oneplustwo F5 build thread - Page 5 - diyAudio
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diyAudio Member

Join Date: Jan 2008
Location: So.Cal.
Quote:
 Originally Posted by oneplustwo Heat Sinks: Got the ones that Antek uses for this enclosure. \$25 each shipped with the trafo to help minimize costs (also ordered a B1 trafo and small heatsink.)
Did they come black anodized or did you send them out? I cannot locate these either on Antek's Ebay store or the website....

I'm considering these for a mini aleph build

Thanks

diyAudio Member

Join Date: Feb 2009
Quote:
 Originally Posted by oneplustwo Wow, my math sucks after being out of school for so long. Couldn't even properly keep track of the units. I will say, Antek claims it can dissipate up to 150W/channel so I have that going for me. Thanks for the resources, I'll do some reading. Ultimately, I'll probably just try it as is and see how much rise I get with an actual measurement.
150W on 0.6C/W?
150W x 0.6/W = 90C above ambient. that cooking the transistors.

diyAudio Member

Join Date: Feb 2009
Quote:
 Originally Posted by geraldfryjr I believe (although I am still learning about heatsink's myself) if the material is rated at .6 C/W per inch then your 5 inches of heatsink material should be rated at .6/5= .12 C/W. At 180 watts of dissipation the heatsink will be 180*.12= 21.6 degrees celsius above the ambient Temperature. This seems to be just about right. If I am wrong about this please somebody jump in here and correct me on this !!! I have been scoping out heatsink's for my build and I have been thinking of using some Ximatec CPU coolers. Newegg.com - XIGMATEK Gaia SD1283 120mm Long Life Bearing CPU Cooler bracket included LGA 2011 i7 i5 775 1155 AMD and dual fan push pull compatible For \$30 this one is rated at .15 C/W at least and is fairly quiet with a fan at 16-24 dba. XIGMATEK One of these will allow 333 watts of dissipation at temperature rise of 50 degrees celsius. It maybe a bit on the warm side with a total heatsink temp. of 75 degrees celsius. But, It is still below the safe limit for the devices as long as the heat pipe don't explode. It is not uncommon for these to be run at levels of 200 watts or so. I am considering about 2 to 4 of these would be good per channel for a Turbo F5 build. I will mount these to a thick aluminium or copper bar heat spreader to mount the output devices to. I am anxious to see how your build turns out. The only thing holding me back right now is were to source the JFET's so I don't end up paying so much for the shipping for just a few pieces. Keep on DIYin' jer
no. you don't doble the disipation with doble lenght. if 1 inch give you 0.6C/W you need 4 inches to get down to 0.3C/W. 16 inches to get 0.15C/W and so on.

Last edited by AudioSan; 18th February 2012 at 02:07 PM.

diyAudio Member

Join Date: Apr 2009
Location: San Francisco
Quote:
 Originally Posted by boywonder Did they come black anodized or did you send them out? I cannot locate these either on Antek's Ebay store or the website.... Did you contact them directly and ask about purchasing these individually? I'm considering these for a mini aleph build Thanks
They came black anodized. They are not listed individually but if you email John directly, he can send you a quote.

diyAudio Member

Join Date: Apr 2009
Location: San Francisco
Quote:
 Originally Posted by AudioSan no. you don't doble the disipation with doble lenght. if 1 inch give you 0.6C/W you need 4 inches to get down to 0.3C/W. 16 inches to get 0.15C/W and so on.
Ah, that makes more sense. So for 5", I'm looking at just under 0.3C/W.

Quote:
 Originally Posted by AudioSan 150W on 0.6C/W? 150W x 0.6/W = 90C above ambient. that cooking the transistors.
Assuming the above holds, then the 150W x 0.3/W =~ 45C above ambient. That seems to be within the operating parameters. And if I'm only worried about 62W with the F5, then I'm feeling better about things! Should be right around 20C above ambient.

Is that a fair conclusion? Regardless, like I mentioned earlier, I'll build it and measure the temp rise and go from there!

Last edited by oneplustwo; 18th February 2012 at 03:38 PM.

diyAudio Member

Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
43C temperature rise for 62 Watts

The Natsink natural convection heatsink simulator estimates a 43C temperature rise for 62 Watts using the Antek/Par-Metal heatsink. Some of my input data could be incorrect, but here is what I get:
Attached Images
 heatsink1.jpg (45.4 KB, 427 views) heatsink2.jpg (27.0 KB, 420 views)

diyAudio Member

Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Quote:
 Originally Posted by oneplustwo Ah, that makes more sense. So for 5", I'm looking at just under 0.3C/W. Assuming the above holds, then the 150W x 0.3/W =~ 45C above ambient. That seems to be within the operating parameters. And if I'm only worried about 62W with the F5, then I'm feeling better about things! Should be right around 20C above ambient. Is that a fair conclusion? Regardless, like I mentioned earlier, I'll build it and measure the temp rise and go from there!
That 150W rating is for both channels, so 2 x 62W x .3C/W = 37.2C above ambient. Natsink gives about 43C above ambient. Getting pretty warm.

 18th February 2012, 05:08 PM #48 diyAudio Member   Join Date: Feb 2008 Location: Jackson,michigan Thanks, Audiosan,For the correction, I couldn't remember off the top off my head if was halved by 2X of the area or the square of X of the area. Running through the calculator programs I had realized that I may have misspoke on that. Thanks Again !!! Jer
diyAudio Member

Join Date: Apr 2009
Location: San Francisco
Quote:
 Originally Posted by lhquam The Natsink natural convection heatsink simulator estimates a 43C temperature rise for 62 Watts using the Antek/Par-Metal heatsink. Some of my input data could be incorrect, but here is what I get:
Thanks for running the sim! I'm on a mac so I couldn't run it. The only number that is slightly different from what you had is the total height should be 2.3" or 59mm.

That won't make a material difference, but just for accuracy sake.

Also, just wondering if the ambient air is set at 25 or 40C? It wasn't clear to me in the screen shot. That should be closer to 20C... at least in my house!

Last edited by oneplustwo; 18th February 2012 at 06:39 PM.

diyAudio Member

Join Date: Mar 2010
Location: Olalla, Oregon: Land of the 100 Valleys
Quote:
 Originally Posted by oneplustwo Thanks for running the sim! I'm on a mac so I couldn't run it. The only number that is slightly different from what you had is the total height should be 2.3" or 59mm. That won't make a material difference, but just for accuracy sake. Also, just wondering if the ambient air is set at 25 or 40C? It wasn't clear to me in the screen shot. That should be closer to 20C... at least in my house!
Yes, rerunning the sim with total-height 59mm didn't make a significant difference.

I set the ambient air at 25C.

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