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#81
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Shielded mains cable
"Eeyore" wrote in message ... Iain Churches wrote: "Eeyore" wrote The only UK maker of serious audio specific test gear was Radford, later to become Wayne Kerr Radford, later still dropping the Radford. Hi Graham. I am getting indignant e.mails by the bucketfull, People asking: "Have you never heard of Dawe Instruments, Solartron, Pye Electronics, Levell UK, Farnell, Feedback Electronics etc etc" Anyone would think it was I who made the above statement:-) LOL ! Well, I even still have some Levell kit myself (oscillator and microvoltmeter) but I never considered it to be audio specific nor especially well made either as it happens. About 36 yrs ago I did actually buy a Feedback Instruments sweep generator for Studiomaster's R&D lab. In those days before modern automated test gear it was quite handy to look a frequency response with. Feedback are still going strong, with educational establishments as their main client base, I think. They make a variable phase oscillator with a separate meter uint, which is a very quick and accurate way to measure phase response. I have one of these. http://www.fbk.com/test-measurement/vpg608.asp I have however failed to mention Bruel and Kjaer. I still have a chart recorder of theirs here ! Leader Instruments made a kind of asian knock-off of it too with inbuilt oscillator as a self-contained response measurement set. I was thinking about UK based makers. Sound Technology should have a mention too. They made some very fine test kit specifically for audio but seemingly later vanished without trace. Then again there was Tektronix's excellent SG505 sig-gen and matching AA501 analyser. Designed by the same guys who went on to become Audio Precision. Hewlett Packard had an all-in-one audio sig-gen and analyser which I once used for a couple of weeks. It was OK but I wasn't especially keen on it. HP seem to have made a lot of stuff in the UK. I have a distortion analyser made there, Audio Precision is still my fave by a long way, although I have some ideas to design a remote control surface for the Prism Sound analyser that would make it more user friendly. Don't know their products. I must do a little Googling. Lastly, a word of loathing for Neutrik's A2. God, I *HATE* that POS. It seems they took the UK made Technical Projects self-contained test set and buggered it up ! Hmm. Yes. You see the Neutrik everywhere, they must have sold by the thousands. Let me know if you need any info about the Ferrograph RTS. Cheers Iain |
#82
Posted to rec.audio.tubes
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Shielded mains cable
"Eeyore" wrote in
message Peter Wieck wrote: A shielded mains cable *might* be useful against heavy transients from equipment nearby, How ? *might* be useful against noise from switching power- supplies, *might* be useful against local rF sources (and if you discount this, you have never experienced CB interference from truckers with massive (and illegal) linear amps on their rigs). Operative word in all cases is *might*. It'll do nothing about the unscreened cable in the wall so will have effectively zero impact. This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. |
#83
Posted to rec.audio.tubes
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Shielded mains cable
Arny Krueger wrote: "Eeyore" wrote Peter Wieck wrote: A shielded mains cable *might* be useful against heavy transients from equipment nearby, How ? *might* be useful against noise from switching power- supplies, *might* be useful against local rF sources (and if you discount this, you have never experienced CB interference from truckers with massive (and illegal) linear amps on their rigs). Operative word in all cases is *might*. It'll do nothing about the unscreened cable in the wall so will have effectively zero impact. This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. Look at the equipment using it. I'm sure it's being used to contain / reduce EMI. I'd have to check out what's happening. It's simply a myth that having a screened cable stops the cable radiating (or receiving) like an aerial AIUI. It seems more likely to me that the screened mains cable may be operating as some kind of low-pass filter. Graham |
#84
Posted to rec.audio.tubes
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Shielded mains cable
"Eeyore" wrote in
message Arny Krueger wrote: This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. Look at the equipment using it. Problematical if it radiated EMI. I'm sure it's being used to contain / reduce EMI. Yup. I'd have to check out what's happening. It's simply a myth that having a screened cable stops the cable radiating (or receiving) like an aerial AIUI. Then how does it contain/reduce EMI? It seems more likely to me that the screened mains cable may be operating as some kind of low-pass filter. I think that a power cable has to act like a low pass filter for very high frequency radiated EMI. However, it might radiate some EMI over an inital short segment. The shield would trap that, even though the EMI is filtered out by the other end of the cable. Graham |
#85
Posted to rec.audio.tubes
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Shielded mains cable
"John Byrns" wrote in message
I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. |
#86
Posted to rec.audio.tubes
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Shielded mains cable
In article ,
"Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? To explore this issue further I asked Graham "But what is the SNR at 1 MHz vs. 1 kHz?" Graham's answer was "Quite low !" Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#87
Posted to rec.audio.tubes
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Shielded mains cable
"Eeyore" wrote in message ... west wrote: "Eeyore" wrote west wrote: This shield ground is to eliminate induced RF interference in the AC line. No it isn't. You need to learn what induction is. I didn't think you were the type inclined to toss out a curt diatribe. Perhaps you need to learn the conventions of a civilized dialog. You need to learn the conventions of not talking out of your rectum. Graham I'm glad that you didn't waste any time defining who you are, so from now on I'll know to avoid you and any opinions you might express. |
#88
Posted to rec.audio.tubes
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Shielded mains cable
west wrote: "Eeyore" wrote west wrote: "Eeyore" wrote west wrote: This shield ground is to eliminate induced RF interference in the AC line. No it isn't. You need to learn what induction is. I didn't think you were the type inclined to toss out a curt diatribe. Perhaps you need to learn the conventions of a civilized dialog. You need to learn the conventions of not talking out of your rectum. I'm glad that you didn't waste any time defining who you are, so from now on I'll know to avoid you and any opinions you might express. From previous posts of yours I've noticed that you don't like to sully yourself with technical truths when magical myths will do, so you wouldn't much like what I'd say anyway. Graham |
#89
Posted to rec.audio.tubes
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Shielded mains cable
"John Byrns" wrote in message
In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. To explore this issue further I asked Graham "But what is the SNR at 1 MHz vs. 1 kHz?" Graham's answer was "Quite low !" Not a lot of signal. |
#90
Posted to rec.audio.tubes
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Shielded mains cable
In article ,
"Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, was the power source for the repeaters of which there were a very large number. The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#91
Posted to rec.audio.tubes
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Shielded mains cable
"John Byrns" wrote in message
In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The repeaters had 60 dB gain. If their outputs were standard line levels, then their inputs were in the millivolt range. The actual cable loss per repeater was said to be about 40 dBm or 2100 dB for the entire segment with 51 repeaters. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, 2400 volts was the power source for the repeaters of which there were a very large number. 51 The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Agreed. But the repeaters were tubed. If they were connected purely in series, VCC per repeater would only be about 100 volts. But that's not the quesiton, the signal voltage is the question. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. The telephone system equipment is powered centrally, not from subscriber homes. |
#92
Posted to rec.audio.tubes
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Shielded mains cable
On Jun 2, 10:09 am, John Byrns wrote:
In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, was the power source for the repeaters of which there were a very large number. The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/- Hide quoted text - - Show quoted text - "Bell System" lines receive no power from individual houses. Excepting the early "Princess" phones which had separate local power for the lighted dial, and multi-line sets with similar lighted buttons. When these phones went modular, a very special adaptor was required (for the princess-style). Should I be abuse over your error? Peter Wieck Wyncote, PA |
#93
Posted to rec.audio.tubes
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Shielded mains cable
In article ,
"Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The repeaters had 60 dB gain. If their outputs were standard line levels, then their inputs were in the millivolt range. The actual cable loss per repeater was said to be about 40 dBm or 2100 dB for the entire segment with 51 repeaters. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, 2400 volts was the power source for the repeaters of which there were a very large number. 51 The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Agreed. But the repeaters were tubed. If they were connected purely in series, VCC per repeater would only be about 100 volts. But that's not the quesiton, the signal voltage is the question. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. The telephone system equipment is powered centrally, not from subscriber homes. The "OP" was talking about ADSL which I assume works in a similar fashion to DSL, my DSL modem is powered from my house, not the central office. My telephone isn't powered from the central office either, it is powered from a utility connection to a vault under, well nearly under, the local tennis court where the RT is located. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#94
Posted to rec.audio.tubes
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Shielded mains cable
In article . com,
