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Author Topic: Combining power/signal in one wire idea  (Read 8324 times)

Mac Kerr

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Re: Combining power/signal in one wire idea
« Reply #20 on: November 06, 2015, 08:22:53 pm »

I know, no one makes a powered speaker with a external powersupply, but perhaps they should.

Meyer does. Speaker, Power Supply.

Mac
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Mike Sokol

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Re: Combining power/signal in one wire idea
« Reply #21 on: November 07, 2015, 12:50:16 pm »

Meyer does. Speaker, Power Supply.

Mac

Well, I've always wanted to play with something like this. SoundTube makes a 40 watt ceiling speaker that uses POE (Power Over Ethernet) using CAT-5 cables connectors. http://www.soundtube.com/index.php/products/ip/
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Mike Sullivan

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Re: Combining power/signal in one wire idea
« Reply #22 on: November 09, 2015, 11:37:10 am »

Alright, not to be "that guy" but back on topic, not much was really said...does anyone have an idea of a power cable manufacturer that I could see that would be able to take 12/4 wire, remove the 4th conductor, and replace it with the components of a regular mic cable (2 22-24ga leads and shield), plus whatever other strands to keep the jacket round?  I just want to test it, before spending $150+ on pre-made cables. 
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Jonathan Johnson

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Re: Combining power/signal in one wire idea
« Reply #23 on: November 09, 2015, 11:54:33 am »

Alright, not to be "that guy" but back on topic, not much was really said...does anyone have an idea of a power cable manufacturer that I could see that would be able to take 12/4 wire, remove the 4th conductor, and replace it with the components of a regular mic cable (2 22-24ga leads and shield), plus whatever other strands to keep the jacket round?  I just want to test it, before spending $150+ on pre-made cables.

Um, no. It's impossible to remove a conductor from an SO or similar cable without destroying the jacket in the process. And even if you were willing to do that and remold a new jacket around the assembly, it would likely cost considerably more than a $150 cable. You could, conceivably, do this yourself with heat-shrink tubing, but you would be limited in length to a few feet at most. Since the strength of interference/crosstalk is dependent on length, you may not have a legitimate test. Also, if you wish to use this for anything other than a bench test, the insulation on the microphone conductors would have to be rated to the same voltage as the insulation on the power conductors.
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Michael Thompson

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Re: Combining power/signal in one wire idea
« Reply #24 on: November 09, 2015, 11:59:26 am »

What is wrong with the current product offerings?  Gepco makes a 12AWG version. http://www.gepco.com/products/proav_cable/runone/runone_touring_M.htm

There a companies that will make custom cable, but you'd have to be getting thousands of feet for them to bother.
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Mac Kerr

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Re: Combining power/signal in one wire idea
« Reply #25 on: November 09, 2015, 12:23:49 pm »

Alright, not to be "that guy" but back on topic, not much was really said...does anyone have an idea of a power cable manufacturer that I could see that would be able to take 12/4 wire, remove the 4th conductor, and replace it with the components of a regular mic cable (2 22-24ga leads and shield), plus whatever other strands to keep the jacket round?  I just want to test it, before spending $150+ on pre-made cables.

Back in reply #3 I gave you 3 options, now in reply #24 you have another. How many options do you need to test the concept?

I don't need to test the concept because I use these cables on almost every show in some way or another.

Mac
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Tim McCulloch

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Re: Combining power/signal in one wire idea
« Reply #26 on: November 09, 2015, 01:14:59 pm »

Mike, maybe I'm dense but what is the concern here?  Inductive noise?  If you have balanced signals in the line you're fine.

We routinely (as in, every fucking day) run 300' multi pair analog mic snakes with #8/5 conductor 120/208v. service to FOH.  And for about 50' of the run, it's all on top of the feeder.

Nada problemo for contemporary music shows.  If you're doing whisper quiet theatre or corpy work it may take not running the snakes on top of the feeder, but for the getting signal and power to a wedge?  Any problems you have will not be because of the Siamese cable...
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Jonathan Johnson

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Re: Combining power/signal in one wire idea
« Reply #27 on: November 09, 2015, 03:08:56 pm »

Mike, maybe I'm dense but what is the concern here?  Inductive noise?  If you have balanced signals in the line you're fine.

We routinely (as in, every fucking day) run 300' multi pair analog mic snakes with #8/5 conductor 120/208v. service to FOH.  And for about 50' of the run, it's all on top of the feeder.

