amp heatsinks.

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Commercial home amps have internal heatsinks with very thin fins.
Yet heatsinks from Jaycar etc have rather thick fins.
Which actually works better, thin or thick fins??

Re: amp heatsinks.



"S Roby"
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**  More description needed.

Commercial amps have all kinds of different heatsink designs.


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** Depends how they are made, ie extruded, machined or fabricated.

  The ones used in domestic amps are the very lowest COST for their job.



..........  Phil



Re: amp heatsinks.


On Mon, 24 Oct 2005 05:39:52 GMT, snipped-for-privacy@gooble.gooble (S Roby) put
finger to keyboard and composed:

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I would expect that the heatsink with the most surface area per unit
volume would work best, all other things being equal.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Re: amp heatsinks.



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**There's no one, correct answer. The heatsinks you've seen usually take two
forms.
1) A slab of flat aluminium bar, is (for want of a better term) 'planed',
until very thin strips of metal are formed, curved and away from the bar.
The central bar is reasonably thick and there's lots of surface area, so it
works well.
2) A central bar of aluminium has an accordion shaped piece of aluminium
bonded to it, with approximately the same effect as #1.

Thick fins allow more thermal mass and, in some cases better heat transfer.


--
Trevor Wilson
www.rageaudio.com.au



Re: amp heatsinks.



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forms.
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until very
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is
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bonded to
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Trevor,

what is the significance of thermal mass in a heatsink? With constant
dissipation
isn't thermal mass irrelevant?

-Andrew M



Re: amp heatsinks.



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**Sort of, however:

* Amplifiers do not generate constant amounts of heat.
* Large amounts of aluminium allow better heat transfer (lower thermal
resistance).


--
Trevor Wilson
www.rageaudio.com.au



Re: amp heatsinks.


to keyboard and composed:

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forms.
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until very
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bar is
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bonded to
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dissipation
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Heatsinks move heat in three ways - conduction, convection, and
radiation. For a given geometry, a heatsink's mass determines its
conduction efficiency, its surface area its convection efficiency, and
its radiation efficiency is improved by anodising or painting it. For
a typical finned heatsink there is an optimal spacing below which
efficiency begins to decrease. My memory is not good enough, but I
believe the reason involves some principle of fluid dynamics, maybe
drag. In any case closely spaced fins more readily collect dust.

If I were you I'd search for app notes and datasheets from companies
specialising in this field. I expect heatsink design is more of an
empirical exercise than a theoretical one.

This article looks useful:
http://www.electronics-cooling.com/Resources/EC_Articles/JUN95/jun95_01.htm

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

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