Peter Wieck wrote: On Jun 2, 10:09 am, John Byrns wrote: In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, was the power source for the repeaters of which there were a very large number. The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/- Hide quoted text - - Show quoted text - "Bell System" lines receive no power from individual houses. Excepting the early "Princess" phones which had separate local power for the lighted dial, and multi-line sets with similar lighted buttons. When these phones went modular, a very special adaptor was required (for the princess-style). Should I be abuse over your error? You are welcome to if you first explain what my error is? The "OP" was talking about ADSL, so I was referring to my AT&T DSL modem which is powered from my home with electricity I provide for it. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#95
Posted to rec.audio.tubes
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Shielded mains cable
On Jun 2, 9:22 pm, John Byrns wrote:
In article . com, Peter Wieck wrote: On Jun 2, 10:09 am, John Byrns wrote: In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, was the power source for the repeaters of which there were a very large number. The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/-Hide quoted text - - Show quoted text - "Bell System" lines receive no power from individual houses. Excepting the early "Princess" phones which had separate local power for the lighted dial, and multi-line sets with similar lighted buttons. When these phones went modular, a very special adaptor was required (for the princess-style). Should I be abuse over your error? You are welcome to if you first explain what my error is? The "OP" was talking about ADSL, so I was referring to my AT&T DSL modem which is powered from my home with electricity I provide for it. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/- Hide quoted text - - Show quoted text - And you made a blanket statement. The ADSL unit you have at home is powered by your mains, yes. However, what gives between it and the "switch" is 100% powered by the Company. Keep in mind that part of the "Bell System" tariffs is that _NO_ external power sources are applied to their lines for security and operational safety purposes. Imagine the situation if somehow straight line-voltage found a way into the Phone Lines..... And exactly why I used the Princess Phone analogy. The princess had a light which was powered from a local source, but much care was taken to make sure that the source could not impinge on the line. The electronics in the ADSL are local-power. The signal is "Bell System" power. Peter Wieck Wyncote, PA |
#96
Posted to rec.audio.tubes
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Shielded mains cable
In article . com,
Peter Wieck wrote: On Jun 2, 9:22 pm, John Byrns wrote: In article . com, Peter Wieck wrote: On Jun 2, 10:09 am, John Byrns wrote: In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, was the power source for the repeaters of which there were a very large number. The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. "Bell System" lines receive no power from individual houses. Excepting the early "Princess" phones which had separate local power for the lighted dial, and multi-line sets with similar lighted buttons. When these phones went modular, a very special adaptor was required (for the princess-style). Should I be abuse over your error? You are welcome to if you first explain what my error is? The "OP" was talking about ADSL, so I was referring to my AT&T DSL modem which is powered from my home with electricity I provide for it. And you made a blanket statement. The ADSL unit you have at home is powered by your mains, yes. However, what gives between it and the "switch" is 100% powered by the Company. Keep in mind that part of the "Bell System" tariffs is that _NO_ external power sources are applied to their lines for security and operational safety purposes. Imagine the situation if somehow straight line-voltage found a way into the Phone Lines..... And exactly why I used the Princess Phone analogy. The princess had a light which was powered from a local source, but much care was taken to make sure that the source could not impinge on the line. The electronics in the ADSL are local-power. The signal is "Bell System" power. Peter, you are playing the old internet game of putting words in someone's mouth and then claiming they made an error because the words you put in their mouth were in error. You are taking my statement completely out of its original context and also trying to ascribe some "blanket" meaning to it that it never had. This thread was originally about "Shielded mains cable", as is typical of internet threads, topic drift occurred and the issue of phone line bandwidth was brought into the discussion. At that point Eeyore/Graham commented that phone lines had a bandwidth of at least 1 MHz, citing the example of ADSL as proof. At that point I asked what the signal to noise ratio of a phone line was at 1 MHz, and also why the range of DSL was less than the range of voice. Someone answered that the attenuation of a phone line was greater at 1 MHz than at voice frequencies, so the range of DSL less than range of voice signals, dodging the issue of signal to noise ratio. Thinking there might be more involved than simply attenuation, I attempted to draw out all the issues relating to signal to noise ratio by asking the question, if attenuation were all there was to it, wouldn't it be true that "a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to?" At that point Arny Krueger commented "I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there." This raised the issue of "high voltages" running "through people's houses and backyards" to which I responded "Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment." This is my statement that you are taking exception to and calling a "blanket" statement. I guess you could say that is a "blanket" statement in the sense that "there is local power available in the house to power the equipment" which is true, but notice I didn't say this "local power" was used to power all the telephone equipment in a house, just that power was available. I was simply pointing out that there was no need for the telephone company to transmit high voltage power through people's back yards and into their house to power equipment as was done with the Trans-oceanic telephone cables. My point was that "local" power was available in the house to power equipment like DSL modems, I made this statement because that is how my AT&T DSL modem is powered, i.e. from "local" power I provide, not from "high voltage" transmitted through my backyard on the telephone cable. What is your point, are you saying I am wrong when I stated that DSL modems and the like are powered "locally"? Your statement that "The signal is 'Bell System' power" is also certainly wrong, or at least half wrong. The downstream signal may be "Bell System" power, but the upstream signal is clearly my "local" power. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#97
Posted to rec.audio.tubes
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Shielded mains cable
On Jun 3, 10:21 am, John Byrns wrote:
In article . com, Peter Wieck wrote: On Jun 2, 9:22 pm, John Byrns wrote: In article . com, Peter Wieck wrote: On Jun 2, 10:09 am, John Byrns wrote: In article , "Arny Krueger" wrote: "John Byrns" wrote in message In article , "Arny Krueger" wrote: "John Byrns" wrote in message I also meant to ask why DSL doesn't have the same range as voice transmitted from the exchange over the same pair? AFAIK, it is becasue the higher frequencies DSL works at have more line loss. For example, my sources say that heavier gauge telephone wire gives greater DSL range at a given data rate, or a higher data rate for a given distance. Yes, the greater loss as the frequency increases is obvious, if that were all there was to it, logic would say that a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to? I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there. I don't know what the signal voltage used on the Trans-oceanic telephones cables was, but I would be surprised if it was unusually high. The high voltage you are referring to, which I think was several thousand volts positive at one end of the cable and several thousand volts negative at the other end of the cable, was the power source for the repeaters of which there were a very large number. The repeaters were powered in series like Christmas tree lights, and IIRC the power feed was a constant current. Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment. "Bell System" lines receive no power from individual houses. Excepting the early "Princess" phones which had separate local power for the lighted dial, and multi-line sets with similar lighted buttons. When these phones went modular, a very special adaptor was required (for the princess-style). Should I be abuse over your error? You are welcome to if you first explain what my error is? The "OP" was talking about ADSL, so I was referring to my AT&T DSL modem which is powered from my home with electricity I provide for it. And you made a blanket statement. The ADSL unit you have at home is powered by your mains, yes. However, what gives between it and the "switch" is 100% powered by the Company. Keep in mind that part of the "Bell System" tariffs is that _NO_ external power sources are applied to their lines for security and operational safety purposes. Imagine the situation if somehow straight line-voltage found a way into the Phone Lines..... And exactly why I used the Princess Phone analogy. The princess had a light which was powered from a local source, but much care was taken to make sure that the source could not impinge on the line. The electronics in the ADSL are local-power. The signal is "Bell System" power. Peter, you are playing the old internet game of putting words in someone's mouth and then claiming they made an error because the words you put in their mouth were in error. You are taking my statement completely out of its original context and also trying to ascribe some "blanket" meaning to it that it never had. This thread was originally about "Shielded mains cable", as is typical of internet threads, topic drift occurred and the issue of phone line bandwidth was brought into the discussion. At that point Eeyore/Graham commented that phone lines had a bandwidth of at least 1 MHz, citing the example of ADSL as proof. At that point I asked what the signal to noise ratio of a phone line was at 1 MHz, and also why the range of DSL was less than the range of voice. Someone answered that the attenuation of a phone line was greater at 1 MHz than at voice frequencies, so the range of DSL less than range of voice signals, dodging the issue of signal to noise ratio. Thinking there might be more involved than simply attenuation, I attempted to draw out all the issues relating to signal to noise ratio by asking the question, if attenuation were all there was to it, wouldn't it be true that "a properly equalized amplifier would be all that would be needed to make the range of DSL on a given cable independent of the bit rate, so there must be more to it than Graham is admitting to?" At that point Arny Krueger commented "I don't think so. There are practical limits to what you can accomplish