Nada problemo for contemporary music shows.  If you're doing whisper quiet theatre or corpy work it may take not running the snakes on top of the feeder, but for the getting signal and power to a wedge?  Any problems you have will not be because of the Siamese cable...

Agreeing with Tim here. If it didn't work, they wouldn't sell it. At least they wouldn't be able to sell it to professionals. They might be able to sell it to audiophools.

Mr. Sullivan may be thinking that the current offerings of Siamese cables are too thick and bulky, so replacing one of the wires in a 12/4 configuration with an audio signal cable would make for a smaller, easier-to-handle package. There is a technical problem with doing so.

In a typical SO cable, as well as a typical microphone cable, the conductors are twisted around each other. This gives a degree of common-mode rejection to prevent crosstalk between adjacent pairs. If you replace one of the conductors of an SO cable with a different signal pair, you have effectively negated some of the common-mode rejection by making the new low-voltage pair inductively part of the high-voltage pair.

Depending on the twist of the low-voltage (audio signal) cable, you may retain some of the common-mode rejection properties of the signal cable, or you may completely negate them, allowing the audio signal to be heavily contaminated by the 60 Hz signal (and any line noise) present in the power cable.

Constructing the Siamese cable in a parallel, rather than twisted, configuration preserves the common-mode rejection properties of both cables.

P.S. -- I'm not an electrical engineer, but I play one on the Internet. There are people on this forum who are electrical engineers, and if they call "bull" on my arguments, I will defer to them.

P.P.S. -- It is very important to coil and lay out Siamese cables properly. Improper coiling and layout could negate common-mode rejection if the cable is allowed to become twisted so that the audio signal cable is wrapped around the the power cable.

EDIT: Corrected name in paragraph 2.
« Last Edit: November 09, 2015, 04:31:11 pm by Jonathan Johnson »
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Michael Thompson

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Re: Combining power/signal in one wire idea
« Reply #28 on: November 09, 2015, 04:07:55 pm »

Agreeing with Tim here. If it didn't work, they wouldn't sell it. At least they wouldn't be able to sell it to professionals. They might be able to sell it to audiophools.

Mr. Thompson may be thinking that the current offerings of Siamese cables are too thick and bulky, so replacing one of the wires in a 12/4 configuration with an audio signal cable would make for a smaller, easier-to-handle package. There is a technical problem with doing so.

In a typical SO cable, as well as a typical microphone cable, the conductors are twisted around each other. This gives a degree of common-mode rejection to prevent crosstalk between adjacent pairs. If you replace one of the conductors of an SO cable with a different signal pair, you have effectively negated some of the common-mode rejection by making the new low-voltage pair inductively part of the high-voltage pair.

Depending on the twist of the low-voltage (audio signal) cable, you may retain some of the common-mode rejection properties of the signal cable, or you may completely negate them, allowing the audio signal to be heavily contaminated by the 60 Hz signal (and any line noise) present in the power cable.

Constructing the Siamese cable in a parallel, rather than twisted, configuration preserves the common-mode rejection properties of both cables.

P.S. -- I'm not an electrical engineer, but I play one on the Internet. There are people on this forum who are electrical engineers, and if they call "bull" on my arguments, I will defer to them.

P.P.S. -- It is very important to coil and lay out Siamese cables properly. Improper coiling and layout could negate common-mode rejection if the cable is allowed to become twisted so that the audio signal cable is wrapped around the the power cable.

Dear Jonathon,
I have no problem with siamese cable.  I have thousands of feet in my inventory.  I was asking why the original poster feels that the products already on the market are not options for him.  If he (original poster) wants 12AWG instead of the more common 14AWG, their are companies that make it.  I know Mike is a common name.  Please don't mix us up.
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Jonathan Johnson

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Re: Combining power/signal in one wire idea
« Reply #29 on: November 09, 2015, 04:32:01 pm »

Dear Jonathon,
I have no problem with siamese cable.  I have thousands of feet in my inventory.  I was asking why the original poster feels that the products already on the market are not options for him.  If he (original poster) wants 12AWG instead of the more common 14AWG, their are companies that make it.  I know Mike is a common name.  Please don't mix us up.

Thank you for pointing out my error. I have fixed my response above.
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Re: Combining power/signal in one wire idea
« Reply #29 on: November 09, 2015, 04:32:01 pm »


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