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#1
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Coax as speaker cable???
I'm embroiled in a discussion on aus.hifi with a poster who recommends the
use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA |
#2
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"kyser" wrote in message ... I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? All twin cables have capacitance, inductance and resistance. These values are quoted for cables that must conform to a standard such as the one you cite. You can therefore calculate the effect, taking into account the length of cable, and other impedance in the speaker circuit. In this case, unless you have some new kind of tweeter, and VHF hearing, I shouldn't bother. How such a discussion got you embroiled god only knows. I think you will find that resistance is the most important feature of a speaker cable. For most valve amps, virtually anything will do nicely, since the output impedance is likely to be much greater than any reasonable speaker cable. My advice is quit the embroilment, it's not worth spending time on. Patrick Turner? Anyone? cheers, Anyone |
#3
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kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The RG58's do have a rather high capacitance, on the order of 30 pF per foot (~100 pF per meter). So for an extreme case let's take, say, a 100 meter run (over 300 feet). The capacitance would be .01 uF. On an 8 ohm system, assuming a 0-ohm amplifier output impedance, that would put the 3 dB corner at about 2 megahertz. *Well* above the human range of hearing. So from a capacitive POV, not to worry. Inductance and lumped inductance/capacitance effects don't significantly come into play at audio frequencies either. Again, not to worry. The only problem I can see is ordinary, every-day resistance. The center conductor in RG58 is quite small, perhaps only about 20-gauge. Let's see... (I love my Google) - 10.4 ohms per 1000 feet. So to continue the same example, you'd be losing about 1/3 of your output power in the stupid speaker wire! Bad idea. But you've just given me an idea. If audiophools are going for el-cheapo coax, they'll just love LMR400! This stuff is big and ugly (about 1/2" in diameter), stiff as a board and impossible to work with, has an aluminum foil *and* a braided tinned copper shield, foam dielectric (low capacitance), and very thick single-strand center conductor. Try running *that* crap through a building and up a tower in the dead of winter sometime! I can get it for about a buck a foot. If I sell it for $5 a foot, that would be suitable revenge both on LMR400 and on the audiophools that buy it! ;-) Cheers, Fred -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects, Vacuum Tubes & other stuff: | | http://www.dogstar.dantimax.dk | +--------------------------------------------+ |
#4
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"Fred Nachbaur" wrote
...So to continue the same example, you'd be losing about 1/3 of your output power in the stupid speaker wire! Bad idea. ... Just to make it clear that this example is for 100 metres! cheers, Ian |
#5
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"Fred Nachbaur" wrote in message
... The RG58's do have a rather high capacitance, on the order of 30 pF per foot (~100 pF per meter). So for an extreme case let's take, say, a 100 meter run (over 300 feet). The capacitance would be .01 uF. On an 8 ohm system, assuming a 0-ohm amplifier output impedance, that would put the 3 dB corner at about 2 megahertz. *Well* above the human range of hearing. So from a capacitive POV, not to worry. Inductance and lumped inductance/capacitance effects don't significantly come into play at audio frequencies either. Again, not to worry. The only problem I can see is ordinary, every-day resistance. The center conductor in RG58 is quite small, perhaps only about 20-gauge. Let's see... (I love my Google) - 10.4 ohms per 1000 feet. So to continue the same example, you'd be losing about 1/3 of your output power in the stupid speaker wire! Bad idea. SNIP Cheers, Fred Hi Fred: Thanks, I'm really not up on LC networks ..... My other concern was based on stories of musicians using guitar cables as speaker cables on high power amps (eg 100W Marshalls etc, or BIG bass amps) and damaging the output stages as a result. This guy is a dealer, and recommends the use of coax as speaker cable "because of its low inductance". Personally, I can see no possible advantage, some potential problems, and I'd give it a miss. Thanks also for your kind offer, but I'll pass on that, too! 8^) Cheers David (still got those 6U8As I bought off you) |
#6
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"Ian Iveson" wrote in message
... "kyser" wrote in message ... I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? All twin cables have capacitance, inductance and resistance. These values are quoted for cables that must conform to a standard such as the one you cite. You can therefore calculate the effect, taking into account the length of cable, and other impedance in the speaker circuit. In this case, unless you have some new kind of tweeter, and VHF hearing, I shouldn't bother. I have NO intention of using th stuff. IMO, it's a daft idea. How such a discussion got you embroiled god only knows. The usual argument about exotic speaker cables vs good quality figure-8 (with my backing the latter). THEN I discovered he was using coax. I think you will find that resistance is the most important feature of a speaker cable. For most valve amps, virtually anything will do nicely, since the output impedance is likely to be much greater than any reasonable speaker cable. A point I made very early in the discussion ........ My advice is quit the embroilment, it's not worth spending time on. And spoil the fun deflating his arguments? |
#7
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Hi RATs!
