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40.0.40.10
In Reply to: I had a dream ... posted by mikeyb on March 14, 2007 at 10:42:51:
Down near the bottom of the thread Henry has simulation pictures that show what is really happening with a low L first choke power supply. Its not too damn hard to understand. While Jeff may have not been the best at explaining it, Henry has done a fine job of explaining it.I have a Biomedical Electrical Engineering degree from Purdue University, and the EE in me would never settle for anything other than this low L first choke power supply. With this approach it is easy to reduce the dynamic impedance of the power supply down to around 65 ohms. The conventional choke input power supply that meets critical inductance normally has a dynamic impedance nearing 400 ohms.
Conventional EE thinking says if you want to feed a load, then you want your source impedance to be no more than 1/10 of your load impedance. Which power supply do you, as an EE, think will be a better power source for a 300B amplifier; the 400 ohm, or the 65 ohm one?
Until you have tried one of these power supplies, I don't think you have any grounds to stand on. Jeff's methods are strange, but he did discover something that the old timers had missed. I believe the primary reasons this has gone undiscovered for so long are the following: 1.) No scientific mind would have followed Jeff's methods. 2.) We did not have simulation software like PSUDII in the 1920's. 3.) This is the year 2007, and new discoveries are occuring everyday.
Rgs, JLH
P.S. As a side note, you did know that in the mid 20th century an attempt was made to close the U.S. patent office under the rational that everything that was useful had already been invented and there was no need to keep it open. Mind you, this was before the PC was invented.
Follow Ups:
"As a side note, you did know that in the mid 20th century an attempt was made to close the U.S. patent office under the rational that everything that was useful had already been invented and there was no need to keep it open. Mind you, this was before the PC was invented."Urban Legend. Sorry. The oft-misquoted speech was from the Commissioner who was asking for the Patent Office to be expanded, certainly not closed.
> Conventional EE thinking says if you want to feed a load, then you want your source impedance to be no more than 1/10 of your load impedance. Which power supply do you, as an EE, think will be a better power source for a 300B amplifier; the 400 ohm, or the 65 ohm one?Jeff isn't the only one experiencing difficulty in the explanation department. The above statement is crudely simplistic, inappropriate for this application, and wholly ignorant of the dynamics of filtering pulsed DC. I've analyzed the low DCR concept in depth, and I think I have a pretty good understanding of how it works. I am not one of its detractors. Nevertheless, it is only one means by which to reach the finish line. These ongoing claims that it represents a sonic/engineering breakthrough are not only contentious and misleading, but may constitute the worst case of narrow-minded wishful thinking that I have seen here in quite some time.
The 'flywheel' supply (will we ever stop putting it in quotes?) that Henry described is not really what Jeff is pushing. Jeff is advocating low L and low C supplies in a general way, as a desirable approach on its own grounds. The supply that Henry described is a specific application that happens to include low L and low C, but also depends on a balance or 'tuning' (sorry, Henry) that needs to be there or the benefits (as identified by Henry) are lost entirely.To get to the point: it's possible that Jeff built a flywheel supply (no quotes!) but it's VERY unlikely. In fact, I found that I can't calculate the odds because my calculator has only 12 digits. Really, the odds that Jeff and Henry are (were) talking about the same thing is astronomically small. Not that either thing isn't interesting on its own, but they're still different things.
To really get to the point for real this time: Henry did not explain in engineering terms why Jeff likes his particular style power supply.
"Henry did not explain in engineering terms why Jeff likes his particular style power supply."Nor would he admit to it, even if he had! ;-)
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Boo!
Wow, no one can replace Ivan303 !And to set the record straight, Jeff Medwin certainly didn't develop Low C, HY. DCR supplies, Dennis Fraker did so in his first Serious Stereo SE 2A3 amp, prototyped by him, way back in 1992 , and UNchanged since then ! And it certainly uses NO flywheels.
Jeff built that type of Low C, HY, DCR supply in February 2007, with Greg's 245 SE amp in Kansas City, and reported on the supply configuration and our listening results on-Forum, when it blew us both away !!
didn't it go back further than 92? --
Hi Fred,Well, in the 1980s, I can recall Dennis and Dr. Halijak PhD. EE were having custom made 1.0 HY @ 10 ohm chokes made.
I believe he finished his first S.S. SE 2A3 amp in 1992, but Freddie, that was still fifteen years ago.
in anticipation of having my head removed, but here goes:You make some great points, many of which I tend to agree with (those that I understand, at least), but I would like to tweak one just a little.
> > > 1.) No scientific mind would have followed Jeff's methods. < < <
I would say that *some* scientific or researchers of science, would follow his methods, but that *most* engineering minds (the appliers of science) would not have. There are different methods that are available to researchers – it seems that Jeff's are unconventional, perhaps somewhat original, and may be criticised by the general EE community, however, in time the accumulation of practical evidence may support his findings, despite said criticism.
I am interested in these developments and am approaching them with a relatively open mind, however I do recognise that further evidence is required to support Jeff's hypotheses. For me, evidence must include practical application, in a range of amplifiers. Perhaps I will try Jeff’s latest formula for myself…
That said, I may be full-o-cr*p. I am just a 'mature' final year HSc student with a growing interest in medical research and a past life in quality management. My skills may not translate well to this topic; my assumptions may be way off base...
Kind regards
Raymond
Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
between those with pioneering spirit and all the rest. I have always thought that curiosity drives all scientific desire/research and action drives all scientific discovery....and invention.Nowhere is this difference more evident than in the so called 'culture war' of contemporary American politics. But I leave that discussion for elsewhere.
I have yet to see any engineering data that actually describes the sonic differences between various tubes.
What measurement describes how/why thoriated tungsten filiments sound differently than nicad?
What data describes the sound of box [shaped] plates compared with cylindrical plates?
What data explains the different sound of graphite plates as opposed to metal?
Same for sonic differences between steel, nickel and nano-glass core materials. What about core geometry?
For these, one must EXPERIENCE the various designs to even know that a difference exists, much less what sounds best. I have seen discussion where, absent this date, some would argue that NO such differences exists. Hmmmm. :)
Any Philo Farnsworths here?
Your audio-specific examples get my point across better than my more general explanations.There is much evidence - ie. consistent outcomes across a range of applications / subjects / environments - that is not necessarily backed by definitive theories. A little research into the mechanisms of action for drug / phyto / nutrition therapies will soon indicate this.
Yes, a plausible or accurate explanation of a mechanism of action is hugely beneficial to improve our understanding and therefore application and further development, but perhaps the most important (or only) 'evidence' are the results of practical application. Perhaps there is some Zen in science.
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