Does wire size affect signal quality...
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SSLtech
Well-known member
[quote author="BYacey"]Finer wire favoring high frequencies?? As you go up in frequency in the RF region the larger the diameter the better, due to skin effect[/quote]
Well, yes for uninsulated wire... but 1mm² of wire has less surface area then two 0.5mm² insulated conductors. and four 0.25mm² insulated conductors has even more. Taking it to the extreme, you get a lot more surface area using a lot less copper if you use 100 x 0.01mm² conductors.
This is not such a physically obstructive problem with straight wire and cables, but if you need to wrap it around a lot... -like in a toroid inductor- you can get much better results by using Litz wire. In Crown K2 amplifiers (which are basically switching amplifiers) they need to use inductors to filter the RF from the output, they want plenty of inductance but they don't want much resistance. They get much better results using litz-wound toroids than they can possibly do with regular wire-wound inductors.
It's an odd application, and very unlike the kind of DIY we encounter, but there is something to it, though not appreciable in most applications.
Litz effect can becom measurable at AF, though it multiplies with length.
Keith
Well, yes for uninsulated wire... but 1mm² of wire has less surface area then two 0.5mm² insulated conductors. and four 0.25mm² insulated conductors has even more. Taking it to the extreme, you get a lot more surface area using a lot less copper if you use 100 x 0.01mm² conductors.
This is not such a physically obstructive problem with straight wire and cables, but if you need to wrap it around a lot... -like in a toroid inductor- you can get much better results by using Litz wire. In Crown K2 amplifiers (which are basically switching amplifiers) they need to use inductors to filter the RF from the output, they want plenty of inductance but they don't want much resistance. They get much better results using litz-wound toroids than they can possibly do with regular wire-wound inductors.
It's an odd application, and very unlike the kind of DIY we encounter, but there is something to it, though not appreciable in most applications.
Litz effect can becom measurable at AF, though it multiplies with length.
Keith
dpaton
Well-known member
The idea behind Litz cables has to do with Skin Effect. SE is the tendency of high frequency signals (MHz) to migrate to the edge of a conductor and not travel at it's core. It's why high power FM broadcast transmitters use copper pipe (greatly simplified for this discussion) for moving their 50kW+ of (for my local Clear Channel station) 103.5MHz from point A to point B.
Where SE stops (in terms of frequency) has been a point of great debate amongst audiophooles for a very long time. Litz wire has also been around for decades and decades, so it's not at all a new thing, and I'm very suprised that there's a newish patent claim on it.
It's well documented that at 20kHz there is no SE worth worrying about.
The same for 40kHz, if you think like I do. Around 75-100kHz is where I'd start to think hard about good coax instead of normal wire. Above 500kHz there's no reason to use anything OTHER than coax. The nature of coax is such that it deals with skin effect very nicely. Twisted pairs, especially if they're single ended (signal and ground, like Kimber's PB&J), not so much.
To delve into a little math:
The equation to calculate skin depth is 2.6*K/SQRT(f), giving skin depth in mils (thousandths of an inch); K = 1 for copper, f is frequency in MHz.
My handy envelope tells me that at 60Hz, skin depth is about 1/3 of an inch. 40kHz, it's 13mil (0.013", still fine for 8451, but getting close to the edge). 75kHz pushes the skin depth out to 9.5mil (0.0095"), which is a little more significant, and at 100kHz it bumps out to 8.2mil where coax should definitely be used. Up at FM, it's a whopping 0.26mil (0.00026") which is the reason for the pipe.
DISCLAIMER:
I'm by no means an authority of electrical propogation in cables, but I am an engineer, and I have worked on everything from DC to light (well, 51GHz...), so I like to think that my opinions are based in supportable fact. This is an area where many a good man has gone down in flames from the heat of the arguments that erupt between the two opposing camps. My Nomex is on, and I've got a bucket of water at the ready :green:
-dave
Where SE stops (in terms of frequency) has been a point of great debate amongst audiophooles for a very long time. Litz wire has also been around for decades and decades, so it's not at all a new thing, and I'm very suprised that there's a newish patent claim on it.
It's well documented that at 20kHz there is no SE worth worrying about.
