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In Reply to: RE: Nobody here ever said tubes don't need break in. (nt) posted by cpotl on August 25, 2015 at 06:52:07
I think this is the article he is referring to.
Infamous sockpuppet
Edits: 08/25/15Follow Ups:
no, but that one is also interesting...you should go to the Gedlee website and read the source material for this particular article by Keith Howard. There you can see the plots, the distortion types measured in a lot more detail.
You should also read the Master's Thesis of Daniel Cheever (also found on the web as .pdf) and I found another more recent thesis
http://www.dancheever.com/main/cheever_thesis_final.pdf
http://projekter.aau.dk/projekter/files/9852082/07gr1061_Thesis.pdf
and to expand on the topic.
Infamous sockpuppet
"I think this is the article he is referring to."
Hmm... not sure. Your first link http://www.gedlee.com/downloads/THD_.pdf is to an article by Keith Howard on a new proposed weighting for characterising distortion. The second one you gave seems to be a sort of summary of points in a presentation he gave at an Audio Engineering Society lecture. It has some discussion of how non-linear transfer functions can be used to create specific harmonic distortions, and some related ideas. There is also a link there to some free software he has provided, one of which apparently allows one to introduce any desired harmonic distortions to a .wav file.
I don't see anything there that reports any experiments that "debunk" the idea that SET amplifiers may be creating distortion effects, or colourations, that listeners like.
Chris
"Hmm... not sure. Your first link http://www.gedlee.com/downloads/THD_.pdf is to an article by Keith Howard on a new proposed weighting for characterising distortion."As it turns out it was not the article he was referring to, nonetheless it does touch on the topic by the same author.
The reason for the weighting schemes are (From the article) "higher order nonlinearities (which give rise to high order distortion products in a sine wave measurement) are more aurally objectionable then lower order ones and should be given greater weight in any subjectively relevant measure of distortion level."
Now, we have to surmise that devices (SETs for example) that produce predominantly low, even-order harmonics is going to be producing a more accurate signal, that's just the way it is.
(The beneficial consequence of this is that subtle acoustical textures will become un veiled, this is where the "richness" comes from.)
This doesn't mean it is adding a bunch of fuzz to warm up the sound, on the contrary.
Also keep in mind that all devices are going to produce some sort of distortion or "colorations".Now, this isn't the end of the story, all devices are also going to interact with speaker nonlinearities, however to keep this point succinct, it is better to keep the harmonics low and even ordered before it gets to the speaker. As mentioned before, this is what differentiates the SET power stage vs solid state small signals.
Pretty easy myth to debunk really. The human ear is sensitive to un correlated side-bands produced by harmonics.
It's all about avoiding some IMD to gain a little more accuracy.
Infamous sockpuppet
Edits: 08/25/15
> "The human ear is sensitive to un correlated side-bands produced by harmonics."
Yes.
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Big speakers and little amps blew my mind!
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