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Author Topic: liquid cooled subs? alternative?  (Read 6348 times)

John Roberts {JR}

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Re: liquid cooled subs? alternative? heat sink?
« Reply #10 on: October 01, 2006, 04:09:03 pm »

Christian Effendy wrote on Sun, 01 October 2006 14:29

Wow, I didn't know that. Can you give me recommendation on where can I get those kind of FF? I think I need them, most problem I've found here are burned-up voice coils.
For tweeters, I've found that FF also smooth the freq. response. Will the same thing applied for woofers?

Thanks
Christian


http://www.ferrotec.com/products/ferrofluid/audio/

They offer two series of ferro fluid ("0" and "S")  presumably for woofers or full range use. I can't say that I've ever seen it used in such applications but I'm no speaker guy.

There was also a mention about it degrading from extended use above 125'C while it will tolerate 225'C transients, so good luck.

JR
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Wayne Parham

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Re: liquid cooled subs? alternative?
« Reply #11 on: October 02, 2006, 02:48:46 pm »


Quote:

Ferrofluid does not need a "sealed gap". It is held in place by the magnetic field in the gap. Venting is sometimes/almost always needed with woofers. Because the air displacement can blow a significant amount of the fluid out of the gap during high excursions.


That's right, exactly.  The point I was making is that some mechanism needs to be employed to deal with splash, especially in a subwoofer application.  You have to seal it some way or the fluid will separate and leak away.  Splash guards, alternate venting, something - The large gap and long excursion of a subwoofer make ferrofluid leakage a problem.

I imagine leakage is why there are more hifi tweeters and mids with ferrofluid than there are high-power subs that use ferrofluid.  It seems like a good solution to me, but the leakage problem is probably the hardest one to solve.  Eminence told me that's why they don't use ferrofluid - Too much leakage.  I forget if I heard that from Jerry McNutt or Chris Rose, but I do recall talking to them about it in the context of an upgraded LAB12 driver I was looking at having them make for me a couple years back.

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Paul Gariepy

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Re: liquid cooled subs? alternative? heat sink?
« Reply #12 on: October 09, 2006, 03:31:57 pm »

heres an idea:

have vents on side of spider and a big pc fan on back of magnet. instant active and continus cooling.

maby even vent the hot exhaust out the ports?

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Wayne Parham

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Re: liquid cooled subs? alternative? heat sink?
« Reply #13 on: October 10, 2006, 01:07:21 pm »


Paul Gariepy wrote on Mon, 09 October 2006 14:31

maby even vent the hot exhaust out the ports?


Surprisingly, the air coming from the vents isn't hot, not even warm.  Voice coil temperature can be 450
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John Roberts {JR}

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Re: liquid cooled subs? alternative? heat sink?
« Reply #14 on: October 10, 2006, 01:43:48 pm »

Wayne Parham wrote on Tue, 10 October 2006 12:07


Paul Gariepy wrote on Mon, 09 October 2006 14:31]maby even vent the hot exhaust out the ports?
==============

Surprisingly, the air coming from the vents isn't hot, not even warm.  Voice coil temperature can be 450
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Wayne Parham

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Re: liquid cooled subs? alternative? heat sink?
« Reply #15 on: October 10, 2006, 04:18:46 pm »


There's no question that loudspeaker venting is a good idea.  But as to how much heat is actually transferred from a loudspeaker voice coil into the cooling vent air, I suggest a simple test.  Connect a loudspeaker to an amplifier and run it at high power levels.  Check the temperature of the air coming from the vent.  You might be surprised.
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Christian Effendy

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Re: liquid cooled subs? alternative? heat sink?
« Reply #16 on: October 11, 2006, 02:51:56 pm »

Yeah, and with what you gonna measure the temperature of that air? Your body thermometer needs few minutes to do so Smile Most thermometer won't be fast enough to measure the temperature of air moving as fast as that.
Maybe the different is just few degrees and can't be felt by your hand. And the air moving back and fort in very rapid succession, as fast as the cone moving right? Your skin will be very confused to noticed the difference
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Mac Kerr

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Re: liquid cooled subs? alternative? heat sink?
« Reply #17 on: October 11, 2006, 03:03:27 pm »

Christian Effendy wrote on Wed, 11 October 2006 14:51

Yeah, and with what you gonna measure the temperature of that air? Your body thermometer needs few minutes to do so Smile Most thermometer won't be fast enough to measure the temperature of air moving as fast as that.
Try this.

Mac
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Paul Gariepy

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Re: liquid cooled subs? alternative? heat sink?
« Reply #18 on: October 12, 2006, 12:25:56 pm »

ok this calls for an experiment....

I have a digital temp meter and a laser temp meter and a bunch of pc fans, now i need to choose a speaker to "cook" and see if i can get some results. I'll keep you posted.


i just saw this... Tom beat me to it (and then some)! lol

http://www.freepatentsonline.com/4757547.pdf
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Mark "Bass Pig" Weiss

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Re: liquid cooled subs? alternative?
« Reply #19 on: October 15, 2006, 04:00:27 am »

Another very sticky issue is certain weak points in the voice coil assembly. One area that I have seen prone to failure in commercially produced woofers and lead drivers is the portion of the voice coil winding that turns 90
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