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Ethernet over XLR – Can I do this ???
Old 6th November 2018
  #1
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Ethernet over XLR – Can I do this ???

We recently moved into an old recording studio that has 4 feet of isolation between tracking room and the control room. The studio was built in the 80's and has plenty of XLR (analog) connectivity through the wall.

I would like to put a digital snake in the tracking room and send the CAT6 cable through to the Control room - the CAT6 would connect to the Digital board. But, it is impossible to run an ethernet cable through the wall.

So, I am hoping I can use XLR wires as a portion of the CAT6 run… Attached is a diagram of what I need.

I am asking if
a. There is a product on the market that can do this
b. If I could simply solder together an adapter system using 4 XLR runs – making sure I put the 4 “pairs” of the CAT6 with pins 2 & 3 of the four XLR’s.

Texas
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Ethernet over XLR – Can I do this ???-ethernet-over-xlr.jpg  
Old 6th November 2018
  #2
Gear Guru
 
jwh1192's Avatar
if you remove the panels on each side of the 4 foot insulated wall ... what do you see .. there might be a very simple way to pass a couple Cat Cables through where the XLR cables go through !!

and if you have done this and there is absolutely No Way in Hell ... then you could try wiring up the CAT connectors to 4 XLR's ... it is usually the other way round .. where you want to send audio down CAT cables ..
Old 6th November 2018
  #3
Gear Nut
 

Understand that Category cable is designed with a specific characteristics to carry the very high frequencies used in high-speed data transmission. Category cable CAN be used to carry audio signals because audio frequencies are so low the cable type doesn’t really matter. The reverse is not true and trying to use old mic lines to transport data is almost certain to be an unhappy experience.
Old 6th November 2018
  #4
Gear Head
 

radial makes a product called the catapult (and the catapult mini) that pass balanced audio signals (analog xlr or digital AES) through cat5 cables passively. I'm not an expert here, but it looks like they're making use of ONLY the copper in the cat5 cabling. Catapult - Radial Engineering

Looking at this, I'd like to think you could use it for the opposite of its original purpose, but you might check with someone at Radial before proceeding.
Old 6th November 2018
  #5
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It might work but as mentioned before me, you are loosing the whole "Shielded twisted pair" concept which could result in speed drops, connectivity drops etc.
But I guess you'll never know till you try
Old 6th November 2018
  #6
Lives for gear
Yikes! Ethernet over XLR audio cables? Here are some data points to help you use your time more efficiently by working on drilling a path between the rooms for some proper Cat5E or Cat6 cables:

Ethernet cabling has 4 pairs, the Green has 65.2 twists per meter, the Blue pair has 64.8 turns per meter, the Orange pair has 56.2 turns per meter, and the Brown pair has 51.7 turns per meter. This is done to spread and minimize the crosstalk influence of the individual pairs. The baud rate (not to be confused with the bit rate) of the MLT-3 for Fast Ethernet, or PAM-5 for Gigabit Ethernet will be in the 125Mhz range.

Digital snakes are notorious for not even using regular Ethernet encoding schemes. Last time I checked, there were 11 different wire protocols for digital snakes. For example, AES50 used by Midas/Behringer uses a pair in one direction for the clock and another pair in one direction for the bit-data/sound. I accidentally made an AES50 cable with regular Cat5 rather than Cat5E and it didn't work at all. This does not bode well for trying twisted audio cables.

Rats!, an interruption, gotta go. Get out that drill!
Old 6th November 2018
  #7
Gear Guru
 
jwh1192's Avatar
i still think there is a path existing ... the XLR panels that are there now have a path from room to room .. just need to investigate it ..
Old 17th June 2019
  #8
Gear Head
 

Ethernet uses an 8 conductor cable. You cannot really use it with 3 pin XLRs. However Neutrik make ethernet connectors in XLR shells which may work for you.
Old 17th June 2019
  #9
Gear Nut
 

It guaranteed won't work.
Get an electrician to run you a couple of CAT6's. They have some specialised tools and techniques to get cable through where you might think it's impossible.

I know you only need one, but the cost of doing 1 vs doing a few will be minimal

-John
Old 22nd August 2019
  #10
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Quote:
Originally Posted by MediaGary View Post
...
Ethernet cabling has 4 pairs, the Green has 65.2 twists per meter, the Blue pair has 64.8 turns per meter, the Orange pair has 56.2 turns per meter, and the Brown pair has 51.7 turns per meter. This is done to spread and minimize the crosstalk influence of the individual pairs. The baud rate (not to be confused with the bit rate) of the MLT-3 for Fast Ethernet, or PAM-5 for Gigabit Ethernet will be in the 125Mhz range.

...
As an audio engineer and IT tech/installer and also because of the info quoted above, I believe this should absolutely be doable if done right and am wondering if anyone here has tried it yet.

Electrically, Cat5/5e/6 is fancy phone wire with extra care to avoid cross-talk at higher voltages. Some but not all Cat6 is shielded; there is a plastic separator in the wire that aids in signal isolation. Analog mic wire is (or should be) a shielded pair and has very good frequency response (close but not quite as good as RG59 wire) and should transmit signal safely and without noise up to 250 ft. If 4 mic wires are punched down on a phone block in a metal box where all shields are grounded together and each colored pair is tied into a single mic line (1 mic wire per color set) everything should work fine. I have done this in server rooms for broadcast stations (WVIZ Cleveland for example) but those runs were very short (less than 3 ft) and the gear was proprietary.

