Leaving your hifi powered on
I left my Cyrus 2 on from 1993 to 2011. It worked perfectly for 18 years (and still does).
Just a thought.
If you had a fire and the fire officer attributed it to the hifi being left on, would your insurance cover you for repairs??.
If it's got an off switch, then surely we should use it shouldn't we or am I being just stupid
I've never heard of silicon transistors needing to warm up to operate properly. In days of yore, when we had germainium transistors, they did need to warm up. I remember an Elliot 803 computer we had at college that took 1/2 hour to get to operating temperature. Silicon devices are pretty temperature independent at usual household temperatures I believe.
Chris
I'm pretty sure others know better or would explain more but AFAIK the main reason for transistor amps harmonic distortion is thermal fluctuations due to varying current flow. if you can make them work in more or less stable temperature they will distort less. therefore transistor will run hotter than room temperature.
That doesn't really make sense! Transistor based devices will run hotter than room temperature because they are heat sources but the amount of heat they dissipate is pretty small (unless you have a Class A amp 
) so they won't generally speaking get very hot. I think the main reasons for harmonic distortion in all circuits, transistor or otherwise, are (a) poor design and (b) poor components. If you keep your equiment well ventilated I doubt there is much temperature effect.
Chris
That doesn't really make sense! Transistor based devices will run hotter than room temperature because they are heat sources but the amount of heat they dissipate is pretty small (unless you have a Class A amp ) so they won't generally speaking get very hot. I think the main reasons for harmonic distortion in all circuits, transistor or otherwise, are (a) poor design and (b) poor components. If you keep your equiment well ventilated I doubt there is much temperature effect.
Chris
well, if you could get hold on open loop THD measurements you'd see that class A measures better than AB. class AB measures well on THD mainly due to excessive use of negative feedback. in class A power stages drain maximum amount of current at all time and excess is dissipated as heat but in this state transistors operate in more stable (thermally) environment. hence lower harmonic distortion. that's how I understand it works like. that's how I can now explain in my own words what I red somewhere else.
While not wishing to take sides here, can I point out an inconsistency. Some would leave their amp on to keep the components at an ideal temperature yet leave it in stand-by using 0.4 watt – maybe enough power to melt a snow flake, but not enough to keep components at a working temperature!
In most cases, a system in stand-by removes the voltage from almost all the working components. So switching from 'stand-by' to 'on', in effect, turns on the components, so stressing them (if it does) as much as switching on at the wall socket.
So, the two views are: leave fully on, or put off (either at the socket or in stand-by for convenience).
As regards class A amplifiers, if you want to keep them at working temperature you will need to play music through them all the time to keep the output transistors hot.
There is always a fire risk in leaving equipment on stand-by.
Andrew
As regards class A amplifiers, if you want to keep them at working temperature you will need to play music through them all the time to keep the output transistors hot.
Sorry, not thinking straight! What I said would be the case for class A/B, so that the output transistors for the class A operation are kept hot. A full class A would naturally pass a high current through its output stage and stay hot. Not very wise or economically to leave a class A amplifier on all the time.
Andrew
All very interesting. Has anyone's ears been completely offended by the sound coming their 'cold' hi fi equipment?
All very interesting. Has anyone's ears been completely offended by the sound coming their 'cold' hi fi equipment?
Yup when I bought my new amp into the house from being in a cold car all day. Sounded miles better after it had warmed up to room temperature. 
That doesn't really make sense! Transistor based devices will run hotter than room temperature because they are heat sources but the amount of heat they dissipate is pretty small (unless you have a Class A amp ) so they won't generally speaking get very hot. I think the main reasons for harmonic distortion in all circuits, transistor or otherwise, are (a) poor design and (b) poor components. If you keep your equiment well ventilated I doubt there is much temperature effect.
Chris
well, if you could get hold on open loop THD measurements you'd see that class A measures better than AB. class AB measures well on THD mainly due to excessive use of negative feedback. in class A power stages drain maximum amount of current at all time and excess is dissipated as heat but in this state transistors operate in more stable (thermally) environment. hence lower harmonic distortion. that's how I understand it works like. that's how I can now explain in my own words what I red somewhere else.
Nope! Class A has inherently less distortion because there is no "cross over" which you get in Class B.
Chris
My amp does'nt sound bad from cold but a lot better after about 30 to 45 mins warmed up:)
Nope! Class A has inherently less distortion because there is no "cross over" which you get in Class B.
Chris
that too but also:
"There are advantages to class-A output-stage operation. As both transistors are conducting current throughout the entire signal cycle, there's no crossover distortion, which means less need for negative feedback. Both the current gain and the cut-in voltage of a transistor are dependent, in a nonlinear manner, on the transistor's junction temperature; if that fluctuates, then the current amplification of the transistor will be modulated by the change in temperature. With class-A operation, the transistors are handling the same average current at all power levels. Those transistors are therefore in thermal equilibrium and are not being operated anywhere near the cut-in voltage. With class-A operation, the power supply is under constant stress, whether or not the signal is present. As long as the maximum signal-voltage swing remains below the troughs of the rectifier ripple, the power supply is effectively regulated."
look, I'm not making this up.
Nope! Class A has inherently less distortion because there is no "cross over" which you get in Class B.
Chris
that too but also:
"There are advantages to class-A output-stage operation. As both transistors are conducting current throughout the entire signal cycle, there's no crossover distortion, which means less need for negative feedback. Both the current gain and the cut-in voltage of a transistor are dependent, in a nonlinear manner, on the transistor's junction temperature; if that fluctuates, then the current amplification of the transistor will be modulated by the change in temperature. With class-A operation, the transistors are handling the same average current at all power levels. Those transistors are therefore in thermal equilibrium and are not being operated anywhere near the cut-in voltage. With class-A operation, the power supply is under constant stress, whether or not the signal is present. As long as the maximum signal-voltage swing remains below the troughs of the rectifier ripple, the power supply is effectively regulated."
look, I'm not making this up.
Nope! Class A has inherently less distortion because there is no "cross over" which you get in Class B.
Chris
that too but also:
"There are advantages to class-A output-stage operation. As both transistors are conducting current throughout the entire signal cycle, there's no crossover distortion, which means less need for negative feedback. Both the current gain and the cut-in voltage of a transistor are dependent, in a nonlinear manner, on the transistor's junction temperature; if that fluctuates, then the current amplification of the transistor will be modulated by the change in temperature. With class-A operation, the transistors are handling the same average current at all power levels. Those transistors are therefore in thermal equilibrium and are not being operated anywhere near the cut-in voltage. With class-A operation, the power supply is under constant stress, whether or not the signal is present. As long as the maximum signal-voltage swing remains below the troughs of the rectifier ripple, the power supply is effectively regulated."
look, I'm not making this up.
I'm sure you're not making it up! I've never studied the variance of transistor performance with temperature BUT I find it hard to believe that there is a significant effect at day to day temperatures.
Chris
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My amplifier (a venerable Harmon Kardon HK1200) sounds a little harsh when first powered up, but hits its stride within half an hour. I've never been in the habit of leaving kit switched on when not in use, but my CD player only goes to standby unless you unplug it, and my Graham Slee headphone amp doesn't even have a standby mode. They're both unplugged if I'm away for more than a day or two.
NAD C565BEE, Harmon Kardon HK1200, B&W DM620, Graham Slee Novo, Sennheiser HD650