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Old 2nd February 2004, 07:10 PM   #1
dumdum is offline dumdum  Wales
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Default Importance of Heatsinking

Well... would they? I have just been reading this.

So, could many/most mass-market amplifiers do with improved heatsinking? Would improved heatsinking result in greater power output and more powerful sound?
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Old 2nd February 2004, 08:50 PM   #2
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I just think better heatsinking leads to better component reliability.
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Old 2nd February 2004, 09:01 PM   #3
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The lifetime of the amp is very dependent of the temperature. You can also damage the amp easier if the cooling is not good and you have not so good protection circuits.

Dumdum, nice language (your location).
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Old 3rd February 2004, 04:59 AM   #4
dumdum is offline dumdum  Wales
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but no one has answered my question....

Can a bigger heatsink result in greater power output? If transistor derating occurs as early as 30degC.. can an amplifier that is operating closer to ambient result in more power i.e. less wasted power and less transistor derating?
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Old 3rd February 2004, 07:21 AM   #5
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Improved heatsinking would not give you a greater output power and more powerful sound!!!!
To achieve this you have to improve the heatsinking + the power supply + add some extra output devices!!!!
Many mass-market amplifiers are running just below their upper limit, and relies on a fast protection circuit for not to blow up
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Old 3rd February 2004, 10:07 AM   #6
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That doesn't make sense!! Please explain further.. Why bother with heatsinks at all? If derating occurs as early as 25degC then any excess of this temperature must be decreasing power output????!!!

Help. Someone.. it's perplexing me.
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Old 3rd February 2004, 10:54 AM   #7
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Default A small fan hides a multitude of sin - just like negative-feedback ;-)

If you want to try out the idea, just use a fan. Easy to change back to normal when you are finished. Aim the air on the transformer as well.
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Old 3rd February 2004, 10:56 AM   #8
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I'm not quite sure what kind of answer you are looking for

Let me clear one thing up!
Output power are NOT determent by the size of the heatsink,
but by Volts and Ampere!

A 1000W amplifier can deliver 1000W without heatsinks (but only in few mS before it blows up due to the missing cooling).

Most mass-market amplifiers have build-in protection circuits, that limits the maximum output voltage and current to a limit, where there manufacturer are sure that the amp will survive!

Adding more heatsinks doesn't change the protection circuit or raise the voltage from the power supply or adds more current output.

However if the standard amp gets hot during operation, additional heatsinking could be a good idea, having following effects:
- Expand the lifetime of the output devices
- Prevent the temp. protection circuit (if any) to cut off the amp
as soon as before...

Hope this have helped
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Old 3rd February 2004, 10:59 AM   #9
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Quote:
Originally posted by dumdum
That doesn't make sense!! Please explain further.. Why bother with heatsinks at all? If derating occurs as early as 25degC then any excess of this temperature must be decreasing power output????!!!

Help. Someone.. it's perplexing me.
No...de derating occurs at 25 degC but for the permissible dissipation in the transistor...the power output is function of the rail voltage and the current that the amp can supply to the load...

In a car analogy ...a bigger radiator don't make de car more powerfull...only let the car give the maximal power during more time...
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Old 3rd February 2004, 11:00 AM   #10
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Quote:
Originally posted by dumdum
That doesn't make sense!! Please explain further.. Why bother with heatsinks at all? If derating occurs as early as 25degC then any excess of this temperature must be decreasing power output????!!!

Help. Someone.. it's perplexing me.
Even if you have to derate the power with temperature, a heatsink
will allow you to dissipate more power, you start the derating from
a higher power level.

As a simplified example, suppose a transistor can dissipate 1 W
up to 25 deg and then derates lineraly up to 125 deg, where it
cannot dissipate any power at all. This means, that you can
dissipate 1W @ 25deg, 0.5W @ 75 deg and 0W @ 125 deg.
Now suppose you attach a heatsink that allows you to dissipate
10W up to 25 deg. Now you can dissipate 10W @ 25 deg, 5W @ 75
deg and 0W @ 125 deg. Quite a difference, even though you have
to derate the power.
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