Just buy some and listen a few months. If you like it, it is good. If not, don't expect anyone to respect you Music is wonderful. 'Net arguments are less fun, for some of us Happy Ears! Al Alan J. Marcy Phoenix, AZ PWC/mystic/Earhead |
#8
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kyser wrote:
I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? I have seen Pro-audio speaker coax cable. I think it was made Hitachi and/or Belden. It was a lot thicker than RG58 though. Best regards, Mikkel C. Simonsen - anyone in this case |
#9
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For crying out loud, don't the audiophools know that 2" Heliax is the
best for speaker cable? -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
#10
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Fred Nachbaur wrote: kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The RG58's do have a rather high capacitance, on the order of 30 pF per foot (~100 pF per meter). So for an extreme case let's take, say, a 100 meter run (over 300 feet). The capacitance would be .01 uF. On an 8 ohm system, assuming a 0-ohm amplifier output impedance, that would put the 3 dB corner at about 2 megahertz. *Well* above the human range of hearing. So from a capacitive POV, not to worry. Inductance and lumped inductance/capacitance effects don't significantly come into play at audio frequencies either. Only in wire line telephone work. Cheers, John Stewart Again, not to worry. The only problem I can see is ordinary, every-day resistance. The center conductor in RG58 is quite small, perhaps only about 20-gauge. Let's see... (I love my Google) - 10.4 ohms per 1000 feet. So to continue the same example, you'd be losing about 1/3 of your output power in the stupid speaker wire! Bad idea. But you've just given me an idea. If audiophools are going for el-cheapo coax, they'll just love LMR400! This stuff is big and ugly (about 1/2" in diameter), stiff as a board and impossible to work with, has an aluminum foil *and* a braided tinned copper shield, foam dielectric (low capacitance), and very thick single-strand center conductor. Try running *that* crap through a building and up a tower in the dead of winter sometime! I can get it for about a buck a foot. If I sell it for $5 a foot, that would be suitable revenge both on LMR400 and on the audiophools that buy it! ;-) Cheers, Fred -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects, Vacuum Tubes & other stuff: | | http://www.dogstar.dantimax.dk | +--------------------------------------------+ |
#11
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kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA Most ppl manage to ignore Thevenim's Theorem that tells you all the R's in a series circuit need to be added in to get the final answer. The part left out in this case is usually the speaker R which in most cases is by far the largest component in an amp output circuit. It is also the reason why damping factors greater than say 5 don't do much. Many will argue with the above. Better get out the text books!!1 Cheers, John Stewart |
#12
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In message , kyser
writes I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA Co-ax will have high capacitance but VERY low inductance. As the inductance of speaker leads has far more effect than the shunt capacitance then yes, co-ax will make an excellent speaker lead. The problem is than RG58 isn't exactly a power cable so resistive losses will be high. -- Chris Morriss |
#13
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"john stewart" schreef in bericht ... kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA Most ppl manage to ignore Thevenim's Theorem that tells you all the R's in a series circuit need to be added in to get the final answer. The part left out in this case is usually the speaker R which in most cases is by far the largest component in an amp output circuit. It is also the reason why damping factors greater than say 5 don't do much. Many will argue with the above. Better get out the text books!!1 Cheers, John Stewart And it's about time the WWF does something against the use of snake oil in general ...... |
#14
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"kyser" wrote in message ... I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? ** Doug Self has published articles in Electronics World ( formerly Wireless World) about the use of co-ax for speaker leads and concluded that it was one of the best options in terms of performance for price. For a 5 metre run, RG58 or similar has no adverse effects and showed less resistance and much less inductance than 10 amp rated (1 sq mm) twin flex. Fits nicely into an XLR plug too. ............. Phil |
#15
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Mogami makes coaxial that is very good
Studios use it all the time. "Mikkel C. Simonsen" wrote in message ... kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? I have seen Pro-audio speaker coax cable. I think it was made Hitachi and/or Belden. It was a lot thicker than RG58 though. Best regards, Mikkel C. Simonsen - anyone in this case |
