The thermal protection of amplifiers is always a concern, since overheating is a sure way to reduce the life of semiconductors and other components. Where you do not want to use a fan (such as in Project 42 – Thermo-Fan for Amplifier Cooling), then a complete shutdown can be performed.
This project is really a mixture of ideas, some simple, and others even simpler. The system I have installed in my biamp unit is fan cooling. Once a preset temperature is reached, the fans start, and remain on until the amp is turned off again. This is crude, but very effective. It only operates if I am listening LOUD on a very hot day, which means that the fans have probably only operated about 5 times in their life. I do know about it when they operate because they are fairly noisy (although I have reduced the operating voltage which quietens them down a bit), but at least I know that the amp is protected.
Even simpler is to just switch off the power when the amp overheats. I would use this as a backup to the thermo-fan or fan controller if I left the amp powered on all the time. While I don’t do this, a lot of people do, and although it does waste a certain amount of electricity, the greatest concern is fire.
At least a simple precaution or two should be taken to ensure that one does not come home to a pile of ashes that used to be a home – this actually happened to a friend of mine, and from what I saw, there is not a lot to recommend it.
Because I use Australian conventions for mains (Active, Neutral and Earth), you might need to translate these to the conventions where you live. They are sometimes referred to as Line, Neutral and Earth (UK), or Line-Hot, Line-Cold and Ground (one – of many – US conventions I have seen).
Basically, the active is the lead that will kill you, the Neutral is the lead that MIGHT kill you (if the plug or socket is wired incorrectly), and Earth is the safety grounding lead (Green-Yellow nearly everywhere for new equipment).
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