Ok, so this is a question that I encounter approximately once per year and I never seem to figure it out.
Is there any worth in running a balanced XLR cable across a room and then into a RCA adapater? At the XLR end the cable will be grounded. The RCA end doesn't have a shield pin so at this end the cable is ungrounded.
Would you expect an XLR cable to perform better than an RCA cable in the above situation?
I had a search around the web. Found some contrasting information that was mostly too technical for me. Does a balanced cable have any use if it's not grounded at both ends? Could it in fact perform better than otherwise?
(Personally I would imagine the waves or whatever potentially interfering are going to hit the shield regardless of whether it is connected to both ends. But I don't have a degree in sound engineering.)
using XLR balanced cables - do they have to be grounded at both ends?
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- KVRist
- Topic Starter
- 49 posts since 22 Sep, 2012
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- KVRAF
- 15269 posts since 8 Mar, 2005 from Utrecht, Holland
Leavin ground off at one end prevents ground loops! I cant measure signfinant improved qualty of balanced connections and I tried
We are the KVR collective. Resistance is futile. You will be assimilated. 
My MusicCalc is served over https!!
My MusicCalc is served over https!!
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- KVRAF
- 4205 posts since 21 Oct, 2001 from my bolthole in the south pacific
Balanced lines are used because they preserve frequency response and reduce hum/noise on long cable runs - anything over 6 feet and you are losing treble on RCA connections and guitar leads. Full symmetrical balanced lines - TRS or XLR - deliver 6dB hotter signals too.
Imagine a stage performance in a large auditorium or at an outdoor festival (eg Woodstock) where the mics and lines from the stage run to stage boxes and then back through the audience in multicore cables to the mixing desk and from the desk back to power amps by the stage to drive the PA. If this was all done with unbalanced lines the sound quality would be absolutely horrendous - high noise levels (summed in the mixing desk from all the unbalanced lines acting as aerials picking up RFI and AC hum) and significant high frequency roll-off from the long cable runs - the line is effectively an RC filter.
Imagine a stage performance in a large auditorium or at an outdoor festival (eg Woodstock) where the mics and lines from the stage run to stage boxes and then back through the audience in multicore cables to the mixing desk and from the desk back to power amps by the stage to drive the PA. If this was all done with unbalanced lines the sound quality would be absolutely horrendous - high noise levels (summed in the mixing desk from all the unbalanced lines acting as aerials picking up RFI and AC hum) and significant high frequency roll-off from the long cable runs - the line is effectively an RC filter.
"I got a car battery and two jumper cables that argue different."
Rust Cohle
Rust Cohle
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- KVRist
- Topic Starter
- 49 posts since 22 Sep, 2012
neither of you guys really answered this part of the question - does XLR with one end ungrounded, give a better sound quality than RCA with both ends ungrounded?
as to ground loops, i'm not sure what they are, but most people i know or interact with seem to be of the opinion that XLR should be grounded at both ends - anyway as soon as you plug it into an XLR socket it's automatically routed to ground (in normal devices)(as far as I know)
also why would microphones use XLR if the sound quality wasn't superior to say a standard audio cable featuring two wires? (the microphone isn't grounded obviously)... although on second thoughts maybe it serves primarily to reduce the chance of electric shock to the singer.
ok keen to hear more thoughts on this if anyone has them? thanks
as to ground loops, i'm not sure what they are, but most people i know or interact with seem to be of the opinion that XLR should be grounded at both ends - anyway as soon as you plug it into an XLR socket it's automatically routed to ground (in normal devices)(as far as I know)
also why would microphones use XLR if the sound quality wasn't superior to say a standard audio cable featuring two wires? (the microphone isn't grounded obviously)... although on second thoughts maybe it serves primarily to reduce the chance of electric shock to the singer.
ok keen to hear more thoughts on this if anyone has them? thanks
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- KVRAF
- 4205 posts since 21 Oct, 2001 from my bolthole in the south pacific
You seem to have some dodgy assumptions operating. RCA shield is usually grounded to the chassis inside whatever device you are connecting. The shielding only screens RFI effectively if it is grounded.
"I got a car battery and two jumper cables that argue different."
Rust Cohle
Rust Cohle
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- Beware the Quoth
- 33164 posts since 4 Sep, 2001 from R'lyeh Oceanic Amusement Park and Funfair
Balanced XLR is three connections, including ground. RCA is two, including ground.rosko12 wrote:Is there any worth in running a balanced XLR cable across a room and then into a RCA adapater? At the XLR end the cable will be grounded. The RCA end doesn't have a shield pin so at this end the cable is ungrounded.
When the XLR is balanced? Yes, when long distances are involved.Would you expect an XLR cable to perform better than an RCA cable in the above situation?
http://www.soundonsound.com/sos/jan02/a ... aq0102.aspI had a search around the web. Found some contrasting information that was mostly too technical for me. Does a balanced cable have any use if it's not grounded at both ends?
my other modular synth is a bugbrand
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- Beware the Quoth
- 33164 posts since 4 Sep, 2001 from R'lyeh Oceanic Amusement Park and Funfair
You're being inconsistent with what you're comparing, which is not helping. XLR is a plug/socket format. That could, and is, be found on 'a standard audio cable featuring two wires'. With a shield around the two wires. Or it could be found a standard audio cable featuring one wire with a shield around the wire. The shield is what will be connected to ground.rosko12 wrote:also why would microphones use XLR if the sound quality wasn't superior to say a standard audio cable featuring two wires?
The number of wires has nothing to do with the plug/socket format. Strictly speaking balanced has nothing to do with the plug/socket format either, as long as there are enough connections made to support a balanced connection.
Balanced connections have two instances of the signal and a ground, and need 3 connections at each end. They're better for long cable runs. They could be XLR connections, or any other connector, though.
Also, some microphones need phantom power... which needs all three connections.
my other modular synth is a bugbrand
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- KVRist
- Topic Starter
- 49 posts since 22 Sep, 2012
are you saying that a microphone has only one wire for audio and the other two are connected to the ground? surely not. i'm thinking microphone uses two cables for audio and the other one is a shield which is connected to the ground at (obviously) only one end of the cable. Or is the third cable simply not relevant unless phantom power is used?
anyway thankyou all for the replies. i am still a bit confused about all this but one day when i have better access to resources and test equipment i will probably solve it. in the meantime it is just a not-very-important issue among many other not-very-important issues that occasionally nags me in my slightly nerdy desire to understand everything.
anyway thankyou all for the replies. i am still a bit confused about all this but one day when i have better access to resources and test equipment i will probably solve it. in the meantime it is just a not-very-important issue among many other not-very-important issues that occasionally nags me in my slightly nerdy desire to understand everything.
