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General audio topics that don't fit into specific categories.

RE: here's one: odd ordered harmonic distortion

I don't quite agree with you about the odd harmonics.

Based on the research I have been doing it seems more that a monotonic pattern of alternating even and odd harmonics gives a closer to nature presentation to the sound.

As an example at a given level, let's say at 1 watt you get -50db 2nd harmonic then you should have something like -70db 3rd and then -90 db 4th and then -110 db 5th. If your amp makes this pattern at all frequencies (Distortion at different frequencies should always be the same pattern) then it will likely sound really good. It is also nearly impossible to achieve this pattern with negative feedback.

Also, as Cheever notes the actual pattern that is correct is SPL dependent, because what is correct to the brain is also changing with SPL.

This means that the sensitivity of the speaker will also affect the result because the pattern generated by most amps is dependent on output power.

This then speaks highly for speakers that will get loud with little power because many amps will have a better harmonic pattern at lower powers.

Of course you are right that amps with predominantly odd order harmonics (a rather damning indictment of push/pull amps IMO) are really barking up the wrong tree and the harmonic pattern is nowhere close to what the ear/brain expects. But so too would be an amp that somehow makes only even order harmonics...particularly if they don't fall away exponentially.

Another crime you often see with amps is the "picket fence" harmonic pattern where harmonics go out basically to infinity with little to no drop in level with higher order. This is almost guaranteed to mess up the highs and shorten soundstage and veil low level resolution.


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