Warm-up time for amps and preamps

rvpiano 

Half hour sounds about right to me. 

How long does it take for your system to sound good from a cold start?
I try to keep my system on most of the time. But occasionally I turn it off and it sounds like crap for a good half-hour to an hour.
i know there has been discussion here on the virtue of leaving tube preamps on all the time.
But my solid state amp (modified NuForce mono blocks) technician advises turning even them off occasionally.

Rvpiano,

I would say check with the equipment manufacturer/designer’s recommendation. If your ears tell you otherwise, then go with your ears. I leave my Naim equipment on 24/7 based on manufacturer’s recommendation. From my experience throughout the years, the Naim preamp takes 2 to 3 days to achieve optimal performance, the power amp takes several hours from cold. Most Naim users leave their equipment powered up 24/7.

As for my sources, I switch all of them off when I am done with the listening. The CD player has a standby switch and is warm to the touch when it’s on standby.

The "correct" answers totally depend on what you are trying to achieve. 
If you want superior sound quality and don't care a lick about the life of your components, then by all means leave the equipment on 24/7.

Most tube equipment manufacturers will tell you in the owners manual that leaving the equipment on will significantly degrade the life of the tubes.

if, you are like me and own tubed power amps and tubed pre-amps, then you get what you pay for.  I don't look forward to replacing my power tubes every 2000 hours, and since I have a policy to not leave equipment on when I'm not using it (refrigerator aside), then I turn them off.

Unless the equipment has some sort of low power usage standby circuitry, the life of the tubes will degrade quickly leaving them on.

Take for example, my Audio Research REF 250 (not SE) amps.  Audio Research told me that new tube sets for the amps are $1,030 for each amp.  Well, that is an expense that I'm not looking forward to, and will not hurry this expense. 

For my Mark Levinson 23.5 amps, well, they get quite warm and replacing the capacitors and other components is quite expensive.

Heat not only quickly degrades the power supply capacitors, but also degrades the heat sink compound used on the power transistors.  When this stuff dries out, it is a problem.  When I upgrade or just routinely service ss amps, I remove each power transistor, test them to see if they are still operating within spec (many do not over the years), and replace them when necessary, along with all the mica insulators and heat sink compound. 

Anyway, if all you care about is superior sound quality and don't care a lick about life of components, then leave the equipment on.  but, think of it this way.  Do you leave your TV on 24/7?  What about the lights?  No, you turn them off for a reason.

You don't want your house to burn down when you aren't there.

My system sounds great after about 30 minutes warm up.  So, I plan ahead and turn the system on before I listen.  Then I turn it off when down.

But, that's me.

Enjoy

Not all SS amps are created equally.  As an example, my Gato AMP-150 has a warm up feature as they have determined that it takes a full 2 hours of operation to achieve optimum conditions.  With this warm up feature, it takes only takes 15 minutes.