In Reply to: RE: another commentary... posted by dave slagle on April 28, 2012 at 23:43:06:
As long as triodes are used without NFB in a SET, we can only really talk about harmonics and polarities of the harmonics. Phase other than 0 and +/-180 degrees is possible to design out over most of the audio band. With NFB, phase will come into play due to lack of ultra wide bandwidth to go through the entire audio range. And, only with NFB does an increase of higher order harmonics happen.
Even order distortion is built up by not cancelling it (PP does that). Even order distortion is partially cancelled with two cascaded similar tubes (like 6922 -> 6922) as their polarities are inverted with each other. I never put two similar tubes (except for each different channel) in the same system once I listened to my system without tube duplication in one channel. Every time I tried it again, it was awful to my ears. It sounds better to try a different tube every time and let the blend mix itself, tuned by ear.
Still, the ear is not an even harmonic only distorter. It does have low order 3rd and 5th harmonics self generated (there is some ear symmetry). The 45 SET output stage as Mr. Cheaver's master's thesis wrote, "scored", in his viewpoint, as closest to the human ear for the similar distortion transfer function over all other amps outputs. At least, this was how I read it.
The general "good distortion" amp has only low order harmonics, and a natural to the ear magnitude progression for each harmonic, and a similar distortion tracking to the ear by volume.
This does not mean that PP is a worse option every time for everyone. That's just not true.
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Follow Ups
- RE: another commentary... - commentary 00:10:35 04/29/12 (7)
- RE: another commentary... - Tre' 21:52:36 04/30/12 (6)
- RE: another explanation... - commentary 22:02:08 05/04/12 (4)
- RE: another explanation... - Tre' 09:53:43 05/05/12 (2)
- RE: another explanation... - commentary 19:16:33 05/05/12 (1)
- RE: another explanation... Editing all of "NEXT QUESTION" reply - commentary 19:38:21 05/05/12 (0)
- I forgot important details in the above explanation. To remove my mistakes... - commentary 02:59:56 05/05/12 (0)
- RE: another commentary... - TubeDriver 09:08:12 05/01/12 (0)