Any thoughts about using ballanced mic cable for long interconnects in a single ended setup, like what to do with the screen? Is it best left floating? attached to signal ground at one end?
I'm just curious about noise pickup through interconnect screen and if there are any advantages in using a ballanced cable in this way instead of a coaxial one in runs of around 5 metres.
I'm just curious about noise pickup through interconnect screen and if there are any advantages in using a ballanced cable in this way instead of a coaxial one in runs of around 5 metres.
No, it'll provide less shielding unless the shield acts as ground for both; which some equipment that's ok and others it isn't.
Coaxial shield doesn't stop noise so much as it takes advantage of skin effect, for audio. It's because the shield, the return, is also playing the impedance game among other things for single ended.
Balanced on the other hand take advantage of a low impedance path for the shield so it actually attenuates and differs noise to a high level.
The properties of balanced cable is a bit different, so I wouldn't expect them to work necessarily.
Connecting a shield at one end to ground provides a drain, but no attenuation to speak of so it's uses are insignificant compared to what balanced does...
Coaxial shield doesn't stop noise so much as it takes advantage of skin effect, for audio. It's because the shield, the return, is also playing the impedance game among other things for single ended.
Balanced on the other hand take advantage of a low impedance path for the shield so it actually attenuates and differs noise to a high level.
The properties of balanced cable is a bit different, so I wouldn't expect them to work necessarily.
Connecting a shield at one end to ground provides a drain, but no attenuation to speak of so it's uses are insignificant compared to what balanced does...
A grounded screen will provide protection from audio frequency electric fields. The twisted pair would provide some protection from audio frequency magnetic fields, provided that the sending end is 'floating'. This is how tonearm wiring works, or a microphone, but probably not a single-ended source. I would use coax for unbalanced connections.
Thanks i normally only use coax, there are some who claim great things about pseudo balanced interconnects where the screen is connected to ground at one end but they don't all agree on which end.
I thought it was probably just another load of rubbish but if anyone here thinks differently, please let me know.
I thought it was probably just another load of rubbish but if anyone here thinks differently, please let me know.
It seems quite a number of cable manufacturers sell pseudo balanced interconnects, Chord being one of them. The only advantage i can see is that i could use cheap mic cable which has low capacitance. That could be an advantage with 15 foot inters.
Hi Fi Terminology » The Chord Company
If you scroll down to - co-axial cable, Chord say they feel that analogue signals can be better carried via a pseudo balanced configuration cable. I notice they dont attempt to explain why they "feel" this to be the case.
Hi Fi Terminology » The Chord Company
If you scroll down to - co-axial cable, Chord say they feel that analogue signals can be better carried via a pseudo balanced configuration cable. I notice they dont attempt to explain why they "feel" this to be the case.
I have had signal cables running alongside power cable at times, this video makes me think....
https://www.youtube.com/watch?NR=1&feature=endscreen&v=DOoyrsi6ctk
https://www.youtube.com/watch?NR=1&feature=endscreen&v=DOoyrsi6ctk
This Henry W. Ott paper should also be of interest:
"Balanced vs. Unbalanced Audio System Interconnections" (pdf file)
http://www.hottconsultants.com/pdf_files/Audio Interconnections.pdf
More by Henry Ott
home page
"Balanced vs. Unbalanced Audio System Interconnections" (pdf file)
http://www.hottconsultants.com/pdf_files/Audio Interconnections.pdf
More by Henry Ott
home page
As for unbalanced RCA interconnects, Bill Whitlock is very vocal about 'abandoning unbalanced interconnects ages ago.
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https://www.youtube.com/watch?NR=1&feature=endscreen&v=DOoyrsi6ctk
Just looked at it now. Not very informative.
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Henry W. Ott spends many pages on shielded interconnects in his book "Electromagnetic Compatibility Engineering".
EMC Books
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While different experts have different views on how balanced interconnect shields should be connected Tony Waldron has a good case for connecting the shield at both ends..
'Tony Waldron's Audio & EMC ranting and ravings'
Tony Waldron's EMC ranting and ravings
I've read posts on here where it was claimed that running signal cable alongside power cable had no negative effect. That video shows 2 volts imposed on an unshielded signal cable by an adjacent power cable. I found that quite informative.
Two volts across an un-connected wire pair isn't very informative about how much noise will be in the signal. Unconnected wires drive a near-infinite impedance, and noise has to act on a real impedance. Connect one end to, say 600 ohm impedance and the other end to 10k, and then measure it. A few nano-volts, maybe?
That is true, provided that the signal cable has either a good quality shield (unbalanced connection - and assuming no ground loops) or a very tight twist (balanced connection with high CMRR).davym said:
Unshielded? See above.
Unsurprising.
Unbalanced connections are usually fine for domestic audio, provided they are short and you use coax and you don't hit problems with ground loops. Longer connections should be balanced and use twisted pair.
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