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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Debbie Dunkley on August 24, 2014, 05:53:23 PM
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This has happened to me before and I find it so frustrating. Last night we had no signal coming from the overhead mic on the kit. It was connected to small stage box and snake to console. At the gig we did the usual - made sure phantom was on (don't laugh - it happens), check all connections, switch out mic cable and the mic but nothing. Decided to use a 50ft cable direct and we were good to go. Everything related to it being the snake.
I check it today twisting the multicore back and forth to see if there is a break that only shows up when the cable is bent but everything checks out. I used a tester so all 3 wires were tested per channel. This kind of thing drives me mad.
It's like when your car engine is creating a funny noise but every time you take it to the shop, the noise isn't there……..
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That could be an issue with the connector at (in) the stagebox. Open up the box and take a look? Mark C.
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Was it in channel 7? I always have trouble with phantom on 7.
Gremlins.
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Check with a cable directly to the console eliminating the stage box and snake before you start tearing things up.
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Was it in channel 7? I always have trouble with phantom on 7.
Gremlins.
Channel 3 of almost any sub-snake. The damn hi-hat channel and +48v....
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Check with a cable directly to the console eliminating the stage box and snake before you start tearing things up.
That's what I did with that 50 footer Bob. Mic to XLR cable to QU16. Worked fine.
I have to admit to purchasing an inexpensive snake - don't hate me. It is only 8 channel 30 ft and was purchased for the drum kit only. Keeps things neat using 10ft xlr's. I didn't invest in a more expensive one because I am so careful with my gear (as you know ) and I baby this thing wrapping it in a piece of foam and transporting it in a small rolling case. I figured I'd get some mileage out of it before I experienced any problems.
Also I have a 50ft and 100 ft snake and didn't want to pay a fortune for another one.
If all contacts from the stage box through to the fan check out, can there still be problems inside??
Oh I also use it in my studio and it is really handy…
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Check out how? Cable tester?
I've switched from using a cable tester (Whirlwind) to using a condenser mic and headphones. Once a year I check all my cables and snake channels by speaking into the mic and listening.
Some cables will show continuity, lighting up the green lights on the tester, but when listening I have found I can hear signal degradation quite easily. Marginal cables are then sold on Ebay...
Bazinga!!!
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Che
:D
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That's what I did with that 50 footer Bob. Mic to XLR cable to QU16. Worked fine.
I have to admit to purchasing an inexpensive snake - don't hate me. It is only 8 channel 30 ft and was purchased for the drum kit only. Keeps things neat using 10ft xlr's. I didn't invest in a more expensive one because I am so careful with my gear (as you know ) and I baby this thing wrapping it in a piece of foam and transporting it in a small rolling case. I figured I'd get some mileage out of it before I experienced any problems.
Also I have a 50ft and 100 ft snake and didn't want to pay a fortune for another one.
If all contacts from the stage box through to the fan check out, can there still be problems inside??
Oh I also use it in my studio and it is really handy…
For snakes the most common failure point is the male XLR connectors at the fan out. The next is when the strain relief on the stage box gets loose and the cable twists inside, eventually transferring that tension to the terminations with the XLR-Fs. Note that stage boxes using XLR connectors with insulation displacement terminations are particularly susceptible.
The final failure mode is the metal contact sleeve inside the XLR-F. Sometimes they fatigue and don't snugly fit the pins.
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For snakes the most common failure point is the male XLR connectors at the fan out. The next is when the strain relief on the stage box gets loose and the cable twists inside, eventually transferring that tension to the terminations with the XLR-Fs. Note that stage boxes using XLR connectors with insulation displacement terminations are particularly susceptible.
The final failure mode is the metal contact sleeve inside the XLR-F. Sometimes they fatigue and don't snugly fit the pins.
So it makes sense for me to take things apart then.
First, before i do that I'll use my plug in tester. Today I used my tester with probes but if the connectors can get slightly sloppy like you say, I would need to plug in a couple of cables to the input and one to the output of my plug in tester and then use the probe tester on each of those ends. That would check how well the xlr connectors seat, correct?
Then if that seems fine, I'll start taking things apart.
I like taking things apart so I won't mind.
I'll report back …..
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Was it in channel 7? I always have trouble with phantom on 7.
Gremlins.
How did you know Dick? Now that's weird !! ???
