andrewg112 Posted March 24, 2011 Share Posted March 24, 2011 Hello,Im 99% sure ive seen this post done before, but cant seem to find it. If someone could nudge me in the right direction that would be super! Basically, we are a few shows into a two week run of shows. We hired 6 Headsets & 1 Master Station... as you do! Problem is, its got a nasty buzz on the headsets, and we are not really sure why. Personally I think it could be a cable issue, as with hire cables, they are transported alot, and flex could have gone or something. Our lighting chap seems to think that whenever there are certain lights on (or being dimmed) the buzzing seems to get more intense. Not really sure how to go about sorting it so any ideas would be super. Thanks,Andy Link to comment Share on other sites More sharing options...
timsabre Posted March 24, 2011 Share Posted March 24, 2011 Could be faulty cable...Start with master station and one beltpack connected... add cables and beltpacks one at a time until buzz appears... identify faulty part by swapping bits... replace. You don't say if the cabling is installed or just temporary. With installed cabling you can't do this as it's all permanently connected together - try substituting lengths of mic cable instead. Link to comment Share on other sites More sharing options...
ramdram Posted March 24, 2011 Share Posted March 24, 2011 Do you hear the buzz when the dimmers are not connected to the supply? If no then your surmise is likely to be correct. IF you find that cables, power and signal, have to cross over for any reason then it is usually a good ploy to arrange the cross overs at right angles. Probably best to avoid laying the different cables next to or near each other anyway. That is most likely to be the problem from what you report. This next bit is an exercise for any cables and it is included just FYI. Presuming you have a problem with the actual comms cable(s) itself...you can do the substitution thing with the cables then that's a good start. OR just add cables one by one to find the iffy one OR if you have the budget then perhaps a Millenium cable tester (or similar, ** laughs out loud **). If you still have the problem then a word with the hire folk with a view to a replacement. Dimmers can produce a lot of noise by virtue of them being dimmers. HTH Link to comment Share on other sites More sharing options...
CharlieH Posted March 24, 2011 Share Posted March 24, 2011 Hello,Im 99% sure ive seen this post done before, but cant seem to find it. If someone could nudge me in the right direction that would be super! Basically, we are a few shows into a two week run of shows. We hired 6 Headsets & 1 Master Station... as you do! Problem is, its got a nasty buzz on the headsets, and we are not really sure why. Personally I think it could be a cable issue, as with hire cables, they are transported alot, and flex could have gone or something. Our lighting chap seems to think that whenever there are certain lights on (or being dimmed) the buzzing seems to get more intense. Not really sure how to go about sorting it so any ideas would be super. Thanks,AndyIf this is really obvious then I apologise in advance; just though I would try to help http://www.blue-room.org.uk/public/style_emoticons/default/wink.gif We had this a few years ago on our comms at school. It buzzed really loudly whenever the dimmers were somewhere between 0% and 100%. We fixed it by moving the PSU away from the dimmers, and putting it on the lighting tower; and this has completely eradicated it! Again, not sure if this is something that people do as a matter of course but just in case it isn't I thought I might mention it. http://www.blue-room.org.uk/public/style_emoticons/default/biggrin.gifCharlie Link to comment Share on other sites More sharing options...
dbuckley Posted March 24, 2011 Share Posted March 24, 2011 Cables can be a problem, especially if the comms kit came from a lighting company, as many do; one otherwise competant hire company in my parts has some of its XLR comms cables wired wrong, so the screen is in fact the signal. Yes, it buzzes like a bitch. Link to comment Share on other sites More sharing options...
mac.calder Posted March 24, 2011 Share Posted March 24, 2011 The other great one is when LX companies send out DMX cable instead of audio cable for comms. Comms are such a simple thing, but they can be a little fussy. Link to comment Share on other sites More sharing options...
