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#1
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Menno van der Veen Masterclass
Don't know if anyone is interested but I got this little snippet in the
email form Elektor today: http://tinyurl.com/82upa5 He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Cheers Ian |
#2
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
Ian Bell wrote: Don't know if anyone is interested but I got this little snippet in the email form Elektor today: http://tinyurl.com/82upa5 He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Well, the DF does change during a wave cycle. Ra isn't constant at all points; if it was, there'd be less THD and IMD. Patrick Turner. Cheers Ian |
#3
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
"Ian Bell" wrote in message
Don't know if anyone is interested but I got this little snippet in the email form Elektor today: http://tinyurl.com/82upa5 Nice touch, promising an article and slamming us with an advertisement. :-( |
#4
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
In article ,
Patrick Turner wrote: Ian Bell wrote: Don't know if anyone is interested but I got this little snippet in the email form Elektor today: http://tinyurl.com/82upa5 He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Well, the DF does change during a wave cycle. Ra isn't constant at all points; if it was, there'd be less THD and IMD. It sounds to me like you are saying this isn't really a new discovery, but has always been part of the known THD and IMD. -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
#5
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
"Patrick Turner" wrote in message
Ian Bell wrote: Don't know if anyone is interested but I got this little snippet in the email form Elektor today: http://tinyurl.com/82upa5 He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Well, the DF does change during a wave cycle. Ra isn't constant at all points; if it was, there'd be less THD and IMD. DF changes during a wave cycle is of course always there if the amp is nonlinear, and all amps are at least a tiny bit nonlinear. It is only going to have the possibiilty of being an audible problem with amplifiers that have quite a bit of nonlinear distortion. Whether you would hear this second order effect among the primary effects of all that nonlinearity seems doubtful. |
#6
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
"Patrick Turner" wrote in message ... Ian Bell wrote: Don't know if anyone is interested but I got this little snippet in the email form Elektor today: http://tinyurl.com/82upa5 He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Well, the DF does change during a wave cycle. Ra isn't constant at all points; if it was, there'd be less THD and IMD. Patrick Turner. Cheers Ian .... christened? --- named, surely!! Does this mean, thanx to a new parameter surfaced by Menno van der Veen, MSc., leading[??] designer of valve amplifiers and output transformers, yet -another- type of DFM has to be designed and marketed? It will cost a bomb! Bad enough to fork out £160 + return train fare for Brum. Jim |
#7
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
Ian wrote:
He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Menno is fond of copyright, e.g. "super triode". It doesn't mean that the named entity is new, but rather that his particular analysis is new, in form or in detail. How about "perveance distortion"? (copyright Ian Iveson, just now). This is the distortion arising from variations in valve perveance according to signal level. Of course it's part of the total distortion we all know about, but I am the first to isolate it and give it a name. As for DDFD, surely that must be something in the frequency domain? Otherwise it's a stupid name. DF is not the same as output impedance. Neither is it a property of an amplifier or a speaker. Rather it arises from the relationship between the two. From memory, the closest he gets in the book cited in your link is a plot of the frequency response of an amp + loudspeaker, in terms of SPL probably, with several different examples of amp output impedance. Predictably, the output impedance is pretty much related to the amplitude of the variations in SPL with frequency. Extending analysis in that direction, dynamic changes in output impedance, and hence in DF, will lead to dynamic variation in the amplitude of SPL variations with frequency. Can that be called distortion? What about the consequent IMD, arising from both the speaker and the output stage? That would not be part of the usual measured IMD of an amp with a sine wave and constant load, I suppose. Er, in case that paragraph doesn't make sense: a plot of SPL v frequency is wriggly, and if the output impedance of the amp is greater, then the wriggles are greater but more or less in the same places. If the output impedance varies dynamically, then so do the amplitudes of the wriggles. Different wriggle amplitudes will result in different levels of IMD. AFAIK, once you subtract all the forms of distortion which already have names from a typical amp output, then there isn't much distortion left worth naming. OTOH, standard measurements are designed to isolate the forms of distortion that already have names. Menno is sensitive to the sales of Plitron transformers. My guess is that he has divided up total distortion in a way that serves the purpose of isolating a particular aspect that can be shown to depend on transformer quality. I consider it certain that, in that lecture, he will go on to demonstrate that DDFD is minimised by the use of Plitron output iron. The book, BTW, is worth a read if you can sort the wheat from the chaff and reorganise it in your head. My advice is to minimise the OPT turns ratio. Ian |
#8
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
Ian Iveson wrote:
Extending analysis in that direction, dynamic changes in output impedance, and hence in DF, will lead to dynamic variation in the amplitude of SPL variations with frequency. Can that be called distortion? What about the consequent IMD, arising from both the speaker and the output stage? That would not be part of the usual measured IMD of an amp with a sine wave and constant load, I suppose. A lot of work was done in the 1950s with regard to DF and output impedance, there seems to have been a period where amps were produced with variable DF, ie +ve, zero and -ve output impedances. Maybe you should read some of the papers from that period, they were far from groping in the dark. -- Nick |
#9
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
Actually there is more...
