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Church and H.O.W. – Forums for HOW Sound and AV - Your Displayed Name Must Be Your Real Full Name To Post In The Church and HOW Forums => Church Sound => Topic started by: Gordon Waugh on September 12, 2011, 04:07:15 PM
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My multicore XLR snake has 24 sends and 4 returns. However, I would like to use 5 returns: L main, R main, and 3 stage monitors. May I use one of the send cables as a return--with the appropriate adapter at each end (male-male at the fantail and female-female at the stage box)?
The only complication I can think of is if the return cables are thicker than the send cables. Then the send cable might be too thin for the return signal because return signals typically carry a higher current than send signals.
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My multicore XLR snake has 24 sends and 4 returns. However, I would like to use 5 returns: L main, R main, and 3 stage monitors. May I use one of the send cables as a return--with the appropriate adapter at each end (male-male at the fantail and female-female at the stage box)?
The only complication I can think of is if the return cables are thicker than the send cables. Then the send cable might be too thin for the return signal because return signals typically carry a higher current than send signals.
Nothing wrong with this at all. I have a 16/4 snake, and I regularly use two of the "microphone" channels as returns so that I can run my L/R, and 4 monitors with no side effects at all.
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My multicore XLR snake has 24 sends and 4 returns. However, I would like to use 5 returns: L main, R main, and 3 stage monitors. May I use one of the send cables as a return--with the appropriate adapter at each end (male-male at the fantail and female-female at the stage box)?
The only complication I can think of is if the return cables are thicker than the send cables. Then the send cable might be too thin for the return signal because return signals typically carry a higher current than send signals.
If you're talking about sending signal from power amps through a snake return.......DON'T. You can send line level signals TO a power amp from the board via the snake channels with the proper adaptors, but not signals from power amps to your speakers.
Check out the full name requirement for Forum participation.......
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If you're talking about sending signal from power amps through a snake return.......DON'T. You can send line level signals TO a power amp from the board via the snake channels with the proper adaptors, but not signals from power amps to your speakers.
Check out the full name requirement for Forum participation.......
It's a line-level output from the console's aux send out.
Thanks for pointing out I omitted my name. It's fixed now.
Gordon Waugh
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It's a line-level output from the console's aux send out.
Thanks for pointing out I omitted my name. It's fixed now.
Gordon Waugh
Line level will work just fine.
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As another idea, maybe for the future:
If you're handy with a soldering iron, you could make an (up to) 8-channel drive snake using UTP cable and balanced-capable connectors (XLR, TRS). Use pins 2 and 3, keeping the shield disconnected. I recommend EtherCon connectors (http://www.neutrik.com/us/en/dataconnectors/204_291104954/etherCON_Cable_Connector_Carriers_productlist.aspx) on each end of the main trunk and make short breakout tails (8 XLR-->1 EtherCon); that would make it very reliable. You can then tape it to the "regular" snake and shouldn't have problems with long cable runs.
Just be aware that the devices on
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As another idea, maybe for the future:
If you're handy with a soldering iron, you could make an (up to) 8-channel drive snake using UTP cable and balanced-capable connectors (XLR, TRS). Use pins 2 and 3, keeping the shield disconnected. I recommend EtherCon connectors (http://www.neutrik.com/us/en/dataconnectors/204_291104954/etherCON_Cable_Connector_Carriers_productlist.aspx) on each end of the main trunk and make short breakout tails (8 XLR-->1 EtherCon); that would make it very reliable. You can then tape it to the "regular" snake and shouldn't have problems with long cable runs.
Just be aware that the devices on
I wouldn't recommend this because without the shield you are way more susceptible to ground loop hum, cross talk, and a host of other potential issues.
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I wouldn't recommend this because without the shield you are way more susceptible to ground loop hum, cross talk, and a host of other potential issues.
With no shield connection there there would be no ground loop and much of the noise and crosstalk resistance would be provided by the twisted pairs in combination with balanced circuits and differential inputs.
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With no shield connection there there would be no ground loop and much of the noise and crosstalk resistance would be provided by the twisted pairs in combination with balanced circuits and differential inputs.
Personally, I would prefer to keep as much electromagnetic interference, and crosstalk out of my cables as possible. I don't know any audio guys that would do this unless they absolutely had to, especially since we are talking long distances (probably 50'-100').
The following is a quote from Wiki about ground loop hum:
"Any noise currents induced into a balanced audio shield will not therefore be directly modulated onto the signal, whereas in a two-conductor system they will be. This also prevents ground loop problems, by separating the shield/chassis from signal ground."
