# Mic cable install



## mstaylor (Feb 13, 2012)

I am again doing a project that isn't beyond my ability but is beyond my technical knowledge. I need to install new mic jacks in a multi use breakout rooms. The existing jacks are getting very undependable, installed in 1979, and instead of chasing problems I am going to use new cable and wall jacks. My problem is I am not sure the proper spec on the cable. It will be pulled into studded walls and through drop ceilings. 
We are changing all the equipment, I already have the new amps, room combiner and data cabinet. Suggestions from the experienced install guys? Thanks ahead of time.


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## mstaylor (Feb 13, 2012)

Any suggestions for good wall jacks would be great also.


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## Nelson (Feb 13, 2012)

I'm sure others with far more experience that I have will chime in, but for wall jacks, I only use Switchcraft. I just replaced a badly abused Switchcraft C3M that was installed in a gymnasium in 1978. I replaced it only because it became corroded from condensation that has been collecting in it every winter for the past 34 years! I could have taken it apart, cleaned it, and put it back together, but they aren't too expensive, so I just replaced it with a new C3M.


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## tk2k (Feb 13, 2012)

Get ones attached to a plate. XLR takes a lot of beating, and the in-wall jacks have to last many years. Since you're experiencing this problem now, you already know this. Basically don't skimp on the end jacks. I know some people will tell you differently, but get something sturdy. Neutrik is always my choice. 

In terms of the cable, it's a balanced audio signal so you shouldn't really run into much trouble with shielding, but if you want get yourself some higher gauge balanced audio cable.


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## museav (Feb 13, 2012)

mstaylor said:


> I am again doing a project that isn't beyond my ability but is beyond my technical knowledge. I need to install new mic jacks in a multi use breakout rooms. The existing jacks are getting very undependable, installed in 1979, and instead of chasing problems I am going to use new cable and wall jacks. My problem is I am not sure the proper spec on the cable. It will be pulled into studded walls and through drop ceilings.
> We are changing all the equipment, I already have the new amps, room combiner and data cabinet. Suggestions from the experienced install guys? Thanks ahead of time.


You should be able to get wall plates loaded with Switchcraft or Neutrik XLR3F receptacles from a number of sources. If you need custom layouts and/or labeling then you may want to look to someone like ProCo, RCI, PanelCrafters, etc.

As to the cable, it sounds like it might be best to use plenum rated cable. You might also want to avoid 'flexible' or rubber jacketed cable for installations as the jackets can be easily nicked or torn when being pulled. Belden 9451P and West Penn 25291B are sort of the industry standards for that application although Canare, Gepco, Liberty, Mogami and others offer comparable cables. I personally often specify line and mic level cable that is AES/EBU digital audio compatible such as Belden 1801B and West Penn DA252401, a simple attempt at potentially supporting future changes.


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## MarshallPope (Feb 13, 2012)

I would definitely suggest getting jacks that are screwed to the wall plates as opposed to riveted. It's such a pain to knock out the rivets when a jack needs to be replaced because of someone kicking it and jamming the little push-to-release button.


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## howlingwolf487 (Feb 13, 2012)

I agree with Brad that you should go for plenum rated cable rated for use with digital signals. It's never fun re-running cables. Also, you may want to consider running some similarly-rated Cat6/Cat7 UTP or STP cable. You may also need to use fire blocking caulk when transitioning between floors, etc. Consult your local AHJ (Authority Having Jurisdiction) with any questions.

Is there conduit already in place or will you be running between studs?


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## FMEng (Feb 14, 2012)

You really need to know two things:

1. Whether the cable does pass through a plenum space.
2. Whether there is potential need for AES/EBU connectivity.

Answering yes to either of those greatly increases your cost. Plain old Belden 9451 (non-plenum) is $200 per thousand feet. Belden 9451P (plenum) is $400. Belden 1801B is $1,100 per thousand. The 1801 is bigger so it takes more conduit fill. If it behaves like similar products, 1801B would be a bit trickier to solder because of insulation shrink-back. 

As others have said, Neutrik or Switchcraft connectors. I tend to prefer Switchcraft for wall plates as their latch works a bit better. I prefer Neutrik for all else.