#16
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kyser wrote:
I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA You could use TWO lengths with the braid and centre all twisted together! Low R (good), low capacitance (doesn't matter.) If you get it free, then you're ahead of the game. If you have to buy it - don't... just use flat twin flex thicker than 16 gauge for tube amps, or thicker than 14 gauge for (quietly...) solid state amps. Cheers, Roger -- Roger Jones, P.Eng. Thornhill, Ontario, Canada. "Friends don't let friends vote Liberal" |
#17
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"Andy Cowley" wrote in message ... doug wrote: Mogami makes coaxial that is very good Studios use it all the time. For video. It's no good, it's 75 ohm, you'd need 4 ohm or 8 ohm for speakers. Anyway it seem to cost a dollar an inch. ;-) ** It is not possible to make a 8 ohm co-ax cable. But it *is* possible to make an interwoven cable with lots of insulated strands have a characteristic of 8 ohms. Such cable was sold as "Tocord" and by Mogami too IIRC. ............ Phil |
#18
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Phil Allison wrote:
"Andy Cowley" wrote in message ... doug wrote: Mogami makes coaxial that is very good Studios use it all the time. For video. It's no good, it's 75 ohm, you'd need 4 ohm or 8 ohm for speakers. Anyway it seem to cost a dollar an inch. ;-) ** It is not possible to make a 8 ohm co-ax cable. But it *is* possible to make an interwoven cable with lots of insulated strands have a characteristic of 8 ohms. Such cable was sold as "Tocord" and by Mogami too IIRC. ........... Phil Did ya notice the smileys? Irony is lost on you? Litzendracht wire (q.v) is what you are describing. Oh, and it is possible to make 8 ohm coax although I can't conceive of a reason for doing so. Assuming an air dielectric (relative permittivity, Er ~= 1) and a 1 mm diameter inner conductor, the inside diameter of the outer conductor would need to be 1.14 mm. If we consider a more realistic polythene or ETFE (cousin to PTFE) dielectric (Er ~= 2.6) then the dimension would be 1.24 mm. - not impossible at all. In fact if you wound some copper tape over RG213 and used the outer and your tape, with the original jacket as the dielectric, you'd probably be pretty close. The characteristic impedance of coaxial conductors, Z0, is given by Z0 = (138/(sqrt Er)) * log (R/r) . R is inner dia. of outer, r is diameter of inner, conductors. Making coax with Z0 ~100 is difficult, though. best Andy, M1EBV |
#19
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There is absolutely no good reason to try and make your speaker wires
8 ohm transmission lines. There are more than a few good reasons not to! One is the capacitance per foot would likely cut your highs. Another is the impedance of your speakers is only 8 ohms at dc. And another is the impedance of your amp is only a small fraction of an ohm. The reason transmission line matches are important at RF frequencies is mostly to do with the voltage changes along the line caused by "standing waves". These variations occur at 1/4 wavelength intervals 1/4 wavelength at audio frequencies is on the order of 30,000 meters/4. A really long distance. Long enough to be entirely insignificant. -Chuck, WA3UQV Phil Allison wrote: "Andy Cowley" wrote in message ... doug wrote: Mogami makes coaxial that is very good Studios use it all the time. For video. It's no good, it's 75 ohm, you'd need 4 ohm or 8 ohm for speakers. Anyway it seem to cost a dollar an inch. ;-) ** It is not possible to make a 8 ohm co-ax cable. But it *is* possible to make an interwoven cable with lots of insulated strands have a characteristic of 8 ohms. Such cable was sold as "Tocord" and by Mogami too IIRC. ........... Phil |
#20
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"Andy Cowley" wrote in message ... Phil Allison wrote: "Andy Cowley" wrote in message ... doug wrote: Mogami makes coaxial that is very good Studios use it all the time. For video. It's no good, it's 75 ohm, you'd need 4 ohm or 8 ohm for speakers. Anyway it seem to cost a dollar an inch. ;-) ** It is not possible to make a 8 ohm co-ax cable. But it *is* possible to make an interwoven cable with lots of insulated strands have a characteristic of 8 ohms. Such cable was sold as "Tocord" and by Mogami too IIRC. ........... Phil Did ya notice the smileys? Irony is lost on you? ** One only smiley - no irony at all in sight. Litzendracht wire (q.v) is what you are describing. Oh, and it is possible to make 8 ohm coax although I can't conceive of a reason for doing so. ** Lemme see ..... hmmmm ..... what on earth has an 8 ohm impedance ???? ..... Practically nothing ...... hmmmm - just a few stupid speakers ...... Not worth bothering with really - who would spend their money on fancy speaker cables ??? No-one of course !!!! How silly of me ........... Assuming an air dielectric (relative permittivity, Er ~= 1) and a 1 mm diameter inner conductor, the inside diameter of the outer conductor would need to be 1.14 mm. If we consider a more realistic polythene or ETFE (cousin to PTFE) dielectric (Er ~= 2.6) then the dimension would be 1.24 mm. - not impossible at all. In fact if you wound some copper tape over RG213 and used the outer and your tape, with the original jacket as the dielectric, you'd probably be pretty close. ** Reckon you can make one with a 2mm dia core ( ie 3 sq mm of copper ) 0.1 mm thick insulation then 3 sq mm of outer copper and that is still a practical and flexible cable ??? If so, you have a nice little earner on your hands - shame about the 4 nF per metre capacitance though. .............. Phil |
