Are you hot?

[bandphan]

My amp seems to warm but never gets hot having an open design and massive heat sinks driving 5 ohm loads. My avr is driving three channels 4 and 6 ohm nominal and stays cool, nice that its vented on the sides as well.

 

[Tiguron]

My receiver is in a pretty confined space. It ran pretty hot to the touch when I first set it up. I added a 4 inch fan hooked up to a 12V adapter. Now it runs very cool, almost no heat.

 

[Adam]

If I rememeber correctly, commercailly available solid state devices spec their range from from around -25Celcius to 60 Celcius. Millitary grade go from around 50 C to 100C. TLS, one thing you forgot mention are the heat dissapation curves. If your running your semiconductor around 60 C, teh ambient air temp better be below 25C or you have a heat sink to conduct teh heat away. I think 60C is at its upper limit.

Not all manufacturers adhere to the same limits, but almost all commercial grade parts that I've seen go from 0 C to 70 C, and that's almost always an ambient air temperature. Industrial grade normally goes -40 C to around 100 C. Military grade and automotive parts are similar, going from around -55 C to 125 C and up. The actual component maximum temperature limits are higher. The maximum ambient temperature is based on the junction-to-ambient resistance (when there's a junction, or case-to-ambient resistance), maximum junction (or case) temperature, and the maximum power.

I asked about the 60 C recommendation because I haven't seen any parts rated to 60 C.

 

[TLS Guy]

Not all manufacturers adhere to the same limits, but almost all commercial grade parts that I've seen go from 0 C to 70 C, and that's almost always an ambient air temperature. Industrial grade normally goes -40 C to around 100 C. Military grade and automotive parts are similar, going from around -55 C to 125 C and up. The actual component maximum temperature limits are higher. The maximum ambient temperature is based on the junction-to-ambient resistance (when there's a junction, or case-to-ambient resistance), maximum junction (or case) temperature, and the maximum power.

I asked about the 60 C recommendation because I haven't seen any parts rated to 60 C.

Sure the devices are rated at above 60 C. However you can see that as you drive the devices hotter their life span is shortened.

My basic rule of thumb is that if a heat sink is too hot to touch, that is too hot and a bigger heat sink, or cooling is required. That seems to have got me by pretty well. If I can keep my fingers on a heat sink, I'm happy.

 

[3db]

Not all manufacturers adhere to the same limits, but almost all commercial grade parts that I've seen go from 0 C to 70 C, and that's almost always an ambient air temperature. Industrial grade normally goes -40 C to around 100 C. Military grade and automotive parts are similar, going from around -55 C to 125 C and up. The actual component maximum temperature limits are higher. The maximum ambient temperature is based on the junction-to-ambient resistance (when there's a junction, or case-to-ambient resistance), maximum junction (or case) temperature, and the maximum power.

I asked about the 60 C recommendation because I haven't seen any parts rated to 60 C.

Thanks for the quick refresher. I haven't seen this stuff for well over 20 years. Heat flow is like a series circuit where the resistance to heat flow comes from thejunction itself, the case that the semiconductor is wrapped in and the resistance of heat travelling off the case to free air. When one straps a heat sink on a device, your effectively lowering the thermal resistance allowing more heat to travel from the junction to to free air which allows the device to operate nearer its thermal limit. I would not run a device at 60Celcius without employing some kind of cooling mechanism such as a fan and or heat sink. If you look at the heat dissipation curves, the higher the ambient temp, the lower power should be run through that device. Its kind of vaguely similar to running your engine at red line all the time. Do that and it wears out quicker. Run a semiconductor at its rated max temp and it too will wear out much sooner.

 

[newaudiofile]

I have also tested how hot i'm running. It was 34 - 40 degress celcius. Ambient temperature in the room is about 25. Outside now is about -5.

I tested this because i had covered the amp to prevent dust from gathering in the AVR.

I have to say that I was surprised that it was not running hotter.

Posted this already on the wrong thread