Originally Posted by noah katz
Chas, how long do you run sine waves in your tests, and/or what's the standard industry test duration for max sine wave power?
In todays world it all really depends on the amplifier. I say that because older amplifiers would run all day long with a sine wave at just below clipping. OTOH, the old amplifiers were not capable of the power levels available today. A good solid amplifer will run just below clipping all day with adequate cooling. That being said, there are not too many good, solid, high power amplifiers. Because of the different types of amplifiers (A, AB, H, D, E, F,G, etc.) they are not all meant for long duration sine wave testing. Some will only pass a 20 ms on/ 100 ms off burst test and call it a day. Some people think that is closer to 'real world' testing and is more meaningful. When an amp will run a sine wave for more than 30 seconds or longer, I will usually let it go for 5 minutes and monitor the heat build up on the chassis with a non contact infra red thermometer. You tend to get a feel for when a protection circuit will kick in and turn the amp off. Most amps won't go for more than a minute at full power these days without a protection circuit kicking in, usually thermal.
You also have to look at a big difference between a home amplifier and a pro amplifier. Most home amplifiers use only passive cooling. If they have the capability to put out large amounts of power (over 500 watts), they usually weigh a lot (approaching and over 100 pounds) but will usually run a sine wave all day long. For a sound system operator, this would be ridiculous to haul around because of space limitations, heat, and fuel costs. But a pro amp that is actively cooled, weighs 20 pounds, can be stacked 7 units high in a portable rack and has the capability to run all day at over 1000 watts makes a lot more sense.
When you adapt a pro amp to your home environment and then want it to perform like a home amplifier, you must give some leeway in measuring the specifications. kind of like wanting a sporty model of a Peterbilt.