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Check out how? Cable tester?
I've switched from using a cable tester (Whirlwind) to using a condenser mic and headphones. Once a year I check all my cables and snake channels by speaking into the mic and listening.
Some cables will show continuity, lighting up the green lights on the tester, but when listening I have found I can hear signal degradation quite easily. Marginal cables are then sold on Ebay...
Bazinga!!!
This. Right. Here.
I had 3 mic cables that were recently repaired, fail on a panel discussion set up. All had the same symptom - "noise" of the random type (not a hum or buzz) on phantom-powered lectern mics. But they pass the DC cable tester...
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Gonna plug in a mic tomorrow…..
Sorry Dick, didn't see your comment post till now…..
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So it makes sense for me to take things apart then.
First, before i do that I'll use my plug in tester. Today I used my tester with probes but if the connectors can get slightly sloppy like you say, I would need to plug in a couple of cables to the input and one to the output of my plug in tester and then use the probe tester on each of those ends. That would check how well the xlr connectors seat, correct?
It's not clear whether you just checked continuity for each pin, or also tested for shorts between pins (and the case of the snake). A short from pin 2 or 3 to 1 will stop a condenser mic from working, but a dynamic will be fine (perhaps with some hum, since it's no longer balanced). I had a problem like this recently with a brand new mic cable. My first thought was that pin 1 simply wasn't connected, but it turned out to be a short from pin 3 to 1.
Dick's suggestion to use a real condenser mic and headphones is also a good suggestion. That will find problems like an insulation breakdown in a cable or connector that only happens when there is 48V present. Since you have a QU16, set up a channel with a brickwall limiter, so you don't blow your eardrums when you do find that intermittent cable!
GTD
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Wow I had this same issue Saturday with an overhead condenser. Had HA all the way down and was still getting noise/signal through the roof anytime anyone made a sound on stage. Swapped the cable, noise went away, cable tested fine on my cable tester. I figured cable must not have been actual issue and threw it back in the bag. Guess I better get it back out. Very fortunate to read this post and get this info concerning condenser mics and cables. Thanks.
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If the mic works but is noisy the issue may be leakage or conduction between some of the cable leads. If the tester just tests that the leads are connected at both ends it might not test for insulation between leads. Or not.
JR
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all XLR connectors are not standard size. The connectors on your tester may be just enough different to make contact. Are there any off brand neutrik type connectors in the mix? I would be suspect if there were.
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Fixed it…
I checked with a mic (dynamic actually) and not working.
Tested all pins one more time on tester -works.
I opened up the box and all was well in there. I opened up the XLR plug in question (which was channel 7 -Dick..too weird )...and VOILA ! It was obvious. Bad manufacturing (Go figure)… The earth and cold wires had been cut too long and were looped around in there. They obviously weren't touching in the time I have owned it - which BTW has only been 6 months - and a slight movement - short! …easy fix. I was dreading it being in the cable somewhere but this thing has had no abuse so I would have been surprised if it had been.
Anyway…there it is.
Thank you everyone for your suggestions……...you can all go about your business again (till the next time I need you) ::)
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I told you so (nudge, nudge...wink, wink).
A tip for the box ends of your snakes:
Get some nice hard maple or oak, cut to the length of the box and fasten them to the bottom with some self-tapping screws of just the right length. Be sure to recess the heads of the screws and to position them so as not to hit anything vital inside.
This will keep you from gradually wearing off the heads of the screws that hold the box together when it gets dragged around. It's amazing how quickly concrete can render them smooth and useless.
Also gives you a bit of extra freeboard if the deck is awash...
Carry on.
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Fixed it…
I checked with a mic (dynamic actually) and not working.
Tested all pins one more time on tester -works.
I opened up the box and all was well in there. I opened up the XLR plug in question (which was channel 7 -Dick..too weird )...and VOILA ! It was obvious. Bad manufacturing (Go figure)… The earth and cold wires had been cut too long and were looped around in there. They obviously weren't touching in the time I have owned it - which BTW has only been 6 months - and a slight movement - short! …easy fix. I was dreading it being in the cable somewhere but this thing has had no abuse so I would have been surprised if it had been.
Anyway…there it is.
Thank you everyone for your suggestions……...you can all go about your business again (till the next time I need you) ::)
You might also want to check all of the other male connectors as they may have the same problem it just hasn’t shown itself yet.
