leave amps on?

Four for, one against. My NAD 218thx and Adcom 5006 are on. Thanks all, Jon

I called Mondial to talk with them about pros and cons of leaving my Aragon 8008BB turned on continuously. The owner's manual says to turn it off, that it should reach operating temperature in about 20 minutes. Mondial says that if the power supply has been designed for "soft turn-on", then reliability impacts due to power cycling shouldn't be an issue, and that in truth, the transistors reach normal operating temperature in about 5 minutes. Another reason they recommend turning the unit off is protection against line transients (such as lightning strikes). Bottom line is that Mondial recommended very firmly to me turn the amp off and asserted that there's no good reason to leave a well-design amp turned on. I'll add that another point in favor of turning an amp off is that heat is the #1 enemy of electronics (reliability-wise). The 8008BB, being a class A amp, runs hot. No sense having the components cook away for no reason at all. Besides, with a quiescent power draw of around 300 watts, that's about one buck's worth of juice per day here in NY state. I heard a difference in the sound of the amp after leaving it on overnight when it was fairly new, but now that it has several hundred hours on it, it seems to take only a few CD tracks to "loosen up" after being turned on, and after that I really don't notice further sonic differences. So I normally switch the amp off at the end of the night. Steve

I left my Threshold S/300 Series II on for eight years running. I hear that minimizing the number of thermal cycles makes them last longer. Works for me!

I leave my amps on 24/7 unless there is an electrical storm, then I unplug 'em. Like Rsuminsby, I have had Adcoms for many years, and it takes about 45min for the sound to noticeably change, but it really takes a day or so before they fully stabilize (the new MOSFET ones take a bit longer). The reason to leave a Solid State amp on is so you don't have to wait for it to warm up, but keeping the amp on also stabilizes the bias. When an amp is first turned on, the bias is high and needs to settle with the ambient temperature. As the amp warms up, the ambient temperature rises, which, in turn, lowers the bias. If you can imagine a scale or a see-saw leveling off, you get the idea. This bias settling takes quite a while, so I find a day is usually good. Once you play music and get the amp hotter, the settling time becomes a bit faster, because the transistors are operating in their quiescent range.

I have a aragon 4004 that at first I would turn off after listening. But I found that the amp took a long time to warm up. Now I leave it on and in case I want to show off the system to a neighbor it's ready to go. Unless your amp is class A I would leave it on. Good listening Bret

I once had a pair of Adcom GFA-555s and left them on for over a year...saved me having to warm them up before listening. Took them about 30 minutes to really come up to temperature and sound better. Not essential, though, as long as you fire up the system well in advance of a listening session. Play some pink noise while you're decanting the wine!

Both my Quad 405-2 and my Bryston 4B sound better when left on all the time, so that's what I do. Bryston specifically states that it is perfectly okay to do this. It is the normal practice in pro audio. I even read a review of the Bryston 4B-ST in which the author thought the amp was grainy and harsh until he forget to turn it off one night. After that he thought it was the best amp for the money that he'd ever heard. In any case, try it out yourself and decide. Hope this helps. Joel.