RE: [Repeater-Builder] Re: LOOONG audio runs
> On Sun, 28 Feb 2010, Mike Morris WA6ILQ wrote: > > 2) the pair that was receiving the problem was a high > impedance load > > or an unbalanced load (i.e. one side grounded). Use an > ungrounded 600 > > ohm winding from a transformer on each end of each pair. > > The nominal impedance of a copper pair from CAT5 is 110-ohms, > not 600. Actually, unless something has changed or I'm totally losing it, balanced Ethernet over Cat3 or higher is 100 ohms. AES3 (aka AES/EBU) digital audio over balanced lines is 110 ohms. IIRC, the tolerance for Ethernet is +/- 15% and for AES it's +/- 20%. AES/EBU can be run over Cat5/5e/6/7 cabling, typically with excellent results. Back to the analog world. Unless you're going long distances, the characteristic transmission line impedance doesn't have a very big effect at audio frequencies. It's not until you get up to a significant fraction of a wavelength that it starts to "act like a transmission line". At small fractions of a wavelength, there's no "room" for standing waves to form, so current and voltage are, for all intents and purposes, always in-phase. At 20 kHz, one wavelength is somewhere around 10 miles (ignoring VF). That's not to say that there's no advantage to using "the right cable" at audio frequencies. Twist rate, capacitance (both between conductors as well as to the shield), gauge/resistive loss, etc. all have an effect, good and bad, even down in the AF range. --- Jeff WN3A
Re: [Repeater-Builder] Re: LOOONG audio runs
At 12:38 PM 02/28/10, you wrote: On Sun, 28 Feb 2010, Mike Morris WA6ILQ wrote: > 2) the pair that was receiving the problem was a high impedance load > or an unbalanced load (i.e. one side grounded). Use an ungrounded 600 > ohm winding from a transformer on each end of each pair. The nominal impedance of a copper pair from CAT5 is 110-ohms, not 600. -- Kris Kirby, KE4AHR Disinformation Analyst I agree with you 100% - but 150 ohm transformers are not as common as 600 ohm transformers, and we had to solve the problem that day. We used what was available. Splicing a 1:1 600 ohm transformer into each end of each audio run fixed the problem. If transformers with a center-tapped 660 ohm winding had been available we would have used 1/2 of the winding that was facing the CAT5 cable since the impedance of 1/2 of a 600 ohm winding (i.e. from the center tap to one outside end) is 150 ohms. The ideal transformer configuration for driving CAT5 or CAT6 is one that has split windings that total 150 ohms that faced the cable and 600 ohms facing the end equipment. Monospaced font time: -+ +-- ! ! ) !! ( 600 ohm ) !! ( 45 ohm winding ) !! ( winding ) !! ( ) !! ( ) !! ! ) !! + ) !! ) !! ) !! + ) !! ! ) !! ( ) !! ( 45 ohm ) !! ( winding ) !! ( ) !! ( ! !! ! -+ !! +--- The 600 ohms is the audio equipment side. The two 45 ohm windings in series give 150 ohms (CAT5 CAT6 side). The inner winding ends can be tied together in normal use, or used DC remote style for switching far end equipment on or off or changing modes. Mike WA6ILQ
Re: [Repeater-Builder] Re: LOOONG audio runs
Kris, the reason we don't put T-1 on cable pairs is of course NEXT & FEXT. The receive level from a T-1 MUX is 6 Volts P:P so it will spill all over the cable. The standard for T-1 in seperately shielded pairs. We do use twisted pairs at a cross connect panel for short runs... (DSX-1 Panel) The HDSL technology does allow for T-1 on cable pairs but it uses 2B1Q protocol and there is really only 12 channels of the T-1 signal on each pair. 2B1Q was developed by Northern Telecom in Ottawa. 73 John VE3AMZ Retired, Bell Canada and MTS Allstream - Original Message - From: "Kris Kirby" To: Sent: Sunday, February 28, 2010 11:20 AM Subject: Re: [Repeater-Builder] Re: LOOONG audio runs > On Sat, 27 Feb 2010, JOHN MACKEY wrote: >> Using balanced audio in a broadcast environment, I have on rare >> occasions experienced issues with cross-talk between long runs of >> un-shielded balanced audio lines. (inductive pickup??) I always >> wondered if the wires were truly balanced when that happened. > > That's probably NEXT or FEXT, which is near-end cross-talk and far-end. > Bell documented this stuff somewhere; I've read the book. There's a > reason why they don't run the T1 lines with the voice lines or why they > don't stuff the entire binder full of T1s. > > Of course, that same book explained how to use the cable pairs as > resistors to heat up the cable, which has been done a few times in NYC, > resulting in dead pairs in the cable due to too much power/heating on a > given pair. > > -- > Kris Kirby, KE4AHR > Disinformation Analyst > > > > > > > Yahoo! Groups Links > > >
