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Everything posted by Backfire

  1. I think perhaps you are under a misapprehension about the time-scale of the signal travel time through the amplifier, in comparison to the time-scale of the musical rhythm. The time delay is totally insignificant. There may be other objections that could be levelled at feedback in some circumstances, but a time delay that interferes with the beat of the music is not one of them.
  2. Absolutely! And your "Ministry of Silly Wires" is such a gem that it alone justifies the continuation of the thread! If I am ever again tempted to argue with logic against the Gentleman from Missouri, I will remind myself of the Ministry of Silly Wires and have another laugh...
  3. A few days ago you advised everybody to take your reports about amplifier performance with a grain of salt, because you hadn't understood what was going on. Do you have any updates on this?
  4. If a choke or transformer has a winding constructed from, say, 100 feet of 24 AWG wire, and you modify the last 2 inches of each end of that wire by replacing it with, say 16 AWG wire, then the percentage effect of your modification on the current carrying properties of the winding will be absolutely negligible. If you leave 99.7% of the wire (the part you can't get at because it is inside the transformer) unchanged, and modify only the little bits that stick out of the transformer, then you will have no worthwhile improvement at all.
  5. I agree fully about speaker wires. The wisest thing about speaker cable choices I ever read was recently on another audio forum: The most important Characteristic of Speaker Cables is ........ Length. If they are not long enough to reach from your Amplifier to your speaker, you will not hear anything at all.
  6. It depends what, if any, accompanying explanations went along with these offerings. One can imagine, for example, that a manufacturer might offer cables in 3ft, 6ft and 12ft lengths, but that, of itself, does not imply that the said manufacturer has some crazy idea that these are the only lengths that will provide optimal audio performance. It could just mean that those happen to be the lengths they offer. If you can provide documentation where this Fulton chap expounded on the specific superiority of these particular lengths, then that might indeed argue against the charitable interpretation that he was joking with you. It would then tend to favour the suggestion that some of his ideas were a bit wacky. By the way, that 14 1/4 ft length seems to be 3/8inch short of being a multiple of three times the 57 1/8 inch basic unit.
  7. I was actually trying to be non-insulting, and give the chap the benefit of the doubt, by supposing that he might have been having a little innocent joke at your expense. If he really was making some universal assertion that wires needed to be 57 1/8 in length for optimal audio performance then indeed I would question his credentials. Anyone with a modicum of common sense and an understanding of basic physical principles would question them.
  8. The charitable view would be that it is your leg that has been pulled. If not, then questions certainly arise about the credentials of those who have told you some of these things.
  9. I think it might be the case that some Christians have a sense of humour too. I do think that leg-pulling is the most charitable explanation for why they might have said these things...
  10. It seems like a bit of stretch, to generalise from distressed baboons listening to ultrasonic signals to saying "It is THE best basic length for audio applications." This chap Fulton seems to have had a bit of a sense of humour. Do you not think it possible that he, and also the small High End audio Manufacturer from Montana, might have been having a bit of fun pulling your leg? Perhaps they felt you present a rather tempting target for a little gentle persiflage?
  11. Why? What is the supporting evidence for this assertion? Is this supposed to apply to all audio systems in all circumstances? And what does it even mean? Does the 57 1/8 inches include the length of wire inside the loudspeaker cabinet, between the speaker terminals and the speaker? Or does it only count the wire outside the speaker cabinet?
  12. I know, as you told us, you are busy ordering your components for your next amplifier, but if you do have a spare moment, could you please spell out what technical advantages you think the $1K+ bypass capacitors in the Serious Stereo amplifier that you spoke of have over standard capacitors that would cost a fraction of the price? Mr EE gave what one might call the "mainstream EE"'s answer to what qualities a bypass capacitor should have. I would still like to understand what advantages you think the $1K expenditure would confer, and why it couldn't be achieved with a much cheaper standard component.
  13. It is interesting that if one goes to the "technical information" on the Serious Stereo web site, one can find, for example, "Carrying Handles are hot-forged Chromium-Steel with Grade 8 retainers held by Loctite ® threadlocking agents" but no information is given about such things as the power output, the frequency response or the distortion. I guess that is a pretty good indicator of where the priorities of the manufacturer lie.
  14. Out of curiousity, do you have any idea what particular property the $1K+ bypass capacitors have that would account for their expense? What, technically, are they able to do that cheaper, standard capacitors cannot do?
  15. Hopefully you did at least de-gauss your cable ties, as recommended by the late gentleman from the AA Tweakers' Forum!