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## mstaylor (Feb 14, 2012)

howlingwolf487 said:


> I agree with Brad that you should go for plenum rated cable rated for use with digital signals. It's never fun re-running cables. Also, you may want to consider running some similarly-rated Cat6/Cat7 UTP or STP cable. You may also need to use fire blocking caulk when transitioning between floors, etc. Consult your local AHJ (Authority Having Jurisdiction) with any questions.
> 
> Is there conduit already in place or will you be running between studs?


It is going in stud bays. I will be pulling in CAT5 for wall control and mic cable for mic inputs. I have seven breakout rooms that are separated by air walls. Our problem is three fold, the jacks are getting worn out, the current jacks are line level and go to an amp to half a building away, then return to the speakers. I then have to tie a board to the jack to control the mics. There is a switch system to turn each room on and off. What that means is I can produce signal from any room and then decide which rooms recieve it. What I can't do is produce signal in more than one room at a time. 
What our intention is to install an eight way amp and a combiner so I can produce sound in each room and keep it there or combine rooms send it there. I'm all good with all the parts of the system except the simplist part of the system, the danggone mic wire and wall jacks. Thanks for all the advice.


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## museav (Feb 14, 2012)

FMEng said:


> The 1801 is bigger so it takes more conduit fill.


Off topic, but this reminded me of the fact that when addressing both initial installations and future provisions, people often overlook the importance of aspects such as conduit size and routing. I often spend many hours on a project working out the conduit including trying to account for 'worst case' scenarios and potential future additions or changes, its an investment upfront to both make installation easier and support the long term viability of the system.

I have seen people that to minimize the infrastructure cost will assume that the smallest size cabling possible would be used and use that as the basis for sizing conduit. That can be a less than optimal approach based on assumed savings that may not be valid.

A large part of the cost of conduit is the physical installation and within certain conduit size ranges the difference in installation costs, and thus the difference in overall cost, may be minimal. For example, there is typically a limited if any difference in labor cost between 3/4", 1" and 1-1/4" conduit and thus once both the hardware and labor are taken into consideration there is generally not that much of a difference in the overall installed cost.

Thus when defining the conduit for a project it may be better to make assumptions such as using 1801B or even 1800F cable or accounting for some additional number of cables that may be added. I will often increase the conduit requested by one size over what is required just to make the installation easier and help accommodate the almost inevitable unexpected conditions and future changes. Especially in the long term, the cost of not including such planned provisions can easily be more than the cost of incorporating them.


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## mstaylor (Feb 14, 2012)

museav said:


> Off topic, but this reminded me of the fact that when addressing both initial installations and future provisions, people often overlook the importance of aspects such as conduit size and routing. I often spend many hours on a project working out the conduit including trying to account for 'worst case' scenarios and potential future additions or changes, its an investment upfront to both make installation easier and support the long term viability of the system.
> 
> I have seen people that to minimize the infrastructure cost will assume that the smallest size cabling possible would be used and use that as the basis for sizing conduit. That can be a less than optimal approach based on assumed savings that may not be valid.
> 
> ...


I completely agree about oversizing conduit. I also always pull an extra conductor or pull line to make future pulls easier. I did a lighting install where I sized the conduit for what I was doing with no allowance. I will never do it again, all it did was screw myself.


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## BillESC (Feb 14, 2012)

I strongly recommend recessed wall plug boxes such as this one. They can be loaded with your choice of connector types.




Most surface mount connectors are damaged when someone pushes a table, road case or other item up against a protruding connector.


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## mstaylor (Feb 14, 2012)

BillESC said:


> I strongly recommend recessed wall plug boxes such as this one. They can be loaded with your choice of connector types.
> 
> 
> 
> Most surface mount connectors are damaged when someone pushes a table, road case or other item up against a protruding connector.


Point well made.


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## museav (Feb 15, 2012)

I've had great luck with recessed wall boxes in hotels, convention centers, etc. and a bit less luck with corporate, house of worship and similar applications where they don't always have a dedicated tech staff to help set up. The Owners and/or Architects/Interior Designers often want the boxes painted to match the wall or trim and without any labeling with the result that people don't always look behind the door for a microphone input. It's the dilemma that if you are too successful at making the connections visually unobtrusive then they can also be difficult for users to find. So you simply need to consider what works best for the application.