Re: [Repeater-Builder] Re: LOOONG audio runs
On Sun, 28 Feb 2010, Mike Morris WA6ILQ wrote: > 2) the pair that was receiving the problem was a high impedance load > or an unbalanced load (i.e. one side grounded). Use an ungrounded 600 > ohm winding from a transformer on each end of each pair. The nominal impedance of a copper pair from CAT5 is 110-ohms, not 600. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] Re: LOOONG audio runs
And watch the level and the impedance - I've helped to fix several situations that had excessive crosstalk on adjacent pairs, and each time it's been one of two causes: 1) a too-high audio level on the pair that was the source of the problem. Solution: No more then zero dbm on any pair... 2) the pair that was receiving the problem was a high impedance load or an unbalanced load (i.e. one side grounded). Use an ungrounded 600 ohm winding from a transformer on each end of each pair. Mike WA6ILQ At 11:34 AM 02/28/10, you wrote: Don't forget, CAT cables have different twist rates for each pair to minimize crosstalk between them. If one pair doesn't work, try another. From: larynl2 To: Repeater-Builder@yahoogroups.com Sent: Sun, February 28, 2010 12:27:53 PM Subject: [Repeater-Builder] Re: LOOONG audio runs A friend of mine full-time broadcast engineering told me he can detect zero crosstalk between pairs within the same CAT 5 cable at line level. As you suspect, balance is very important. Laryn K8TVZ --- In <mailto:Repeater-Builder@yahoogroups.com>Repeater-Builder@yahoogroups.com, "JOHN MACKEY" wrote: > > Using balanced audio in a broadcast environment, I have on rare occasions > experienced issues with cross-talk between long runs of un-shielded balanced > audio lines. (inductive pickup??) I always wondered if the wires were truly > balanced when that happened. > > I prefer to used shielded balanced wiring for long runs. Yahoo! Groups Links <mailto:repeater-builder-dig...@yahoogroups.com>repeater-builder-dig...@yahoogroups.com <mailto:repeater-builder-fullfeatu...@yahoogroups.com>repeater-builder-fullfeatu...@yahoogroups.com <mailto:repeater-builder-unsubscr...@yahoogroups.com>repeater-builder-unsubscr...@yahoogroups.com
Re: [Repeater-Builder] Re: LOOONG audio runs
Don't forget, CAT cables have different twist rates for each pair to minimize crosstalk between them. If one pair doesn't work, try another. From: larynl2 To: Repeater-Builder@yahoogroups.com Sent: Sun, February 28, 2010 12:27:53 PM Subject: [Repeater-Builder] Re: LOOONG audio runs A friend of mine full-time broadcast engineering told me he can detect zero crosstalk between pairs within the same CAT 5 cable at line level. As you suspect, balance is very important. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY" wrote: > > Using balanced audio in a broadcast environment, I have on rare occasions > experienced issues with cross-talk between long runs of un-shielded balanced > audio lines. (inductive pickup??) I always wondered if the wires were truly > balanced when that happened. > > I prefer to used shielded balanced wiring for long runs. Yahoo! Groups Links http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: LOOONG audio runs
A friend of mine full-time broadcast engineering told me he can detect zero crosstalk between pairs within the same CAT 5 cable at line level. As you suspect, balance is very important. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, "JOHN MACKEY" wrote: > > Using balanced audio in a broadcast environment, I have on rare occasions > experienced issues with cross-talk between long runs of un-shielded balanced > audio lines. (inductive pickup??) I always wondered if the wires were truly > balanced when that happened. > > I prefer to used shielded balanced wiring for long runs.
