IOW means 'in other words'.
The 'citation' I've been referring to is the study by General Electric that was done back in the 1960s. In it, they found that people will tolerate quite a bit of even-ordered harmonics added (up to 40%), but were not tolerent at all of odd orders, objecting to vanishingly small levels. The study showed that the human ear uses odd ordered harmonics as the primary means for determing loudness.
What this means for audio design is that designing with an eye to remove this harmonic content (+9th odd orders) will result in a more relaxed presentation.
If you want to see how this works in the tubes vs transistor thing, all you would have to do is run a sine wave into a preamp, run it up to clipping and view the output with a scope- the tube unit will have a rounded waveform at clipping, the transistor unit will look on a scope like somebody cut off the top of the waveform with a scissors. This 'cut off' area is a place where odd ordered harmonics abound.
Semiconductors, even FETs, by their very nature tend to generate these harmonics more than tubes, even if not being overloaded. It is something that comes with the territory in things solid state.
The 'citation' I've been referring to is the study by General Electric that was done back in the 1960s. In it, they found that people will tolerate quite a bit of even-ordered harmonics added (up to 40%), but were not tolerent at all of odd orders, objecting to vanishingly small levels. The study showed that the human ear uses odd ordered harmonics as the primary means for determing loudness.
What this means for audio design is that designing with an eye to remove this harmonic content (+9th odd orders) will result in a more relaxed presentation.
If you want to see how this works in the tubes vs transistor thing, all you would have to do is run a sine wave into a preamp, run it up to clipping and view the output with a scope- the tube unit will have a rounded waveform at clipping, the transistor unit will look on a scope like somebody cut off the top of the waveform with a scissors. This 'cut off' area is a place where odd ordered harmonics abound.
Semiconductors, even FETs, by their very nature tend to generate these harmonics more than tubes, even if not being overloaded. It is something that comes with the territory in things solid state.