CAT-5 cable for analog and digital audio?

David Kulka · 6th January 2005

A friend tells me that people are starting to use standard CAT-5 data cable for balanced analog and digital audio wiring, with excellent results.

I guess the idea is that with the tightly twisted pairs in communications cable, the shield is unneccessary. Many of the best audiophile cables are unshielded, and that's not even balanced audio. And phone wires run for miles in close proximity to high voltage power lines with very little audible hum, even when monitored through a good quality phone patch.

Of course, this would not work with phantom power, perhaps not with mic lines at all. But for line level, it's interesting. The cost savings would be significant. Maybe what's good for ethernet can be good for AES and analog audio as well. Comments?

Waylon · 6th January 2005

this definately works for AES/EBU runs.

Brad Blackwood · 6th January 2005

Never used it for analog, but used it quite a bit for long AES runs in my room at Ardent. Even built a dig patchbay using CAT5 cables and a CAT5 patchbay...

Waylon · 6th January 2005

Thats exactly what I did for Forerunner when they had thier Sony DMX / DA 78 and PT setup.. built a 96 point, 192 channel AES patchbay for like 300 bucks.

it was a little cheape than the Z-systems option

ottor · 8th January 2005

Belden's MediaTwist cable is very versatile and quite cheap.

PRR · 9th January 2005

> people are starting to use standard CAT-5 data cable for balanced analog and digital audio wiring, with excellent results. ...with the tightly twisted pairs in communications cable, the shield is unnecessary. ... phone wires run for miles in close proximity to high voltage power lines with very little audible hum, even when monitored through a good quality phone patch. ....would not work with phantom power, perhaps not with mic lines at all.

Balanced twisted shielded cable with vast CMRR is a superstition, or perhaps preventative precaution. Indeed it is very expensive to pull a lot of low-price cable, run into interference, and then have to re-wire with fancy stuff.

If you live in a low-noise environment (no overhead AM transmitter, no megawatt power vaults under the floor) you can often get away with very simple systems.

I've used UN-balanced circuits on any old wire that suits the need. 25 years ago I hung a pair of amplified mikes on twisted magnet-wire, three strands L-R-G. The current incarnation uses cheap speaker wire, CAT-3, and a short run of cheap shielded twisted-pair strung 100 feet all over the walls of the rehearsal hall. That has only about gain of 7 amplification inside the mikes, feeds 36V 30mA power to the mikes and returns audio as unbalanced 47 ohm source 470 ohm load. The old clacky elevator and even the new dimmered lights don't bother it.

My rack is all unbalanced on RCA cables. "Shielded", but some of those are cheap 50% spiral shield. BTW, there is a 200A 3-phase fusebox on the wall 5 feet away from the rack. And the rack is particle board.

The other end of that chain runs 300 feet through balanced CAT3 (balanced not so much for CMRR, but because I needed a transformer anyway to protect against bad building grounds and miswired guest recorders). Note: I can run the mikes unbalanced because they "float", hung by plastic insulated wires, and are not grounded at the far end. "My" ground is all in one 4' rack. But when I send signal to guest recorders out in the house, I break the ground so their grounding problems do not come back to me. Same would apply in a larger facility with multiple racks. And when you need a transformer anyway, going balanced is not expensive and does dodge many problems.

About 10 years ago I started seeing a product that APPEARs to convert unbalanced audio to low-Z balanced with CAT-type jacks, to put audio on existing net-wires. Guessing, they run 2 of the 4 pairs as balanced lines, and ground the other 2 pairs for some shielding (100MbpS Ethernet works this way).

One potential problem: twisted pair is always around 90-120 ohm characteristic impedance. That really does not apply for short audio runs, and indeed you won't find pre-installed EtherNet links much longer than 300 feet. But 300' is about 10,000pFd, which is around 1K ohms at the top of the audio band. So you can drive it with true 600 ohm outputs (150 ohms would be better), but cheap gear with TLO72 outputs will strain in the top octave with 10,000pFd load.