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Personally, I would prefer to keep as much electromagnetic interference, and crosstalk out of my cables as possible. I don't know any audio guys that would do this unless they absolutely had to, especially since we are talking long distances (probably 50'-100').
The following is a quote from Wiki about ground loop hum:
"Any noise currents induced into a balanced audio shield will not therefore be directly modulated onto the signal, whereas in a two-conductor system they will be. This also prevents ground loop problems, by separating the shield/chassis from signal ground."
Wikipedia is not necessarily the unchallengable oracle.
A ground loop by definition is an alternate or additional path to ground - in audio terms, this is through a shield conductor connected between two different devices that are also grounded through other means (the ground pin of the power cord, the rack rails the equipment is mounted in, the conductive surface the gear is sitting on, etc.).
In the suggestion above, each pair of the UTP connects to the + and - of the device - pins 2 and 3, which (in pro gear) drive a differential input that subtracts common noise across those lines. There is no ground connection here, and therefore no ground loop potential.
UTP cable is occasionally used for this purpose, and generally does work fine, however it's not very rugged, and without the shield can't provide phantom power.
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Personally, I would prefer to keep as much electromagnetic interference, and crosstalk out of my cables as possible. I don't know any audio guys that would do this unless they absolutely had to, especially since we are talking long distances (probably 50'-100').
The following is a quote from Wiki about ground loop hum:
"Any noise currents induced into a balanced audio shield will not therefore be directly modulated onto the signal, whereas in a two-conductor system they will be. This also prevents ground loop problems, by separating the shield/chassis from signal ground."
http://www.audiosystemsgroup.com/AES-RFI-SF08.pdf (http://www.audiosystemsgroup.com/AES-RFI-SF08.pdf)
http://www.audiosystemsgroup.com/IEEE-Tutorial05.pdf (http://www.audiosystemsgroup.com/IEEE-Tutorial05.pdf)
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UTP cable is occasionally used for this purpose, and generally does work fine, however it's not very rugged, and without the shield can't provide phantom power.
Good things to point out, TJ.
I will agree somewhat on the lack of ruggedness concern (although there are tougher versions out there).
The missing shield is a non-issue since I recommended it for use as a drive snake, where it will be dealing with line level signals.
If this is a viable option for the OP, I'm sure a number of people on here could provide info on preferred cable type, etc.
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Good things to point out, TJ.
I will agree somewhat on the lack of ruggedness concern (although there are tougher versions out there).
The missing shield is a non-issue since I recommended it for use as a drive snake, where it will be dealing with line level signals.
If this is a viable option for the OP, I'm sure a number of people on here could provide info on preferred cable type, etc.
I knew you knew about the phantom power issue, and that your recommendation was appropriate for a drive snake. I wanted to mention that limitation in case someone extended the idea to include send lines.
As to a recommendation for a preferred cable type, I would suggest that the preferred cable type would be traditional multicore line such as:
http://www.canare.com/ProductItemDisplay.aspx?productItemID=60
http://whirlwindusa.com/catalog/bulk-connectors-multipins-adapters/bulk-cable/belden-individually-jacketed-ij-multipair-cable
and other similar types.
The UTP recommendation is pretty much based on being cheap, which may be fine within some limitations, however I suggest that finding a "rugged UTP cable" would be less preferable to finding an appropriate multicore.
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With no shield connection there there would be no ground loop and much of the noise and crosstalk resistance would be provided by the twisted pairs in combination with balanced circuits and differential inputs.
In the suggestion above, each pair of the UTP connects to the + and - of the device - pins 2 and 3, which (in pro gear) drive a differential input that subtracts common noise across those lines. There is no ground connection here, and therefore no ground loop potential.
UTP cable is occasionally used for this purpose, and generally does work fine, however it's not very rugged, and without the shield can't provide phantom power.
I knew you knew about the phantom power issue, and that your recommendation was appropriate for a drive snake. I wanted to mention that limitation in case someone extended the idea to include send lines.
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The UTP recommendation is pretty much based on being cheap, which may be fine within some limitations, however I suggest that finding a "rugged UTP cable" would be less preferable to finding an appropriate multicore.
You pretty much said this, but I just wanted to stress that while UTP doesn't provide a ground path and therefore should be immune to ground loops, that ONLY applies where both the input and output are balanced floating without reference to ground. Once you reference either the output or input to ground, you have the potential for introducing a ground loop.
