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#161
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
"Bob H." wrote: So, let's see, will it be prejudice that wins or desire for a stunning sound ? These probably do sound great with a transistor amp. But most are 87dbM/m with 4 ohm nominal impedance and who-knows-what impedance dips. Also most have high-order crossovers pretty much right in the middle of the vocal range. A tube amp would have to be able to supply some power. I'll stick with my Cornwalls (alinco), Hammer super 12's, and fostex full rangers, and all their inherent evils. : ) Of course, they might sound ok in a small japanese apartment with a tube amp. I'll stick you down for the prejudice category then ! Full range speakers are a joke ! You're allowing your listening to be determined ( and minimised ) by obsolescent practice. Graham |
#162
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
"Bob H." wrote: Whoops, I meant 87 db/M 87dbM/m with 4 ohm nominal impedance and who-knows-what impedance dips. and alnico. (alinco), Hammer super 12's, and fostex Good God ! You think that Alnico magnets somehow produce superior sound over other magnets ? Is that lame or what ? Graham |
#163
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
Full range speakers are a joke ! Oh, but they're a wonderful-sounding joke, and make me give me a sense of satisfaction and relaxation while listening to music. Goosebumps are regularly present. Isn't that where we want to be in the end of it all? And BTW, you speakers might sound great with tube amps. I never said they wouldn't. They just have some characteristics I've found to be detrimental with low power tube amplification. I could be completely wrong. They could indeed sing. Try them yourselves, and let me know if they do. You might need at least 20 wpc to start with, however. PS, one of my favourite amps is a Harmon Kardon SS amp. I still own it today, and can't bear to part with it. I've got new sets of output transistors, and one of these days I'll put them in and balance them..... anyone have and ideas on how to replace the 100mf coupling caps with something reasonable? They're the only signal caps in the amplification chain, as far as I can see. Man, Nora Jones just sounds better and better. Currenly on a 6em7 SE amp, of which I disconnected the output iron, and kludged in a CF circuit for my AKG headphones. I'm stuck in a hotel in Vancouver for a couple of weeks. My source is my laptop, playing wave files through a M-audio transit usb soundcard. There's a place called Lee's Electronics which had some 3.3 mf Solens for a good price. Highly recommended if in the area. They're really friendly, to boot. DIY forever, Bob H. You're allowing your listening to be determined ( and minimised ) by obsolescent practice. Graham |
#164
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
It's just a quick way to date the speakers.
Why don't you buy an Emerson rack stereo and just get it over with? It has all the specs you're looking for. You're obviously quite distrubed with this whole tube audio thing. Bob H. |
#166
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
Bob Quintal wrote: wrote in oups.com: Bob Quintal wrote: wrote in oups.com: Bob Quintal wrote: Prune wrote in 4.76: John Larkin wrote in : http://www.eng.yale.edu/qlab/papers/.../PRL_shotnoise. They call it "current noise" right in the abstract, as the Vishay people do. They can call it George. The mechanism by which the noise is generated is that of shot noise. irregardless of the name. Why do you think that? I think that because I've spent the last 30 years studying the physics of electronic components, both active and passive, in order to generate reliability assessments, failure analyses, and other such administratrivia. The summation of a shot noise profile and a Johnson noise profile mirrors the measured results most closely. Shot noise and Johnson noise are both "white" which is to say, frequency independent. What kind of noise profile lets you separate the two? Voltage vs Time. given a resistor in thermal equiibrium, apply a step increase to the current through the resistor. some noise will follow the change in current instantly. additional noise will track the Johnson noise expected from the change in temperature generated by the change in current, which is not instantaneous, but dependent on the ability of the substrate to sink the additional heat generated by the current That could also be explained by hypothesising a range of thermal paths to the substrate within the resistor - the less effectively heat-sunk resistance paths would heat up faster and further. If you are saying that you are seeing more white noise than you'd expect from the resistance and temperature of your device, you can't claim that the excess is shot noise - there are other sources of white noise. Yes, there are additional possibilities. Analysis of these sources doesn't account for all observed behavious, therefore some noise is shot noise. You can't explain it any other way, so it has to be shot noise. Not all that convincing. -- Bill Sloman, Nijmegen |
#167
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
Hi Eyesore,
Your arrogance is no joke. You listen with your asshole. Sigh. Try your ears, sometime. Happy Ears! Al Eeyore wrote: Full range speakers are a joke ! You're allowing your listening to be determined ( and minimised ) by obsolescent practice. Graham |
#168
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