with line equalization. The limits of practicality depend on the application. Trans-oceanic telephones cables used very high voltages. Cables that run through people's houses and backyards can't go there." This raised the issue of "high voltages" running "through people's houses and backyards" to which I responded "Cables that run through people's houses and backyards don't have to go there, there is local power available in the house to power the equipment." This is my statement that you are taking exception to and calling a "blanket" statement. I guess you could say that is a "blanket" statement in the sense that "there is local power available in the house to power the equipment" which is true, but notice I didn't say this "local power" was used to power all the telephone equipment in a house, just that power was available. I was simply pointing out that there was no need for the telephone company to transmit high voltage power through people's back yards and into their house to power equipment as was done with the Trans-oceanic telephone cables. My point was that "local" power was available in the house to power equipment like DSL modems, I made this statement because that is how my AT&T DSL modem is powered, i.e. from "local" power I provide, not from "high voltage" transmitted through my backyard on the telephone cable. What is your point, are you saying I am wrong when I stated that DSL modems and the like are powered "locally"? Your statement that "The signal is 'Bell System' power" is also certainly wrong, or at least half wrong. The downstream signal may be "Bell System" power, but the upstream signal is clearly my "local" power. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/- Hide quoted text - - Show quoted text - John: Your equipment, exactly as the light in the Princess Phone is locally powered. And that is exactly as far as it goes. The ADSL Modem induces a signal onto the "Bell System" powered line, but does not add any power to that line from any local source. That is the point... and with some thought, that is why it is rather obvious why a digital signal would not have near as much range as an analog signal due to cliff effects if nothing else. Peter Wieck Wyncote, PA |
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In article .com,
Peter Wieck wrote: John: Your equipment, exactly as the light in the Princess Phone is locally powered. True, I don't believe I stated otherwise. And that is exactly as far as it goes. Not quite. The ADSL Modem induces a signal onto the "Bell System" powered line, but does not add any power to that line from any local source. Wrong, the signal power transmitted by my DSL modem into the "Bell System" phone line comes from my "local" power source, not from a "Bell System" power source, and it adds power to the line. I think you need to study up on how DSL works, it sounds like you are being confused by the way "Bell System" POTS Telephones work. When I was a young boy my Grandmother had a "General Telephone" Telephone at her summer home which operated differently than a "Bell System" Telephone, all the power for speech and signaling delivered by the phone to the line came from "local" sources, so all phones don't even operate in the same way with respect to power sources. That is the point... and with some thought, that is why it is rather obvious why a digital signal would not have near as much range as an analog signal due to cliff effects if nothing else. Huh, could you elaborate on that, it sounds like complete nonsense at first blush, am I missing something? What are "cliff effects", it sounds like something to do with college exams? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
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On Jun 3, 5:42 pm, John Byrns wrote:
In article .com, Peter Wieck wrote: John: Your equipment, exactly as the light in the Princess Phone is locally powered. True, I don't believe I stated otherwise. And that is exactly as far as it goes. Not quite. The ADSL Modem induces a signal onto the "Bell System" powered line, but does not add any power to that line from any local source. Wrong, the signal power transmitted by my DSL modem into the "Bell System" phone line comes from my "local" power source, not from a "Bell System" power source, and it adds power to the line. I think you need to study up on how DSL works, it sounds like you are being confused by the way "Bell System" POTS Telephones work. When I was a young boy my Grandmother had a "General Telephone" Telephone at her summer home which operated differently than a "Bell System" Telephone, all the power for speech and signaling delivered by the phone to the line came from "local" sources, so all phones don't even operate in the same way with respect to power sources. That is the point... and with some thought, that is why it is rather obvious why a digital signal would not have near as much range as an analog signal due to cliff effects if nothing else. Huh, could you elaborate on that, it sounds like complete nonsense at first blush, am I missing something? What are "cliff effects", it sounds like something to do with college exams? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ Yikes... exactly how does your ADSL modem "add power" to the "Bell System" lines? Cliff Effects: Digital signal 'falls off a cliff' when it degrades beyond use. Analog signal degrades on a more-or-less linear basis. Pretty elementary stuff. Peter Wieck Wyncote, PA |
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Eyeso why do you qualify your contention further on down the thread?