The same for 40kHz, if you think like I do. Around 75-100kHz is where I'd start to think hard about good coax instead of normal wire. Above 500kHz there's no reason to use anything OTHER than coax. The nature of coax is such that it deals with skin effect very nicely. Twisted pairs, especially if they're single ended (signal and ground, like Kimber's PB&J), not so much.
To delve into a little math:
The equation to calculate skin depth is 2.6*K/SQRT(f), giving skin depth in mils (thousandths of an inch); K = 1 for copper, f is frequency in MHz.
My handy envelope tells me that at 60Hz, skin depth is about 1/3 of an inch. 40kHz, it's 13mil (0.013", still fine for 8451, but getting close to the edge). 75kHz pushes the skin depth out to 9.5mil (0.0095"), which is a little more significant, and at 100kHz it bumps out to 8.2mil where coax should definitely be used. Up at FM, it's a whopping 0.26mil (0.00026") which is the reason for the pipe.
DISCLAIMER:
I'm by no means an authority of electrical propogation in cables, but I am an engineer, and I have worked on everything from DC to light (well, 51GHz...), so I like to think that my opinions are based in supportable fact. This is an area where many a good man has gone down in flames from the heat of the arguments that erupt between the two opposing camps. My Nomex is on, and I've got a bucket of water at the ready :green:
-dave
Ptownkid
Well-known member
Ahem
[quote author="Ptownkid"]So what gauge hook-up wire do you all use?[/quote]
[quote author="Ptownkid"]So what gauge hook-up wire do you all use?[/quote]
SSLtech
Well-known member
[quote author="Ptownkid"]Ahem
[quote author="Ptownkid"]So what gauge hook-up wire do you all use?[/quote][/quote]
No simple answer. -It depends on how much current is destined to be forced through the wire. I think you'll find it's that way for everyone.
Keith
[quote author="Ptownkid"]So what gauge hook-up wire do you all use?[/quote][/quote]
No simple answer. -It depends on how much current is destined to be forced through the wire. I think you'll find it's that way for everyone.
Keith
Ptownkid
Well-known member
well, for example, the green pre.
> I cut it three times and it's still too short.
Are YOU the jerk who wired my house????
Seriously: two boxes four feet apart, I found joined with three scraps of wire "spliced" together, without solder or wire-nuts, laying on old dry wood.
> Litz wire has also been around for decades and decades
1920s, IIRC.
> I'm very suprised that there's a newish patent claim on it.
A) Not on Litz per se, but on some odd combination of Litz and solid. Maybe this is so non-obvious it was never thought of before. Maybe it was thought-of many times, and discarded for having no advantage.
B) The US patent office will sell papers on dang near anything today. They don't have the budget to inspect patent applications properly. They check that the fee is attached, check for grossly unpatentable claims, and issue the paper. Whether it is valid or not can be left to the courts, if and when someone cares to dispute it. Since the vast majority of patents are never put to practice or production, and even fewer are ever disputed, this makes good sense.
> http://www.webervst.com/gauge.htm - that calculator says I should be using 50' of #5 AWG for a 4 ohm load at 500W power. I haven't seen much 5 guage wire used with touring production companies.
That calculator is bogus, even for a company that sells wire. (But they do say it is limited to 20', so you should not tease it with 50'.)
The math they use is: 20-(sqrt(sqrt(power/resistance) * 6 * (length/6)))
BUT the power does not matter. Oh, it matters one way: 1,000W in 4Ω would melt #40, while 10W would not. But they clearly are not computing the melting current: from the answers it gives, and by the fact it depends on length which does not affect melting.
Dave's 1% rule is conservative for Hi-Fi. Damm the wasted power; we usually have plenty and anyway 1% loss is inaudible. The real limit, in Hi-Fi, is damping: should be over 10, over 40 is better. That leads to 10% or 2.5% copper loss, with 1% if you want to be very-very sure and can afford the price.
Way I see it: if I can get the amp and speakers in a better location, particularly audience coverage and bass loading, that trumps slightly less damping. Also if I work for cheap, I want a good-enuff answer, not an ideal answer (which of course tends to be infinitely fat wire). So I use 100 feet of #16/2, and don't fret the many-percent power "loss" and bass-bump.