The phone company can sometimes run balanced cable (and formerly open-wire) for miles cleanly, though I very much remember when hummm was always on the line. Phones have got a lot cleaner in the last 10-20 years. And in the last 10-5 years, those old miles-long lines have been cut and stubbed into digi-boxes on poles: few suburban folk in the USA have an analog line even a mile long. Mine runs to the graveyard and goes digital, instead of going the long way around the hill to the downtown telco switch (they sold the building).

aurt · 25th January 2005

Mediatwist can be very handy. The local Univision affiliate moved to new digs recently and wire the whole joint, audio, video, dig, and analog with it. It seems that it was easier to spec one type of cable and have someone make baluns to put on any gear that would need it. The mediatwist, and datatwist, advantage is that the pairs are bonded to keep the twist stable and consistant. It's built not to radiate rf when ethernet is running through it, and if it can't radiate, it also can't pick up interferance. I built a room recently using it for all AES, MIDI, and 422 signals. I also did a neat little RJ45 patchbay for it. I'm using it for AES in six other rooms.

David Kulka · 9th February 2005

Speaking of which, this sounds interesting, and I'll be there...

THE SOCIETY OF TELEVISION ENGINEERS
GENERAL MEETING NOTICE
SPOUSES AND GUESTS ARE WELCOME
Thursday, February 17th, 2005
LOCATION: The Castaways Restaurant, Starlight Room,1250 Harvard Rd., Burbank, CA 91501 (818) 843-5013

PROGRAM: Using Category 5,5e,6 for Audio and Video Applications

Can you use Category 5 or enhanced versions (5e, 6) to carry analog and digital audio? Or analog or digital video? How about S-video, RGB or VGA? Or broadband/CATV? How about SDI? Of course you can! For some applications, baluns are required. Exactly how to use, and when not to use, Category cables is discussed. Included is a tutorial on balanced lines and how they reject noise and crosstalk, and concludes with a live demo running SDI down Category 6.

Steve Lampen brings humor and an invigorating style to the subject of cable and infrastructure. If you’ve not heard Steve, trust me, don’t miss this one! N.S.

Speaker: Steve Lampen is Multimedia Technology Manager for Belden Electronics Division of Belden . He has worked for Belden for thirteen years. Prior to Belden, Steve had an extensive career in recording, sound reinforcement, radio broadcast engineering and installation, film production, and electronic distribution. Steve holds an FCC Lifetime General License (formerly a First Class FCC License) and is an SBE Certified Radio Broadcast Engineer. On the data side he is a BICSI Registered Communication Distribution Designer. Steve is the holder of four patents in audio control circuitry. He won the “Brian Schwab Award of Excellence” for his paper “Return Loss Headroom” at the 2002 Iowa DTV Symposium. He has published two books on wire and cable. The latest, "The Audio-Video Cable Installer’s Pocket Guide" is published by McGraw-Hill. His column "Wired for Sound" appears in Radio World Magazine.

Social Hour: 6:00 PM
Dinner: 6:50 PM
Meeting: 7:50 PM
DINNER: $30.00 per person with RSVP
$35.00 per person w/o RSVP
CASH OR CHECK ONLY
Sliced London Broil
Grilled Mash Potatoes
Fresh Seasonal Vegetables
Warm Rolls and Butter
Coffee/Tea/Decaf/Iced Tea, Chocolate Cake

RESERVE: For STE dinner reservations call (310) 348-3313, or send a fax using the form below, or send an Email to chomer@univision.net.
Leave your name and the number of people in your party by 4 PM, Tuesday, February 15. We cannot guarantee dinner servings without a reservation. Please RSVP early. Note that your reservation is a commitment to purchase a dinner and that you may be billed if you do not cancel before on the meeting date.

SOCIETY OF MOTION PICTURE & TELEVISION ENGINEERS (www.hsmpte.org) (818) 771-8103

geerlingguy · 11th January 2011

Just wanted to post a link to a page i have up with some information about a Cat5e cable run I worked on at a Cathedral in St. Louis. We ran balanced and line-level audio over 500' (for the longest run), and it was very clear.

