Listening fatigue is one of the main reasons that speaker manufacturers keep designing and redesigning tweeters. They can cause it, but there is certainly a contribution from the amplifier too. Everything in the chain of reproduction from the microphone in the studio or auditorium to the recording of the disc to the CD player or cartridge and the amplifier and the speaker ALL PRODUCE SOME DISTORTION, and it is layer upon layer of compounded distortion by the time it reaches your ears.
Some tweeters are very accurate sound reproducing devices, but they will reveal every tiny bit of distortion coming from your CD player, turntable, or amplifier, all of which contribute a share. Some cheaper tweeters simply PRODUCE distortion when driven vary hard. ANY tweeter will produce distortion if driven TOO HARD.
Speaker designers only use the best tweeters in very expensive speakers. This is partly because the tweeter itself is more expensive, but a more compelling reason is that they know from listening tests that if you listen to that tweeter with a typical receiver or amplifier it will definitely produce listener fatigue due to the significant distortion levels present in such an amplifier, because the good tweeter will faithfully reproduce the distortion. Sometimes it is best to take the edge off of the truth.
When Home Theater magazine tests a receiver, they do a 5-channel test which determines how much power they put out with 5 channels fully driven, and they determine the rating at the point where distortion reaches 1%. For a typical receiver with a 100 watt per channel rating with 2 channels driven, the test will find that the receiver puts out about 65 to 80 watts with 5 channels driven at 1% distortion. This is ONLY the amplifier distortion, which does not take into account all the other distortion in the chain.
In any case, HT receivers typically have a lot less power and a lot more distortion than the typical consumer is aware of, and if you get high quality speakers and hook them to such a receiver, the speakers will be excellent reproducers of the amplifier distortion. Sometimes a more forgiving tweeter with a little less accuracy is better with cheap amplifiers.
When you get amplifiers with very high accuracy and very low distortion, which unfortunately tend to cost thousands of dollars to design, build,and bring to market, then of course you want better and more accurate speakers, which also will cost a lot more money because of more rigid expensive cabinet designs and more expensive driver designs, more precise crossover components, etc. etc.The bottom line, though, is that listener fatigue is simply the ears and brain telling you that they don't like what is being fed to them; distortion. It is there, even if it is too subtle to hit you in the face all of the time.
Originally Posted by buzzy_
IMO people mistakenly blame the speakers. Really, do you think the speakers were that badly designed? Any hobbyist designing speakers can avoid that problem.
I'd be willing to be that the vast majority of the time, it's the room and/or the placement. Those can have a huge effect on throwing the frequency response off.