Reliabilty, Keeping Equipment Powered on or off?

So many with different opinions.
IMHO, i would rather deal it a more scientific way. Generally, if the measured temperature on the chassis (using a temp probe) is less than 35 degree C, it is safe for equipment to remain on 24/7. If you need to be more specific, just open up the chassis and measure the heat of the components inside (i won't be responsible for any damages to your equipment and to your own safety), if the temp of the components is hovering around 40-45 degree C, it is still OK to be on for 24/7, BUT with one caveat , you gotta search for the lowest temp rating of internal capacitors. If it is rated at 70 degree C, then the internal ambient temp and\or components gotta to be less than half of that, i.e. 35 degree C or lesser. Capacitors life span and other electronic is affected by temp and their specification rating would drift faster over time due to heat.

I was told as rule of thumb the components that run hot - not just warm, should be left on at all times along with good line protection. I think this applies to most if not all power amps that operate in class A. Extreme temperature cycling puts a lot of stress on electronic components and can reduce their life expectancy even when they are designed to handle those conditions.

If they (audio equipments) are designed to handle those conditions, then of course , it should be left on without problems. It's those equipments that use poor quality parts that have "borderline" specifications on heat, current, mechanical tolerance (thermal expansion) etc..  that we should take note of irregardless they are running hot during idle or operating in Class A or not.
regards,
-phil

I've previously noted that leaving things on even at the suggestion of amp designers is the domain of wasteful boneheads who, as an example of wasteful boneheadedness (!), might also leave their cars running at all times to insure proper engine lubrication without that pesky "start up" stress, and leave refrigerator doors open to obviate door hinge wear, etc. I've since completely changed my stance on this issue (although I turn my rig off so I don't have to think about it blowing up when I'm not listening to it) as the rampant wasteful tendencies of people have irretrievably set our demise in motion, so you might as well waste whatever energy you can. After all, your audio playback standards can make you happier, and will help assuage any stress from, for example, an area of African farm land the size of Alaska recently being rendered unusable from rising sea water contamination. Who cares? Get yer Mahler on and you can let the kids worry about all the other stuff...  

There’s no one right answer anymore.

The biggest issue with on/off cycles was the initial current surge that goes through the transformer and power supply capacitors. They are much better now than 40 years ago, and many amp makers have added soft-start circuits which prevents this from occurring.

So the concern for turn-on surges is less than it was historically and leaving your devices on 24/7 has a down side. All power supply capacitors are rated for a certain number of operating hours so even while you are away you are running the clock down on them.

The higher temperature caps a vendor used, the longer they will last in general.

The other thing to consider is AC surges and spikes. Depending on where you live, like say Florida, these can really wear down the caps quickly. Of course, you also run the issue of a power surge happening when you are away.

So, I’d say keep your low power equipment turned off unless you have a good surge supressor. Then leave them on all the time. :)

As for big items like the Krell’s and tube power amps, I have a tough time stomaching the damage to the environment I’d be causing. If they are relatively recent models, I wouldn’t be surprised if they already had built in soft-start circuits as well as more modern caps that are less vulnerable.

Personally I’m off in class D land so for a total of 15 Watts at idle I leave my stereo amps all the time through a Furman surge protector. :) The amps are also excessively well cooled, so the wear and tear on them operating 24/7 is much less than your Krells I'm afraid.

Best,


Erik