#21
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"Chuck Harris" wrote in message ... There is absolutely no good reason to try and make your speaker wires 8 ohm transmission lines. ** There is - but you are too dumb to see it. There are more than a few good reasons not to! One is the capacitance per foot would likely cut your highs. ** What rot. Another is the impedance of your speakers is only 8 ohms at dc. ** More rot. And another is the impedance of your amp is only a small fraction of an ohm. ** Huh ???????????? The reason transmission line matches are important at RF frequencies is mostly to do with the voltage changes along the line caused by "standing waves". ** True enough for FRO - but irrelevant for audio and most video lines. These variations occur at 1/4 wavelength intervals 1/4 wavelength at audio frequencies is on the order of 30,000 meters/4. ** Do you understand the word "irrelevant" ??????? A really long distance. Long enough to be entirely insignificant. ** I am thoroughly sick of arguing with ******wit** ham radio jerk-offs about transmission lines. Read closely: Standing waves are NOT the issue for audio or video, something **else** is. That something is capacitance and inductance. For audio and video *signal* lines cable capacitance attenuates the high frequencies. For loud speaker lines cable inductance does the same. A line impedance matched to its characteristic Z at the receiving end does NOT lose highs. Such a line is resistive as a load. Capice ??????? ............ Phil |
#22
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Phil,
I am not stupid enough to understand your "engineering principles". But I am stupid enough to understand transmission lines, so BITE ME! -Chuck, WA3UQV Phil Allison wrote: "Chuck Harris" wrote in message ... There is absolutely no good reason to try and make your speaker wires 8 ohm transmission lines. ** There is - but you are too dumb to see it. There are more than a few good reasons not to! One is the capacitance per foot would likely cut your highs. ** What rot. Another is the impedance of your speakers is only 8 ohms at dc. ** More rot. And another is the impedance of your amp is only a small fraction of an ohm. ** Huh ???????????? The reason transmission line matches are important at RF frequencies is mostly to do with the voltage changes along the line caused by "standing waves". ** True enough for FRO - but irrelevant for audio and most video lines. These variations occur at 1/4 wavelength intervals 1/4 wavelength at audio frequencies is on the order of 30,000 meters/4. ** Do you understand the word "irrelevant" ??????? A really long distance. Long enough to be entirely insignificant. ** I am thoroughly sick of arguing with ******wit** ham radio jerk-offs about transmission lines. Read closely: Standing waves are NOT the issue for audio or video, something **else** is. That something is capacitance and inductance. For audio and video *signal* lines cable capacitance attenuates the high frequencies. For loud speaker lines cable inductance does the same. A line impedance matched to its characteristic Z at the receiving end does NOT lose highs. Such a line is resistive as a load. Capice ??????? ........... Phil |
#23
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Phil Allison wrote:
"Chuck Harris" wrote in message ... There is absolutely no good reason to try and make your speaker wires 8 ohm transmission lines. ** There is - but you are too dumb to see it. There are more than a few good reasons not to! One is the capacitance per foot would likely cut your highs. ** What rot. Another is the impedance of your speakers is only 8 ohms at dc. ** More rot. And another is the impedance of your amp is only a small fraction of an ohm. ** Huh ???????????? The reason transmission line matches are important at RF frequencies is mostly to do with the voltage changes along the line caused by "standing waves". ** True enough for FRO - but irrelevant for audio and most video lines. These variations occur at 1/4 wavelength intervals 1/4 wavelength at audio frequencies is on the order of 30,000 meters/4. ** Do you understand the word "irrelevant" ??????? A really long distance. Long enough to be entirely insignificant. ** I am thoroughly sick of arguing with ******wit** ham radio jerk-offs about transmission lines. Read closely: Standing waves are NOT the issue for audio or video, something **else** is. That something is capacitance and inductance. For audio and video *signal* lines cable capacitance attenuates the high frequencies. For loud speaker lines cable inductance does the same. A line impedance matched to its characteristic Z at the receiving end does NOT lose highs. Such a line is resistive as a load. Capice ??????? ........... Phil Prime asshole. An idiot with a teeny little bit of knowledge. Doh. Let's stop humouring him. Andy |
