What could I expect to hear from a Class A amp?

My class A runs damn hot.
It really needs a week of warm up before sounding it's best?
On the advice I got calling the Sugden factory, I turn mine off between listening sessions.

"On separate issue, would all that heat for 24/7 at full power take toll on the circuit board? Of course the counter arguments would be the on/off as you said, and the expansion/contraction fatigue cycle due to the hot/cold."

Spatine - the only perishable component inside of SS amp is electrolytic capacitor (other than ON/OFF switch). Rush current does nothing to electrolytic capacitor other than heating it slightly (very short time and very low ESR) in spite of large momentary current. Electrolytic caps die of dehydration. Each increase in temperature of 10 deg Celsius cuts their life in half (water evaporates from electrolyte). Eventually drier capacitor has higher ESR and starts heating up to the point of runaway. In critical application (lots of current) they get to thermal runaway and explode (they have fuse to relieve pressure). The other way to damage them is to leave them without voltage for years. Aluminum oxide layer that serves as isolator is eaten by electrolyte but presence of voltage builds this layer back.

Fairy tales about rush current (turning ON) damaging equipment comes from two sources. First is the bulb or tube that breaks on power ON since cold filament has many times lower resistance. Second is the fact that if you do anything around your amp like for instance moving speakers while amp is OFF and create short it might damage amp when you turn it ON and you will blame turning ON (rush current).
Sometimes also mechanical component tends to break at start-up like for instance computer's hard disk.

Circuit boards, resistors, film and ceramic caps, transformers etc last forever even in extended temperatures. As for semiconductors - as long as they operate at sensible junction temperature (let say under 125 deg C) they also last forever. There are electronic circuits with semiconductors being turn ON/OFF hundreds times a second and they last for over 25 years. Simple example of it is seven segment multiplexed display.

As for sound being optimal after a week of continuous operation - it's possible. I don't have class A amp, don't have experience with them and perhaps less than "golden ears".

People who calculate reliability are probably ready to kill me for saying all this but statistical analysis they use is something else. When I walk with my dog we have statistically 3 legs each. Also statistically tattoos are causing motorcycle accidents.

It takes about 1 second of on time for a solid state amp to sound its best. The last piece of electronic equipment I saw that took any longer on time to sound its best was a tube television set from the 60's. (cannot speak for tube amps of today). Even that TV took only a few minutes to settle. Turning the amp on and off between listening sessions will not change the amp's lifespan in any meaningful way. Nor does an amplifier that is on but not driving a load use a great deal of energy so it shouldn't change your utility bill anymore than leaving a porch lite on 24-7. In short, these issues are of no more practical significance than the issue of how many angels can dance on the head of a pin.

>>03-16-09: Musicnoise
It takes about 1 second of on time for a solid state amp to sound its best<<

If you read Nelson Pass' comments on his First Watt products, he feels it takes about an hour for them to reach optimum performance.

Not one second.

Kijanki -- Really excellent post!

As you undoubtedly recall, we discussed (and somewhat disagreed about) these matters a while back in the following thread, which discussed whether or not it is best to leave a system on all the time (although it was not addressing Class A specifically):

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1228170308

For those who may be interested, in the last of my posts dated 12-3-08 in that thread I addressed the statistical aspects of this question.

Re your post above, I agree 100%, with the slight qualification that the phrase "last forever" be taken to mean "very unlikely to fail within a reasonable period of ownership."

Near the end of the other thread, in which a lot of people threw in a lot of conflicting opinions, one person asked if a consensus could be stated. I was the only one who responded, and I said:

I'm hesitant to declare that we have a general consensus. But in terms of reliability I would say the diversity of opinion we have seen is consistent with the opinion I expressed that, considering your frequent but not extreme usage patterns, you won't be going too far wrong either way.

In terms of sound quality, optimal warmup time is going to be system dependent, and probably listener dependent as well, so if you choose to have your system off during the day see if you notice continued improvement in sound quality following whatever warmup period you choose to use initially.

Perhaps this is a bit of an anticlimactic conclusion in view of all that has been said, but I think that any conclusions beyond these simple ones are unprovable, are probably not universal, and in terms of longevity probably don't make a lot of difference anyway.

Musicnoise --

Nor does an amplifier that is on but not driving a load use a great deal of energy so it shouldn't change your utility bill anymore than leaving a porch lite on 24-7.

That is not even close to being true in the case of a Class A amp.

It takes about 1 second of on time for a solid state amp to sound its best.

I don't think too many Audiogoner's would agree with you, based on their own listening experience. Although I am an electrical engineer, and I tend to be among the first here to recognize that perceptions about equipment performance that derive from listening experience can often be distorted by expectations, failure to control extraneous variables, etc., I would agree with them that you are incorrect about this. Notwithstanding the fact that to my knowledge a solid technical explanation of warmup effects has not been offered in the context of audio.

Regards,
-- Al