How to choose right heatsink!?

Stabist · 29th September 2002, 08:15 PM

Hi!

I have some problems with designing the chassis for my Zen v4.

The thing is - I can get a heatsink a with 300x300x40 mesaurements - or the same one but cut on two identical halfs - that's 300x150x40. BUT now - if i check out the K/W diagram - the curve is more and more horizontal aproaching 150mm height (that's the point where the diagram ends) - at that point the K/W is around 0.32; I guess that at 300mm height it is somewhere 0.22-0.25K/W
So - if I use the lower one for just one channel - if Zen v4 has cca 100W disipation - that's 32°C over temp ..
If I use the big one for both (2x100W dissipation) - somewhere around 45-50°C over temp ...

Is that conslusion correct or not?!?

OK - so the solution is to make 15cm high chassis - but unfortenly the min. is at least 23cm because other demands

And also another thing - I would like to place heatsinks exclusively as a FRONT panel.
SO - my solution - if I place two 300x150 both on front - BUT leave between them cca 2cm of space - so the front panel would be 300x320 - will that improve cooling enough or not?!? Or are just my conslusions about cooling efficiency wrong and 300x300 will do his job just fine??
Same heatsinks Marijan (the picture and description of his amp is in passdiy/gallery) had used for his A2 monoblocks - two 300x200 for each monoblock. And he's quite satisfied with the result ... And as far as I know - each heatsink had to cool down 150W dissipation ...
Any sugestions very welcomed!

Another question - A3 and Zen v4 - can for both be used the same chassis with same heatsinks?? I think that dissipation is similar in both cases or am I wrong?

skaara · 29th September 2002, 09:06 PM

It is correct, but if you would use 1 big heatsink for 1 channel then it would be only 20°C over temperature and thats very good I guess..

Stabist · 29th September 2002, 09:17 PM

Skaara - your sugestion has only one failure - it increases the costs for the chassis for cca 85% of the price

And also - I would really like to make an amp with only front panel as heatsink ...

OK, there is also another solution that I might put as an option - front panel 300x300 heatsink - for main 4 mosfets ..
In the rear 300x50 heatsink as the top 5 cm of back panel for other 2 mosfets ...
That should be more than enough!

Peter Daniel · 29th September 2002, 09:57 PM

Quote:

Originally posted by Stabist

SO - my solution - if I place two 300x150 both on front - BUT leave between them cca 2cm of space - so the front panel would be 300x320 - will that improve cooling enough or not?!? Or are just my conslusions about cooling efficiency wrong and 300x300 will do his job just fine??

I think that leaving the space between sinks in that arrangement won't change much. The drawback here is uneccessary complexity of the chassis in return for dubious results.

Stabist · 29th September 2002, 10:22 PM

Peter - I assume the problem is in temperature of the air - it is allready warmer and altough I would separate heatsinks - the cooling efficiency cannot be improved - am I correct?

Btw - what about my comparison - if same model of the heatsink, just 200mm high is enough for 150W of A2 - then 300mm high surely must be enough for 200W of my stereo v4??
Because concerning that K/W diagram Marjan couldn't reach heatsink temp at around 60°C (around 35°C over temperature) -but he did it without problems!

Peter Daniel · 29th September 2002, 10:30 PM

Yes, its mostly the temp of air around heatsink.

And in this case 300mm should be enough for 200W.

29th September 2002, 08:15 PM	#1
Stabist diyAudio Member Join Date: Sep 2002 Location: Slovenia	How to choose right heatsink!? Hi! I have some problems with designing the chassis for my Zen v4. The thing is - I can get a heatsink a with 300x300x40 mesaurements - or the same one but cut on two identical halfs - that's 300x150x40. BUT now - if i check out the K/W diagram - the curve is more and more horizontal aproaching 150mm height (that's the point where the diagram ends) - at that point the K/W is around 0.32; I guess that at 300mm height it is somewhere 0.22-0.25K/W So - if I use the lower one for just one channel - if Zen v4 has cca 100W disipation - that's 32°C over temp .. If I use the big one for both (2x100W dissipation) - somewhere around 45-50°C over temp ... Is that conslusion correct or not?!? OK - so the solution is to make 15cm high chassis - but unfortenly the min. is at least 23cm because other demands And also another thing - I would like to place heatsinks exclusively as a FRONT panel. SO - my solution - if I place two 300x150 both on front - BUT leave between them cca 2cm of space - so the front panel would be 300x320 - will that improve cooling enough or not?!? Or are just my conslusions about cooling efficiency wrong and 300x300 will do his job just fine?? Same heatsinks Marijan (the picture and description of his amp is in passdiy/gallery) had used for his A2 monoblocks - two 300x200 for each monoblock. And he's quite satisfied with the result ... And as far as I know - each heatsink had to cool down 150W dissipation ... Any sugestions very welcomed! Another question - A3 and Zen v4 - can for both be used the same chassis with same heatsinks?? I think that dissipation is similar in both cases or am I wrong?

29th September 2002, 10:30 PM	#6
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	Yes, its mostly the temp of air around heatsink. And in this case 300mm should be enough for 200W. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

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29th September 2002, 09:06 PM	#2
skaara diyAudio Member Join Date: Jun 2002 Location: Europe, Slovenia	It is correct, but if you would use 1 big heatsink for 1 channel then it would be only 20°C over temperature and thats very good I guess..

29th September 2002, 09:17 PM	#3
Stabist diyAudio Member Join Date: Sep 2002 Location: Slovenia	Skaara - your sugestion has only one failure - it increases the costs for the chassis for cca 85% of the price And also - I would really like to make an amp with only front panel as heatsink ... OK, there is also another solution that I might put as an option - front panel 300x300 heatsink - for main 4 mosfets .. In the rear 300x50 heatsink as the top 5 cm of back panel for other 2 mosfets ... That should be more than enough!

29th September 2002, 10:22 PM	#5
Stabist diyAudio Member Join Date: Sep 2002 Location: Slovenia	Peter - I assume the problem is in temperature of the air - it is allready warmer and altough I would separate heatsinks - the cooling efficiency cannot be improved - am I correct? Btw - what about my comparison - if same model of the heatsink, just 200mm high is enough for 150W of A2 - then 300mm high surely must be enough for 200W of my stereo v4?? Because concerning that K/W diagram Marjan couldn't reach heatsink temp at around 60°C (around 35°C over temperature) -but he did it without problems!

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