Bob H. wrote: Full range speakers are a joke ! Oh, but they're a wonderful-sounding joke, and make me give me a sense of satisfaction and relaxation while listening to music. Goosebumps are regularly present. Isn't that where we want to be in the end of it all? YIKES & yikes. A couple of preliminary statements so as to establish my position clearly: a) I have no difficulty with other individual's tastes and preferences, as long as they do not attempt to dictate mine. b) I believe that Full Range, Single Driver, conventional horn (e.g. Lowther) speakers are a joke. So, I do not own any. c) I also believe that under very specific conditions and with very specific sources, FR/SD/CH speakers can sound ethereally beautiful. I have heard such, so this is an opinion based on experience. But I still do not own any, nor would I expend funds to own any... at any price. The difficulties I have experienced with the above is that when they are required to produce substantial volume using orchestral sources with very wide dynamic and peak-to-average ranges, they fail. Sometimes miserably, some times just awfully, but they fail. And this is irrespective of the amp(s) that may be driving them. There is a part of this hobby that attempts to do more-with-less, the goal is to get the maximum performance out of the least amount of power. To that end, FR speakers are a useful tool. If one chooses (or simply prefers) sources amenable to this sort of reproduction, this solution can be quite elegant. But limited. My opinion. There is a part of this hobby (to which I subscribe, primarily) that takes more of a brute-force approach, expecting to get as close to the Original Source Reproduction as is possible given the tools available. I am quite realistic in that I understand that tube equipment is a series of compromises from the git-go (as is SS, but slightly less so), the goal being to get as close as possible. As well, *I* choose not to limit my source material to the system, but attempt to go the other way. So: I own numerous pairs of multiple-driver, (relatively) inefficient speakers, the most efficient of which is rated at 86db/M. All my (three, soon four) tube amps are PP, and based from EL-84 through KT-88 outputs. My SS amps range from 40wpc/rms/8 to 200wpc/rms/8. Each has its place in the choir, but I do not have the same expectations from the 17 watt amp as from the 200 watt amp. Nor do I match them to the same speakers in the same sized rooms and so forth. Some are sub/sat systems, some are set up with a "Hafler Circuit" poor-man's surround system, all are pretty damned nice in my opinion, which with the addition of my wife's is the only one that counts in my home. Others are entitled to the same privileges in their homes. There are enough idiots, dangerous advisors and incompetent pseudo-enginneers in this group without getting into a ****ing-contest over one's choice of poison. Writing for myself, I cannot imagine drinking Night Train Express, but millions of gallons are drunk every year. And at the very same time, "designer Vodkas" (unflavored) I take as a serious joke much as little speaker cable towers... but again, millions of gallons are sold. De gustibus non est disputandum, just not my money, thank you. If we recognize that there are different approaches and different tastes and solutions based on those tastes, we might be able to discuss more of the hobby than those choices and the various idiocies attached thereto. Opinions asked should be rendered, of course. But without the invective unless dealing with invincible ignorance or malicious intent as appears to be more and more common recently. And any creature or exudation that attempts to dictate a singular taste or result is fair game. Peter Wieck Wyncote, PA |
#169
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
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#170
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
John Larkin wrote:
On Sun, 23 Jul 2006 17:44:28 +0000 (UTC), (Ken Smith) wrote: In article , Phat Bytestard wrote: [....] Anything above absolute zero not only emits IR energy, but electrical noise as well. (speaking of electrical mediums, of course) The truth is that they emit wide band electromagnetic noise. The spectrum goes from DC to daylight. The bit that happens to be conducted out on the leads we call electrical noise. There is IR and microwave and radio noise there too. The Johnson noise spectrum doesn't quite make it to daylight, but peters out in the thz region. It couldn't be true white noise, because then the power would be infinite. John Classical equipartition says that the mean energy per degree of freedom is kT/2. There are simple ways to show that this is flat with frequency, classically speaking. This breaks down where the Planck rolloff sets in, at a frequency of order kT/h. The proportionality constant k/h is about 20 GHz/K, so at room temperature it rolls off somewhere around 6 THz. [There's actually another factor of about 1.26 since the Planck function is (hf/kT)/(exp(hf/kT)-1) instead of the usual one-pole rolloff we're used to in circuits, so the 3 dB frequency is actually closer to 8 THz at room temperature.) The optical emission isn't flat with frequency, but has a peak frequency proportional to temperature, and a FWHM of about two octaves. The reason for this is that there are a lot more degrees of freedom as you go to higher frequency--each 1-Hz slice corresponds to an annular sphere in k-space, whose volume goes as f**2. Optical spectra are commonly quoted in per-wavelength units, and converting from differential frequency to differential wavelength gets you another factor of f**2, so in per-wavelength terms the number of degrees of freedom goes as lambda**-4. Cheers, Phil Hobbs |
#171
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
"Bob Quintal" wrote in message
... John Larkin wrote in : On 22 Jul 2006 18:03:38 GMT, Bob Quintal wrote: I *do* work at 120 dB s/n ratios over DC-50 KHz bandwidths and I do use surface-mount thickfilm resistors. Pretty much the same here, Cool. I do NMR gradient-coil drivers. What do you do? John amongst other things, image sensor front ends for telescopes. It just so happens that I am about to get involved in a project that includes the design of low noise sensor electronics in a rather small space. Having never worked with surface mount components before, what would you gents suggest for prototyping equipment? Would the use of flex circuit boards make any difference in your choice? Many thanks in advance, Stuart Welwood |
#172
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
Hi RATs!
