Weather-induced amp performance variation

Pretty dramatic changes in the sound of a system and amp also occur due to variations in the amounts of AC power line pollution and noise during differnt parts of the day and night, especially if you don't use a line conditioner of some kind.
I also heard that changes in the barometric pressure can cause a system, particularly the speakers, sound alittle different on different days.
Also, proper warm-up is essential, especially in solid-state amps and preamps. If they are played from a cold start, there can be huge variations and fluctuations in the sound quality as they go through their warm-up period.

Don't forget that the weather can play havoc with your sense of hearing.

Eldarthford: I guess age of the listener has much too do as age of equipment :-)

If you leave a high bias amp turned on, the device tends to stabilize temperature. It will not shift measurably unless there is a measurable shift in room temperature. Most common amps that are biased for lower level Class AB operation will undergo the greatest temperature swings, hence the bigger variations in sonics that they suffer from. Then again, going from room temperature to sustained operating temperature is still more of a swing / temperature change than going from idling but powered on up to operating temperature. On top of that, the temperature swing isn't as drastic, resulting in a slight increase in circuit stability and more consistent sonics.

Optimally, one would have a climate controlled room just for the amplifiers outside of the listening room. This would allow one to run Class A amps with enough airflow to allow them to stay cool to the touch. So long as the temperature remained consistent and the amps were adjusted in-room, both the electrical performance and sonics would be improved. I wish i was rich enough to try something like that : ) Sean
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