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## mstaylor (Feb 16, 2012)

museav said:


> I've had great luck with recessed wall boxes in hotels, convention centers, etc. and a bit less luck with corporate, house of worship and similar applications where they don't always have a dedicated tech staff to help set up. The Owners and/or Architects/Interior Designers often want the boxes painted to match the wall or trim and without any labeling with the result that people don't always look behind the door for a microphone input. It's the dilemma that if you are too successful at making the connections visually unobtrusive then they can also be difficult for users to find. So you simply need to consider what works best for the application.


The other side of the coin is if you can't find it you probably shouldn't use it.


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## BillESC (Feb 16, 2012)

mstaylor said:


> The other side of the coin is if you can't find it you probably shouldn't use it.



Well said.


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## TimmyP1955 (Mar 5, 2012)

Install new wall connectors. I prefer Neutrik (gold contacts), but SwitchCraft last a long time as well. Yep, screws not rivets.

Check the connectors on the other end, and their termination and strain relief.

If you still have problems, then replace the cable - which may be a lot more difficult than you think. (Among other things, it may not be a home run - there may be a junction box someplace.)


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## tdeater (Mar 13, 2012)

I can echo getting good quality connectors, Neutrik would be my first choice. For cable, you need CL2 rated wire for in wall use. Do not go with plenum unless you have a plenum rated space. Plenum cable costs a lot more, and is not needed unless you are crossing an air plenum. An air plenum space is typically above the ceiling tiles if they did not duct the return air, instead used the space above the drop ceiling as the return air duct. I have many locations that are plenum. A way to tell, but not always true, is to look in the ceiling at the return air grille. If it is just open to the space, it is probably plenum. If it has ductwork attached to it that leave that space, it is probably not plenum. I say probably because there are always exceptions....


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## museav (Mar 13, 2012)

tdeater said:


> Plenum cable costs a lot more, and is not needed unless you are crossing an air plenum. An air plenum space is typically above the ceiling tiles if they did not duct the return air, instead used the space above the drop ceiling as the return air duct. I have many locations that are plenum. A way to tell, but not always true, is to look in the ceiling at the return air grille. If it is just open to the space, it is probably plenum. If it has ductwork attached to it that leave that space, it is probably not plenum. I say probably because there are always exceptions....


I agree that plenum rated cable does cost more and is not always required, however it can be relatively cheap insurance if you aren't sure or if things may ever change. There are also many schools and corporations that only use plenum cable for their voice and data networks and in those cases I tend to apply that same approach for audio and video cabling. Also don't forget the interim classification for riser cable, often required when running in chases between floors.

You can also encounter plenums in other applications, for example the space under raised floors in areas such as computer rooms may be used as a plenum. The Fox Theater here uses a displacement ventilation system where the entire area under the main floor seating is a supply plenum with the air pushed up from below through holes in the floor with 'mushroom' caps on them.


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## Morte615 (Mar 30, 2013)

mstaylor said:


> It is going in stud bays. I will be pulling in CAT5 for wall control and mic cable for mic inputs. I have seven breakout rooms that are separated by air walls. Our problem is three fold, the jacks are getting worn out, the current jacks are line level and go to an amp to half a building away, then return to the speakers. I then have to tie a board to the jack to control the mics. There is a switch system to turn each room on and off. What that means is I can produce signal from any room and then decide which rooms recieve it. What I can't do is produce signal in more than one room at a time.
> What our intention is to install an eight way amp and a combiner so I can produce sound in each room and keep it there or combine rooms send it there. I'm all good with all the parts of the system except the simplist part of the system, the danggone mic wire and wall jacks. Thanks for all the advice.



Something to think about is a digital snake, especially if you are already running Cat5. It may seem like it's more expensive at first but at this point you only have to run 1 cable for as many jacks as you want, and if you want to upgrade again at a later date you don't have to re-run cable, just purchase a new end box. At the very least I would run 2 Cat 5 cables to every room, depending on layout of room probably on opposite walls or at least in the same jack for redundancy.

If you want to run regular jacks you can run them local to a single location that you can then plug in the digital snake and run Cat5 between rooms.


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