UTP simply shouldn't be relied upon for unbalanced connections. Your Big-Box-Special CAT5e/CAT6 that comes in a 1000' spool is intended for fixed installation where it is not subject to repeated flexing or abrasion. It is also does not recover well from kinks and tight bends. That's why for audio applications, you should choose a durable product made with stranded conductors, preferably designed with audio applications in mind.
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You pretty much said this, but I just wanted to stress that while UTP doesn't provide a ground path and therefore should be immune to ground loops, that ONLY applies where both the input and output are balanced floating without reference to ground. Once you reference either the output or input to ground, you have the potential for introducing a ground loop.
UTP simply shouldn't be relied upon for unbalanced connections.
Traditional multicore really shouldn't be used for unbalanced connections either - or rather, you shouldn't run unbalanced connections longer than a few feet over any kind of wire.
You are of course correct though - grounding the pair will certainly create a ground loop.
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Thank you all.
In my situation, I have plenty of unused sends on my multicore cable. I picked up a male-male XLR adaptor and a female-female XLR adaptor. So, I can now use an unused send cable as a return cable.
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Thank you all.
In my situation, I have plenty of unused sends on my multicore cable. I picked up a male-male XLR adaptor and a female-female XLR adaptor. So, I can now use an unused send cable as a return cable.
If you're going to use the channels that way all the time, you might want to just change out the connectors on the snake or make some male-male and female-female mic cables. Also, be careful using adapters on the head of the snake; it's easy for them to cause damage to the connector they're plugged into if they get stepped on or something puts pressure on them.
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If you're going to use the channels that way all the time, you might want to just change out the connectors on the snake ...
Good idea, Justin. I hadn't though of that.
When we switched to electronic drums, we no longer needed several of the drum mic channels. However, the one drum channel has been a blessing and a curse. The sound engineer now has no control over the mix of the individual drum components. I wish we had gotten drums with multiple outputs.
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If you're going to use the channels that way all the time, you might want to just change out the connectors on the snake or make some male-male and female-female mic cables. Also, be careful using adapters on the head of the snake; it's easy for them to cause damage to the connector they're plugged into if they get stepped on or something puts pressure on them.
I've done this many times as well and use the short adapter cables so that there is less strain at the connections. For some reason the solid gender changers seem to go bad at a much higher rate than a good male-male or female-female cable.
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The only complication I can think of is if the return cables are thicker than the send cables. Then the send cable might be too thin for the return signal because return signals typically carry a higher current than send signals.
This part has been bugging me since I first read it. Other than custom bundled cables and power snakes with speaker level returns are there standard multi core bundles that use a larger gauge wire for returns? Every reel of bulk I've ever gotten has had the same configuration per channel and did not have designated returns until it was terminated. On pre-made snakes the only indication of a "return line" was a different shrink wrap size or color along with labeling. Am I way off here? Have I been mis-informed all these years?
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This part has been bugging me since I first read it. Other than custom bundled cables and power snakes with speaker level returns are there standard multi core bundles that use a larger gauge wire for returns? Every reel of bulk I've ever gotten has had the same configuration per channel and did not have designated returns until it was terminated. On pre-made snakes the only indication of a "return line" was a different shrink wrap size or color along with labeling. Am I way off here? Have I been mis-informed all these years?
All the multicore I have used is just like you describe, Lee.
However, if the snake is anything like the Whirlwind Medusa Power series (http://whirlwindusa.com/catalog/snakes-splitters-and-multiwiring-systems/snakes/medusa-power-series-audio-snakes-hand-made-rochest), the returns could be larger gauge speaker wire to allow a powered mixer to run the amp outs through it. Whirlwind's model has 4 "normal" returns and 2 "speaker" returns. however.
Maybe the OP can post a picture or give us more info on the labelling of the snake and box.
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All the multicore I have used is just like you describe, Lee.
However, if the snake is anything like the Whirlwind Medusa Power series (http://whirlwindusa.com/catalog/snakes-splitters-and-multiwiring-systems/snakes/medusa-power-series-audio-snakes-hand-made-rochest), the returns could be larger gauge speaker wire to allow a powered mixer to run the amp outs through it. Whirlwind's model has 4 "normal" returns and 2 "speaker" returns. however.
Maybe the OP can post a picture or give us more info on the labelling of the snake and box.
I don't have the snake with me right now, but I do know it has standard cables. it contains no speaker cables. All of my speakers are self-powered.