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[Clemeth L. Abercrombie]

I am working on an installation and need to get a balanced line level signal (+4dBu) from one room in a building to another.  The problem is the run would be approximately 600-1000 feet (I am in the process of refining this number).  

There is currently no networked audio in the installation.  What would you suggest is the best way to make this audio signal transfer?  Wireless(through two sets of walls)? Audio Via Ethernet (if so what devices)? Some sort of signal amplification? Thanks.

[BruceOlson]

Put it on a twisted pair of wires and send it on over.  Around 4000 feet life get's a little more interesting, 600-1000 is easy if the output and input as well as the wiring has equal impedances on both sides of the balanced line.  If you don't have an input with good CMRR, then an input transformer (with a Faraday shield) near that input will solve that problem.  If you need to send a bunch of different circuits the same place, then one of the network solutions starts to make sense.

[Charlie Zureki]

Bruce C. Olson wrote on Tue, 23 September 2008 01:02

Put it on a twisted pair of wires and send it on over.  Around 4000 feet life get's a little more interesting, 600-1000 is easy if the output and input as well as the wiring has equal impedances on both sides of the balanced line.  If you don't have an input with good CMRR, then an input transformer (with a Faraday shield) near that input will solve that problem.  If you need to send a bunch of different circuits the same place, then one of the network solutions starts to make sense.

+1

Cheers,
Hammer

[Ryan Montgomery]

CSI makes a fiber optic combo (4040 series), 20hz-20k 24db max. I've used it for installs anywhere from 500' to 5000'.

[Josh Millward]

Bruce C. Olson wrote on Tue, 23 September 2008 02:02

Put it on a twisted pair of wires and send it on over.  Around 4000 feet life get's a little more interesting, 600-1000 is easy if the output and input as well as the wiring has equal impedances on both sides of the balanced line.  If you don't have an input with good CMRR, then an input transformer (with a Faraday shield) near that input will solve that problem.  If you need to send a bunch of different circuits the same place, then one of the network solutions starts to make sense.

another +1 from me too.

I read the original post and I thought, "How about you just plug it in."

If everything is balanced and isolated there should be zero problems. If it isn't balanced and isolated, make it so. It is a hell of a lot cheaper to stick a good quality transformer on one or both ends of a twisted pair than it would be to try and do some sort of fiberoptic or balun related thing... of course baluns typically just balance the line and shoot it across Cat5 rather than a phone pair or even a mic line between the two locations.

It should not be very difficult to get very high quality audio between two locations that are under 1000 cable feet apart.

[Ivan Beaver]

Just think.  The telephone company runs wires much longer.  Those are balanced also.

He doesn't need to try and do anythng "fancy" when basic stuff will do.

[Craig Hauber]

I ran 650' the other day with an SM-58 and didn't have any proplems, And that was with a passive split and a whole lot of connection points in the line.
Mic plugged into return snake (300') cross-patched into the splitter then returned to FOH and also to the monitor board with no issues.  Would be a piece-of-cake for a line-level signal!

[Clemeth L. Abercrombie]

Thank you all for the great information.  

I would only comment that what is appropriate for telephone quality signals is not exactly appropriate for audio transfer in an install designed for music presentation.  

[Brad Weber]

Clemeth L. Abercrombie wrote on Fri, 26 September 2008 09:17

I would only comment that what is appropriate for telephone quality signals is not exactly appropriate for audio transfer in an install designed for music presentation.

I think you may be associating the electronics and processing aspects with the signal transmission aspects when those are two separate issues.  Many of the practices and standards for audio signal transmission come directly out of the telephone industry where they have long had to send low level signals large distances.  And who do you think was one of the earliest and largest adopters of switched networks and fiber optic transmission?

[Ivan Beaver]

Clemeth L. Abercrombie wrote on Fri, 26 September 2008 09:17

Thank you all for the great information.   I would only comment that what is appropriate for telephone quality signals is not exactly appropriate for audio transfer in an install designed for music presentation.

And what makes you say that?

If you are comparing the audio "quality" then let's go even further.

If I wanted to make a different comparison, then I would say that there is now way I would use the same loudspeaker technology for a concert, that is used in my portable TV set.

And by that "technology" I and referring to a magnet with a moving coil and cone attached.  It is the same for both BTW.

Yeah the basic parts are the same, but HOW IT IS USED, it what makes the difference.

Do not associate telephone quality with a balanced line.  One is the "transport" and the rest is the associated electronics-as Brad says.

[Hal Bissinger/COMSYSTEC]

Brad and Ivan are absolutely correct. In the days before "digital" the telephone company handled analog audio for such things as links between studio to studio and studio to transmitter and lots of other things. These weren't "telephone quality" and were much longer that the 1000 feet you are worried about.

-Hal

[Ivan Beaver]

I could be mistaken, but I have heard stories about the reverb chamber at RCA that other studios would "rent" by sending a signal from their studios into the RCA chamber and back via phone lines.

If that is true, then that "phone line" is responsible for carrying the reverb for many famous recordings.

[Charlie Zureki]

Ivan Beaver wrote on Fri, 26 September 2008 16:56

I could be mistaken, but I have heard stories about the reverb chamber at RCA that other studios would "rent" by sending a signal from their studios into the RCA chamber and back via phone lines. If that is true, then that "phone line" is responsible for carrying the reverb for many famous recordings.

Hello,

    But the Band Width was terrible.

Cheers,
Hammer

[Ivan Beaver]

Of the actual signal or the final recording that was released due to the limits of the day?

[Charlie Zureki]

Ivan Beaver wrote on Fri, 26 September 2008 20:28

Of the actual signal or the final recording that was released due to the limits of the day?

   Probably Both...



  Cheers,
  Hammer

[Hal Bissinger/COMSYSTEC]

Keep in mind that as distances increased other factors came into play. Repeaters or amplifiers and radio/microwave links of the day were probably more to blame for noise, distortion and reduced bandwidth than the balanced line.

-Hal

[Joseph White]

As long as the signal has balanced terminations on both ends you should have no problem. I take analog 720p video and send it as far as 2500' by running it balanced and it comes out crystal clear. Use good quality cable and don't run it conduit next to 120v or something stupid like that. The industry standard way to do that is to just plug it in.

[Tim Padrick]

Ivan Beaver wrote on Fri, 26 September 2008 20:28

Of the actual signal or the final recording that was released due to the limits of the day?

Limits of the day?  Phooey.  I have a 90's LP of a symphony recording that was done in 1949 - it sounds about as good as any symphony recording I've ever heard - so good that I did not notice that it is mono until about the 6th playing.

[Karl Winkler]

Ivan Beaver wrote on Fri, 26 September 2008 15:56

I could be mistaken, but I have heard stories about the reverb chamber at RCA that other studios would "rent" by sending a signal from their studios into the RCA chamber and back via phone lines. If that is true, then that "phone line" is responsible for carrying the reverb for many famous recordings.

True, but those were special, dedicated high-fidelity phone lines not the same as normal, switched lines for voice-only.

-K

[Hal Bissinger/COMSYSTEC]

True, but those were special, dedicated high-fidelity phone lines not the same as normal, switched lines for voice-only.

And that is what I was referring to. They were called an audio pair. Not too many years ago I remember it being used to distribute BGM to restaurants by some company. I couldn't believe it was still being done that way considering satellite delivered Muzak etc.

There was a video service for 4Mhz(I believe) analog video also.

-Hal