Ashley R Posted March 25, 2011 Share Posted March 25, 2011 Ive found the most common culprit for buzz on a comms system is the Dimmers, if one station or the cabling runs near where the dimmers are, when you fade in/out of a scene (i.e. when not at either 100% or 0%) you will get an enormous amount of buzz. Solution, move cabling and station away from the dimmers. Also if you have run the cabling for the comms next to any power leads, especially if they are ones hooked up to the dimmer, then you will also get buzz, as suggested above, put the cables at right angles wherever they cross, and make sure there is space between the power and comms cables. Link to comment Share on other sites More sharing options...
andrewg112 Posted March 25, 2011 Author Share Posted March 25, 2011 Dimmers are downstairs, in a room. Lighting Board and Comms Master are upstairs. Do you think its worth putting it on a different circuit? Chap who works lights was nasty and told me he would put on as much money as I had, I would never get the buzz away or even reduced. Im not one to bet, but id like to prove him wrong! Cheers,Andy Link to comment Share on other sites More sharing options...
ramdram Posted March 25, 2011 Share Posted March 25, 2011 Try to solve the prob as suggested above...then if successful get a bank loan, ** laughs out loud **. Ref the circuit; am I correct in assuming you mean phases? It would be a shrewd notion to keep the lighting circuits on two phases and the sound on the third IF possible. However you say the dimmers are in their own separate apparatus room...probably the dimmers are across all three phases and don't forget each dimmer may be wired three phase anyway. You did not mention in your first post if this was an ongoing prob in the venue or that you had first noticed it. You mentioned hire cables so can we then presume it has only just become apparent? If so then the comms cable laying needs to be revisited, as it is going to be the easiest being the smallest...hopefully. Try the separation ploy, possibly rerouteing the comms cable in a completely different path. If you do resolve the issue don't forget to let us know. It all adds to the fund of info. Link to comment Share on other sites More sharing options...
Brian Posted March 25, 2011 Share Posted March 25, 2011 The audio on comms is unbalanced so the whole setup is very sensitive to cable type and earthing issues. Pin 1 carries the audio return, the power return and does shielding duties. In any system pin 1 should NOT be connected to the XLR shells. Your cables need to be decent shielded mic cables. Leaving packs and headsets on top of things like video monitors or other kit which radiates magnetic fields will induce hum into the system. Link to comment Share on other sites More sharing options...
dbuckley Posted March 25, 2011 Share Posted March 25, 2011 Have you attempted to narrow down the problem like TimSabre suggested above? Are you using entirely seperate comms cabling, not using multis or in-building wiring? Are all the intercom components from the same manufacturer? As Brian noted, intercom audio (or at least commonly used in theatre party line systems) have unbalanced audio, and thus are inherently susceptible to picking up dimmer buzz, but its often possible to reduce dimmer buzz to acceptable, and even almost-non-existant levels. Link to comment Share on other sites More sharing options...
boatman Posted March 25, 2011 Share Posted March 25, 2011 My money is on Brian's suggestion that one (or possibly more) of the cables has pin 1 connected to the XLR shell and it's touching a mains earth somewhere. A couple of years ago we had a very similar fault in one of our village halls. It turned out to be a loose strand on the shield of one cable which was touching the shell. Unfortunately, it took several hours to find the offending connector. Link to comment Share on other sites More sharing options...
elliot.Williams Posted March 27, 2011 Share Posted March 27, 2011 Hello,Im 99% sure ive seen this post done before, but cant seem to find it. If someone could nudge me in the right direction that would be super! Basically, we are a few shows into a two week run of shows. We hired 6 Headsets & 1 Master Station... as you do! Problem is, its got a nasty buzz on the headsets, and we are not really sure why. Personally I think it could be a cable issue, as with hire cables, they are transported alot, and flex could have gone or something. Our lighting chap seems to think that whenever there are certain lights on (or being dimmed) the buzzing seems to get more intense. Not really sure how to go about sorting it so any ideas would be super. Thanks,Andy Just a thoght maybe there is a phone or I I pod ir somethign near it and then the buzzing starts that happened to me in a show. :/ Link to comment Share on other sites More sharing options...
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