Clever subject switching, but not unnoticeable, asshole doubletalker. "Eeyore" wrote in message ... west wrote: "Eeyore" wrote west wrote: "Eeyore" wrote west wrote: This shield ground is to eliminate induced RF interference in the AC line. No it isn't. You need to learn what induction is. I didn't think you were the type inclined to toss out a curt diatribe. Perhaps you need to learn the conventions of a civilized dialog. You need to learn the conventions of not talking out of your rectum. I'm glad that you didn't waste any time defining who you are, so from now on I'll know to avoid you and any opinions you might express. From previous posts of yours I've noticed that you don't like to sully yourself with technical truths when magical myths will do, so you wouldn't much like what I'd say anyway. Graham |
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There's eyesore's strawman...changing the topic to not embarrass herself.
"Eeyore" wrote in message ... Iain Churches wrote: Here in Europe, many studios are using tube power amps, mic preamps and outboard processing also. !!! Maybe the antique 'boutique' stuff. Graham |
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What the heck does that have to do with shielded AC lines, asshole eyesore?
"Eeyore" wrote in message ... Iain Churches wrote: "Eeyore" wrote Iain Churches wrote: Here in Europe, many studios are using tube power amps, mic preamps and outboard processing also. !!! Maybe the antique 'boutique' stuff. Studios provide what clients ask for. Simple as that. Market research is an important factor in any successful business. You don't need to do much research to know that Teletronix / Urei optical compressors are much liked. http://www.barryrudolph.com/mix/bombfactory.html These days you can get them as digital plug-ins though. |
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Hey stupid, ever hear of twisted pair? Know the narrow bandwidth your
working with? Stay out of topics you know nothing about. There's no twisted pair that can attenuate that bull****. "Eeyore" wrote in message ... Iain Churches wrote: One guy a retired German broadcast engineer told me that it was standard practice in analogue equipment racks for *all* cables to be screened with RF shields. Typical Germanic overkill ! :~) Have you ever considerd why your phone line doesn't hum appreciably despite consisting of maybe 7 km of unscreened wire ? Graham |
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west wrote: Eyeso why do you qualify your contention further on down the thread? Clever subject switching, but not unnoticeable, asshole doubletalker. Bugger off you know-nothing pontificating nitwit. I'm sick of the likes of you pulluting the world with your idiot know-nothing stupid jibes. Graham |
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"Arny Krueger" wrote in message . .. "Eeyore" wrote in message Arny Krueger wrote: This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. Look at the equipment using it. Problematical if it radiated EMI. I'm sure it's being used to contain / reduce EMI. Yup. I'd have to check out what's happening. It's simply a myth that having a screened cable stops the cable radiating (or receiving) like an aerial AIUI. Then how does it contain/reduce EMI? If you notice, eyesore doesn't offer any plausible explanation for his disagreement. Even though I and many manufacturers like GE, Phillips, Siemens used this technique for over 20 years on sophisticated medical systems, some costing over a million dollars, it means nothing to eyesore. I believe he's another one that simply can not say "I'm wrong and I learned something today." west |
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west wrote: "Eeyore" wrote Iain Churches wrote: Here in Europe, many studios are using tube power amps, mic preamps and outboard processing also. !!! Maybe the antique 'boutique' stuff. There's eyesore's strawman...changing the topic to not embarrass herself. There is virtually ZERO *new* tube gear in pro-audio. Such as there is is almost exclusively in the 'toy box' category such as signal processing equipment designed to intentionally alter the sound. Professionals aren't gullible idiots like you. They'll use tube gear to *add colouration* when it's felt necessary. No professional labours under the mythical belief that tubes are 'more accurate'. Graham |
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west wrote: What the heck does that have to do with shielded AC lines, asshole eyesore? It's called 'thread drift' you brain dead ****wit. Graham |