RE: [Repeater-Builder] Re: LOOONG audio runs
On Sun, 28 Feb 2010, Chris Curtis wrote: > My favorite is direct burial + shielded cat cable. > > I've got some here that I've been using for controller to device > hookups. As well as the run from the house to the shed. > > Shielded with 100% foil and a joke of a braid. It is "flooded" with > "goo" to keep the moisture out as well. > > Nice stuff for the $$ Of course, there's always fiber, but now you have to have power sources at both ends. Interestingly enough, I've watched the price of fiber come down over the last ten years, aside from changing connectors and increasing patch-panel capacities... Once it is installed properly (and people & critters kept away) the stuff will last through a few generations of switch equipment. -- Kris Kirby, KE4AHR Disinformation Analyst
Re: [Repeater-Builder] Re: LOOONG audio runs
On Sat, 27 Feb 2010, JOHN MACKEY wrote: > Using balanced audio in a broadcast environment, I have on rare > occasions experienced issues with cross-talk between long runs of > un-shielded balanced audio lines. (inductive pickup??) I always > wondered if the wires were truly balanced when that happened. That's probably NEXT or FEXT, which is near-end cross-talk and far-end. Bell documented this stuff somewhere; I've read the book. There's a reason why they don't run the T1 lines with the voice lines or why they don't stuff the entire binder full of T1s. Of course, that same book explained how to use the cable pairs as resistors to heat up the cable, which has been done a few times in NYC, resulting in dead pairs in the cable due to too much power/heating on a given pair. -- Kris Kirby, KE4AHR Disinformation Analyst
RE: [Repeater-Builder] Re: LOOONG audio runs
Underground gel filled , several types one of them being as you describe foil lined and it is cheap and extremly resistant to the egress of time and rf To: Repeater-Builder@yahoogroups.com From: demo...@rollanet.org Date: Sun, 28 Feb 2010 07:47:23 -0600 Subject: RE: [Repeater-Builder] Re: LOOONG audio runs My favorite is direct burial + shielded cat cable. I've got some here that I've been using for controller to device hookups. As well as the run from the house to the shed. Shielded with 100% foil and a joke of a braid. It is "flooded" with "goo" to keep the moisture out as well. Nice stuff for the $$ Kb0wlf > -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > buil...@yahoogroups.com] On Behalf Of John J. Riddell > Sent: Saturday, February 27, 2010 9:49 PM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Re: LOOONG audio runs > > Skipp, yes you can get shielded Cat 5. I've used it a few times when > running near > AC fixtures etc. > > 73 John VE3AMZ > > > > - Original Message - > From: "skipp025" > To: > Sent: Saturday, February 27, 2010 10:43 PM > Subject: [Repeater-Builder] Re: LOOONG audio runs > > > >> Joe wrote: > >> I wonder if CAT 6 would be better than CAT5 due to the > >> difference in twist? > >> Joe > > > > A number of different items in the specifications would be > > worth examining... like how much C per foot and I don't > > believe "CAT" network cables are shielded. > > > > s. > > > >> > Oz, in DFW wrote: > >> > Make sure you use twisted pair. Station wire like that use to > wire > >> > houses is often not twisted. Ethernet cable is good and has a high > >> > twist pitch - better for this application. > >> > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > Yahoo! Groups Links > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.435 / Virus Database: 271.1.1/2705 - Release Date: > 02/26/10 19:39:00 _ View photos of singles in your area! Browse profiles for FREE http://clk.atdmt.com/NMN/go/150855801/direct/01/
RE: [Repeater-Builder] Re: LOOONG audio runs