#24
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kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The typical inductance of a 3 metre speaker cable is perhaps 2 uH, and the roll off is well above 20 kHz, as the pole formed by the LR filter is at 637 kHz.. The capacitance between the pair of cables used may only be 200 pF, causing a pole at some RF frequency. the L&C components would form an LC filter, which would display resonances at some RF, but generally, the L and C components of speaker cables are utterly negligible and have SFA effect on the engineering measurements. But I will not be one to say that ppl hear changes to the sound when they change cables. I won't say that arguments rage over bits of wire. I won't say that cable sales are greased and oiled with Oille De La Reptile Products&Promoters. What you hear is your truth for you, but in all my experience, once the DCR is below 1/100 of the speaker Z there is SFA change to the measurements with different cables within the audio band. There is no reason why RG58 would not be a suitable speaker cable, where power is low, say normal listening, when the current may only be 0.25 amps average in a domestic lounge. Cat 5 cables used in various ways is also great, as is lamp flex from a hardware store. Clean tight connectors are probably more important. There has been a prize offered by the Worldwide Society of Skeptics of $100,000 offered to the first person/company to demonstrate in a double blind AB test that one cable sounds different to another. The prize seems safe, its never been awarded over the last 30 years. Bell wire, that really thin figure 8 twin flex is awful stuff, but over 3M it still manages to be OK. Some dudes say really thin solid enamelled wire, or strips of foil work well, or "sound better" Every would be guru has his own idea. Patrick Turner. |
#25
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Patrick Turner wrote:
kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The typical inductance of a 3 metre speaker cable is perhaps 2 uH, and the roll off is well above 20 kHz, as the pole formed by the LR filter is at 637 kHz.. The capacitance between the pair of cables used may only be 200 pF, causing a pole at some RF frequency. the L&C components would form an LC filter, which would display resonances at some RF, but generally, the L and C components of speaker cables are utterly negligible and have SFA effect on the engineering measurements. Hi Patrick, I have heard one explanation for sound improvements from odd speaker cable remedies that I find plausable. Some of the "boutique" amplifiers are so incredibly unstable at frequencies above the audio spectrum that the RF characteristics of the cable can start, or stop the amp from oscillating. Amps that are oscillating always sound awful! -Chuck, WA3UQV |
#26
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"Phil Allison" wrote in message
u... ** There is - but you are too dumb to see it. Hey Phil, Have you ever seen that you are the only intelligence amongst a sea of "****wits"? Have you ever thought about the converse of this statement? Tim -- "That's for the courts to decide." - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms |
#27
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"Chuck Harris" wrote in message
... Patrick Turner wrote: kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The typical inductance of a 3 metre speaker cable is perhaps 2 uH, and the roll off is well above 20 kHz, as the pole formed by the LR filter is at 637 kHz.. The capacitance between the pair of cables used may only be 200 pF, causing a pole at some RF frequency. the L&C components would form an LC filter, which would display resonances at some RF, but generally, the L and C components of speaker cables are utterly negligible and have SFA effect on the engineering measurements. Hi Patrick, I have heard one explanation for sound improvements from odd speaker cable remedies that I find plausable. Some of the "boutique" amplifiers are so incredibly unstable at frequencies above the audio spectrum that the RF characteristics of the cable can start, or stop the amp from oscillating. Amps that are oscillating always sound awful! -Chuck, WA3UQV This was one of the arguments I advanced at aus.hifi for NOT using coax, given that the people who do so are just as likely to use some form of "exotic" amp of unknown stability. |
#28