XLR over Cat5 - Balanced XLR Mic-Level & Line-Level Audio over Cat5 & Cat5e Cabling | Life is a Prayer.com

6th January 2005	#1
David Kulka Lives for gear Join Date: Oct 2004 Location: Burbank, CA, USA Posts: 1,026 Thread Starter	CAT-5 cable for analog and digital audio? A friend tells me that people are starting to use standard CAT-5 data cable for balanced analog and digital audio wiring, with excellent results. I guess the idea is that with the tightly twisted pairs in communications cable, the shield is unneccessary. Many of the best audiophile cables are unshielded, and that's not even balanced audio. And phone wires run for miles in close proximity to high voltage power lines with very little audible hum, even when monitored through a good quality phone patch. Of course, this would not work with phantom power, perhaps not with mic lines at all. But for line level, it's interesting. The cost savings would be significant. Maybe what's good for ethernet can be good for AES and analog audio as well. Comments? __________________ http://studioelectronics.biz Service & Restoration of UREI dbx Eventide Marshall AMS Tube Gear and more

6th January 2005	#3
Brad Blackwood Craneslut Join Date: Jun 2002 Location: The home of Rock-n-Roll, Memphis, TN Posts: 1,896	Never used it for analog, but used it quite a bit for long AES runs in my room at Ardent. Even built a dig patchbay using CAT5 cables and a CAT5 patchbay... __________________ euphonic masters

6th January 2005	#4
Waylon Gear addict Join Date: Apr 2004 Posts: 404	Thats exactly what I did for Forerunner when they had thier Sony DMX / DA 78 and PT setup.. built a 96 point, 192 channel AES patchbay for like 300 bucks. it was a little cheape than the Z-systems option __________________ But, whatever you do, don't go with cheap XFMRs, you may have to use them someday. - Remoteness

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8th January 2005	#5
ottor Gear interested Join Date: Feb 2003 Location: Sydney Posts: 13	Belden's MediaTwist cable is very versatile and quite cheap.

9th January 2005	#6
PRR Gear interested Join Date: Jan 2005 Location: eastern USA Posts: 2	> people are starting to use standard CAT-5 data cable for balanced analog and digital audio wiring, with excellent results. ...with the tightly twisted pairs in communications cable, the shield is unnecessary. ... phone wires run for miles in close proximity to high voltage power lines with very little audible hum, even when monitored through a good quality phone patch. ....would not work with phantom power, perhaps not with mic lines at all. Balanced twisted shielded cable with vast CMRR is a superstition, or perhaps preventative precaution. Indeed it is very expensive to pull a lot of low-price cable, run into interference, and then have to re-wire with fancy stuff. If you live in a low-noise environment (no overhead AM transmitter, no megawatt power vaults under the floor) you can often get away with very simple systems. I've used UN-balanced circuits on any old wire that suits the need. 25 years ago I hung a pair of amplified mikes on twisted magnet-wire, three strands L-R-G. The current incarnation uses cheap speaker wire, CAT-3, and a short run of cheap shielded twisted-pair strung 100 feet all over the walls of the rehearsal hall. That has only about gain of 7 amplification inside the mikes, feeds 36V 30mA power to the mikes and returns audio as unbalanced 47 ohm source 470 ohm load. The old clacky elevator and even the new dimmered lights don't bother it. My rack is all unbalanced on RCA cables. "Shielded", but some of those are cheap 50% spiral shield. BTW, there is a 200A 3-phase fusebox on the wall 5 feet away from the rack. And the rack is particle board. The other end of that chain runs 300 feet through balanced CAT3 (balanced not so much for CMRR, but because I needed a transformer anyway to protect against bad building grounds and miswired guest recorders). Note: I can run the mikes unbalanced because they "float", hung by plastic insulated wires, and are not grounded at the far end. "My" ground is all in one 4' rack. But when I send signal to guest recorders out in the house, I break the ground so their grounding problems do not come back to me. Same would apply in a larger facility with multiple racks. And when you need a transformer anyway, going balanced is not expensive and does dodge many problems. About 10 years ago I started seeing a product that APPEARs to convert unbalanced audio to low-Z balanced with CAT-type jacks, to put audio on existing net-wires. Guessing, they run 2 of the 4 pairs as balanced lines, and ground the other 2 pairs for some shielding (100MbpS Ethernet works this way). One potential problem: twisted pair is always around 90-120 ohm characteristic impedance. That really does not apply for short audio runs, and indeed you won't find pre-installed EtherNet links much longer than 300 feet. But 300' is about 10,000pFd, which is around 1K ohms at the top of the audio band. So you can drive it with true 600 ohm outputs (150 ohms would be better), but cheap gear with TLO72 outputs will strain in the top octave with 10,000pFd load. The phone company can sometimes run balanced cable (and formerly open-wire) for miles cleanly, though I very much remember when hummm was always on the line. Phones have got a lot cleaner in the last 10-20 years. And in the last 10-5 years, those old miles-long lines have been cut and stubbed into digi-boxes on poles: few suburban folk in the USA have an analog line even a mile long. Mine runs to the graveyard and goes digital, instead of going the long way around the hill to the downtown telco switch (they sold the building).

