gettin eddycated...
sorry steve, i skipped a step
how about: "if you feed two tones into a circuit with 2nd order nonlinearity sufficient to give 10% 2nd harmonic with a single sine" - not an unreasonable elide in a discussion of cs jfet distortion measurements
if we are further finely parsing statements then “3nd harmonic should be as low as possible” is inconsistent, after all the 3rd harmonic of a single sine also falls under the masking curve, if the forward masking threshold is aprox (f/fo)^-4 then 1% 3rd harmonic shouldn’t be any more of a problem than 10% 2nd – so more broadly construing padamiecki’s statement seems in order
at risk of being "freddified" as well i'm including a simulation:
ps I agree with dimitri, real data is great, even better when it improves our models, which requires some consideration of how to measure in terms that can be compared with the theory
sorry steve, i skipped a step
how about: "if you feed two tones into a circuit with 2nd order nonlinearity sufficient to give 10% 2nd harmonic with a single sine" - not an unreasonable elide in a discussion of cs jfet distortion measurements
if we are further finely parsing statements then “3nd harmonic should be as low as possible” is inconsistent, after all the 3rd harmonic of a single sine also falls under the masking curve, if the forward masking threshold is aprox (f/fo)^-4 then 1% 3rd harmonic shouldn’t be any more of a problem than 10% 2nd – so more broadly construing padamiecki’s statement seems in order
at risk of being "freddified" as well i'm including a simulation:
ps I agree with dimitri, real data is great, even better when it improves our models, which requires some consideration of how to measure in terms that can be compared with the theory
Re: gettin eddycated...
please find and read a "feedback-paper-acrobat.pdf" that I found at diyaudio. I forgot the link or addres. Again somebody was first!
jcx said:sorry steve, i skipped a step
how about: "if you feed two tones into a circuit with 2nd order nonlinearity sufficient to give 10% 2nd harmonic with a single sine" - not an unreasonable elide in a discussion of cs jfet distortion measurements
if we are further finely parsing statements then “3nd harmonic should be as low as possible” is inconsistent, after all the 3rd harmonic of a single sine also falls under the masking curve, if the forward masking threshold is aprox (f/fo)^-4 then 1% 3rd harmonic shouldn’t be any more of a problem than 10% 2nd – so more broadly construing padamiecki’s statement seems in order
at risk of being "freddified" as well i'm including a simulation:
ps I agree with dimitri, real data is great, even better when it improves our models, which requires some consideration of how to measure in terms that can be compared with the theory
please find and read a "feedback-paper-acrobat.pdf" that I found at diyaudio. I forgot the link or addres. Again somebody was first!
Re: Re: gettin eddycated...
the Boyk and Sussman article isn't hopeless (after all thier discussion begins with: “In all cases, with and without feedback, intermodulation terms dominate the harmonic distortion terms of the same order. We all know this must be true but we usually forget it.”) but they are really late to the game and missed many prior refs that cover the same material - and anyone citing Cheever for support loses points on many levels
the Cheever thesis is an embarrassment to the issuing institution and a parody of the scientific method - the list of true statements about feedback and solid state amplifiers is much shorter than the list of howling errors, Cheever can’t even identify the dominant pole cap in the Hafler amp he uses
I keep trying but few seem to really be willing to look at real references rather than pass around superficially impressive looking papers that just happen to be on the web
"Multitone Testing of Sound System Components - Some Results and Conclusions, Part 1: History and Theory" JAES V 49#11 nov 2001 by Czerwinski et al at Cerwin Vega – with 119 references it is a truly thorough and relatively recent review article of the history of distortion measurement back to the dawn of audio reproduction
Cherry, “Estimates of Nonlinear Distortion in Feedback Amplifiers” JAES V48#4 2000 is another jewel that clarifies and simplifies distortion analysis without the obscuring Volterra math
ps please try to avoid duplicating image links in quotes, the free service i'm using imposes bandwidth limits (maybe not a probelm on the same page? i don't know)
padamiecki said:
the Boyk and Sussman article isn't hopeless (after all thier discussion begins with: “In all cases, with and without feedback, intermodulation terms dominate the harmonic distortion terms of the same order. We all know this must be true but we usually forget it.”) but they are really late to the game and missed many prior refs that cover the same material - and anyone citing Cheever for support loses points on many levels
the Cheever thesis is an embarrassment to the issuing institution and a parody of the scientific method - the list of true statements about feedback and solid state amplifiers is much shorter than the list of howling errors, Cheever can’t even identify the dominant pole cap in the Hafler amp he uses
I keep trying but few seem to really be willing to look at real references rather than pass around superficially impressive looking papers that just happen to be on the web
"Multitone Testing of Sound System Components - Some Results and Conclusions, Part 1: History and Theory" JAES V 49#11 nov 2001 by Czerwinski et al at Cerwin Vega – with 119 references it is a truly thorough and relatively recent review article of the history of distortion measurement back to the dawn of audio reproduction
Cherry, “Estimates of Nonlinear Distortion in Feedback Amplifiers” JAES V48#4 2000 is another jewel that clarifies and simplifies distortion analysis without the obscuring Volterra math
ps please try to avoid duplicating image links in quotes, the free service i'm using imposes bandwidth limits (maybe not a probelm on the same page? i don't know)
Re: Re: Re: gettin eddycated...
"Multitone Testing of Sound System Components - Some Results and Conclusions, Part 1: History and Theory" JAES V 49#11 nov 2001 by Czerwinski et al at Cerwin Vega – with 119 references it is a truly thorough and relatively recent review article
ok,
is there any link to this? please send,
sorry for duplicating the links
"Multitone Testing of Sound System Components - Some Results and Conclusions, Part 1: History and Theory" JAES V 49#11 nov 2001 by Czerwinski et al at Cerwin Vega – with 119 references it is a truly thorough and relatively recent review article
ok,
is there any link to this? please send,
sorry for duplicating the links
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