Hello, John. Nice to hear from you! 🙂
I was just delving at Roger Russell's splendid McIntosh website:
http://www.roger-russell.com/wire/wire.htm#differences
He has always said that cable is cable, of course. 😎
He seems to think some exotic high capacitance cables can tip badly designed amplifiers into measurable change of waveform. But, yes, we're not finding the smoking gun here to encourage the use of cable lifters.
I was just delving at Roger Russell's splendid McIntosh website:
http://www.roger-russell.com/wire/wire.htm#differences
He has always said that cable is cable, of course. 😎
He seems to think some exotic high capacitance cables can tip badly designed amplifiers into measurable change of waveform. But, yes, we're not finding the smoking gun here to encourage the use of cable lifters.
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Back in the late '70s when the fancy cable craze started, several of them were notorious for causing fashion amps to oscillate and flame out. I think we could safely call that a "measurable change of waveform."😀
Seriously folks, there is one and only one case where using cable-lifters has physics behind it.
• not the case of hardwood floors
• not the case of tile floors
• not the case of thin natural fiber carpeting over pressboard
• not the case of thicker '70s shag over most-anything
• not the case of formica, acrylic tile or linoleum flooring
• not the case of any basically insulating flooring
Nope. The only case is
• The case of metallic sheet flooring
• The particular case of ferromagnetic flooring
That's it. In theory metallic, conductive sheathing either around (conduit) or under (flooring) or next to (plenum sheet metal) may act as a significant pickup of induced EMF. More-so when the material is ferric and magnetically coupled. Which is almost always.
But seriously: how many people have galvanized steel sheeting as a flooring material, or a wall material? (Hmm… all those new houses that eschew wood 2×4 for made-on-the-spot galvanized cold-rolled steel 2×4 'studs'… But they're vertical. And periodic. Maybe along the edges where walls abut floors? Hmm…) OK, maybe there is a fairly common case among dwellers in modern, cheap-âss condominium and/or McMansion housing. But the rest of us? NO METAL FLOORS likely to be encountered, ever.
And that is the only case I can think of. Been trying for decades too…
SY does mention the "fissioning amplifiers" demonstrations, but most of those (and I got to see a couple of live demonstrations) were actually fabrications, secret switches and the like. P. T. Barnum and his Audio Circus. To sell useless snake oil.
GoatGuy
• not the case of hardwood floors
• not the case of tile floors
• not the case of thin natural fiber carpeting over pressboard
• not the case of thicker '70s shag over most-anything
• not the case of formica, acrylic tile or linoleum flooring
• not the case of any basically insulating flooring
Nope. The only case is
• The case of metallic sheet flooring
• The particular case of ferromagnetic flooring
That's it. In theory metallic, conductive sheathing either around (conduit) or under (flooring) or next to (plenum sheet metal) may act as a significant pickup of induced EMF. More-so when the material is ferric and magnetically coupled. Which is almost always.
But seriously: how many people have galvanized steel sheeting as a flooring material, or a wall material? (Hmm… all those new houses that eschew wood 2×4 for made-on-the-spot galvanized cold-rolled steel 2×4 'studs'… But they're vertical. And periodic. Maybe along the edges where walls abut floors? Hmm…) OK, maybe there is a fairly common case among dwellers in modern, cheap-âss condominium and/or McMansion housing. But the rest of us? NO METAL FLOORS likely to be encountered, ever.
And that is the only case I can think of. Been trying for decades too…
SY does mention the "fissioning amplifiers" demonstrations, but most of those (and I got to see a couple of live demonstrations) were actually fabrications, secret switches and the like. P. T. Barnum and his Audio Circus. To sell useless snake oil.
GoatGuy
Yep, carpet, pad and 8 inches of concrete here.
I think a lot of this type of stuff comes from the simple phenomena of people just noticing more things about a recording when it's on it's second or third playback, and those nuances that were unnoticed the first time around popping out.
Anyone who's seen an episode of brain games on television knows how easy it is to troll your brain, and a lot of the people who sell silly things like wire lifters and isolator pucks count on it.
this subject might be an offshoot of lead acid batteries stored on bare concrete floors , strange how some myths have a life of their own.
