Should an audio system be left on at all times?

Kijanki
All 'lectronics is subject to failure. The metal interconnects used in ICs and discrete devices 'moves' under the pressure of the flow of electricity. The break will usually occur when the line goes over an edge, where the metal is thinnest and current density is highest.
When we (my company) introduces a part, especially a new technology/revision, part of the specification includes Lifetime. Parts are put thru a rapid aging cycle while under electrical stress. 1000 hours is typical and an industry standard. There is an accepted rate of failure, usually highest at lower hours.....so-called infant mortality.
That being said, I have never had a SS failure...cap, resistor, I/C, discrete device. My old amp was on as continuously as possible for 20 years. Other stuff switched as needed.
My company makes a line of 'HiRel' and some of our stuff even finds its way into output and power supplies.....and makes full-on class 'd' modules.
Everything has a MTBF, even if it is a HUGE number.
I personally count on Infant Mortality of new equipment. Do a run in for a couple weeks and call it good.

Doesn't current surge, the first 1/2 cycle to saturate a transformer count as stress?

"Doesn't current surge, the first 1/2 cycle to saturate a transformer count as stress?"

Yes it does create rush current - but there is no evidence that it shortens life of electrolytic caps. It does nothing to transformer or rectifier.

You won't fint MTBF on any datasheet of any transitor, diode, IC (digital or analog) etc. - probably because it is in order od few hundred years. The question was if switching on/off is shortening life compare to keeping it constantly on - it doesn't. It will shorten life of switches, relays, tubes but not the SS stuff.

You won't fint MTBF on any datasheet of any transitor, diode, IC (digital or analog) etc. - probably because it is in order od few hundred years.

Yes, but when you combine hundreds or thousands of devices into a system, the several hundred year mtbf of an individual device essentially gets divided down by the number of devices (with each device receiving greater or lesser weight in the overall calculation depending on its individual mtbf).

There is an entire branch of engineering that deals with this, known as Reliability Engineering. MIL-HDBK-217F, that I linked to above, provides an inkling of how involved it can be.

Regards,
-- Al

Almarg - when you have hundreds of thousand od devices you increase chance that one, or connection between them, might be faulty. If number of devices should decide alone on reliability then Pentium processor that contains milions of transistors should fail every day. What about system that contain thousand of Pentiums - it should fail constantly.

It is not even relevent to audio gear that contains small amount of components. Stress done to wires inside of IC caused by current flow cannot be that bad since we have some of ICs working (and often in bad environment) for about 50 years (and first ones were poorly made).

If you believe that SS amp is more prone to failure from switching on and off - please tell me what fails!!!
(Don't count cases when you turn system off to modify something - like shorting speaker wires and then turn amp on again with failure.)

Kijanki -- I was NOT one of those who said that a ss amp is more prone to fail if switched on and off -- please re-read the posts I have made in this thread.

Audio gear does not contain a small number of components. A typical high-end system will contain hundreds, and perhaps thousands, of components, especially if you include passive components such as decoupling capacitors (not electrolytics), resistors, etc.

One of the fundamental advantages of integrated circuit technology is that it is integrated, meaning that an integrated circuit containing millions of transistors will have VASTLY greater reliability, and longer mtbf, than a circuit containing a corresponding number of discrete transistors.

A supercomputer containing thousands of Pentiums WILL experience failures somewhere in the system almost constantly, perhaps daily, and a great deal of thought goes into their design to provide redundancy that can overcome the low overall reliability.

If you do not, or will not, understand the concept that system mtbf is reduced as a function of the number of devices in the system, I can only tell you that you are wrong and you should research the matter further, including in MIL-HDBK-217F.

Again, I did not say, and I do not believe, that a solid state amp is necessarily more prone to failure if switched on and off regularly. In fact, most of my previous comments are probably closer to being consistent with yours than most of the comments posted by others in this thread.

Regards,
-- Al