Wireless Program sound upgrade/replacement?

[The_Bruce]

Hi Folks,
I've recently taken up the reins of Technical Director of a university theatre program (yes, thank you for your congratulations and your sympathies), where we have two spaces: a black box studio theatre built in '89, and a 550-seat proscenium mainstage that was built in 1967. They've both seen renovations in their time, and somehow, miraculously, the in-wall patch panels still work.

HOWEVER. The Program sound wiring running to the TD's office does NOT, and during the last renovations in 2006, the contractors said that they were unable to get it working. I imagine that sometime in the last 60 years, it became a mouse's breakfast.

So, my question is, knowing that modifying the building would require paperwork submitted to the university and buildings and grounds, signed in triplicate and authorized by the pope and all that, what is a reasonable solution to getting program sound in my office so I can keep an eye on shows, dress rehearsals, etc? Is this a good use for a Dante line, for instance?

For reference, my office is on the other side of the building from the studio theatre, through several concrete walls.

 

[MNicolai]

First thing I would do is power the system down, disconnect what is probably 70V wiring off the amplifier for paging/back-of-house, turn any wall attenuators up, and take a toner and multimeter to trace the wires/conduits. I would start at the TD's off. Disconnect the speaker, test for continuity between the wires, and between each wire and conduit ground. If any of those 3 tests beeps at you, you have a wiring fault. Then next step, whether that test beeps at you or not, is tracing the cabling back toward the amplifier to find the source of the issue. Follow the conduit/wiring by scouting through the ceilings and look for pull boxes. In each pull box, open it up and look for anything obvious like skinned cable jackets or faulty wire splices. Keep working your way toward the amplifier or a branch of the system that is known to be working.

Usually with these kinds of issues, one of (5) things has happened:

1. Someone drilled into a wall or ceiling and cut into your cabling without realizing there was a conduit in the wall they were drilling into to mount a new WAP, camera, or TV.
2. A cable got skinned and is shorting to conduit ground.
3. A speaker got blown up.
4. The audio simply isn't patched to that branch of the system.
5. There's a faulty termination somewhere, either at a splice or a 70V attenuator.

Chances are you can trace down the issue within 3-4 hours if you go through it methodically and start ruling out possibilities by process of elimination, identifying along the way which branches of the system are clean while trying to identify any faults along the way.

One of the tips for troubleshooting with a toner. If you connect a cable toner to a 70V speaker, you should hear the tone come out of the speaker. That's helpful in knowing whether the speaker works -- and if you hear any other speakers nearby beeping, you know which branch of speakers that room is also tied in with.

I generally see the 1st one more often than not -- but sometimes after enough years, the cabling is disconnected altogether and left abandoned/coiled in a rack or pull box somewhere because it wasn't labeled and nobody could figure out where it went to. To that end, I would look for 2-conductor speaker wire near the rack that's suspiciously unlabeled, disconnected, or not in use -- if you find any, throw a toner on it and see if that speaker in your office starts beeping.

Troubleshooting is easiest if you have 2 people and a set of radios so when you're toning things out, you can be troubleshooting one of the cabling while another person is at the other end near the rack room trying to find a cable that'll beep at them.

 

[The_Bruce]

First thing I would do is power the system down, disconnect what is probably 70V wiring off the amplifier for paging/back-of-house, turn any wall attenuators up, and take a toner and multimeter to trace the wires/conduits. I would start at the TD's off. Disconnect the speaker, test for continuity between the wires, and between each wire and conduit ground. If any of those 3 tests beeps at you, you have a wiring fault. Then next step, whether that test beeps at you or not, is tracing the cabling back toward the amplifier to find the source of the issue. Follow the conduit/wiring by scouting through the ceilings and look for pull boxes. In each pull box, open it up and look for anything obvious like skinned cable jackets or faulty wire splices. Keep working your way toward the amplifier or a branch of the system that is known to be working.

Usually with these kinds of issues, one of (5) things has happened:

1. Someone drilled into a wall or ceiling and cut into your cabling without realizing there was a conduit in the wall they were drilling into to mount a new WAP, camera, or TV.
2. A cable got skinned and is shorting to conduit ground.
3. A speaker got blown up.
4. The audio simply isn't patched to that branch of the system.
5. There's a faulty termination somewhere, either at a splice or a 70V attenuator.

