Another heat sink size question

Status
Not open for further replies.
Jump to Latest
#21
dmills said:
But you are running audio, not CW power, so your average power is going to be much lower then 120W, general audio design assumes 1/8th maximum power for thermal calculations, so heatsinks can be lot more reasonable.
Click to expand...

Thanks for answers. 🙂

So 120W of maximum output only dissipates 15W (1/8)?

Like this build here:

http://www.diyaudio.com/forums/chip-amps/79303-chip-amp-photo-gallery-231.html#post3287193

Surely it can not dissipate 120W, or even 60W.

These ones seems to be quite a typical size:

http://www.diyaudio.com/forums/chip-amps/79303-chip-amp-photo-gallery-225.html#post3236454

http://www.diyaudio.com/forums/chip-amps/79303-chip-amp-photo-gallery-227.html#post3259479
 
Last edited:
#22
Navyblue said:
I presume if I have build dozens of these things, I can take a look at a heat sink and tell if it is enough.
Click to expand...

Yes, pretty much.
But it includes both the practice, looking at data, and learning the basics.

Pretty of the chip amp datasheets is that they include both graphs and examples to calculate the heatsink C/W number.
Picking the heatsink still means going through data, not pics.
(a couple of heatsink manufacturers have catalogues, of their entire range, that can be downloaded)

Do it often enough, and you'll know a lot of standard heatsinks by type number & C/W range, plus able to tell in a second that the first reply you got was incorrect.
 
#23
read the datasheet for the 3886.
It shows you to the power dissipation vs power output in the plots.
A 4780 is a pair of 3886 with it's dissipation crippled by having the same Thermal interface AREA shared between the two chipamps.
 
Status
Not open for further replies.
Top Bottom