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"Andy Cowley" Phil Allison wrote: Not worth bothering with really - who would spend their money on fancy speaker cables ??? Audiophools, simpletons, believers in voodoo science, and people with more money than sense. ** So you missed the bleeding obvious joke ? If so, you have a nice little earner on your hands - shame about the 4 nF per metre capacitance though. Transmission line, sunshine. No capacitive loading - AN INFINITE LENGTH OF IT LOOKS LIKE AN 8 OHM RESISTOR TO THE DRIVING SOURCE, DUMMY. ** Not if it ain't correctly terminated. The impedance of a hi-fi speaker at 1 MHz is what ???? An unterminated length of co-ax looks like a pure capacitor. A shorter length transforms the load according to the transmission line equation. Given that speaker leads are short compared to the electrical wavelength corresponding to their frequency - 15 km at 20 kHz - the transformation is absolutely negligible and the source sees the load with no modification. ** Bizarre ham radio nonsense. Narrow band RF transmission line theory cannot be applied to wide band audio or video. Every ham in the world thinks it can. You obviously don't understand transmission lines at all. ** You are obviously a dickhead. ............. Phil |
#29
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"Chuck Harris" wrote in message ... Phil, I am not stupid enough to understand your "engineering principles". ** Keep working on it - it is never too late to learn how wrong you are. But I am stupid enough to understand transmission lines, so BITE ME! -Chuck, WA3UQV ** Do I "chuck" before or after reading that ham call sign? ......... Phil |
#30
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"Andy Cowley" wrote in message ... Phil Allison wrote: "Chuck Harris" wrote in message ... There is absolutely no good reason to try and make your speaker wires 8 ohm transmission lines. ** There is - but you are too dumb to see it. There are more than a few good reasons not to! One is the capacitance per foot would likely cut your highs. ** What rot. Another is the impedance of your speakers is only 8 ohms at dc. ** More rot. And another is the impedance of your amp is only a small fraction of an ohm. ** Huh ???????????? The reason transmission line matches are important at RF frequencies is mostly to do with the voltage changes along the line caused by "standing waves". ** True enough for FRO - but irrelevant for audio and most video lines. These variations occur at 1/4 wavelength intervals 1/4 wavelength at audio frequencies is on the order of 30,000 meters/4. ** Do you understand the word "irrelevant" ??????? A really long distance. Long enough to be entirely insignificant. ** I am thoroughly sick of arguing with ******wit** ham radio jerk-offs about transmission lines. Read closely: Standing waves are NOT the issue for audio or video, something **else** is. That something is capacitance and inductance. For audio and video *signal* lines cable capacitance attenuates the high frequencies. For loud speaker lines cable inductance does the same. A line impedance matched to its characteristic Z at the receiving end does NOT lose highs. Such a line is resistive as a load. Capice ??????? ........... Phil Prime asshole. An idiot with a teeny little bit of knowledge. Doh. Let's stop humouring him. Andy ** You have not the slightest idea what the facts are Andy. So you post mindless abuse. Hams really are the pits. ............ Phil |
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"Tim Williams" wrote in message ... "Phil Allison" wrote in message u... ** There is - but you are too dumb to see it. Hey Phil, Have you ever seen that you are the only intelligence amongst a sea of "****wits"? ** Hey Tim, - have you any idea what a pig ignorant ****head you are ?? Can you debate with facts at all?? Or are you typing with one hand like I suspect ?? ............ Phil |
#32
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"Patrick Turner" wrote in message ... There has been a prize offered by the Worldwide Society of Skeptics of $100,000 offered to the first person/company to demonstrate in a double blind AB test that one cable sounds different to another. The prize seems safe, its never been awarded over the last 30 years. ** You just made that stoty up didn't you Pat. Such a cash prize *is* on offer for demonstration the existence of telepathy. ........... Phil |
#33
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kyser wrote: "Chuck Harris" wrote in message ... Patrick Turner wrote: kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The typical inductance of a 3 metre speaker cable is perhaps 2 uH, and the roll off is well above 20 kHz, as the pole formed by the LR filter is at 637 kHz.. The capacitance between the pair of cables used may only be 200 pF, causing a pole at some RF frequency. the L&C components would form an LC filter, which would display resonances at some RF, but generally, the L and C components of speaker cables are utterly negligible and have SFA effect on the engineering measurements. Hi Patrick, I have heard one explanation for sound improvements from odd speaker cable remedies that I find plausable. Some of the "boutique" amplifiers are so incredibly unstable at frequencies above the audio spectrum that the RF characteristics of the cable can start, or stop the amp from oscillating. Amps that are oscillating always sound awful! -Chuck, WA3UQV This was one of the arguments I advanced at aus.hifi for NOT using coax, given that the people who do so are just as likely to use some form of "exotic" amp of unknown stability. A length of coax sourced & terminated in other than it's characteristic impedance will support standing waves. Wavelenght depends on the cables electrical length. You are absolutely correct IMO with your argument. It's possible that a length of that cable could drive an SS Amp which usually has large BW into instablity. Would be an interesting experiment. Anyone got one they would like to sacrifice? John Stewart |
#34
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"john stewart" A length of coax sourced & terminated in other than it's characteristic impedance will support standing waves. ** That is not so - source impedance can be any value as long as the cable is terminated correctly. Wavelenght depends on the cables electrical length. ** Yeah, right, velocity factor is 70% of c. You are absolutely correct IMO with your argument. ** Huh ? It's possible that a length of that cable could drive an SS Amp which usually has large BW into instablity. Would be an interesting experiment. ** Good luck finding such an amp - the vast majority have output "Zobel" networks that make them stable with any value of capacitance. A few hundred picofarads is nothing. ............. Phil |
#35
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On Wed, 01 Oct 2003 12:35:41 -0500, the highly esteemed Tim Williams
enlightened us with these pearls of wisdom: "Phil Allison" wrote in message u... ** There is - but you are too dumb to see it. Hey Phil, Have you ever seen that you are the only intelligence amongst a sea of "****wits"? Have you ever thought about the converse of this statement? Tim Tim, would you please killfile Phil. Lets keep the Earth beautiful ;-) -- Greg --The software said it requires Win2000 or better, so I installed Linux. |
#36
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"Greg Pierce" wrote in message news Tim, would you please killfile Phil. Lets keep the Earth beautiful ;-) ** Greg, I see "trash can " is your email name - refers to your brain no doubt. ............. Phil |
#37
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Phil- You have made some very good points. However..........
Phil Allison wrote: "john stewart" A length of coax sourced & terminated in other than it's characteristic impedance will support standing waves. ** That is not so - source impedance can be any value as long as the cable is terminated correctly. You are correct. However, cable terminated correctly is a special case. Any other condition will result in multiple reflections. Whenever I was making measurements in COAX I was damn sure that the source was as close to a match as I could get it. Otherwise, accuracy goes out the door!! Wavelenght depends on the cables electrical length. ** Yeah, right, velocity factor is 70% of c. Depends on the cable used & varies from about 65% to 80% of c. You are absolutely correct IMO with your argument. ** Huh ? Still think it's worth a look. It's possible that a length of that cable could drive an SS Amp which usually has large BW into instablity. Would be an interesting experiment. ** Good luck finding such an amp - the vast majority have output "Zobel" networks that make them stable with any value of capacitance. Not all amplifiers bow at the altar of Zobel. There are many out there, in particular built by amatuers who don't know what Zobel is & don't care. A few hundred picofarads is nothing. It's 20 to 30 pF / ft. A 1/4 wavelength at 10 MHz is about 17 ft in RG58. Many power FET's would have no problem with that. ............. Phil Just some thoughts. I could be out to lunch. Can we use your SS amp as the basis of a trial????? Cheers (And Beers), John Stewart |
#38
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"john stewart" wrote in message ... Phil- You have made some very good points. However.......... Phil Allison wrote: "john stewart" A length of coax sourced & terminated in other than it's characteristic impedance will support standing waves. ** That is not so - source impedance can be any value as long as the cable is terminated correctly. You are correct. However, cable terminated correctly is a special case. ** A very common special case with 75 ohm video. Any other condition will result in multiple reflections. ** Only if the frequency being fed in is high enough - otherwise the cable adds inductance in series with the load or capacitance in parallel with the source. The former if the load is less than Zo and the later if it is more. Whenever I was making measurements in COAX I was damn sure that the source was as close to a match as I could get it. Otherwise, accuracy goes out the door!! ** Co-ax is often only approximately the speced Zo - the