Chances are you can trace down the issue within 3-4 hours if you go through it methodically and start ruling out possibilities by process of elimination, identifying along the way which branches of the system are clean while trying to identify any faults along the way.

One of the tips for troubleshooting with a toner. If you connect a cable toner to a 70V speaker, you should hear the tone come out of the speaker. That's helpful in knowing whether the speaker works -- and if you hear any other speakers nearby beeping, you know which branch of speakers that room is also tied in with.

I generally see the 1st one more often than not -- but sometimes after enough years, the cabling is disconnected altogether and left abandoned/coiled in a rack or pull box somewhere because it wasn't labeled and nobody could figure out where it went to. To that end, I would look for 2-conductor speaker wire near the rack that's suspiciously unlabeled, disconnected, or not in use -- if you find any, throw a toner on it and see if that speaker in your office starts beeping.

Troubleshooting is easiest if you have 2 people and a set of radios so when you're toning things out, you can be troubleshooting one of the cabling while another person is at the other end near the rack room trying to find a cable that'll beep at them.

Thanks for the detailed reply, and I may be able to use this in other areas, but the program sound system here has been out of commission for long enough that all I have in my office, and in the sound booth, is wiring. No speakers, no 70V amp, and no obvious infrastructure for connecting speakers or amplifiers. I'm getting the strong impression that, if I want program sound in this office, or paging elsewhere, I may need to start from the ground up.

 

[FMEng]

Do you have spare network cabling into those locations? If so, network cables can easily carry line level, balanced, analog audio to powered speakers. I'd be happy to expand on the idea if it would be applicable.

 

[MNicolai]

Hard to really advise you on which way to go here without putting eyes on it. Network solutions are possible but not ideal -- and probably more expensive. On a university campus, doing something on the campus network like adding Dante can also be a pretty big PITA. If you have spare network connections though at your sound booth, mixer, and office, you could ask IT if they can put those on a dedicated VLAN or small isolated switch for you. In that case, you could throw Dante-based monitors at your desired locations and a Dante input widget at your mixer or DSP if you don't already have Dante-capable equipment. Whether this is easy or not though probably depends on how many spare network drops you have in these areas and how easy it is to work with your IT dept.

As for a 70V solutions, I would look above the ceilings in those rooms and see if you can find conduit stubs through walls that may allow you to run 16/2 cabling easily. If you can map out a pathway from your audio rack or sound booth to your office, then you can order the materials and probably get it all installed in 4-6 hours. Just be cognizant if the return air isn't ducted (i.e. open diffusers where the area above the ceilings it being used as an air return), then you will need plenum-rated speaker cabling.

In a building that old, it's pretty common to see low-voltage cabling running in all directions in the ceilings. I'd be pretty surprised if there weren't conduit stubs or existing pathways you could use to pull wire through free-air without having to run new conduit or blow holes in walls.

 

[FMEng]

Dante is great for many things, but it seems like overkill for this. Analog audio on unshielded, twisted pair usually works just fine, and it takes very little cost or effort to try. No need for widgets, network switches, routing software, Dante enabled speakers, etc. Consider the fact that broadcast quality audio was conveyed through miles of UTP phone lines. The telephone companies did it for 80 years. This is one of those things that tends to fall into a technological generation gap.

 

[The_Bruce]

Dante is great for many things, but it seems like overkill for this. Analog audio on unshielded, twisted pair usually works just fine, and it takes very little cost or effort to try. No need for widgets, network switches, routing software, Dante enabled speakers, etc. Consider the fact that broadcast quality audio was conveyed through miles of UTP phone lines. The telephone companies did it for 80 years. This is one of those things that tends to fall into a technological generation gap.

There may, in fact, be a suitable network cable run already - knowing that standard phone line will probably do fine for auido (as long as it's in good shape), I'll see if I can give it a shot. Thanks.

 

[FMEng]

The magic trick is to employ an audio transformer on at least one end. That eliminates any concerns about ground loops or less than ideal common mode rejection.