Since no single driver can do everything, apparently they can do nothing. Big G's small mind is so coy. Gee, big G, do you then propose that all full range speaker systems, with as many drivers as you like, sound the same, just like all passive devices, save the odd sicko resistor? It is going to be fun for you when you grow up. Happy Ears! Al Eeyore wrote: There is no single driver that can properly recreate 20Hz to 20kHz. It's easy to see why 2 and 3 way systems are the norm. Graham |
#173
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
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#174
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
" wrote: Hi RATs! Since no single driver can do everything, apparently they can do nothing. Big G's small mind is so coy. Gee, big G, do you then propose that all full range speaker systems, with as many drivers as you like, sound the same, just like all passive devices, save the odd sicko resistor? What on earth are you rabbiting on about ? It is going to be fun for you when you grow up. You're pathetic. A tribute to audiophoolery. Graham |
#175
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
"Stuart Welwood" wrote in
: "Bob Quintal" wrote in message ... John Larkin wrote in : On 22 Jul 2006 18:03:38 GMT, Bob Quintal wrote: I *do* work at 120 dB s/n ratios over DC-50 KHz bandwidths and I do use surface-mount thickfilm resistors. Pretty much the same here, Cool. I do NMR gradient-coil drivers. What do you do? John amongst other things, image sensor front ends for telescopes. It just so happens that I am about to get involved in a project that includes the design of low noise sensor electronics in a rather small space. Having never worked with surface mount components before, what would you gents suggest for prototyping equipment? Would the use of flex circuit boards make any difference in your choice? Many thanks in advance, Stuart Welwood We've seen good results using boards with rigid sections coupled with flex sections. You might also want to investigate Sealed Chip On Board techniques. I can't say more, but here is one university paper that deals with the subject:. http://www.css.taylor.edu/ ~physics/minielec/publications/paper.html -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
#176
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
John Larkin wrote: On 23 Jul 2006 20:10:35 -0700, wrote: Shot noise and Johnson noise are both "white" which is to say, frequency independent. What kind of noise profile lets you separate the two? The Johnson noise voltage is there with no bias, and the shot noise depends on the current through the part. Perfectly correct, but that would be a current dependence profile, which doesn't seem to be quite what was being described. -- Bill Sloman, Nijmegen |
#177
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On 24 Jul 2006 15:46:38 -0700, wrote:
John Larkin wrote: On 23 Jul 2006 20:10:35 -0700, wrote: Shot noise and Johnson noise are both "white" which is to say, frequency independent. What kind of noise profile lets you separate the two? The Johnson noise voltage is there with no bias, and the shot noise depends on the current through the part. Perfectly correct, but that would be a current dependence profile, which doesn't seem to be quite what was being described. Bob didn't specify that it was a frequency profile, you did. All he said was "profile." I think his correct point is that one can use simple techniques to separate them. Additional argument is just being a pain in the ass. John |
#178
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
You will note that carbon comps are available in SURFACE MOUNT packaging, so *somebody* with major engineering chops sees reasons to keep using them. I think carbon comps are better in handling pulsed power, like in radar or flash tube circuits etc. Mark |
#179
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Mon, 24 Jul 2006 10:09:16 GMT, spud Gave us:
On 23 Jul 2006 11:03:26 GMT, Bob Quintal wrote: Prune wrote in . 144.76: John Larkin wrote in : http://www.eng.yale.edu/qlab/papers/..._shotnoise.pdf They call it "current noise" right in the abstract, as the Vishay people do. They can call it George. The mechanism by which the noise is generated is that of shot noise. irregardless of the name. Please take this in the spirit of childish pedantry it's intended but it makes me cringe when presumably educated people use the "word" irregardless. A simple, "regardless" will do. Thank you, s. INCONCEIVABLE! ;-] |
#180
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
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#181
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin
Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. |
#182
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Mon, 24 Jul 2006 11:33:03 -0600, "Stuart Welwood"