margin is 15% at least. It's possible that a length of that cable could drive an SS Amp which usually has large BW into instability. Would be an interesting experiment. ** Good luck finding such an amp - the vast majority have output "Zobel" networks that make them stable with any value of capacitance. Not all amplifiers bow at the altar of Zobel. There are many out there, in particular built by amateurs who don't know what Zobel is & don't care. ** Still, they are most unlikely to be bothered by a few hundred pF. A few hundred picofarads is nothing. It's 20 to 30 pF / ft. A 1/4 wavelength at 10 MHz is about 17 ft in RG58. Many power FET's would have no problem with that. ** Cripes - one only has to add a 50 ohm resistor in series with a 1nF cap to the end and all your worries are over. Just some thoughts. I could be out to lunch. Can we use your SS amp as the basis of a trial????? ** Mine has been driving 5 metres of Tocord ( @ 2000pF per metre) for 20 odd years with no issues. ............ Phil |
#39
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kyser wrote: "Chuck Harris" wrote in message ... Patrick Turner wrote: kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The typical inductance of a 3 metre speaker cable is perhaps 2 uH, and the roll off is well above 20 kHz, as the pole formed by the LR filter is at 637 kHz.. The capacitance between the pair of cables used may only be 200 pF, causing a pole at some RF frequency. the L&C components would form an LC filter, which would display resonances at some RF, but generally, the L and C components of speaker cables are utterly negligible and have SFA effect on the engineering measurements. Hi Patrick, I have heard one explanation for sound improvements from odd speaker cable remedies that I find plausable. Some of the "boutique" amplifiers are so incredibly unstable at frequencies above the audio spectrum that the RF characteristics of the cable can start, or stop the amp from oscillating. Amps that are oscillating always sound awful! -Chuck, WA3UQV This was one of the arguments I advanced at aus.hifi for NOT using coax, given that the people who do so are just as likely to use some form of "exotic" amp of unknown stability. The only sort of amp one should buy is one which won't oscillate regardless of whatever load or cables, which both comprise the load which the amp sees. An amp which does oscillate is a BS amp, perhaps also a boutique amp, if sold in amp "boutiques". Patrick Turner. |
#40
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john stewart wrote: kyser wrote: "Chuck Harris" wrote in message ... Patrick Turner wrote: kyser wrote: I'm embroiled in a discussion on aus.hifi with a poster who recommends the use of RG58C/U as speaker cable (with alleged sonic improvements over standard figure-8 type flex). Wouldn't the combined inductance/capacitance of this stuff constitute an LC filter causing signal attenuation or, worse, amp output stage instability over anything but a short run? Patrick Turner? Anyone? TIA The typical inductance of a 3 metre speaker cable is perhaps 2 uH, and the roll off is well above 20 kHz, as the pole formed by the LR filter is at 637 kHz.. The capacitance between the pair of cables used may only be 200 pF, causing a pole at some RF frequency. the L&C components would form an LC filter, which would display resonances at some RF, but generally, the L and C components of speaker cables are utterly negligible and have SFA effect on the engineering measurements. Hi Patrick, I have heard one explanation for sound improvements from odd speaker cable remedies that I find plausable. Some of the "boutique" amplifiers are so incredibly unstable at frequencies above the audio spectrum that the RF characteristics of the cable can start, or stop the amp from oscillating. Amps that are oscillating always sound awful! -Chuck, WA3UQV This was one of the arguments I advanced at aus.hifi for NOT using coax, given that the people who do so are just as likely to use some form of "exotic" amp of unknown stability. A length of coax sourced & terminated in other than it's characteristic impedance will support standing waves. Wavelenght depends on the cables electrical length. You are absolutely correct IMO with your argument. It's possible that a length of that cable could drive an SS Amp which usually has large BW into instablity. Would be an interesting experiment. Anyone got one they would like to sacrifice? John Stewart I have never noticed instablities in normal bandwidth amps when working properly. I know a guy whose SS amps go to 1 mHz, -3db, and lord knows what instability he has. Tube amps usually cut off at about 70 kHz, but still need to be arranged to NOT oscillate, when C loads are used, especially if the OPT has high leakage inductance. L&C in cable/speaker combinations shouldn't affect the amp. If an amp can be made to oscillate, under any circumstances whatsoever, someone ain't done his home work. Unconditional stablity is where we should aim. Patrick Turner. |
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