My favorite is direct burial + shielded cat cable. I've got some here that I've been using for controller to device hookups. As well as the run from the house to the shed. Shielded with 100% foil and a joke of a braid. It is "flooded" with "goo" to keep the moisture out as well. Nice stuff for the $$ Kb0wlf > -Original Message- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > buil...@yahoogroups.com] On Behalf Of John J. Riddell > Sent: Saturday, February 27, 2010 9:49 PM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Re: LOOONG audio runs > > Skipp, yes you can get shielded Cat 5. I've used it a few times when > running near > AC fixtures etc. > > 73 John VE3AMZ > > > > - Original Message - > From: "skipp025" > To: > Sent: Saturday, February 27, 2010 10:43 PM > Subject: [Repeater-Builder] Re: LOOONG audio runs > > > >> Joe wrote: > >> I wonder if CAT 6 would be better than CAT5 due to the > >> difference in twist? > >> Joe > > > > A number of different items in the specifications would be > > worth examining... like how much C per foot and I don't > > believe "CAT" network cables are shielded. > > > > s. > > > >> > Oz, in DFW wrote: > >> > Make sure you use twisted pair. Station wire like that use to > wire > >> > houses is often not twisted. Ethernet cable is good and has a high > >> > twist pitch - better for this application. > >> > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > Yahoo! Groups Links > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.435 / Virus Database: 271.1.1/2705 - Release Date: > 02/26/10 19:39:00
Re: [Repeater-Builder] Re: LOOONG audio runs
I used one twisted pair in un-shielded CAT 5 in my Fire Dept to connect a radio to an audio amplifier system. The run was over 100 ft. The audio was tapped at the internal speaker of the radio at a comfortable listening level. The other end of the wire went into the aux audio input of a audio amplifier, padded down with a 10:1 resistor voltage divider at the input of the amp. I used 1K in series and 100 ohm resistor to ground to give me 1/10th the original level to the input of the amp. The voltage divider will also reduce any common mode or differential mode induced noise on the wire by a factor of 10. Being twisted pair that noise should be already low. The amp is feeding 5 speakers all over the building. The run from the amp to the speakers is all using the 70V output of the amp, and there is 70V transformers at each speaker, all Radio Shack vintage. No Hum or RFI in this system that way, and very cheap setup. I believe the audio transformers are blocking any RFI. N3FLR - Frank On 2/27/2010 11:16 PM, larynl2 wrote: Shielding is not usually necessary for line level balanced pair audio on CAT 5 or any good twisted pair. CAT 5 is often used in broadcast audio work. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, "skipp025" wrote: Joe wrote: I wonder if CAT 6 would be better than CAT5 due to the difference in twist? Joe A number of different items in the specifications would be worth examining... like how much C per foot and I don't believe "CAT" network cables are shielded. Yahoo! Groups Links
Re: [Repeater-Builder] Re: LOOONG audio runs
At the multi-FM broadcast transmitter site I work at ALL my network wiring is shielded cat5 or shielded cat6. I have never experienced some of the strange networking problems related to interference that I occasionally hear others complain about. At my studio I had a problem a couple years ago where a server was locking up on the NIC plus a few other problems and it was a 1GB network for the backbone. I replace the UTP-cat5 with shielded cat5 and all the problems went away. -- Original Message -- Received: Sat, 27 Feb 2010 07:55:38 PM PST From: "John J. Riddell" To: Subject: Re: [Repeater-Builder] Re: LOOONG audio runs > Skipp, yes you can get shielded Cat 5. I've used it a few times when > running near > AC fixtures etc. > > 73 John VE3AMZ > > > > - Original Message - > From: "skipp025" > To: > Sent: Saturday, February 27, 2010 10:43 PM > Subject: [Repeater-Builder] Re: LOOONG audio runs > > > >> Joe wrote: > >> I wonder if CAT 6 would be better than CAT5 due to the > >> difference in twist? > >> Joe > > > > A number of different items in the specifications would be > > worth examining... like how much C per foot and I don't > > believe "CAT" network cables are shielded. > > > > s. > > > >> > Oz, in DFW wrote: > >> > Make sure you use twisted pair. Station wire like that use to wire > >> > houses is often not twisted. Ethernet cable is good and has a high > >> > twist pitch - better for this application. > >> > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > >
Re: [Repeater-Builder] Re: LOOONG audio runs