Gave us: "Bob Quintal" wrote in message ... John Larkin wrote in : On 22 Jul 2006 18:03:38 GMT, Bob Quintal wrote: I *do* work at 120 dB s/n ratios over DC-50 KHz bandwidths and I do use surface-mount thickfilm resistors. Pretty much the same here, Cool. I do NMR gradient-coil drivers. What do you do? John amongst other things, image sensor front ends for telescopes. It just so happens that I am about to get involved in a project that includes the design of low noise sensor electronics in a rather small space. Having never worked with surface mount components before, what would you gents suggest for prototyping equipment? Would the use of flex circuit boards make any difference in your choice? Many thanks in advance, Stuart Welwood Flex is expensive. Especially in short run numbers. |
#183
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard
wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John |
#184
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
In article ,
John Larkin wrote: On Sun, 23 Jul 2006 17:44:28 +0000 (UTC), (Ken Smith) wrote: In article , Phat Bytestard wrote: [....] Anything above absolute zero not only emits IR energy, but electrical noise as well. (speaking of electrical mediums, of course) The truth is that they emit wide band electromagnetic noise. The spectrum goes from DC to daylight. The bit that happens to be conducted out on the leads we call electrical noise. There is IR and microwave and radio noise there too. The Johnson noise spectrum doesn't quite make it to daylight, but peters out in the thz region. It couldn't be true white noise, because then the power would be infinite. People have told me a million times not to exaggerate but sometimes I still do. At some point, like the THz range as you suggest, the energy in a photon starts to become too much to be ignored. -- -- forging knowledge |
#185
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin
Gave us: On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John While the wiper is still or moving? While moving, it should be obvious. The locations where conduction is taking place are moving all over the wiper surface, and there are even microscopic arcs taking place If the two mediums were bound together covalently, I'd say no noise, but since oxides and oxygen and dissimilar mediums are concerned (wiper metal over some form of carbon slurry or deposition) I'd say there is room to argue that some noise might occur through those pathways. Wiper still... Interfaces between mediums and oxides, less noise. Tastes great, less filling. |
#186
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard
wrote: On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin Gave us: On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John While the wiper is still or moving? While moving, it should be obvious. Not to me. Noise requires potentials, and resistors don't do that. The locations where conduction is taking place are moving all over the wiper surface, and there are even microscopic arcs taking place Arcs? At audio signal levels? John |
#187
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
John Larkin wrote: On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin Gave us: On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John While the wiper is still or moving? While moving, it should be obvious. Not to me. Noise requires potentials, and resistors don't do that. But as connections are varying, Vout / Vin also varies. This creates the noise. Think of the condition with a DC input and it's more immediately obvious. Graham |
#188
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Mon, 24 Jul 2006 22:51:37 -0700, John Larkin
Gave us: On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin Gave us: On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John While the wiper is still or moving? While moving, it should be obvious. Not to me. Noise requires potentials, and resistors don't do that. The locations where conduction is taking place are moving all over the wiper surface, and there are even microscopic arcs taking place Arcs? At audio signal levels? You are not thinking in the microscopic level. Instead of volts per mil, it would be like millivolts per micron. If oxides keep a "wiper" from making "intimate" contact, there will be tiny little breach events that take place as electron bore through the oxides and the wiper scrapes through. Generally though it would simply be shot noise magnified by passage through a smaller surface area of contact. And end cap has more total surface area of contact than does a pair or a few wiper noses. Sniff, sniff... Hey... that's it! Sniffing Noise! |
#189
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
Phat Bytestard wrote in