Ralph Morrison in his book "Grounding and Shielding in Facilities" suggests that very thing. He writes about running copper or soft steel straps/strips between building areas. Control or signal cables are placed on these straps. He calls it Signal Transport Ground Plane (STGP). see page 184.
Surprised.. and not so surprised this thread made it 12 pages already.. over nothing of any consequence. carry on!
res07njc, the vaguer the problem, the more interest it generates. The really interesting and difficult and technical stuff dies a death very quickly, IME! 😉
Goatguy and Speedskater are at least approaching this with an open mind. 🙂
A metal or magnetic, or highly molecularly resonant and dielectric floor might do some interesting things to a nearby cable.
We don't really care about cable lifters. Clearly snake oil, unless something is very wrong with the equipment or cable. But a few of us gave it some thought, rather than just acted a bit patronising and clever. 😱
Let me tell you what I know about Characteristic impedance - Wikipedia, the free encyclopedia. Every low resistance cable has a certain capacitance and inductance per unit length. The characteristic impedance is just Root L/C. You can make very small 75 ohm cables, or very fat ones. It's just a question of the ratio of the dimensions of the conductors being kept constant. Fatter ones will have lower losses in practise.
The thing I find fascinating, is that if you terminate a cable with a resistor equal to its Characteristic Impedance, there is no reflected wave from the load whatsoever! We needed to know this when designing Transatlantic RF telecom cables that were 3000 miles long and had 1000 booster amplifiers called repeaters to correct resistance losses. The amplifier just sees the load, and the cable might as well not be there.
If you short a cable with a relatively low resistance, the amplifier sees the inductive load. If you leave it near open circuit, the amp sees the capacitative load. Amplifier designers need to know this stuff, because it kicks in with high source impedance.
Why is typical TV aerial coax 75 ohms? That's because an unbalanced Quarter Wave Monopole, and relying on a ground plane, is 77 ohms impedance.
A Half-Wave Antenna is around 300 ohms on a balanced line. Another way of doing things.
None of which solves the problem here, but the science of cables is real. And worth knowing, IMO. 😎
Goatguy and Speedskater are at least approaching this with an open mind. 🙂
A metal or magnetic, or highly molecularly resonant and dielectric floor might do some interesting things to a nearby cable.
We don't really care about cable lifters. Clearly snake oil, unless something is very wrong with the equipment or cable. But a few of us gave it some thought, rather than just acted a bit patronising and clever. 😱
Let me tell you what I know about Characteristic impedance - Wikipedia, the free encyclopedia. Every low resistance cable has a certain capacitance and inductance per unit length. The characteristic impedance is just Root L/C. You can make very small 75 ohm cables, or very fat ones. It's just a question of the ratio of the dimensions of the conductors being kept constant. Fatter ones will have lower losses in practise.
The thing I find fascinating, is that if you terminate a cable with a resistor equal to its Characteristic Impedance, there is no reflected wave from the load whatsoever! We needed to know this when designing Transatlantic RF telecom cables that were 3000 miles long and had 1000 booster amplifiers called repeaters to correct resistance losses. The amplifier just sees the load, and the cable might as well not be there.
If you short a cable with a relatively low resistance, the amplifier sees the inductive load. If you leave it near open circuit, the amp sees the capacitative load. Amplifier designers need to know this stuff, because it kicks in with high source impedance.
Why is typical TV aerial coax 75 ohms? That's because an unbalanced Quarter Wave Monopole, and relying on a ground plane, is 77 ohms impedance.
A Half-Wave Antenna is around 300 ohms on a balanced line. Another way of doing things.
None of which solves the problem here, but the science of cables is real. And worth knowing, IMO. 😎
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You left out the part about "irrelevant to audio frequencies."
That is only true for one special case- care to name it?
I don't know what you are talking about, SY. Perhaps you should explain yourself better. 😕
Tell me what you know, rather than knitpick selectively. A very tiresome forum technique, which I frankly detest. You know what I am saying. 🙄
We are here at this forum to advance the science collectively, IMO. A band of brothers. Any other agenda plain bores me. Sorry.
Transmission line effects are irrelevant for audio frequencies, given how short cables are. So terms such as characteristic impedance or termination have no meaning in the context here.
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