FF. Try it both ways and see if it makes a difference.

10th May 2005, 06:31 AM	#4
CMBYA diyAudio Member Join Date: May 2005 Location: Philadelphia, PA	I suppose there is some fluid dynamics taking place in the gap that may cause that. At certain frequincies It may be more difficult for the ferrofluid to get out of the the way of the former as it moves up and down. Is there any way you could post a curve? I think I know what you mean by the curves looking zig-zag but I want to see if I am thinking of the same thing that you are describing. I am going to look into some of the drivers at my work and see if ther is a correlation between ferrofluid and the jaggedness of curves.