S&L Posted April 21, 2014 Author Share Posted April 21, 2014 As this issue only occurs in the one venue, are you absolutely sure that the mains supply in that venue is up to scratch? Have you asked them for a copy of the paperwork from the last time the installation was tested? I've been in plenty of pubs where I wouldn't want to plug in a phone charger let alone a full PA... I think we can be pretty certain that the wiring in the pub IS NOT up to scratch - to be honest, in all my years of working bars as musician and lately sound engineer, I have yet to come across a pub that I consider to be well set out, well provisioned and fully functional. but the point, hopefully, was to prevent the electrical building system or lighting effect the PA. David's posts at least gives me a basis on which to go away and make sure my gear is as good as I can make it. I definitely don't preclude something odd about the building. But if I can do something from my end to eliminate the problem then it makes sense to at least investigate and try. Link to comment Share on other sites More sharing options...
Shez Posted April 21, 2014 Share Posted April 21, 2014 I'm just wondering whether a dodgy earth connection in their installed wiring could cause problems by feeding any rubbish that the dimmers dump to earth directly in to the rest of your kit. I'm not sure that any amount of tweaking you could do would help with that. Link to comment Share on other sites More sharing options...
sam.spoons Posted April 22, 2014 Share Posted April 22, 2014 t'is a good point http://www.blue-room.org.uk/public/style_emoticons/default/rolleyes.gif pub power is not always kosher. I'd also check all leads connections etc as dbuckley suggests so you are confident your rig is beyond reproach. Then you can complain to the bar owner if his mains installation comes up short Link to comment Share on other sites More sharing options...
dbuckley Posted April 22, 2014 Share Posted April 22, 2014 My worst suspicion is that one of the sockets has a swapped neutral / earth. It's really hard to spot short of getting out the screwdriver and actually visually inspecting the back of the socket, and to all intents and purposes the socket works just fine. But man, does that insert noise onto what is supposedly an "earth". Especially when one of the loads dumping return current into the earth wire is a dimmer!!! Even so, playing the broken record one more time, a correctly configured sound system will reject the interference even under that level of severe provocation. Link to comment Share on other sites More sharing options...
Brian Posted April 23, 2014 Share Posted April 23, 2014 If you haven't got a decent multimeter then buy yourself one and get testing. The simple rule is that NO connection that carries an audio signal should EVER be connected to earth. It gets a bit more complicated than that for unbalanced insert points but it's a good start. Link to comment Share on other sites More sharing options...
david.elsbury Posted April 23, 2014 Share Posted April 23, 2014 Thankfully for S+L there should be no analog inserts on his system so should be easy testing Link to comment Share on other sites More sharing options...
S&L Posted April 23, 2014 Author Share Posted April 23, 2014 yup, always had multimeters (one sat on my desk as I type). So I'm thinking before pulling the amp rack to pieces I should test for resistance/continuity between the main power plug on the rack and all the xlr inputs. the small bar rack is set up as follows:multiboard fixed inside of rack with one main trailing plug,connected to multiboard is a crossover, 2 amps (subs and tops) and a 3rd amp (monitors)2 xlr trailing leads into crossover2 xlr trailing leads straight into monitor ampwith power off, and one probe attached to earth pin of main power plug, I should have no continuity/resistance reading between each and any pin of the 4 xlr in's Link to comment Share on other sites More sharing options...
Brian Posted April 23, 2014 Share Posted April 23, 2014 ...between each and any pin of the 4 xlr in'sYou'll probably see something to Pin 1 as that is for screening only and shouldn't carry any audio. Link to comment Share on other sites More sharing options...
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