Phaelon, SETs are usually not very powerful. A big one is 15 watts, maybe 20. If you really want to hear what they do, the speaker has to be efficient enough that you never bring the amp anywhere near full power.
At full power, the THD is often about 10%! At low power levels, the distortion might be unmeasurable, and what of it there is will usually be lower orders (2nd, 3rd and 4th). At high power the high orders become involved- that is the range of the amp that tells you not to turn the volume up any higher- it *sounds* loud due to to the presence of the 5th and 7th harmonics, which tell the brain how loud the sound is.
So the efficiency of the speaker is paramount and no matter what anyone tells you, to really hear what SETs do you need high efficiency: 97-98 at a minimum if your amp makes 15-20 watts. A 45-based amp needs a speaker that is more like 107 (if you really want to hear what it does anyway). This power limitation is one reason why I don't use SETs. The bigger you make them, the less bandwidth and detail.
At full power, the THD is often about 10%! At low power levels, the distortion might be unmeasurable, and what of it there is will usually be lower orders (2nd, 3rd and 4th). At high power the high orders become involved- that is the range of the amp that tells you not to turn the volume up any higher- it *sounds* loud due to to the presence of the 5th and 7th harmonics, which tell the brain how loud the sound is.
So the efficiency of the speaker is paramount and no matter what anyone tells you, to really hear what SETs do you need high efficiency: 97-98 at a minimum if your amp makes 15-20 watts. A 45-based amp needs a speaker that is more like 107 (if you really want to hear what it does anyway). This power limitation is one reason why I don't use SETs. The bigger you make them, the less bandwidth and detail.