P20 - the best way to turn it off

This is gently warm, far from hot.

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I’d naturally expect a device to warm up by 15 to 20 degrees celsius above room ambient temp. The P15 was designed to operate at 0 - 40 celsius.

Not sure why you have that expectation

Sorry but 43 deg C is radiator hot. I already have two of those in my listening room

I do not think of anything I can leave my hand on indefinitely in perfect comfort as hot.

But if you find this hot, it’s hot for you. :hot_face:

Back when there was only slide rules and marbleized notebooks, I was a process engineer. We would insulate pipes 'n things that exceeded 120F. (48.9C)

The tongue has the highest endurance to heat in the human body. We can sip tea upto 60 celsius :face_with_thermometer: However it is too hot to the touch. Our nervous system starts to get in trouble above 42 (internal body temp). But the power plant would happily feed my gear at 42C

For safety? Efficiency?

The tea and tongue analogy doesn’t work I’m afraid. As you sip tea you also simultaneously take in air and mix it with air which automatically acts to cool the tea. This is further cooled by mixing with saliva to add to the cooling effect. Added to that the amount of tea sipped at any one time is disproportionately small, by volume, to the rest of your mouth. Place your tongue onto the heat sink of an amplifier (NOT TO BE TAKEN LITERALLY) and you will feel the fallacy of your statement

Also if your internal body temp ever got to 42 deg C I don’t think you would know too much about it

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Mostly safety
And efficiency for some reactions.


I’ve told this to a number of people that have been concerned about the heat from their gear. If you can keep your hand on it for more than 15 seconds, there’s nothing to worry about. If it burns your hand, that ain’t a good sign. I keep my house unreasonably cool in the winter (17.5C) and the heatsinks on my BHK 250 after a number of hours playing are simply nice and warm. Far from hot.


A good rule of thumb . . . er hand.


I am using the web interface to switch certain zones on P20 on and off, as needed. I don’t touch P20 itself unless it hangs, which happens occasionally.

I find the web interface much more useful than the remote.

You are a positive addition to the forum because you help me refresh my knowledge. I am glad my memory is still good at my age. LOL. Please make sure you red this.

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Many people survive 42 without any side effects if helped with an ice bag or a cor a cold shower. If left unattended for hours, as noted above, the nervous system is at risk. We need to get you an overseas job job with Baker Hughes or Schlumberger to help you know what your body can endure. They pay very well, and I mean really well.

Although this is not a medical forum I am happy to banter with you on this topic. The article you refer to is concerned with scalds and burns. Yes the human body can tolerate incredible damage to skin and tissue caused by heat, not that you would want to subject it to that unnecessarily and the resultant damage to skin at high temperatures is not pleasant to see. As a health care professional with 35 years experience I can attest to that fact.
In an earlier post you refer to the internal body temperature as being 42 centigrade. That is not the case, normal adult body temperature is considered to range between approximately 36.6 and 37.1 centigrade.
Thank you for commenting on my education, you obviously realised I have a PhD in medicine.

I guess that’s only a good rule of thumb if touching a heat sink directly, not the housing of a component where inner or outer heat sinks transfer their heat (by air or even physical connection) to the housing. Ther a much longer „able to touch time“ than 15 seconds might be critical already imo.

Even when touching a heat sink itself, I only remember the 15 sec range (ok maybe 10 sec :wink: ) from my big full class A amps. I wouldn’t expect such heat from an AB device.

Congratulations on your scientific achievement. Well done.


One needs to exercise some common sense, certainly.

I would investigate if any part of any component is too hot to touch more than briefly.