Please share if you've tried this with success over longer distances, thanks!
Old 22nd August 2019
  #11
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Quote:
Originally Posted by Johnny Trumpet View Post
...I have done this in server rooms for broadcast stations (WVIZ Cleveland for example) but those runs were very short (less than 3 ft) and the gear was proprietary.
Are we talking about the same thing? What is the "this" in the quoted sentence? You ran Ethernet over microphone cable for about 3-feet?
Old 3rd September 2019
  #12
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Ethernet over xlr

Hi, I have recently set up a PA net using xlr lines with cat5 adaptators, up to 100 meters per line, in a stadium and it works with a minimum delay of course
Old 3rd September 2019
  #13
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Pollo's Avatar
 

I also think it might work.
Make sure you connect each twisted pair to one XLR cable, so blue & blue-white go to one XLR, orange & orange-white go to one cable etc.
I think you can ignore the shielding. I've never seen a shielded ethernet cable.
If the cable run is not too long it could work.

But it wil cost you 4 XLR connections. You could probably squeeze 4 ethernet cables in the space that one XLR occupies.

Last edited by Pollo; 3rd September 2019 at 12:00 PM.. Reason: Blame it on the boogie
Old 3rd September 2019
  #14
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Quote:
Originally Posted by Pollo View Post
I also think it might work.
Make sure you connect each twisted pair to one XLR cable, so blue & blue-white go to one XLR, orange & orange-white go to one cable etc.
I think you can ignore the shielding. I've never seen a shielded ethernet cable.
If the cable run is not too long it could work.

But it wil cost you 4 XLR connections. You could probably squeeze 4 ethernet cables in the space that one XLR occupies.
I think this discussion is spreading into two directions.

One direction is @ Alex00 talking about audio over twisted pair Cat5/Cat5e/Cat6 cable. That's readily accomplished, and I have four audio snakes that use shielded twisted pair Cat5e cable. See post: [ Why are Cat5 "snakes" so expensive? ]

Shielded twisted pair (STP) is readily available for normal Ethernet and other signaling requirements like digital snakes; and is absolutely necessary for audio snakes that need to transport the phantom power to the microphones.

The other direction is the OP's objective of running Ethernet protocol (125MHz symbol rate for 100Mbit/sec Fast Ethernet and Gigabit Ethernet) over regular XLR audio cable.

When I thought about the challenge of getting any useful distance of a signal that has a higher frequency than FM radio through common audio XLR cable, my intuition led me to say that it would not work because of the severe attenuation that would be encountered.

I quickly played around with this calculator on the Sengpiel Audio website (a favorite). [http://www.sengpielaudio.com/calculator-cable.htm ]
I used 43pF/meter as the capacitance of the cable, which is the best spec XLR cable that you're likely to find, whereas typical values are about triple that figure. [https://www.belden.com/blog/broadcast/wiring-up-an-xlr ]

The results are that with a very good 100-ohm source impedance driving world class 43pF/meter cable, the -3dB signal loss point for 125-kiloHertz is a very nice 296 meters. At 1.25-MegaHertz that -3dB point is at 30 meters. At 12.5-MegaHertz, it's 3 meters. The calculator returns 'zero' for 125-MHz, but the answer is probably 0.3 meters ... about 11 inches. Normal 120pF/meter XLR cable would push that -3dB loss point number down to about 4 inches.

Okay, enough calculator fun this morning. Somebody with some time on their hands has to go build this beast and report results.
Old 3rd September 2019
  #15
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I suppose I should try it...

Since I am the one who came up with this crazy idea, I should be the one to try it! I will keep you posted.

This will make it easy:
https://www.amazon.com/Covvy-Termina.../dp/B07C1PM8KS

Thanks for all the input.

Marius Perron
San Antonio, Texas
Old 3rd September 2019
  #16
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tymish's Avatar
 

Sorry 90% sure it won't work and that's a stretch. Requires specific impedance and 4 twisted pairs. The other way around, analog audio or AES/EBU digital over CAT5 is just fine.
Old 12th September 2019
  #17
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Quote:
Originally Posted by MediaGary View Post
Are we talking about the same thing? What is the "this" in the quoted sentence? You ran Ethernet over microphone cable for about 3-feet?
yes, this was for a calrec digital mixer for a radio station and that was what the manufacturer specified for a their patch bay
Old 4 weeks ago
  #18
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tymish's Avatar
 

Quote:
Originally Posted by Johnny Trumpet View Post
yes, this was for a calrec digital mixer for a radio station and that was what the manufacturer specified for a their patch bay
Way back in the day as far as networking goes, ethernet did run 10 base over coax.. but that was a long time ago in the late 20th century. Back when ARCnet was still a thing.
Old 4 weeks ago
  #19
Gear Nut
 

Quote:
Originally Posted by tymish View Post
Way back in the day as far as networking goes, ethernet did run 10 base over coax.. but that was a long time ago in the late 20th century. Back when ARCnet was still a thing.
Yep. 10base2
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