Do you leave your SS amp on all the time?

Jmcgrogan: If you've never had your Threshold powered up for at least 3 days consecutive, you've never heard what it can do. Honest.

High bias designs are the most sensitive to thermal cycling / sonics. The lower the bias on the amp, the less differences that you'll notice if cycling power off an don as needed. Higher biased amps ( these run hot at idle ) will always sound better when leaving them turned on. I do agree that it is a good idea to kill the power to them if you will not be around for an extended period of time or if you are expecting severe storms.

I have six amps ( four Threshold products and two Perreaux's ) in one room that idle at about 120* - 130* each. These stay on all the time.

I have two amps ( modified Kinergetics KBA-202A Platinum mono-blocks ) that idle at about 110* in my office system. These stay on all the time.

My HT amps ( Sunfire Signature & Sunfire Cinema Grand Signature ) stay on all the time although these draw VERY little current at idle. As such, they run cool to the touch unless pushing them hard. I could power these down and not really notice much of a difference after about a half an hour of use.

My bedroom amps ( two Quad 405's ) stay on all the time.

My tube based system is powered up and shut down as needed. I am a firm believer in letting tubes "heat up" prior to passing signal. I also let them "heat down" prior to shutting off.

So, do i get the "wattage waster" award or what ??? : ) Sean
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John: My guess is that the amps that you speak of were were probably shoved into an enclosed rack, not allowing proper heat dissipation. These amps require open sides and at least 12" of space above them. Otherwise, you can expect them to cook themselves to death.

I have some of their amps with IGBT's in them also. They do not get turned off. My experience with circuits like this is that you have a greater chance of in-rush current smoking the outputs. On top of this, you now have tremendous thermal swings that occur over a relatively short period of time. This can result in uneven gain characteristics from output device to output device, resulting in reduced stability. Leaving the units powered up reduces all of the above problems to a minimum.

Obviously, one has to take into account that these amps will generate a good amount of heat and have them installed in a manner that will allow more than adequate ventilation. This is true whether the amp is cycled off and on or left on all the time. If placing the amp in a rack, keep in mind that heat rises. This will "warm" the shelf above it, which could transfer heat into the component above the amp.

If you are truly worried about such things, you might want to remove the top lid of the amp. This will allow greater cooling of the insides via natural convection. If you are worried about RFI or small fingers inside of the amp, it would not be hard to fabricate some screening that would act as both a shield and "guard". Sean
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