25th January 2005	#7
aurt Gear interested Join Date: Dec 2004 Location: N. Cal. Posts: 8	Mediatwist can be very handy. The local Univision affiliate moved to new digs recently and wire the whole joint, audio, video, dig, and analog with it. It seems that it was easier to spec one type of cable and have someone make baluns to put on any gear that would need it. The mediatwist, and datatwist, advantage is that the pairs are bonded to keep the twist stable and consistant. It's built not to radiate rf when ethernet is running through it, and if it can't radiate, it also can't pick up interferance. I built a room recently using it for all AES, MIDI, and 422 signals. I also did a neat little RJ45 patchbay for it. I'm using it for AES in six other rooms.

9th February 2005	#8
David Kulka Lives for gear Join Date: Oct 2004 Location: Burbank, CA, USA Posts: 1,026 Thread Starter	Speaking of which, this sounds interesting, and I'll be there... THE SOCIETY OF TELEVISION ENGINEERS GENERAL MEETING NOTICE SPOUSES AND GUESTS ARE WELCOME Thursday, February 17th, 2005 LOCATION: The Castaways Restaurant, Starlight Room,1250 Harvard Rd., Burbank, CA 91501 (818) 843-5013 PROGRAM: Using Category 5,5e,6 for Audio and Video Applications Can you use Category 5 or enhanced versions (5e, 6) to carry analog and digital audio? Or analog or digital video? How about S-video, RGB or VGA? Or broadband/CATV? How about SDI? Of course you can! For some applications, baluns are required. Exactly how to use, and when not to use, Category cables is discussed. Included is a tutorial on balanced lines and how they reject noise and crosstalk, and concludes with a live demo running SDI down Category 6. Steve Lampen brings humor and an invigorating style to the subject of cable and infrastructure. If you’ve not heard Steve, trust me, don’t miss this one! N.S. Speaker: Steve Lampen is Multimedia Technology Manager for Belden Electronics Division of Belden . He has worked for Belden for thirteen years. Prior to Belden, Steve had an extensive career in recording, sound reinforcement, radio broadcast engineering and installation, film production, and electronic distribution. Steve holds an FCC Lifetime General License (formerly a First Class FCC License) and is an SBE Certified Radio Broadcast Engineer. On the data side he is a BICSI Registered Communication Distribution Designer. Steve is the holder of four patents in audio control circuitry. He won the “Brian Schwab Award of Excellence” for his paper “Return Loss Headroom” at the 2002 Iowa DTV Symposium. He has published two books on wire and cable. The latest, "The Audio-Video Cable Installer’s Pocket Guide" is published by McGraw-Hill. His column "Wired for Sound" appears in Radio World Magazine. Social Hour: 6:00 PM Dinner: 6:50 PM Meeting: 7:50 PM DINNER: $30.00 per person with RSVP $35.00 per person w/o RSVP CASH OR CHECK ONLY Sliced London Broil Grilled Mash Potatoes Fresh Seasonal Vegetables Warm Rolls and Butter Coffee/Tea/Decaf/Iced Tea, Chocolate Cake RESERVE: For STE dinner reservations call (310) 348-3313, or send a fax using the form below, or send an Email to chomer@univision.net. Leave your name and the number of people in your party by 4 PM, Tuesday, February 15. We cannot guarantee dinner servings without a reservation. Please RSVP early. Note that your reservation is a commitment to purchase a dinner and that you may be billed if you do not cancel before on the meeting date. SOCIETY OF MOTION PICTURE & TELEVISION ENGINEERS (www.hsmpte.org) (818) 771-8103

11th January 2011	#9
geerlingguy Gear interested Join Date: Jul 2010 Posts: 7	Just wanted to post a link to a page i have up with some information about a Cat5e cable run I worked on at a Cathedral in St. Louis. We ran balanced and line-level audio over 500' (for the longest run), and it was very clear. XLR over Cat5 - Balanced XLR Mic-Level & Line-Level Audio over Cat5 & Cat5e Cabling \| Life is a Prayer.com