  16. If a dead person said a stupid thing, it is still a stupid thing.
  17. To quote Richard Dawkins, "By all means let's be open minded, but not so open-minded that our brains drop out." Let me try one further time to press you on what seems to be one of your key beliefs, namely that the bandwidth of music is vastly greater than the "audio spectrum" up to about 20 kHz that traditional EEs and other scientists assert. For example, in that earlier posting of yours, you said "As to the instantaneous peak , say one millisecond, of Steve Clarke / Solo Druns CD, I do not KNOW what that Instant current is, ....and most EEs do not know is my GUESS. Traditionally trained EEs are typically unconscious as to what the bandwidth of real music is, the " resultant, sums, heterodyne, etc. " various combinations. Want good proof?? Almost all E.E.s scoff and deride my first Audio Mentors use of a 2 GIG Tek scope to study audio ( Robert W. Fulton - about 1984 - till his death in 1988.)" So you are evidently claiming that a CD recording contains real musical detail at frequencies way beyond the usually accepted 20 kHz audible limit? This despite the fact that the engineers and scientists who invented, developed and manufactured the CD player are unequivocally saying that it is impossible for it to reproduce signal information beyond 20 kHz. Presumably you must believe that the EEs who devised and built the system are too dumb to understand what they have blundered into? They stupidly believe that their invention is limited to reproducing signal information up to 20 kHz, whereas in fact you, piddling around in your living room with a little 1930s style home amplifier, know better than the experts who designed the CD player? The designers of the CD player would love it to be true that their invention was capable of reproducing signal detail at frequencies way higher than 20 kHz, and they would proudly shout it from the rooftops...if it were true. But it isn't true, and it is physically and logically impossible for it to be true.
  18. The bandwidth of real music recorded on a CD is by definition restricted to be less than about 22 kHz (one half the sampling rate of about 44 kHz). This is not a matter for subjective opinion, it is a fact. It seems as if you are allowing yourself to become overawed by the artistry of Steve Clarke or whoever, into thinking that there must be higher order detail at frequencies way beyond the audible spectrum. There isn't. This isn't a mater of debate or opinion, it is a cold hard fact. Just like the fact that Steve Clarke's performance has been reduced essentially to a string of 0s and 1s, and the sampling rate in the CD payer is 44 kHz. In analog terms, the audio signal is just a single voltage, which varies as a function of time. There is a maximum voltage that the signal can reach, and it doesn't matter how hard Mr Clarke bangs his drum, that voltage will not be exceeded. The associated current passing through the output tube is then limited too. In a class A amplifier like an SET, the current will in any case never exceed approximately twice the quiescent zero-signal current flow through the tube. (At least, assuming that the amplifier is not being driven into clipping.) It is true that the signal voltage can be Fourier decomposed into a sum of sine waves with the various frequencies, amplitudes and phases needed to represent that audio signal. But there is no sense in which the currents associated with these various frequency components can somehow "add up" to make a total current that is bigger than the actual current corresponding to the audio signal, in the way you seem to be suggesting. The fact that Mr Fulton liked to use a 2 GiG oscilloscope for looking at audio signals in no way "proves" that there must be audio signal information up at those kinds of frequency. Mr EE has made some pertinent observations on this in a recent post on this thread.
  19. Is it possible that you have got the wrong middle initial and a mis-spelled family name of the deceased dean who corresponded with you? A quick search on Google Scholar came up with a Charles A. Halijak, who gave his affiliation as Electrical and Computer Engineering Department University of Alabama at Huntsville, Huntsville, USA in a paper published in 1989.
  20. Since you have emphasized the 1500 amp peak current capability of the decoupling capacitor several times in this thread, would you feel that it would be in sync with the flow and format of the thread to ask what you consider to be the maximum peak currents that could be passing through the output tubes of the amplifier, and why the 1500 amp capability is important?
  21. I have "pondered what the peak instantaneous current might be," and my answer is a couple of hundred milliamps, give or take a bit. I think I saw a post of yours earlier in this thread where someone had asked you a similar question,and you had, if I recall correctly, gone so far as to suggest that no equipment existed that could be capable even of measuring it. A rather extraordinary suggestion. Many people like to think that there are deep mysteries in the world whose understanding is beyond the reach of science and logic. But to imagine that there is so much beyond the reach of science in a little home stereo system is really going a bit far.
  22. OK, so the data sheet indeed confirms that, as I was suggesting, when you write 1.500 A you mean 1,500 A, i.e. one thousand five hundred. So again, my question is why? Why do you think that is important for a cathode bypass capacitor in a little tube amplifier? No, I didn't follow up on you offer of sending me the complete writings of Hasquin and Swenson because the extracts that you presented already in this thread were sufficient for me to see that I am really not interested in receiving the complete unabridged version. I don't know what Hasquin's and Swenson's qualifications really are, but certainly the extracts of Hasquin's writings that you presented did not read like the writing of a person with much understanding of the physical principles involved. It seems to me that you have somehow elevated these gentlemen's writings in you mind to the level of some sacred texts to be conveyed down from the mountain and offered to the non-believers. But again, to re-iterate my question: why do you consider it of importance that a cathode bypass capacitor should be able to handle 1500 amps peak current?
