System should warm-up in less than 1/2 hour. Keeping system on all the time will:
1. Shorten life of your amp since elctrolytic caps life drops by factor of 2 for every 10 deg. Celecius.
2. Create unnecessary risk during tunderstorm/voltage spike (you cannot unplug being not at home or sleeping)
3. Still won't make system sound right from the start since other components need warmup time - for instance tweeters/ferrofluid. |
Pdn: I was talking about SS. As for time - it might vary and I don't know of any rule. I'm pretty sure the same applies to tube gear but have no experience there.
Stanwal: It might be better to leave computers on all the time (because of hard disc) but computers are often replaced before they go bad. The only component that ages in SS amp is electrolytic cap. As far as I know its life is only temperature dependent (except when left unpowered for years).
If your amp is not hot or cold to touch (body temperature) its life is already reduced by half compare to room temperature (10 deg. Celsius difference) - important only if you plan to keep gear for more than 10-15 years. |
Knownothing - I think so. Capacitor companies like Nichicon mention only temperature as limiting factor (and not the rush current). |
Stanwal - I stated what capacitor companies claim. Going bad when not used, that you mentioned, has place when you not use amp for long time (years) and aluminum oxide layer (serving as isolator) depletes eventually lowering allowable voltage and causing short at operating voltage - often exploding from the heat build-up. Caps have fuse (rubber plug) to prevent explosion. It is recommended in such cases to start at lower voltage (Variable transformer) until aluminum oxide layer will build-up again. Unfortunately some power supplies like SMPS either start or not and varying line voltage might not help much.
It is very difficult to compare performance of 25 year old amp with exactly same new one. I replaced power supply cap in old SS amp and got bass control and dynamics I didn't know it had.
I think that capacitors are just drying up and the temperature accelerates it. It might not fail ever but performance will slowly deteriorate since caps ESR rises up (thats why people recap their amps). |
Stanwall - Check this link: http://www.dfrsolutions.com/pdfs/Uprating_of_Electrolytic_Capacitors.pdf
They mention temperature as main factor (and 10 deg C rule). ESR while getting lower at high temperatures (might explain reason for warmup) eventually gets higher from electrolyte evaporation.
Good quality amp equipped with 105 deg C caps might last for very long time while luke warm. I would like to preserve my amp at current state as long as I can. |
Cyclonicman - I don't understand advantage of leaving equipment on all the time either. Other elements of the system - like speakers also need time to warm up (playing time).
Even if Stanwal is right about miniscule effect of time on capacitors (electrolyte evaporation) in low temperatures there is no reason to keep it on - rush current doesn't do anything to capacitors.
I turn my system (class D) on every evening ant turn it off at night. On days of bad weather forecast I unplug it from the wall. |
Bigbucks5: electronic fail when you turn it on when it's not designed properly. You can turn on and off electronics thousand times a second for years and nothing will happen.
Blindjim: Odyssey and others recommend keeping it on because it takes a while to get optimum sound and not for the longevity. If it takes often days to warm-up, as Odyssey says, then keep it on but if it takes only half an hour keep it off since speakers require about the same playing time to warm up. Odyssey even stated that if you don't mind waiting for optimum sound then you can turn it off when not used.
PC is different story - whole idea of kepping it on initially came from mechanical stress on hard disc during start. Now they keep them on because maintanance is often done thru the network.
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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.) |
Blindjim: Yes original question was about longevity - read again
Bigbucks5: I don't know where you getting your information. Electronics that stays on is also constantly switched - electrolytic cap are geting sharp spikes of current, switching power supplies as wel as class D amps constantly switch on off etc. Rush current during power-up doesn't do anything to SS electronics.
Almarg: semiconductors, resistors, capacitors etc don't have MTBF (not in our lifetime). They operate practically forever (except electrolytic caps). LED diodes might loose brightness over time (structure recombines itself to non-emmiting junctions) but it's not a sudden failure and it takes probably 20 years for this to even notice.
People got impression that SS gear will fail most likely during power up/down cycle because of previous experience with tube gear, relays, switches, bulbs, hard disks etc.
The only case I know where SS electronic gets "tired" is with very high power SCR devices (thyristors) switching few hundreds of amperes and it takes very long to fail.
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"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. |
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Almarg - Supercomputers don't fail daily, otherwise we would have serious security problems (unless you talking about software crashes). Audio gear does not contain thousands of components - give me example of one. You will be lucky to find one that contains couple of hundred.
What is interesting about electronics commonly used is that if it does not fail in the first year most likely it won't fail for next 20 years (just opposite to MTBF) and when it does it's usually because of lightning or mechanical failure (switch, relay, motor, plug etc).
Hard discs that have MTBF in order of at least 5 years have 99.9% of time mechanical failure in spite of having a lot of electronics (ICs) on them.
MTBF does not apply to audio gear and probably should not be mentioned (unless we try to predict statistical failure in 500 years). Remember saying about lies big lies and statistics? Statistics already has proven that motorcycle accidents are caused by tatoos. |
Almarg - I'm not clear on reliability and you can probably tell me where I'm making mistake but if we take device like transistor that eventually fails (everything fails) - let say in 100 years then using 1 milion of them would cause earlier failure, and in case of 1 billion of them one would fail every hour - am I right so far?
Now I have pencil on the desk in front of me. It doesn't last forever and will eventually rot - let say in 100 years (used or not). So if I take 1 milion of similar pencils one would rot in an hour after it was manufactured?
Doesn't reilability engineering assume that there might be some (very rare) faulty components (or connections)?
People believe in proportionality and therefore everything has to fail some time but for instance life of steel under stress is infinity of cycles (no fatigue) as long as strees is below certain level (not true for stainless steel and other metals).
Imagine basketball with a rope around it. Add 1m (3 feet) to it and rope will be loose by about foot everywhere (radius increases by 1 foot). Now do the same with our earth around equador, add 1 meter and you'l get axactly same result - gap of 1 foot everywhere around the earth.
r2-r1=(L+1)/2pi - L/2pi = 1/2pi L disappeared. It is very strange and counter intuitive but has certain practical implications. For instance clothing sizes for children cannot be in the same numbering scheme/scale as for adults. |
