.Do you think resistance is important?.I am not looking for all cables.I am only looking in my country for producing.
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You said co-ax don't use OFC copper....
I said resistance of the screen... I am addressing but one aspect of a analogue co-ax cable used for low frequency analogue signals, especially if you have earth connections on the additional components.
Resistance of the screen is very important, especially if you understand how return currents work at different frequencies and want to avoid one of the most common causes of HUM.
I meant i can not find a coax OFC cable in my country.There may be available in another countries.I am not buying for myself.I want to produce cables.
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What has that got to do with anything? All an audio cable needs is a fairly good conductor. Ordinary cheap copper is already much better than necessary - have a look at the theory of potential dividers.umut1001 said:
When I say "use coax" I don't necessarily mean 'use an expensive RF-characterised thick coax cable'. Thin flexible stuff is available. For short runs even simple 'audio' screened wire is good enough. For audio the main requirements are good shield coverage and fairly low shield resistance.torgeirs said:
This emerges after the first post saidumut1001 said:
which implies personal use.umut1001 said:
Two pieces of advice:
1. if you are going to produce cables for sale then it may be helpful to learn about cables, incuding the difference between balanced and unbalanced connections.
2. you may need to use things like OFC copper even though you may be well aware that this makes absolutely no difference to the sound - you can then decide whether to deliberately mislead your customers in your sales blurb or just leave things vague.
First i want to make a cable for myself.I wanted to build with my Teflon cable but AndrewT told me it is not suitable for using as a ipad cable.After this my friend told me that they have many high quality cables and they get them in a good price and i planned why not build some for myself and sell some of them on ebay.I know about difference between balanced and unbalanced cables not PH degree of course.People wants OFC ones.I can not teach people not to buy OFC ones.Some people wants unnecessary things a lot.
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audio-video-cables,twin-and-walkman-cables,TC-3 - 2mkablo.com
Conductor 28x 0.10 mm (2x0.22 mm²) Stranded OFC Wires
Is this coax (even if the core is multistranded and unspecified impedance?) I think it is shielded enough for home audio use and ipad volumes.
It hurts to see the signal ground go through the shield, and the resistance is half of the signal core, but I it only adds up to 0.1 ohm/m. Guess it is inside ipads tolerances🙂
Conductor Resistance(max.) 90 Ω/km
Shield Resistance <50 Ω/km
Conductor 28x 0.10 mm (2x0.22 mm²) Stranded OFC Wires
Is this coax (even if the core is multistranded and unspecified impedance?) I think it is shielded enough for home audio use and ipad volumes.
It hurts to see the signal ground go through the shield, and the resistance is half of the signal core, but I it only adds up to 0.1 ohm/m. Guess it is inside ipads tolerances🙂
Conductor Resistance(max.) 90 Ω/km
Shield Resistance <50 Ω/km
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the graphic makes it look like a lapped screen.
This is the worst of all the screen types and H.Ott tells us "don't use it" or similar words.
This is the worst of all the screen types and H.Ott tells us "don't use it" or similar words.
spiral shield sounds like lapped. Steer clear!
And they lied when they stated 100% coverage.
Even when straight the wires cannot touch over their whole length and all the way around.
Now bend the wire slightly. The gaps open up and one gets <<100% cover around the bend and a bit beyond.
And they lied when they stated 100% coverage.
Even when straight the wires cannot touch over their whole length and all the way around.
Now bend the wire slightly. The gaps open up and one gets <<100% cover around the bend and a bit beyond.
A double wound is better and a return path resistance at least as good as and preferably better than the signal core is preferable, this return current may fight the systems protective earth route for low frequency return currents and the lowest resistance will win, this is a cause of hum.....
Here's a scientific article about audiofrequencies and skineffect:
https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/skincoax/page6.html
Interesting to also see numbers. (There is also modelling of loudspeaker cable on the site) The HF AC effects are very small under 100kHz and the cable can be modelled with DC models.
I think stargrounding is a viable way of tackling grounding and low frequency signal interference also for interconnect.
Guess the HF noise has to be modelled with HF models, but this is often filtered out by the input capasitor in parallell with the input resistance of the amp.
This is an article about stargrounding and routing in PCB. No coax there and still it functions:
http://www.ti.com/lit/an/slyt166/slyt166.pdf
Regards Torgeir
https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/skincoax/page6.html
Interesting to also see numbers. (There is also modelling of loudspeaker cable on the site) The HF AC effects are very small under 100kHz and the cable can be modelled with DC models.
I think stargrounding is a viable way of tackling grounding and low frequency signal interference also for interconnect.
Guess the HF noise has to be modelled with HF models, but this is often filtered out by the input capasitor in parallell with the input resistance of the amp.
This is an article about stargrounding and routing in PCB. No coax there and still it functions:
http://www.ti.com/lit/an/slyt166/slyt166.pdf
Regards Torgeir
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Lapped screen is fine for short audio runs in uncritical situations. It allows the cable to be more flexible than a braided screen. It normally won't have an 'impedance' specified as cable impedance is only meaningful for frequencies higher than audio where lapped screen cables would be less appropriate.
I thought the purpose of the screen was to attenuate interference.
Interference is not just an audio frequency range.
It goes to 2GHz, that we are now using and out past microwave to light frequencies.
Interference is not just an audio frequency range.
It goes to 2GHz, that we are now using and out past microwave to light frequencies.
Interesting a link to a Ti paper that doesn't even mention star grounding, just separate analogue and digital ground planes and (as I keep harping on about) is if you use separate grounds make sure they do not capacitivly couple....
What is the point of that link in connection to co-ax cable?
Have a look on EMC UK to get the figures for commercial EMC requirements...
Dual Band Wi-Fi adds 5GHz, but this is easily catered for with good design practice, that means following the likes of H. Ott and R. Morrison's advice, and RF and star grounds do not mix very well, especially if the screening is sub standard (most).
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