Warm-up time for amps and preamps

" How can you prove that what you hear 45 minutes later from the same source and media sounds any different?"

Why should anyone here have to prove something? If you don't feel its necessary to warm up your system, great. If others want to, that's they're business. Besides, its hard to find an owners manual that doesn't discuss warm up. What proof do you have that they're all wrong?

for the same reason that anyone here should have to exercise correct word choice - a question was asked and people are giving answers


as to how to test - you would want two copies of the same component - warm one up (w/o listening) for an hour or two and then A/B/X them

10-15 years ago had a sound engineer come to my home and plot frequency response with MLSSA software, using test tones and sound level matched by meter. Repeated 5-6 times over the next 3 hours with the differences clearly notable on the visual graphing. Nothing subjective about it so far. Did those differences translate into different sound? Yup. Did I perceive those differences as qualitatively desirable? Yup. This on an all SS system left on 24/7, unless I will be absent for 2+ weeks. Just for the fun of it we repeated this on my and a couple other systems a few times. Same result without respect to components-visually represented differences in response over time, some more so than others, but none stopped changing within our 3-4 hour window of trials.

Oops, premature send. I meant to end by saying that in many instances we continued to see visually represented change long after we believed we heard any additional changes.

Fsilahua...Is SO CORRECT!!  as stated SS equipment has no warm up time.  As with tubes some equipment (not so much with audio) has a low voltage standby current that keeps the filaments warm so as to diminish the start up time when the equipment is turned back on. 

And contrary to popular belief, just because you do not "feel" the amplifier is getting warm, does not mean the buried components on the PCB are not under a lot of stress do to heat and current.  Components fail do to this factor, and to leave your equipment on 24/7 is ludicrous.  Yes there is voltage spikes, but the engineers have taken this into consideration, and incorporated relays in the rail voltage circuits, of most high end amps.  or surge resistors in the less than high end.

So go ahead run your equipment 24/7  the repair shops love you!!

Properly designed electronics doesn't have components under a lot of stress.  There is a lot of industrial and commercial electronics that stays on for decades including home phones, elevator controllers, phone switchboards, cellphone towers etc. Pretty much all cellphones are on 24/7.  Failure is usually caused by external conditions (heat, mechanical stress, water condensation etc).  Test equipment, my company made in 70's, still works today after more than 4 decades of continuous operation.  

Right.  The only exception is tubes.  ARC keeps track of the time on their tubes and puts that info in the display.

There is absolutely no reason why running without input signal would be bad for any class D amp.  This strange advice was given by NuForce technician?  Are they still in business?

I believe the above rests on a misconception; it is advised by NuForce not to turn on their switching amps without speaker load - that is, with the speakers disconnected. I imagine that's what's referred to?

SS gear sounds best when the unit is left on. This is the truth to my ears based on my experience with numerous amps over numerous years. Class D amps most especially. 

Thank you, phusis!

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. 

Small preamp tubes last longer if kept on as the turn on surge etc... shortens their life. Depends on build design, but I have owned tube preamps where the designer told me to keep the unit on unless traveling for best sound and tube life. The amp never got hot and the parts and tubes were cozy warm for long life and wonderful sonics. 

All my SS gear is on 24/7 unless aim way for a couple of days. The amp is in stand by unless i am using it.

Yes, frequent switching on and off in some ways can be more detrimental than leaving the amp permanently on. It depends on what components we are talking about as capacitors or transistors of certain amplifiers can last very long, well over 20 years before a degradation of sound quality is perceived. Naim recommends their solid-state amplifiers to be left permanently on, and the recommended service is every 10 to 12 years for the amplifiers and power supplies.

It may not be recommended to leave tube gear permanently switched on but some solid-state gear are designed to be permanently on without much adverse effects.