[quote=commsysman;21366324]It's the law, sport; the FTC says that all amplifiers have to be tested at 1KHz with an 8 ohm resistor load for 30 minutes at half of the rated power and the distortion published and that the heat sinks must stay below a certain temperature. It is a valid test of the heat sinks.
This distortion spec is a joke, because any amp that isn't actually broken will give you around .01% distortion, which is absolutely meaningless. The same amp will give anywhere from 1% to 8% distortion when amplifying actual MUSIC and with a SPEAKER connected.
Another thing that is a complete lie is that the manufacturer just adds up the individual power ratings of the 7 channels and claims that it has 700 watts of power or what ever. The fact is that the power supply of a 100 watt per channel receiver typically has a power supply that will put out 400-500 watts maximum. If you ever tried to drive all 7 channels to 100w at the same time, fuses will blow or diodes will pop. If you read carefully, the specs always refer to a test with one or maybe 2 channels driven; not more.
An amplifier just loves a resistor for a load, but a speaker system has large amounts of nasty old capacitance and inductance, which can drive the amplifier crazy, and make it distort like hell. How much distortion happens depends mainly on how good the output transistors are, how much current capacity the amplifier power supply has, and how much capacitance and inductance a particular speaker has.
Since these things are expensive to improve, and the engineer who designs these things is on a shoestring budget, your typical HT receiver has a LOT of distortion in its output. I designed amplifiers for a living for 30 years, and I have put hundreds of amplifier circuits through distortion tests on an analyzer, so I KNOW! (how much you actually NOTICE the distortion depends on a lot of variables like what you are listening to, speaker accuracy, and room acoustics; but the distortion is definitely there to hear)
Any moron who says that all amplifiers have low distortion should stop and ask himself why recording studio engineers and other audio professionals spend several thousand dollars each for Bryston, Boulder, Audio Research and similar amps for their monitors. THEY HAVE LESS DISTORTION AND SOUND BETTER...DUHHHH. AND THEY COST THAT MUCH BECAUSE LOW DISTORTION DOES NOT COME CHEAP. Professionals can HEAR the difference and buy what SOUNDS GOOD; low distortion products.
Anyone that all amplifiers have essentially the same amount of distortion has never designed one or properly tested one. People like this probably think that granny's Toyota Celica could win a NASCAR race because all cars are just the same.
There are people on these forums that actually claim that no amplifier has any distortion that is meaningful. My 30 years of designing amplifiers tells me that every amplifier has significant distortion, and that tests on a distortion analyzer prove it every day, and that every attempt to engineer less distortion into an amplifier involves choosing more expensive components. Bryston, Boulder, Audio Research, and other low-distortion amplifiers cost thousands of dollars per channel to buy, and there is a damn good reason why.
Originally Posted by sealteamz6
i heard one person say that Just stay away from receivers that give you cheap 1 khz specs, on the front
channels, like the Yamaha 571