4 sk 102 heatsinks. what amp can it be used for??

[wuffer]

i have 4 SK 102 heatsinks

the height is 100mm

http://www.schuro.de/Daten/Fischer/SK47.pdf

is there any amp i could bould.. i havde the aleph p 1.7 preamp and i was thinking of yet an aleph

can it be done???

[Stabist]

at 100mm height - the factor is 0,4K/W - so I would take 2 and 2 heatsinks per each channel - if you want to stay on the very "safe" side - A3 is the choice - you'll have 20°C rise above ambient temp - with A5 that goes to 30°C ... Still very very OK!

The only thing is that the chassis will be very wide and depth - but quite low ... But personnaly - I like that ...

[wuffer]

thats nice.. i would look at the a5...

[uli]

if you mount 2 of these heatsinks in close proximity and thermally coupled (like making an amp side of 430mm length) the thermal resistance is not reduced in a linear manner. this means that you won´t achieve 0.2 K/W in this case, but rather 0.27 K/W - 0.3 K/W because the 2 heatsinks heat each other.

Uli

[wuffer]

thats not good.. right??

what is the best way to do it if i should use thise heatsinks???

[uli]

put the heatsinks on 4 sides, or build an Aleph 3 - you will be on the safe side(25-30° above ambient temperature)

Uli

[wuffer]

what if i make 2 mono blocks??? strange looking amp then i guess..

[uli]

Uli

[wuffer]

then i would go to the drawing board...

tanks

[jacco vermeulen]

Originally posted by uli
if you mount 2 of these heatsinks in close proximity and thermally coupled (like making an amp side of 430mm length) the thermal resistance is not reduced in a linear manner. this means that you won´t achieve 0.2 K/W in this case, but rather 0.27 K/W - 0.3 K/W because the 2 heatsinks heat each other.

If you look at the graph for this sinkprofile your story is correct if both heatsinks are placed on top of eachother, that's when 0.27 to 0.30 applies.
Heatsinks act like chimneys, place two next to eachother and each retains its function.
More important with Class A amplifiers is to put the heatsinks well above floorlevel so that cool air may flow to the bottom of the heatsink, warm and rise.
If placed parallel to eachother there is the effect of cross influence but with minimal effect.
Put a vertical plate to the open flange side of the heatsink and the thermal factor would be reduced to a significantly lower level than 0.20 at 100 mill (creating a true chimney).
A heatsink like that is extremely costly in production, therefore only done on special order.
Some manufacturers get around that problem by placing the heatsink in a duct, for example take a look at the Vincent SP991.

An idea for the true DIY'r, build a heatsink from 1/2 inch thick alloy plates, tapped and bolted together, with thermal grease at the joints. A heatsink shaped to favor, with excellent cooling ability, and a base plate of more favorable thickness for cooling high bias demands than regular alloy heatsinks.
The really cheeky use copper plates.