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Heat sink orientation help
Heat sink orientation help
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Old 23rd January 2019, 01:56 PM   #11
Zen Mod is offline Zen Mod  Serbia
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Heat sink orientation help
years ago I tried big bada$$ heatsink ;

normally oriented - 350W of heat resulting in 55C on fins

horizontal - hardly 200W

go figure

though - above figure of 70-80W for what is sketched , I based on MF A1 , having 80W of heat thrown in laugh of heatsink , placed horizontally

when in temp. eq. , in summer days , I could manage no more than 3-5secs
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Old 23rd January 2019, 09:22 PM   #12
Itsmee is offline Itsmee  England
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Heat sink orientation help
You could drill lots of small (~3mm) holes in the 'vallys' to allow some air to flow, or add an SMPS powered Peltier heat pump, water/oil cooling maybe...
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Old 23rd January 2019, 09:30 PM   #13
McQuaide is offline McQuaide  United States
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Quote:
Originally Posted by Itsmee View Post
You could drill lots of small (~3mm) holes in the 'vallys' to allow some air to flow, or add an SMPS powered Peltier heat pump, water/oil cooling maybe...

In my opinion DIY amps are hard enough without adding unnecessary complexities and compromises.
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Old 23rd January 2019, 11:05 PM   #14
Itsmee is offline Itsmee  England
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Heat sink orientation help
Agreed, but heat removal isn't a compromise, it's a must.
And it depends on your skill set/level, some people find the casework the easy part.
You could also 'farm out' the machine work.

Last edited by Itsmee; 23rd January 2019 at 11:07 PM.
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Old 23rd January 2019, 11:13 PM   #15
McQuaide is offline McQuaide  United States
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Exactly, horizontal heatsinks with holes is a huge compromise.
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Old 23rd January 2019, 11:23 PM   #16
Itsmee is offline Itsmee  England
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Heat sink orientation help
It wouldn't be my choice, but if a fan was installed inside the case, and a little ingenuity with a plastic bag to make the ducting to the heatsink, voila, job done.

Or holes in the bottom of the case and ZM's Babysitter.

Last edited by Itsmee; 23rd January 2019 at 11:26 PM.
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Old 23rd January 2019, 11:27 PM   #17
Ben Mah is online now Ben Mah  Canada
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The OP also mentioned that he wants to place the heatsinks horizontally because of space limitations. This could mean that the amplifiers would be placed in a tight space with limited air flow, making conditions even worse. Seems to me that air movement by fan is the best way to make this situation work.
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Old 24th January 2019, 12:50 AM   #18
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Old 24th January 2019, 07:34 AM   #19
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I looked back at the Thermal Solutions article to see if I missed a zero, but 3% is their basic conclusion, though that is for a specific heat sink size and fin configuration.



The article Scottjoplin suggested provided a lot of practical information on mounting transistors, and chassis construction but did not address efficiency of horizontal vs vertical as did the thermal solutions paper 6L6 provided. Great article and I have another use for my tiny bicycle torque wrench.


That article points to many mounting and construction considerations that could cause significant changes in heat dissipation. Could there have been changes in the mounting of the transistors between Zen mods measurements of vertical and horizontal heatsink temperatures, or perhaps changes in how the heat sinks transferred heat to the rest of the chassis?


So far this has been a very interesting discussion and I appreciate all your input, I hope we can find a reason why Zen mod's direct experience differs from Thermal solution's predictions. It would be helpful to learn the reason why (or perhaps arrive at the conclusion that thermal solution's 3% conclusion is hot air )



Late, tired and run out of steam, forgive my less than elegant language.



Cheers, Jim
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Old 24th January 2019, 07:48 AM   #20
Zen Mod is offline Zen Mod  Serbia
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Heat sink orientation help
well , time will tell

I know that Japanese made 20L canister , size of matchbox ....... but its sorta hard to repeat

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