And when you get to guitar amps: they (mostly) don't damp the speaker, certainly not any DF=40. So another ohm or two is not going to affect the tone or volume much.
Yes, once when I had $6,000 for amplifiers I threw in $130 for #14 wire. I didn't hear a big change from #16 or even #18 in 20'-80' runs, and it was awkward to route and didn't fit some (cheap) amp terminals. So there is over-kill, and there is "plenty good without losing all your hair and cash".
> well, for example, the green pre.
Flame-bait and audio-fools aside: stuff like preamps, use any convenient wire. Electrical issues suggest using somethng bigger than #40 or #35, but cost and mechanical strength "force" you to use #30, #24, something in there. Bigger wires are a pain to use in small-signal work. Plain ordinary hook-up wire. Radio Shack still sells a 3-pack of "hook-up wire"; it is a bit cheezy and the insulation stinks, but that is what I use when nothing else is handy. The LED wires from PCs are also good, if dead PCs accumulate in your workshop. CAT5 net-wire is great stuff if you can strip the tough plastic, and utterly free if you find someone doing any network wiring (to run 100 feet, they pull 120 feet and then trim the ends; lots of several-foot scraps each with 8 conductors).
Are YOU the jerk who wired my house????
Seriously: two boxes four feet apart, I found joined with three scraps of wire "spliced" together, without solder or wire-nuts, laying on old dry wood.
> Litz wire has also been around for decades and decades
1920s, IIRC.
> I'm very suprised that there's a newish patent claim on it.
A) Not on Litz per se, but on some odd combination of Litz and solid. Maybe this is so non-obvious it was never thought of before. Maybe it was thought-of many times, and discarded for having no advantage.
B) The US patent office will sell papers on dang near anything today. They don't have the budget to inspect patent applications properly. They check that the fee is attached, check for grossly unpatentable claims, and issue the paper. Whether it is valid or not can be left to the courts, if and when someone cares to dispute it. Since the vast majority of patents are never put to practice or production, and even fewer are ever disputed, this makes good sense.
> http://www.webervst.com/gauge.htm - that calculator says I should be using 50' of #5 AWG for a 4 ohm load at 500W power. I haven't seen much 5 guage wire used with touring production companies.
That calculator is bogus, even for a company that sells wire. (But they do say it is limited to 20', so you should not tease it with 50'.)
The math they use is: 20-(sqrt(sqrt(power/resistance) * 6 * (length/6)))
BUT the power does not matter. Oh, it matters one way: 1,000W in 4Ω would melt #40, while 10W would not. But they clearly are not computing the melting current: from the answers it gives, and by the fact it depends on length which does not affect melting.
Dave's 1% rule is conservative for Hi-Fi. Damm the wasted power; we usually have plenty and anyway 1% loss is inaudible. The real limit, in Hi-Fi, is damping: should be over 10, over 40 is better. That leads to 10% or 2.5% copper loss, with 1% if you want to be very-very sure and can afford the price.
Way I see it: if I can get the amp and speakers in a better location, particularly audience coverage and bass loading, that trumps slightly less damping. Also if I work for cheap, I want a good-enuff answer, not an ideal answer (which of course tends to be infinitely fat wire). So I use 100 feet of #16/2, and don't fret the many-percent power "loss" and bass-bump.
And when you get to guitar amps: they (mostly) don't damp the speaker, certainly not any DF=40. So another ohm or two is not going to affect the tone or volume much.
Yes, once when I had $6,000 for amplifiers I threw in $130 for #14 wire. I didn't hear a big change from #16 or even #18 in 20'-80' runs, and it was awkward to route and didn't fit some (cheap) amp terminals. So there is over-kill, and there is "plenty good without losing all your hair and cash".
> well, for example, the green pre.