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west wrote: "Eeyore" wrote in message Iain Churches wrote: One guy a retired German broadcast engineer told me that it was standard practice in analogue equipment racks for *all* cables to be screened with RF shields. Typical Germanic overkill ! :~) Have you ever considerd why your phone line doesn't hum appreciably despite consisting of maybe 7 km of unscreened wire ? Hey stupid, ever hear of twisted pair? You bet. It doesn't have a screen though does it ? Know the narrow bandwidth your working with? DSL signals go just beyond 1MHz down the same telephone cable. What did you say about narrow bandwidth ? Stay out of topics you know nothing about. Bwahahahahahahahaha ! Precious ! Graham |
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west wrote: "Arny Krueger" wrote "Eeyore" wrote Arny Krueger wrote: This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. Look at the equipment using it. Problematical if it radiated EMI. I'm sure it's being used to contain / reduce EMI. Yup. I'd have to check out what's happening. It's simply a myth that having a screened cable stops the cable radiating (or receiving) like an aerial AIUI. Then how does it contain/reduce EMI? If you notice, eyesore doesn't offer any plausible explanation for his disagreement. Even though I and many manufacturers like GE, Phillips, Siemens used this technique for over 20 years on sophisticated medical systems, some costing over a million dollars, it means nothing to eyesore. I believe he's another one that simply can not say "I'm wrong and I learned something today." So you can tell us all about B, H and E fields then can't you ? Graham |
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"Arny Krueger" wrote in message ... "Eeyore" wrote in message Peter Wieck wrote: A shielded mains cable *might* be useful against heavy transients from equipment nearby, How ? *might* be useful against noise from switching power- supplies, *might* be useful against local rF sources (and if you discount this, you have never experienced CB interference from truckers with massive (and illegal) linear amps on their rigs). Operative word in all cases is *might*. It'll do nothing about the unscreened cable in the wall so will have effectively zero impact. This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. Hi Arny. I am grateful to John Woodgate of the ISCE for the answer: "The screen may be intended to reduce emissions *from* the cable, rather than improving immunity. A Class D amplifier, is very likely to interfere with AM radio reception, yours or in adjacent houses. This happens even if the emission standard, EN 55013, (or EN 55103-1 for a professional product) is met, because the amplifier is quite close to the receiver." Regards to all Iain |
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Iain Churches wrote: "Arny Krueger" wrote "Eeyore" wrote Peter Wieck wrote: A shielded mains cable *might* be useful against heavy transients from equipment nearby, How ? *might* be useful against noise from switching power- supplies, *might* be useful against local rF sources (and if you discount this, you have never experienced CB interference from truckers with massive (and illegal) linear amps on their rigs). Operative word in all cases is *might*. It'll do nothing about the unscreened cable in the wall so will have effectively zero impact. This raises the question of why people are using screened power cables at all. I suspect they are trying to address very high frequency radiation which is also being reduced by the inductance and capacitance over the length of the power cable. This would explain why the shielding could be effective, even though its attached to possibly unshielded power wiring in the wall. Hi Arny. I am grateful to John Woodgate of the ISCE for the answer: "The screen may be intended to reduce emissions *from* the cable, rather than improving immunity. A Class D amplifier, is very likely to interfere with AM radio reception, yours or in adjacent houses. This happens even if the emission standard, EN 55013, (or EN 55103-1 for a professional product) is met, because the amplifier is quite close to the receiver." Exactly. That's what I'd expect. Graham |
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Chris Hornbeck said:
Clamp-on ferrite chokes are cheap insurance too. And not nearly as effective as real EMC measures inside the box. Clamp-on ferrites have the disadvantage of the necessary air gap, thereby reducing the effect. I use shielded mains cables on all things digital to prevent radiation *out*, not *in*. -- - Maggies are an addiction for life. - |