: On Mon, 24 Jul 2006 22:51:37 -0700, John Larkin Gave us: On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin Gave us: On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John While the wiper is still or moving? While moving, it should be obvious. Not to me. Noise requires potentials, and resistors don't do that. The locations where conduction is taking place are moving all over the wiper surface, and there are even microscopic arcs taking place Arcs? At audio signal levels? You are not thinking in the microscopic level. Instead of volts per mil, it would be like millivolts per micron. If oxides keep a "wiper" from making "intimate" contact, there will be tiny little breach events that take place as electron bore through the oxides and the wiper scrapes through. Generally though it would simply be shot noise magnified by passage through a smaller surface area of contact. And end cap has more total surface area of contact than does a pair or a few wiper noses. Sniff, sniff... Hey... that's it! Sniffing Noise! What somebody obviously forgot is that microscopic doesn't apply to the wiper contact surface area. Each of the locations where "conduction is taking place" is in parallel with thousands of other locations where "conduction is taking place". This aso prevents arcing because of the shunt resistance of the other contact points. -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
#190
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
(Scott Dorsey) wrote in
: John Larkin wrote: wrote: The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? When you turn the pot, it bounces up and down across the surface. There is mechanical noise, and a corresponding change in resistance that causes electrical noise. When you stop turning the pot, the noise goes away. As a result, these are great for trimmer pots and things that get occasionally adjusted, but unacceptable for controls you'll be riding all day long like channel gains. --scott So its an issue of the wiper arm lacking the proper tension to keep it from bouncing? -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
#191
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
On Tue, 25 Jul 2006 07:09:55 +0100, Eeyore
wrote: John Larkin wrote: On Tue, 25 Jul 2006 05:09:29 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 20:07:24 -0700, John Larkin Gave us: On Tue, 25 Jul 2006 02:28:06 GMT, Phat Bytestard wrote: On Mon, 24 Jul 2006 08:24:37 -0700, John Larkin Gave us: On 24 Jul 2006 10:41:54 -0400, (Scott Dorsey) wrote: John Larkin wrote: On Sun, 23 Jul 2006 04:59:19 GMT, Prune wrote: I've tried cermet potentiometers for volume control, and in a blind test (non-double, used dual switch with my friend) I can't tell the difference between it and a stepped attenuator; however, in 7/10 trials me and 8/10 trials him heard difference between plastic pot and the cermet, both preferring the cermet. Please don't top post. Agreed. But the problem with cermets is they are noisy as hell when you turn them. That's fine for trimmers, but no so good for a volume control on the front panel. What's the origin of the noise? If the wiper drives a high impedance, unstable wiper contact resistance will generate no noise. The surface quality of a first surface mirror is very flat, and very fine grained in the macroscopic view. The "drag surface" of a variable resistor has to be a couple hundred times rougher than that. That is going to produce "noise" when turned, and even when stopped as the contact surface upon the wiper can and likely will always be different tiny points on the wiper surface. It is rougher even than basic grain oriented polished stainless at a certain finish. (maybe a number 4). Pretty rough is the macro surface quality/texture realm. But how does that create electrical noise? John While the wiper is still or moving? While moving, it should be obvious. Not to me. Noise requires potentials, and resistors don't do that. But as connections are varying, Vout / Vin also varies. This creates the noise. Think of the condition with a DC input and it's more immediately obvious. Graham That will just result in a tiny amplitude modulation of whatever sound level is there at that instant, and the sound level is changing all the time anyway, especially so as you're turning the pot on purpose already. That won't be very, whether the pot is cermet, plastic, or wirewound. The difference with DC is that you can't hear DC, but you can hear the small variations in DC - real noise - that a bad pot can create. OK, new audiophool product: volume controls based on variable capacitance. John |
#192
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
rick H wrote:
In sci.electronics.design Phil Hobbs wrote: John Larkin wrote: The Johnson noise spectrum doesn't quite make it to daylight, but peters out in the thz region. It couldn't be true white noise, because then the power would be infinite. Classical equipartition says that the mean energy per degree of freedom is kT/2. There are simple ways to show that this is flat with frequency, classically speaking. This breaks down where the Planck rolloff sets in, at a frequency of order kT/h. The proportionality constant k/h is about 20 GHz/K, so at room temperature it rolls off somewhere around 6 THz. [There's actually another factor of about 1.26 since the Planck function is (hf/kT)/(exp(hf/kT)-1) instead of the usual one-pole rolloff we're used to in circuits, so the 3 dB frequency is actually closer to 8 THz at room temperature.) Something doesn't stack up there, Phil. It's common to replace the exponential term with the series expansion 1 + hf/kT, which is a good approximation down to a few Kelvin (I assume this is the method you talked about which gives the classical result.) The series expansion gives you (with your formula) (hf/kT)/(exp(hf/kT)-1) ~= (hf/kT)/(1 + hf/kT -1) = (hf/kT)/(hf/KT) = 1 which is an interesting (dimensionless) result! Right, I'm quoting the Planck *rolloff*. It's normalized to 1 at low frequency. Cheers, Phil Hobbs |