Flame-bait and audio-fools aside: stuff like preamps, use any convenient wire. Electrical issues suggest using somethng bigger than #40 or #35, but cost and mechanical strength "force" you to use #30, #24, something in there. Bigger wires are a pain to use in small-signal work. Plain ordinary hook-up wire. Radio Shack still sells a 3-pack of "hook-up wire"; it is a bit cheezy and the insulation stinks, but that is what I use when nothing else is handy. The LED wires from PCs are also good, if dead PCs accumulate in your workshop. CAT5 net-wire is great stuff if you can strip the tough plastic, and utterly free if you find someone doing any network wiring (to run 100 feet, they pull 120 feet and then trim the ends; lots of several-foot scraps each with 8 conductors).
I find the insulation used has a greater effect. I have seen Cu wires go green and black inside clear PVC? coverings. Different grades or manybe bad runs of PVC I guess.
One of my cars in the 70s + battery cable went bad it was green very far down the wire.
when working with tube stuff check the voltage rating of the wire.
connections also are more important
One circuit I built(not audio) needed litz like wire because 10amps at 100k square wave does not travel well in standard wire.
One job I interviewed in the past for was at a microwave transistor company. I saw the wire bonding machines(run by humans using microscope like equipment) and like PRR posted the bonding wires used for semiconductors is small stuff.
FWIW my home sound system is biwired with solid core doorbell wire. The crossover is simple and the run is under 3 feet. Why? It was wire I had.
I was into hifi crap in the late 70's, litz wire, silver wire, bad design high cap wire made from multpair ribbon cable etc. Most did nothing I could hear but some could cause power amps to have problems!
One of my cars in the 70s + battery cable went bad it was green very far down the wire.
when working with tube stuff check the voltage rating of the wire.
connections also are more important
One circuit I built(not audio) needed litz like wire because 10amps at 100k square wave does not travel well in standard wire.
One job I interviewed in the past for was at a microwave transistor company. I saw the wire bonding machines(run by humans using microscope like equipment) and like PRR posted the bonding wires used for semiconductors is small stuff.
FWIW my home sound system is biwired with solid core doorbell wire. The crossover is simple and the run is under 3 feet. Why? It was wire I had.
I was into hifi crap in the late 70's, litz wire, silver wire, bad design high cap wire made from multpair ribbon cable etc. Most did nothing I could hear but some could cause power amps to have problems!
Ptownkid
Well-known member
Hmmm, that cat5 suggestion may be the way to go, a local store is selling 25 foot cat5 cables right now for $5 canadian.
Ptownkid
Well-known member
[quote author="PRR"]Flame-bait and audio-fools aside: stuff like preamps, use any convenient wire. Electrical issues suggest using somethng bigger than #40 or #35, but cost and mechanical strength "force" you to use #30, #24, something in there. Bigger wires are a pain to use in small-signal work. Plain ordinary hook-up wire. Radio Shack still sells a 3-pack of "hook-up wire"; it is a bit cheezy and the insulation stinks, but that is what I use when nothing else is handy. The LED wires from PCs are also good, if dead PCs accumulate in your workshop. CAT5 net-wire is great stuff if you can strip the tough plastic, and utterly free if you find someone doing any network wiring (to run 100 feet, they pull 120 feet and then trim the ends; lots of several-foot scraps each with 8 conductors).[/quote]
I'm a tad lost here. What does #40 wire mean. In Canada we go by gauge and #40 is SMALLER than #24
I'm a tad lost here. What does #40 wire mean. In Canada we go by gauge and #40 is SMALLER than #24
G
Guest
Guest
With wire gage, the higher the number, the thinner the wire.#40 is hair wire and #24 is hook up wire size.
andre tchmil
Well-known member
euh euh, can a wire signal be shortend to ground a tiny bit ? 
I mean , will signal pass in a bad way if for instance a tiny wire of the ground shield mesh is touching the hot wire ?
and if so, can this be tested with a cable tester, or with a DMM ?
How much can the cable resistance be ?
I mean , will signal pass in a bad way if for instance a tiny wire of the ground shield mesh is touching the hot wire ?
and if so, can this be tested with a cable tester, or with a DMM ?
How much can the cable resistance be ?
Svart
Well-known member
yes it will pass, but that is a bad thing. you will attenuate to a degree, then it will get worse from there...
andre tchmil
Well-known member
any tips to measure with a DMM ?
I'm suspecting some bad connections somewhere in my setup ;
I'm suspecting some bad connections somewhere in my setup ;
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