morristech Posted March 12, 2015 Share Posted March 12, 2015 I'm fairly certain there must be a thread of this nature somewhere already but my searching skills are poor. If not, then here we go. I was working at a conference earlier today, simple setup of a lectern mic and sound from a laptop, going into the desk via a 3.5mm TRS to 2x phono. The output from the desk was going into the very nice sound system in the IMAX cinema I was in. The same laptop was also running slides for a 10k projector (supplied by the hire company with the rest of the kit), connected via VGA. Separately, these two components were fine. No problems at all. But as soon as I plugged both the VGA and the 3.5mm into the laptop, there appeared to be some interference on the projection. I tried the usual trick of unplugging the laptop, but no luck, so I presume there was an earthing problem with the sound desk?? This could easily have been solved with a DI, but I don't have one in my toolbox and one wasn't supplied. I had heard that my Behringer Cable Tester can be used as an adapter when switched off, so I tried running that between the laptop and desk as I was running out of options. The interference stopped. My cable tester eats 50Hz. If someone can explain to me the physics of this I'd be very grateful! By the time I'd solved it the very helpful venue tech had sourced a DI from another venue across the road and brought it over, so I ended up using that instead, but it's good to know that that's an option in future! Link to comment Share on other sites More sharing options...
Dave m Posted March 12, 2015 Share Posted March 12, 2015 Handy to know! Link to comment Share on other sites More sharing options...
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