Heatsinking

A

Anna K

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Have you noticed that many mass-market amplifiers skimp or overlook optimal heatsinking?

If you glance at the derating curves for your particular transistor, you will see that derating (loss of power output and greater conversion of power to heat) occurs as early as 25degC tranny case temperature...

Surely if you could keep the heatsinks cooler, they would last longer and maybe sound better at elevated levels due to more current being outputted as electrical energy rather than as heat?

I fitted larger heatsinks to my amp and I think (obviously not 100% sure) that I have have noticed a slight improvement in sound... amp is considerably cooler to the touch now at high listening levels... certainly nothginbg will be hurt by doing this and life of the unit will probably be extended..

Anyone...?
 
I've not tried it, but the say that silver loaded heat sink compound can have the same effect.

I might give it a try if I see some at resonable cost.
 
Be aware that many devices actually have a live voltage on the back panel, and must be electrically isolated from the heatsink. Use a suitable material like Bergquist Silpad or Warth K177/K200.

Compounds like Arctic silver have superb thermal performance if applied thinly, but electrical isolation can be an issue.
 
If you glance at the derating curves for your particular transistor, you will see that derating (loss of power output and greater conversion of power to heat) occurs as early as 25degC tranny case temperature...
Click to expand...
That's not what 'derating' means.

Paul
 
Anna,

To survive around here one has to get used to this kind of comments... :latte:
 
The amount of power dissipated in a transistor is defined by the circuit, signal and load and is independent of the temperature. The amount of power you can dissipate in a transistor before it pops is defined by the design and reduces as the temperature inside the transistor rises. The latter reduction is 'derating'. Changing the heatsink has no effect on the amount of power a transistor dissipates.

Paul
 
Originally posted by Paul Ranson
If you have 'thermal runaway' then soon enough your transistor won't be passing any current.

And obviously you can pass more current through a cooler transistor, this is what 'derating' is all about. But it's not what you said in your first post. To be precise it's not current but power that concerns us.

So where's the extra power going to come from?

Paul
Click to expand...

Yes but since even George Bush knows that Power is V x I, therefore if the tranny can output more current and voltage rails are generous, output power will increase..

I am saying that many/most budget mass market amplifiers might be under-specced in the heatsink department. I am wondering whether many of these amps would perform more optimally (yes I mean output more power) if the heatsink was increased in size and better attention was made to clamping the trannies tightly so as to better dissipate heat... I am wondering whether the heatsink is a bottleneck.. I am wondering whether many modern amps with their often over-specced transformers have the voltage capacity to spare.. is heatsinking a power output bottleneck at elevated listing levels?
 
Anna K (Gary) has been banned. Gary, regardless of provocation, or "who started it", threatening physical violence to anyone on the forum or their family and friends is, I'm afraid, a one way ticket to the banned list :mad:

Michael.
 
I don't see any threats or anything?

Or have the offending posts been deleted?
 

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