#193
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
Ken Smith wrote:
In article , John Larkin wrote: The Johnson noise spectrum doesn't quite make it to daylight, but peters out in the thz region. It couldn't be true white noise, because then the power would be infinite. People have told me a million times not to exaggerate but sometimes I still do. At some point, like the THz range as you suggest, the energy in a photon starts to become too much to be ignored. Sometimes that rolloff matters, even in circuits. I'm building electrical detectors (not photodiodes or photoresistors) that detect 200 THz signals by rectification. (Current efficiency level is about 4%, but they've only been working for a month or so, and the next best reported number is about 0.1%.) Cheers, Phil Hobbs |
#194
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
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#195
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
John Larkin wrote: On 24 Jul 2006 15:46:38 -0700, wrote: John Larkin wrote: On 23 Jul 2006 20:10:35 -0700, wrote: Shot noise and Johnson noise are both "white" which is to say, frequency independent. What kind of noise profile lets you separate the two? The Johnson noise voltage is there with no bias, and the shot noise depends on the current through the part. Perfectly correct, but that would be a current dependence profile, which doesn't seem to be quite what was being described. Bob didn't specify that it was a frequency profile, you did. All he said was "profile." I think his correct point is that one can use simple techniques to separate them. Additional argument is just being a pain in the ass. Be that as it may, he didn't support his identification of the excess noise as shot noise with any kind of meaningful argument - he just talked about a "noise profile" which is just a tad unspecific. -- Bill Sloman, Nijmegen |
#196
Posted to rec.audio.tubes,rec.audio.pro,sci.electronics.design
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Vishay talk ******** - was Teflon Film Tin Foil capacitors
John Larkin wrote:
On 25 Jul 2006 09:45:40 -0400, (Scott Dorsey) wrote: When you turn the pot, it bounces up and down across the surface. There is mechanical noise, and a corresponding change in resistance that causes electrical noise. Please explain how a change in resistance creates voltage. It does not create voltage, it creates a change in the drop in voltage from the signal that is already across the pot. If there is no signal and no DC offset, there will be no noise either. But if there is no signal and no DC, there is no need for a pot. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#197
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
Eeyore said:
You're pathetic. A tribute to audiophoolery. Al 's a happy tinkerer. With all respect for your status as a pro designer (so am I, in a smaller and different way), I'm afraid you've lost that ability somewhere along the way............ -- "All amps sound alike, but some sound more alike than others". |
#198
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
"Prune" wrote in message 4.76... Couldn't it be that fine differences can only be heard in ultra high resolution systems, where everything is optimized? Or that while some individual part changes may be inaudible, a number of simultaneous changes would sum to exceed a perception threshold? Yup, the Emperor's new clothes can only be seen in the finest venues. ;-) |
#199
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
"Eeyore" wrote in message ... "Bob H." wrote: Whoops, I meant 87 db/M 87dbM/m with 4 ohm nominal impedance and who-knows-what impedance dips. and alnico. (alinco), Hammer super 12's, and fostex Good God ! You think that Alnico magnets somehow produce superior sound over other magnets ? Is that lame or what ? Yes, there are Alnico gauss and ceramic gauss. The former are more effective. ;-) |
#200
Posted to rec.audio.tubes
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Teflon Film Tin Foil capacitors
"Bob H." wrote in message ups.com... Full range speakers are a joke ! Oh, but they're a wonderful-sounding joke, and make me give me a sense of satisfaction and relaxation while listening to music. Hmm, so you have a preference for rough, limited frequency response? Goosebumps are regularly present. I suggest that you raise the room temperature to 65 degrees F, or higher. |
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