Speakon failure

[Tregilibob]

We have a theatre install that has been in place since approx 1998 (which was a refit) which, amongst other things, has 8 speakon sockets located around the hall, and a patch bay for inputs at the back of the hall.

The sockets are numbers 1-8, and work their way around the room starting with 1 behind the pros arch SL, 2 at a flying position on the front of the pros arch, 3 and 4 are further flying positions in the hall, then continued around the other side ending with 8 behind the pros arch SR.

 

In my years here, we have used 1, 2, 4, 5, 7 and 8 in various configurations, and all has worked well, however, since we have had some building work done, 1 and 2 now no longer work. None of the building work has been anywhere near the outputs, apart from a coat of paint on the walls, and the only thing that has been touched is the patch bay, which was raised from floor level (still wired in) then extended into a new booth that was built. I have had the techs back that extended it, we have checked the wiring up to the existing point, which is fine.

 

I have just been round the theatre, checking all the trunking, which hasn't been touched, checked all the junctions, which are fine, and all the inside all the corners of the trunking I can get to (inc roof space!) which are also fine.

 

Does any one have any ideas about why the speakon sockets would suddenly fail, I don't think the building works have affected them, it could be coincidence.

 

Thanks

 

Tregi

[Oldradiohand]

I presume you've checked the wiring on the back of the sockets for loose screws and corrosion? Could the socket contacts be corroded ? Have you tried replacing the sockets? You could put a shorting plug in the patchbay and go looking for the loop resistance with a meter at any junction boxes.

[pete10uk]

I would say it is too much of a coincidence that 2 speakons fail in the same building at the same time. I've never seen 1 fail.

 

I would say it is a physical fault/damage some where but it should be really easy to find with a continuity tester, a speakon to tails and a screw driver.

[Tregilibob]

I have been round with continuity and a shorting plug, have also checked the wiring on the back of the speakons. I have also checked with the direct wiring contacts, missing out the speakon connector completely....

The only place I haven't been able to check is one corner where these two channels go, but it is not actually possible to get there, as it is behind redundance air handling boxing.... but there would be no reason at all why it would be damaged there (behind the pros arch, at the top, where no wiring/walls/painting has happened....

 

The wires that go from the patch bay to the sockets are one cable, no connections (that I can see) which is approx 35-40 meters.....

[pete10uk]

What you need to do is take off the ends and check the cable, this will rule out speakons but unfortunately if the cable is dead then you need to replace it.

We can't help you with the why or how it's damaged but if it is you need to replace it, the more I think about it the more it have to be the cable fault, I presume that the amp is defiantly outputting a signal?

 

You could try cutting it halfway and just replace the damaged section but if at all possible a whole new piece would be best.

[Andrew Edwards]

Rodents?

[MarkPAman]

I would say it is too much of a coincidence that 2 speakons fail in the same building at the same time. I've never seen 1 fail.

 

Me too!

 

Another thing I've come across was an installed system in one of our dance studios. I'd noticed that there was a speaker lead taped to the wall, bypassing the installed cable which I was told had never worked. It turned out that it was NL4s and that one end was wired 1+ / 1-, but the other end was 1+ / 2+. So that's something to check for in the new bits.

[Tregilibob]

its finding the damage that seems to be impossible, as it goes through walls, ceilings and in trunking in other inaccessible places.

Would doubt rotents, 3rd floor, above a swimming pool, all cabling through metal box trunking, with no sign of being opened apart from my fingerprints.

 

The wiring on the outputs hasn't changed, and I will check the patch bay, but I very much doubt it.

We have checked it without the speakons, wire to wire, no luck.

 

New cable seems to be the only way to go, but that will be a huge horrid job, but as (as I assumed) Speakons don't fail (generally) it might be the only option.

 

 

Thank you.

[alistermorton]

New cable seems to be the only way to go, but that will be a huge horrid job, but as (as I assumed) Speakons don't fail (generally) it might be the only option.

 

Have you belled out the cable alone, completely removing all connectors from the equation? You say you've been to the direct connections - was that with croc clips on the end of the cables?

 

Sorry if I've missed something,

[Chappie]

If the cable is damaged, it may not be cut all the way through. Can you disconnect the ends, tie a new length of cable on to it and pull it through? Or is the route too convoluted to allow that?

[paulears]

If they have extended everything in the patch bay, I don't suppose that it's something really stupid like they've put the spade terminals on the wrong pins? It's so easy to do, especially if the socket in the panel was put in originally upside down, and the installers are used to connecting say, the bottom two in each socket - with it upside down that would be the top two? If they reached in at arms length, they'd never notice they attached to circuit 2, not circuit 1?

[Tregilibob]

The route is very long, with lots of convoluted "why on earth did they do it that way?" points, so pulling through is not going to work, it may be possible to feed through to a certain point....

We have taken the speakon sockets out of the equation, and tested from one end of the cable to the speakon on the other, and swapped to test the other end, no signal.

 

They have been back out to the patch bay, but I will check the upsidedownness (new word?) they did it in a fairly open space, all the cables were labelled before desoldered and reconnecter up afterwards, and we have checked the connection they made. My next step is to try to check where the cable now goes from the wall to the floor, but it is all inside cable management coils (heavy duty, not sure what to call them) but it does seem to be the only corner I haven't been able to get at next.

[Lamplighter]

You could try measuring the capacitance across the cores at each end of the cable. That should give you a good approximation of the fault location.

Brian

[Brian]

Or find a friendly BT-type man with a TDR (aka cable fault location detector).

[Tregilibob]

I have just checked that nothing is wired upside down, which it isn't, and have taken up as much floor as I can to try to see whether there is any damage on the cable as it goes from floor to wall, unfortunately I can't get exactly where it is, but can see it from two sides, not much help, but I know know that they are not protected as they go up the wall, but are as they move through a ceiling void up to the main roof space. I think that is the only point where it could have got damaged, so going to see if our maintenance people can get the floor up so I can check properly.

 

Lamplighter, can you explain what you mean by measuring capacitance, as I googled it and got lost!!!

 

Cable detector is on the list of things to get (husband might have one).

 

Thank you again, although we do have the system working at the moment, it is the most round about way it could be to make it work!