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robert casey said:
We don't use that kind of 'zip cord' here in the UK. An outer jacket is required for a mains lead for safety. As such I'm sure it would be easy to make twisted pair power leads for use from wall socket / plugboird to equipment. I've seen those power cords on stuff from Asia. Blue and brown wires inside a jacket. It should take twisting as well, though it will want to untwist itself until the jacket takes the "set". Be very careful with twisting a cable like this, you might pull the core out of the connectors. -- - Maggies are an addiction for life. - |
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Eeyore said:
None of these companies was notable for high spec audio test gear. They did make general test equipment for sure but nothing to associate them specifically with pro-audio or hi-fi. One used to see lots of Marconi and Racal, I never have myself. A slightly different era perhaps ? I still have this set, it even gets used every now and then: http://img526.imageshack.us/img526/8092/marconiaq9.jpg Nothing like the feel of real ceramic rotary switches and wirewound pots (though my PC with USB preamp and Smaart/RMAA/Cooledit works both faster and more precise). -- - Maggies are an addiction for life. - |
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Sander deWaal wrote: Eeyore said: None of these companies was notable for high spec audio test gear. They did make general test equipment for sure but nothing to associate them specifically with pro-audio or hi-fi. One used to see lots of Marconi and Racal, I never have myself. A slightly different era perhaps ? I still have this set, it even gets used every now and then: http://img526.imageshack.us/img526/8092/marconiaq9.jpg Nothing like the feel of real ceramic rotary switches and wirewound pots (though my PC with USB preamp and Smaart/RMAA/Cooledit works both faster and more precise). Did you know that early Neve consoles used Marconi knobs ? Graham |
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Sander deWaal wrote: Chris Hornbeck said: Clamp-on ferrite chokes are cheap insurance too. And not nearly as effective as real EMC measures inside the box. Clamp-on ferrites have the disadvantage of the necessary air gap, thereby reducing the effect. I use shielded mains cables on all things digital to prevent radiation *out*, not *in*. Exactly. For the dimwits who keep pestering about it........ The reaon it's a waste of time screening the mains cable on typical audio equipment is that it's not a point that's particularly *susceptible* to inteference. Graham |
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Is there any concern for eyesore's sickness ...anybody? Always remember, you
struck the first blow. west "Eeyore" wrote in message ... west wrote: Eyeso why do you qualify your contention further on down the thread? Clever subject switching, but not unnoticeable, asshole doubletalker. Bugger off you know-nothing pontificating nitwit. I'm sick of the likes of you pulluting the world with your idiot know-nothing stupid jibes. Graham |
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Eyeso what's unnatural is using a basic switching device for an
amplifier. What's unnatural is pushing then pulling down a signal. Your absolutely off base when you say tubes are unnatural. Your natural world is antiseptic, no art, no music, no beauty. west "Eeyore" wrote in message ... west wrote: "Eeyore" wrote Iain Churches wrote: Here in Europe, many studios are using tube power amps, mic preamps and outboard processing also. !!! Maybe the antique 'boutique' stuff. There's eyesore's strawman...changing the topic to not embarrass herself. There is virtually ZERO *new* tube gear in pro-audio. Such as there is is almost exclusively in the 'toy box' category such as signal processing equipment designed to intentionally alter the sound. Professionals aren't gullible idiots like you. They'll use tube gear to *add colouration* when it's felt necessary. No professional labours under the mythical belief that tubes are 'more accurate'. Graham |
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west wrote: Always remember, you struck the first blow. My pleasure |
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west wrote: Eyeso what's unnatural is using a basic switching device for an amplifier. What switching device ? |
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