Any drawbacks to using ferrofluid in a low-excursion woofer?

454Casull · 9th December 2006, 03:55 AM

Or retrofitting a pro woofer (of course the excursion would be kept in check)...

Power compression should be reduced, at least.

infinia · 9th December 2006, 05:07 AM

Hi
Unless it's used in a low power midrange the fluid would get blown out of the gap reducing the heat flow benefits of the oil itself. Unless you could ensure this from happing ... I'm really not sure what you are asking/ getting at. Seems most VC power is dissipated by the air flow across the coil and former itself, so wouldn't it be a net loss if using oil for this application as it would block air movement. But like anything else it depends upon all the other factors/details as well?

454Casull · 9th December 2006, 07:28 AM

Unless there is inherent forced-air cooling (such as the dust cap forcing air through notches/vents in the pole piece of JBL's VGC woofers), ferrofluid should conduct heat away from the voice coil much more efficiently, since the thermal conductivity of air is less than almost anything except other gases.

infinia · 9th December 2006, 12:23 PM

A wise man once said "Identify and characterize a problem before you attempt to solve it".

I think this is more complicated than I know how to handle with out empirical data. As you pointed out movement might be a problem here. Possibly adding shearing forces to the oil and it's solid content perhaps reducing it's effectiveness. It's benefits to tweeter design is well known allowing the VC and former to be lighter at higher power levels.

Thermal compression is the problem then devise a test to see how bad it is and if the oil can be a solution indeed.

sreten · 9th December 2006, 12:48 PM

Hi,

My observation is that if something works people do it.

Ferrofluid damped woofers don't exist, tells me it doesn't work.

/sreten.

infinia · 9th December 2006, 01:14 PM

Quote:

Originally posted by sreten
Hi,

My observation is that if something works people do it.

/sreten.

Good thing the innovators don't think like this, else we all would be living like the Amish.
Maybe not a bad thing (Amish) on the other hand.

AKN · 9th December 2006, 01:37 PM

Hi,

I know at least one pro audio manufacturer who uses ferrofluid in their woofers namely Community.

Se for example this Pro sub:
http://www.community.chester.pa.us/f...34e616cc06391f

Would be interesting to see their solution in more detail.

sreten · 9th December 2006, 03:40 PM

Quote:

Originally posted by infinia

Good thing the innovators don't think like this, else we all would be living like the Amish.
Maybe not a bad thing (Amish) on the other hand.

You misunderstand, there were plenty of attempts to make FF woofers,

/sreten.

9th December 2006, 03:55 AM	#1
454Casull diyAudio Member Join Date: Jan 2004 Location: Toronto, ON, Canada	Any drawbacks to using ferrofluid in a low-excursion woofer? Or retrofitting a pro woofer (of course the excursion would be kept in check)... Power compression should be reduced, at least.

9th December 2006, 05:07 AM	#2
infinia diyAudio Member Join Date: May 2005 Location: Californication	Hi Unless it's used in a low power midrange the fluid would get blown out of the gap reducing the heat flow benefits of the oil itself. Unless you could ensure this from happing ... I'm really not sure what you are asking/ getting at. Seems most VC power is dissipated by the air flow across the coil and former itself, so wouldn't it be a net loss if using oil for this application as it would block air movement. But like anything else it depends upon all the other factors/details as well? __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust

9th December 2006, 12:23 PM	#4
infinia diyAudio Member Join Date: May 2005 Location: Californication	A wise man once said "Identify and characterize a problem before you attempt to solve it". I think this is more complicated than I know how to handle with out empirical data. As you pointed out movement might be a problem here. Possibly adding shearing forces to the oil and it's solid content perhaps reducing it's effectiveness. It's benefits to tweeter design is well known allowing the VC and former to be lighter at higher power levels. Thermal compression is the problem then devise a test to see how bad it is and if the oil can be a solution indeed. __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust

9th December 2006, 01:37 PM	#7
AKN No snake oil diyAudio Member Join Date: Aug 2005 Location: In the middle of Sweden	Hi, I know at least one pro audio manufacturer who uses ferrofluid in their woofers namely Community. Se for example this Pro sub: http://www.community.chester.pa.us/f...34e616cc06391f Would be interesting to see their solution in more detail. __________________ / Anders

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9th December 2006, 07:28 AM	#3
454Casull diyAudio Member Join Date: Jan 2004 Location: Toronto, ON, Canada	Unless there is inherent forced-air cooling (such as the dust cap forcing air through notches/vents in the pole piece of JBL's VGC woofers), ferrofluid should conduct heat away from the voice coil much more efficiently, since the thermal conductivity of air is less than almost anything except other gases.

9th December 2006, 12:48 PM	#5
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, My observation is that if something works people do it. Ferrofluid damped woofers don't exist, tells me it doesn't work. /sreten.

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