And the reason he guessed at channel 7 was because that would probably be where one would normally have the overhead mic on a miced up drum kit.
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Hey Debbie
So if the cable seems to otherwise be working ... check and see if pin 1 is connected to the shells on your XLRs. While it shouldn't be a problem, I have seen some funny things happen with some mixers and phantom power. If it is just clip it.
Chinese made cables are typically wired this way even though it does not conform to AES standards.
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Hey Debbie
So if the cable seems to otherwise be working ... check and see if pin 1 is connected to the shells on your XLRs. While it shouldn't be a problem, I have seen some funny things happen with some mixers and phantom power. If it is just clip it.
Chinese made cables are typically wired this way even though it does not conform to AES standards.
A while back we ran into a batch of cables made in our shop that tested perfectly. They had issues in the field though, each cable was microphonic and if you touched the shell you could hear it in the PA.
Cracking them open in the shop, they had been wired incorrectly with shield on pin 3. Continuity tester didn't catch it.
Ended up having to pull and visually check every Neutrik ended XLR in the company inventory to find all of the miswired cables.
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I did check all of them and they are all good except for this one. No funky connections anywhere they shouldn't be Don ….
In fact the soldered joints are quite nicely done actually…this one just missed the mark...
And yes, Dick you are such a clever Sausage !!!
Attaching the box to a board is yet another good idea from Mr. Rees. The strain relief on this snake is also not so hot so I could in fact get creative and with the aid of a board under the box, do something to improve on that too.
Aaaah…it keeps me young ! and speaking of young ( or not so much) …today was the first day I had to use a magnifier to solder …… and I wasn't happy about it …..I used to solder in dark corners of the stage…yeah ...
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And yes, Dick you are such a clever Sausage !!!
Sausage, eh?
I've been called wurst...
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I did check all of them and they are all good except for this one. No funky connections anywhere they shouldn't be Don ….
Sorry ... that doesn't answer the question. The question is "is pin1 connected to the shell"?
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Sorry ... that doesn't answer the question. The question is "is pin1 connected to the shell"?
No Don, that's what I was referring to when I said there were no funky connections anywhere they shouldn't be and referenced your name. All the connections were (are) pin 1 to pin 1 -no connections to the shell.
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Aaaah…it keeps me young ! and speaking of young ( or not so much) …today was the first day I had to use a magnifier to solder …… and I wasn't happy about it …..I used to solder in dark corners of the stage…yeah ...
Don't feel bad Debbie. I'm 28 and already own a jewelers lamp just for soldering.
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One thing I'd add to all the other good things posted. Get a rat sniffer/sender. The sniffer can be used on any line that has phantom on it. It's a great help when in battle mode and troubleshooting. Just turn phantom on (if it isn't already) on the trouble channel then start at the mic and work back.
If the line to the mic tests good then change out the mic with a known good one. If it still doesn't work then it's either the console & after or the operator. If it tests bad then you just work your way back to where it tests good and replace as needed. Mark the questionable stuff and sort it out in the shop later. Lots less guessing, less likely to pull out your hair during the gig too.
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One thing I'd add to all the other good things posted. Get a rat sniffer/sender.
Good advice. Or if you want to make your own, send me a message and I will send the circuit diagrams for my simple single LED tester or my version of the SoundTools sniffer, both of which will show up any failure mode of a 3 way XLR cable.
Steve.
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Sausage, eh?
I've been called wurst…
;D
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One thing I'd add to all the other good things posted. Get a rat sniffer/sender. The sniffer can be used on any line that has phantom on it. It's a great help when in battle mode and troubleshooting. Just turn phantom on (if it isn't already) on the trouble channel then start at the mic and work back.
If the line to the mic tests good then change out the mic with a known good one. If it still doesn't work then it's either the console & after or the operator. If it tests bad then you just work your way back to where it tests good and replace as needed. Mark the questionable stuff and sort it out in the shop later. Lots less guessing, less likely to pull out your hair during the gig too.
Ooooh…more toys …. :)
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Good advice. Or if you want to make your own, send me a message and I will send the circuit diagrams for my simple single LED tester or my version of the SoundTools sniffer, both of which will show up any failure mode of a 3 way XLR cable.
Steve.
Thanks Steve..