If the output impedance, and hence the DF, varies dynamically with signal amplitude, then that part of the output due to the transient response of the speakers will be distorted. I think, but there are too many layers of nonlinearity for me to envisage. If I'd ever had a motorcycle with multi-rate damping, rather than multi-rate springs, I might have got a feel for DDFD. If it leads to distortion in the time domain, then it should feel like some higher-frequency vibration when riding over bumps. There is a 3D graph that probably has a name, and shows SPL on the vertical axis, frequency on the horizontal, and time out from the page. If you give the speaker a kick, then you get a number of ridges at various frequencies, each of which dies away along the time axis. Greater damping will make the ridges shorter. Varying the damping dynamically according to SPL will, I guess, result in the appearance of extra or greater ridges at harmonic frequencies. Perhaps we should all chip in and sponsor you to attend Menno's event? Alternatively, maybe someone would dare to ask about DDFD on rec.audio.tech? They're really clever, but our delegate might get savaged. Ian |
#10
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
Nick Gorham wrote
Extending analysis in that direction, dynamic changes in output impedance, and hence in DF, will lead to dynamic variation in the amplitude of SPL variations with frequency. Can that be called distortion? What about the consequent IMD, arising from both the speaker and the output stage? That would not be part of the usual measured IMD of an amp with a sine wave and constant load, I suppose. A lot of work was done in the 1950s with regard to DF and output impedance, there seems to have been a period where amps were produced with variable DF, ie +ve, zero and -ve output impedances. Maybe you should read some of the papers from that period, they were far from groping in the dark. Actually they were pretty much groping, mostly, from my memory. Perhaps you could help Ian with a summary of what you learned? However, as I realised after I posted, *dynamic* variation in damping factor, i.e. during the wave cycle, adds another and quite different can of worms. Ian |
#11
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
On Jan 2, 3:26*pm, "Arny Krueger" wrote:
"Patrick Turner" wrote in message Ian Bell wrote: Don't know if anyone is interested but I got this little snippet in the email form Elektor today: http://tinyurl.com/82upa5 He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Well, the DF does change during a wave cycle. Ra isn't constant at all points; if it was, there'd be less THD and IMD. DF changes during a wave cycle is of course always there if the amp is nonlinear, and all amps are at least a tiny bit nonlinear. It is only going to have the possibiilty of being an audible problem with amplifiers that have quite a bit of nonlinear distortion. Whether you would hear this second order effect *among the primary effects of all that nonlinearity seems doubtful. We've spent nearly two decades telling you, dear Arny, that there are subliminal effects that cannot (yet) be measured but that nonetheless cause listeners to become uneasy, to prefer on setup to another for reasons which they cannot quite articulate. All that the above tells us is that you don't listen too well. Andre Jute Tear drop vase, tear drop vase, plum distressed -- Cash Register, Heaton's, Bandon, Co Cork, Eire, Christmas 2008 |
#12
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
On Jan 2, 4:41*pm, Andre Jute wrote:
A lot of self-serving crap. And Arny may be a odious jackass, but he is far less dangerous than you are. He represents that segment of the population that has found a kernel of some aspect of the smallest part of a greater "truth" and is riding that kernel for all it is worth. Happily, he doesn't fool too many for too long as he is not terribly clever. You, on the other hand are nothing but a liar, poseur and charlatan with no claims on any sort of truth. Sadly, you are far more clever than Arny and so you do appeal to those 'some of the people' that one can fool 'all of the time'. That the two of you so richly deserve each other is a happy accident, but as one might suggest to any two of your sort making out in public before it gets too hot-and-heavy: Get a room! Peter Wieck Melrose Park, PA |
#13
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
On Jan 2, 2:42*am, Ian Bell wrote:
He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Which he carefully does not define - at least in the teaser. Which leaves what is meant by it open to rampant speculation. Which as Patrick leapt on immediately will *very most likely* (to be distinguished from "almost certainly") turn out to be a subset of already clearly understood and defined sorts of distortion(s) together with a means to 'solve' it and further the means to perhaps profit from it. The analogy that comes to my mind is old wine in new skins. I admit to getting very squirrelly when expected to swallow whole (at a significant cost) any sort of NEW discovery with reference to tube equipment. Not to state that it is impossible - Clarke's Laws suggest otherwise - but that it is quite unlikely. So, who is going to go? A bit far for me, and with that same £160 (not to mention air-fare, food & lodging), I could purchase quite a bit of tube equipment for experimentation and enjoyment in these troubled times. Peter Wieck Melrose Park, PA |
#14
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
"Andre Jute" wrote in message
We've spent nearly two decades telling you, dear Arny, that there are subliminal effects that cannot (yet) be measured but that nonetheless cause listeners to become uneasy, to prefer on setup to another for reasons which they cannot quite articulate. All that the above tells us is that you don't listen too well. Andre I'll bet that you don't know that the above is completely irrelevant to what I said. |
#15
Posted to rec.audio.tubes
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Menno van der Veen Masterclass
Peter Wieck wrote:
On Jan 2, 2:42 am, Ian Bell wrote: He seems to have discovered yet another type of distortion which he has christened Dynamic Damping Factor Distortion (DDFD). Which he carefully does not define - at least in the teaser. Which leaves what is meant by it open to rampant speculation. Which as Patrick leapt on immediately will *very most likely* (to be distinguished from "almost certainly") turn out to be a subset of already clearly understood and defined sorts of distortion(s) together with a means to 'solve' it and further the means to perhaps profit from it. The analogy that comes to my mind is old wine in new skins. I admit to getting very squirrelly when expected to swallow whole (at a significant cost) any sort of NEW discovery with reference to tube equipment. Not to state that it is impossible - Clarke's Laws suggest otherwise - but that it is quite unlikely. So, who is going to go? A bit far for me, and with that same £160 (not to mention air-fare, food & lodging), Now, Peter, you know it would be my privilege to provide food and lodging for you here in the UK. ;-) By the way, all the 6SN7s worked fine. Cheers ian I could purchase quite a bit of tube equipment for experimentation and enjoyment in these troubled times. Peter Wieck Melrose Park, PA |
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