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In Reply to: Tube Distortion and Bias ... a perspective posted by Naz on July 7, 2006 at 08:45:29:
Some primitive manipulation of the figures given, in the same order :2HD 3HD 4HD 5HD THD (wt)
drive: 2.78; 0.1; 0.006; 0.001; 3.002
spkr: 0.27; 0.54; 0.103; 0.026 ; 1.763
dB: -20.3; 14.6; 24.7; 28.3;
drive: 2.09; 0.17; 0.035; 0.004; 2.551
spkr: 1; 0.6; 0.072; 0.03; 2.536;
dB: -6.4; 11.0; 6.3; 17.5;
drive: 0.11 0.004 0.003 0.001 0.131
spkr: 0.4 0.015 0.002 0.001 0.44
dB: 11.2 11.5 -3.5 0.0
drive: 0.035; 0.002; 0.001; 0.001; 0.046
spkr: 0.55; 0.027; 0.001; 0.001; 0.611
dB: 23.9; 22.6; 0.0; 0.0This is interesting because it strongly confirms the results suggested by modelling, namely that the increase in higher order even harmonics roughly correlates with the decrease in second but that the increases in odd order (especially third) are complicated by the importance of the delta mu terms (variation in amplification factor with grid bias and with current) which in turn are somewhat reduced at higher levels of 2HD (because of the presence of cancelling intermodulation terms).
I have also applied a rough "weighted" THD = 2HD = 2 x 3HD + 3 x 4HD + 4 x 5HD.
Mark Kelly
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Follow Ups
- Some manipulation of your figures - Mark Kelly 19:55:36 07/07/06 (4)
- Interesting ... - Naz 01:05:47 07/08/06 (2)
- Possible explanation - Mark Kelly 01:52:25 07/08/06 (1)
- Thanks Mark , are you suggesting ... - Naz 09:09:49 07/08/06 (0)
- Irish, you F'er - Poindexter 20:30:36 07/07/06 (0)
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