Bandwidth question?

Thanks Atmasphere for taming famous American "Bigger-Better"!

Down 3db at 100khz or 300khz is insignifcant. Down 3db is good in that it is designed to reduce oscilation tendencies. At what power is the amp rated at, what is the power output at max or rated power vs. Frequency response and distortion. Measure all at 1wpc and full smoke. Key is the square wave at 10hz. If it deforms, notches or rounds off investigate. I have seen highly rated 100wpc monoblocks that roll off 10db at 20khz, and roll down15db at 50hz. And the square wave was rounding severely at 60hz. They were also voted "best of show".....likely not the product consumers get. I never liked the sound myself of the consumer product. A soft bass confirmed with a bench test, revealed a compromised product. Quality transformers are found with music reference, Quicksilver, EAR, conrad johnson, ARC, and others, but there is junk out there as well....beware jallen

Many thanks for all the responses. To be specific, I am not interested in debating the human hearing bandwidth. Mine is 25hz to 17khz.

I am interested in the how the ultrasonic bandwidth impacts the reproduction of audible frequencies. Many responses have pointed out phase issues, noises (or ultrasonic noise modifying how a component behaves in the audible freqs.)These are very helpful to me. I also realize that bandwidth for amp is dependent on load and output.

Ralph,

Why 10 times the audbile bandwidth is neccessary. A lot of amps are -3db at 100khz. This means faithful playback up to only 10khz, if you are correct.

"Why 10 times the audbile bandwidth is neccessary" - Because of phase shift. Rule of thumb says that phase shift at 1/10 of -3dB cutoff frequency is about 5 deg and that might be significant for proper summing of harmonics.

Glai, there you have it. Our ears are not so sensitive to phase shift at a single frequency, but when a band of frequencies is involved its another matter entirely!