  23. You have spoken often of the 1.500A peak instantaneous current capability of the bypass capacitors, but I never saw a clear explanation of why you think that capability is important. First of all, am I right in suspecting that although yourself (presumably) of US origin, based in the US, you are using the period separator in the way that a comma would normally be used here in the US? i.e. that you mean one thousand five hundred amps? Because if read literally, in standard US notation, you are saying only one and a half amps, which doesn't sound that remarkable at all for a capacitor of that size. So, assuming you mean 1500 amps, my question would be why do you need that? The capacitor is bypassing the cathode resistor of a tube that will be passing at most a couple of hundred milliamps at the high-conduction peak of the audio cycle. There is nothing that could conceivably be capable of sending anywhere remotely close to 1 amp through that capacitor, let alone 1500 amps.
  24. I believe I did address the current issue already, but here it is again. If the power supply voltage holds steady and does not sag during the periods of higher current demand by the amplifier, then by definition it is delivering the required current. The fact that the voltage isn't sagging or varying proves that the current is available when needed. If, for whatever reason, on the other hand, the power supply voltage sags or varies during the peak demands from the amplifier, then that would be a demonstration of a failure to provide the required current during the periods of peak demand. So what is wanted, ideally, is a power supply whose voltage remains fixed and steady under all circumstances. The key ways to approach this ideal are (a) to make sure the power transformer and rectifier are beefy enough for the job, so that even during sustained periods of heavy demand the supply can cope, and (b) to make sure the final reservoir capacitor is large enough that it can hold the voltage steady in the intervals between the arrival of the pulses of rectified mains current that recharge the capacitor every half cycle of the mains supply. One probably ought to distinguish at this point the difference between the current demands of an amplifier operating in class A (like an SET amplifier), and an amplifier operating in class AB (like a typical push-pull amplifier). In a class A amplifier, the average current draw from the power supply is approximately constant, regardless of whether the amplifier is playing a very quiet passage or a sustained crescendo. (Here, the averaging I am speaking of means averaging over the period of the lowest audio frequencies that the amplifier is reproducing.) In a class AB amplifier, on the other hand, the average current draw (averaged in the same way as above) will be much higher for the duration of a loud crescendo than it will be during a quiet passage. So the nature of the demands that the amplifier places on the power supply are very different in the two cases. In fact the situation with the class A amplifier is in many ways much simpler, since if the supply voltage is adequate during a quiet passage then it will essentially be adequate also during a loud passage. The important thing is that the reservoir capacitor should be large enough to hold the voltage steady during the period of the lowest audio frequencies, and also during the interval between the recharging pulses of the mains supply. Since the lowest audio frequencies are in fact lower than the 120Hz frequency of the (full-wave) rectified mains supply, then if the lowest audio frequency averaging is adequate then reservoir capacitance should also be adequate for the mains-power averaging. (Putting the need for audio-cycle averaging in another way, the final reservoir capacitor is in the audio path, and one ideally wants to make sure that this capacitor has extremely low impedance (in comparison to the impedance in the output circuit of the amplifier) at even the lowest audio frequencies, so that very little audio signal appears across it.) In a class AB amplifier, on the other hand, the average (again, averaged over the audio cycles) current demand can rise greatly during a crescendo, and so the requirements for the power supply are more demanding in this case. Now, it becomes important that the power supply be able to withstand a large increase in sustained current demand without the voltage dropping significantly. It is in this case that having a large transformer with a low DC resistance is really important. (In fact total resistance of transformer winding plus rectifier plus choke(s) is what matters. Of course, one is somewhat loading the dice against achieving a low total resistance if one uses a vacuum tube rectifier here.) The feature of constant average current draw in a class A amplifier is not exactly true, in part because of non-linearities at high volume (non-linearities for which an SET amplifier playing at high volume is fairly notorious). So there will be some variation (increase) in average current draw during loud crescendos, and so it would be beneficial in this case also to make sure the supply can maintain a steady voltage under a modest sustained increase in load. I think one of the problems with the low capacitance power supplies that Mr Hasqin and you are advocating is that the capacitance is not really enough to hold the voltage steady during the audio cycles and the mains cycle. (And the very low inductance chokes are not helping much with the mains-cycle averaging either.) So, compared with a "normal" power supply, the low-capacitance low-inductance supply will be causing some fluctuations of the supply voltage. These will have some kind of sonic signature. It does not necessarily mean that the sound will be bad; it is quite possible that the sonic signature has qualities that appeal to the ear of the listener. But one should recognise that to the extent the power supply is failing to hold its output voltage constant, it is imparting some sonic signature on the audio output.
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