Using balanced audio in a broadcast environment, I have on rare occasions experienced issues with cross-talk between long runs of un-shielded balanced audio lines. (inductive pickup??) I always wondered if the wires were truly balanced when that happened. I prefer to used shielded balanced wiring for long runs. -- Original Message -- Received: Sat, 27 Feb 2010 08:16:55 PM PST From: "larynl2" To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: LOOONG audio runs > Shielding is not usually necessary for line level balanced pair audio on CAT 5 or any good twisted pair. CAT 5 is often used in broadcast audio work. > > Laryn K8TVZ > > > --- In Repeater-Builder@yahoogroups.com, "skipp025" wrote: > > > > > Joe wrote: > > > I wonder if CAT 6 would be better than CAT5 due to the > > > difference in twist? > > > Joe > > > > A number of different items in the specifications would be > > worth examining... like how much C per foot and I don't > > believe "CAT" network cables are shielded. > > > > > >
[Repeater-Builder] Re: LOOONG audio runs
Shielding is not usually necessary for line level balanced pair audio on CAT 5 or any good twisted pair. CAT 5 is often used in broadcast audio work. Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, "skipp025" wrote: > > > Joe wrote: > > I wonder if CAT 6 would be better than CAT5 due to the > > difference in twist? > > Joe > > A number of different items in the specifications would be > worth examining... like how much C per foot and I don't > believe "CAT" network cables are shielded. >
Re: [Repeater-Builder] Re: LOOONG audio runs
Skipp- They make Shielded Cat 5 & 6, as well as shielded RJ45 ends. Takes a special crimp tool but it is available. Also, Belden and other wire manufactuers are making special series of Cat cables with low-skew design specifically for the purposes of sending Audio & Video down the Cat cables. We're using baluns all the time for av purposes these days. Can go 1000ft over cat 5 for standard analog audio and baseband video with no significant losses, and we don't use shielded in most cases, never had any interference. Hi-def video formats are shorter distances, passive VGA baluns usually call for shielded cat5 or 6 where as active do not. Tom W9SRV --- On Sat, 2/27/10, skipp025 wrote: From: skipp025 Subject: [Repeater-Builder] Re: LOOONG audio runs To: Repeater-Builder@yahoogroups.com Date: Saturday, February 27, 2010, 9:43 PM > Joe wrote: > I wonder if CAT 6 would be better than CAT5 due to the > difference in twist? > Joe A number of different items in the specifications would be worth examining... like how much C per foot and I don't believe "CAT" network cables are shielded. s. > > Oz, in DFW wrote: > > Make sure you use twisted pair. Station wire like that use to wire > > houses is often not twisted. Ethernet cable is good and has a high > > twist pitch - better for this application. > > Yahoo! Groups Links
Re: [Repeater-Builder] Re: LOOONG audio runs
Skipp, yes you can get shielded Cat 5. I've used it a few times when running near AC fixtures etc. 73 John VE3AMZ - Original Message - From: "skipp025" To: Sent: Saturday, February 27, 2010 10:43 PM Subject: [Repeater-Builder] Re: LOOONG audio runs >> Joe wrote: >> I wonder if CAT 6 would be better than CAT5 due to the >> difference in twist? >> Joe > > A number of different items in the specifications would be > worth examining... like how much C per foot and I don't > believe "CAT" network cables are shielded. > > s. > >> > Oz, in DFW wrote: >> > Make sure you use twisted pair. Station wire like that use to wire >> > houses is often not twisted. Ethernet cable is good and has a high >> > twist pitch - better for this application. >> > > > > > > > > > > > Yahoo! Groups Links > > >
[Repeater-Builder] Re: LOOONG audio runs
> Joe wrote: > I wonder if CAT 6 would be better than CAT5 due to the > difference in twist? > Joe A number of different items in the specifications would be worth examining... like how much C per foot and I don't believe "CAT" network cables are shielded. s. > > Oz, in DFW wrote: > > Make sure you use twisted pair. Station wire like that use to wire > > houses is often not twisted. Ethernet cable is good and has a high > > twist pitch - better for this application. > >
