Apparently not that hot. In previous listening sessions when my F5 got up to peak temperature I had trouble holding my hand on the heatsink for the so called 5 second rule. This caused me some concern so I borrowed a friends infrared temperature gun similar to the one picture here. Amazon.com: HDE Temperature Gun Infrared Thermometer w/ Laser Sight: Home Improvement. At peak operating temperature my heatsinks only measured 46C. I have the top cover off so I tried to measure the mosfets and I got 50C. While I'm happy with these temps I'm wondering if that makes me a bit of a wimp? 
To add some technical data to this post my heatsinks seen in the picture below are 13" x 6" x 3" high. The base flange is 1/2" thick
Regards,
Dan
To add some technical data to this post my heatsinks seen in the picture below are 13" x 6" x 3" high. The base flange is 1/2" thick
Regards,
Dan
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If your thermometer came with a thermocouple, try measuring the temp again using the thermocouple.
Problem with the laser units is reflection. They should be calibrated for the material being measured. Most often they are not set to measure (reflective) metals. Contact testing will give the best results.
Problem with the laser units is reflection. They should be calibrated for the material being measured. Most often they are not set to measure (reflective) metals. Contact testing will give the best results.
Do you know how much?
I have not notice a big temperature decrease when mounting fins horisontally, but on the other hand, I was not pushing to the limits.
How much space is needed below then for airflow to work?
Looking at Pass Firstwatt chassis, they are in fact not positioned correctly?
If that holds, the temperature on the sink on the amp in picture could drop to 33 degrees if it is placed on the front plate with som 20mm spacers?
Could be a nice and quick test
It will certainly run cooler but maybe not quite that cool.
As I said try running it face down sitting on a couple of blocks.
The heatsink needs air to flow across it to work efficiently. That doesn't happen with it mounted horizontally.
Horizontally it is relying more on radiated heat transfer.
In the same vein a small fan can improve the heatsink efficiency by almost 100%.
As I said try running it face down sitting on a couple of blocks.
The heatsink needs air to flow across it to work efficiently. That doesn't happen with it mounted horizontally.
Horizontally it is relying more on radiated heat transfer.
In the same vein a small fan can improve the heatsink efficiency by almost 100%.
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I have no reason to believe that the tool I was using wasn't relatively accurate.
Regards,
Dan
wider gaps >=8mm suit passive airflow.
narrower gaps <=5mm suit actively blown airflow.
A flat plate rib will dissipate a certain quantity of heat.
A thin plate will run cooler at the tip.
A thick plate will run hotter at the tip.
A tapered plate will dissipate more heat relative to it's total weight than either of the parallel faced plates.
Similarly a thick backplate will be hotter further away from the emitting device than a thinner backplate.
For optimum use of material a tapered backplate would be better.
But most heatsinks are specified with the whole backplate face at an isothermal temperature at a fixed differential above ambient temperature. This specification does not show tapering of big backplate heatsinks in a comparatively good light. Some heatsinks use tapering and thermal travel distance to great effect to reduce the heatsink mass (and cost) relative to the dissipation capability.
narrower gaps <=5mm suit actively blown airflow.
A flat plate rib will dissipate a certain quantity of heat.
A thin plate will run cooler at the tip.
A thick plate will run hotter at the tip.
A tapered plate will dissipate more heat relative to it's total weight than either of the parallel faced plates.
Similarly a thick backplate will be hotter further away from the emitting device than a thinner backplate.
For optimum use of material a tapered backplate would be better.
But most heatsinks are specified with the whole backplate face at an isothermal temperature at a fixed differential above ambient temperature. This specification does not show tapering of big backplate heatsinks in a comparatively good light. Some heatsinks use tapering and thermal travel distance to great effect to reduce the heatsink mass (and cost) relative to the dissipation capability.
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True, but I have noticed that I get different readings depending on the
surface and the distance. Dull black surface at 1 cm is my standard.
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