Quote:The confusion comes from the video where the second harmonic (@1590Hz) is mistakenly referred to as an even order harmonic, when in fact it is an odd order harmonic. As Leigh stated, even order harmonics are present, but the odd order harmonics are slightly dominant.
I reviewed the video and you are right, I apologize for starting so much confusion!! I have edited the video and am grateful for having it pointed out to me!
I have to agree with Paul at PS Audio that the harmonic distortion of the amplifier is dwarfed by most loudspeakers, and is in my experience pretty far down there in the overall voicing of an amplifier. The main thing I've learned is that pure odd order harmonics, especially higher ones, appear to short me out a little bit even though I don't consciously hear them at my normal listening volumes. One can speculate that adding the even order harmonics into the mix makes a new soup of the odd order and everything becomes more palpable... but the only way I know to do that is with tubes which bring so many contrasts to the table that the comparison can't really be made. I mean, giant glass high voltage fire bottles vs. tiny pieces of flat sand running at 1/10th the voltage are apples and oranges from any reasonable perspective.
When you look at harmonic distortion in an amplifier, you have an overwhelming urge, if not need to see it gone or reduced as much as possible. You can't help it. In my early days, while developing the 2 watt Zen Triode amplifier, I was on my 30th revision on one amp and 29th revision on the other one when things got really good. I then made the 29 match 30 which was the better of the two, and lived with the matched pair for a few months.
I then started to wonder... got the scope out and measured the amplifier's power, distortion and frequency balance and in so doing got too close to the event horizon when it happened! I got sucked in the black hole of specificationism. Two days later, the amplifier had 50% more power, and half the distortion and I was pretty firkin proud of myself and took the now perfect amplifier into the listening room and it sounded like complete shit. It's spirit was crushed, dimensionality destroyed, transparency became your enemy not your friend, and two years of voicing gone.
This is why you always build two of everything during development. And after that experience I didn't look at any of my amplifiers on the scope until after the amp was done, production samples made, photos shot, web page done, price set, and at least two or three sold. I had to be committed to it 110% so there was no possibility of changing anything. Then and only then would I look at the scope and learn to deal with and digest what I saw from a different perspective which was and still is hard to do.
I would venture to guess that on a production product there are not too many engineers on the planet that could or would even consider designing and building an amplifier without his computer, or scope. This is exactly why despite the overwhelming number of competitors that we have, so few are really even competing. It takes balls to trust your ears in this psychotic hobby where everything is subjective and placebo driven. If it weren't so, no one would care what audio gear looked like on paper. It is this basic element of the hi-end hobby that drives the publishing of specifications in an attempt to make sense of it all and be able to predict what might sound better, and of course we already know it does not.
Steve :)