[fat controller]

My AV amp is on most of the time, and as such it never really gets a chance to get cold - besides, even when it is, it seems to perform pretty much as at any other time (or the speakers are so poor its unnoticeable) - however, my stereo amp (Sony TA-FB940R) sounds thoroughly rough when it is first switched on, and takes a good wee while before it sounds 'itself'.

Would there be any merit in plugging the amp into some kind of timer so that it comes on an hour or so before I am due home, so that it warms up? Would it even warm up if there was no source being played through it?

[diablo]

Has it always been like that ? Seems very unusual to me, I use three amps and they are all ready to go from switch on.

Without any input it would be running at a very low power level and not generating much heat, but why not try it and see.

[Andy2]

This kind of thing is usually caused by the standing current in the output pair (and maybe the drivers as well) being set a little too low. This causes crossover distortion until the transistors warm up and begin to pass a bit more current.
There is usually an adjustment for this, but it is not for the novice as you can end up with a fried amplifier if you get it wrong.
I'd just turn it on an hour before you need it. Even the tiny amount of heat generated in standby will probably be enough to do the trick.

[Nigel Goodwin]

Originally Posted by Andy2

This kind of thing is usually caused by the standing current in the output pair (and maybe the drivers as well) being set a little too low.

Perhaps not?, you allow the amp to warm up BEFORE adjusting the current, so it's quite possible that some amps can be distorted from stone cold.

It's all to do with thermal runaway - as the amp warms up it passes more current, so you need to set it at a point where it can track as the amp gets hotter and hotter.

[Pugwash69]

Once upon a time I used to leave my amp switched on all the time, and just switched the speakers off. Can't be arsed now as common sense says they use less of my electricity when OFF off.

[webbie]

If I remember correctly, my mate's Naim amplifier was designed so the preamp was on all the time and the power amp was switched on/off as the preamp sounded better warm.

[Andy2]

Originally Posted by Nigel Goodwin

Perhaps not?, you allow the amp to warm up BEFORE adjusting the current, so it's quite possible that some amps can be distorted from stone cold.

It's all to do with thermal runaway - as the amp warms up it passes more current, so you need to set it at a point where it can track as the amp gets hotter and hotter.

If the amplifier has such a narrow range of tracking that it has to start up with crossover distortion, then it's a piss-poor design.

[Nigel Goodwin]

Originally Posted by Andy2

If the amplifier has such a narrow range of tracking that it has to start up with crossover distortion, then it's a piss-poor design.

Regardless of the range of tracking, ALL amplifiers are adjusted when warm - usually giving a specific warmup time before making adjustments.

[Andy2]

Yes Nigel, I know how to set the current - but if the loop can't hold the current to a sensible value across a decent range of temperatues (even in a not-very-cold room) then the designer was asleep!

[Glawster2002]

Originally Posted by webbie

If I remember correctly, my mate's Naim amplifier was designed so the preamp was on all the time and the power amp was switched on/off as the preamp sounded better warm.

I've got a Cyrus system and that's designed to be left on Standby when it isn't used to keep temperature critical components at the correct temperature.

[fat controller]

Its always been the same, and in fact its not the first amp I've had that sounds better when warm - admittedly, this one probably shows it a little more than some others (although if you asked my Mrs what it sounded like cold versus warm, she would tell you there is no difference at all!)

I think the problem now is that my stereo amplifier has been relegated somewhat in favour of the A/V amp, as the A/V amp is on from first thing in the morning right through to bedtime (we leave the radio on for the dog during the day ) - the result is that the use of the stereo amp is not has high as it would have been in times gone by.

[soulboy77]

Ah memories of my old Denon AV amp keeping the room warm in winter!

[fat controller]

Originally Posted by soulboy77

Ah memories of my old Denon AV amp keeping the room warm in winter!

Its surprising the heat that both mine chuck out at times - can't be efficient, but I don't give a monkeys as they sound good.

[Glawster2002]

Originally Posted by fat controller

I(we leave the radio on for the dog during the day )

This time of year we leave the radio on in the evening for the cat if we go out as it makes the noise from fireworks less obvious as he's petrified of the bangs.