Copper Heatsinks

[laatsch55]

Now that makes sense Larrt, the half bend part. Titanium......Hmmmmm........


Didn't want to flow at all, because the amount of heat that was needed was way over what the flux and solder needed to wet and flow. Roasted those chemocals out of the mix real quick.

 

[speakerman1]

I'm trying to remember what I was thinking.

Larry

 

[Gepetto]

Brazing would have been easier than soldering. Nice job Lee. Looks very high end with copper heatsinks on it.

 

[laatsch55]

Yes, halfway through the process that occured to me also. Something about the forest for the trees thing......
Feels very high end, 13 more pounds of higher ending.
I can't see a run on these kinda things. In fact if I didn't feel I had to perfect the process before building Ed's set, these would not have been built. Kinda glad I did though, the 700B set will be an appropriate offering to the Pl amp god.

Making mistakes on 1/8 inch by 6" copper plate is not an inexpensive undertaking.

 

[mlucitt]

Those big copper plates look awesome. Knowing they will get warm feels awesome. I would think you could pull out the thermostats on this unit Lee, I know they were spec'd for the aluminum heat sinks but it is unlikely they will be needed for the large copper shark fins you have there. A plus is that you can delete some of that AC wiring on the back of the amplifier.

 

[laatsch55]

Very true Mark. had to get Larrt's 700 done. I did, replaced the zoebel, all is well now. Then the 400 goes up on the bench, my cherry is a non-worker.

 

[speakerman1]

How hot will they get? Do you have a digital therm?

Larry

 

[laatsch55]

Yep Larrt got one I plug into my Fluke, and the two analog from the previous experiment are going on the back wall, one on each side, helds with clay. Then we'll know.
Ed linked me to 10 articles cpomparing copper and aluminum heatsinks.
Here's some--http://www.ecnmag.com/articles/2010/04/comparing-impact-different-heat-sink-materials-cooling-performance
http://www.vettecorp.com/support/downlo ... ore_v6.pdf
http://www.monachos.gr/eng/resources/th ... tivity.htm

http://www.datrondynamics.com/Copper_He ... t_Sink.htm
http://www.thermal-solutions.us/copper-heatsinks.html
http://www.vettecorp.com/product/heat_s ... _sinks.php

http://www.electricmaterials.com/copper-extrusions/

http://www.electricmaterials.com/images ... llMill.pdf
http://www.alphanovatech.com/?gclid=COq ... QgodNzEAJQ

 

[laatsch55]

Had a good talk with Ed on the phone tonight. He suggested as did Don Imlay to run the test 400 at 4 ohms and around 70 watts , so here we go. the object is to see if the thermal cutout switch will activate indicating an overheat condition.

 

[laatsch55]

The temp on the chassis back wall got to 205 deg F. The thermoswitch was supposed to open at 194. Took a good 20 minutes to get there. It was still climbing, would not have been able to stabilize temp.

 

[Skratch]

The thermostats that Phase used were not of the best quality. Their stated tolerance is +/- 5% which I don't believe. On my PLWO 1000 I had the amplifier shut down on hi-temp and when I touched the outputs I could hold my finger on them, they were not 200 degrees probably a lot less.

 

[speakerman1]

I'll bet they are as cool as a babies behind. We used a high temp antisieze. I mean exhaust temps. Would that work as a conductive compound.Here is the spec sheet. Look at the temps.IMHO you are going to have to treat the base for corrosion. It will not take long to reduce the efficiency.Even with this stuff you made them squeal coming out. They are all 12 point bolts. You better not round one off. Snap On 12 pts. Certain tools price is not an option.

http://www.barnhillbolt.com/specs/loctite51007tds.pdf

Larry

 

[laatsch55]

Oh no Larrt, could ot hold the finger on the TO-3 cases, VERY HOT. The heat was being transferred VERY well. A constant 1Khz sine wave is a tough test Larrt. I have never taken out a rail fuse listening to music. But could not keep one in the 400 for anything over 50 watts at 4 ohms. A steady sine wave is tough. In the manual they recommend replacing the 5 amp with an 8 amp for sine wave testing, I di not feel any additional benefit would be gained by burning the poor little 400 up. A real world test of some difficult 4 ohm speaks is needed. First I need to buy a new temp lead for the Fluke to verify case temp, and replace the thermoswitch.

 

[speakerman1]

How hot will they get? Wonder if that C5-A would transfer faster than other materials.

 

[laatsch55]

It might, but I don't think the barriers between the TO-3 and the copper was much of a factor.

 

[Wheel-right]

It might, but I don't think the barriers between the TO-3 and the copper was much of a factor.

Just came across this thread and I know it's old but I was wondering if drilling holes in fins would help with cooling for more air flow even though some mass is removed. Any thoughts? Thanks

 

[laatsch55]

I don't think so, although you are looking for effective radiant area, taking mass out might make the heat conductive effect harder to do if you interrupt the pathway with holes..

It's an old thread but a goody....should be a couple more on the copper heatsink project..

 

[Gepetto]

An interesting math problem...one of those that your 8th grade math teachers gives you in a word problem.

Suppose each hole that you drill is 0.25" in diameter into your 1/8" thick heatsink. The surface area that you remove from both sides of the heatsink as a result equals 0.0981 square inches. The surface area that you add on the circumference of the hole you drilled is 0.0981 square inches. Net zero on radiant area and you have lost conductivity through the heat transfer path.

Next, suppose each hole that you drill is 1.00" in diameter into your 1/8" thick heatsink. The surface area that you remove from both sides of the heatsink as a result equals 1.57 square inches. The surface area that you add on the circumference of the hole you drilled is 0.393 square inches. Big net loss on radiant area and you have lost conductivity through the heat transfer path.

Next, suppose each hole that you drill is 0.125" in diameter into your 1/8" thick heatsink. The surface area that you remove from both sides of the heatsink as a result equals 0.024 square inches. The surface area that you add on the circumference of the hole you drilled is 0.049 square inches. Net gain on radiant area and but you have lost some conductivity through the heat transfer path.

The answer is the usual engineering answer, "that depends"

The rule is that if the hole radius being drilled is less than the thickness of the material being drilled through, you win on surface area. Else you lose.

Also remember that in still air, the topside half of a drilled hole is not as effective as the bottom half.

 

[laatsch55]

Thanks Joe, I thought you might bite on this one!!

 

[WOPL Sniffer]

Just came across this thread and I know it's old but I was wondering if drilling holes in fins would help with cooling for more air flow even though some mass is removed. Any thoughts? Thanks

A fan works perfect and you don't have to hack on your stuff....