the kid Posted August 20, 2015 Share Posted August 20, 2015 We have a 8 rack of EV500series G2packs, that seem to have developed a we weird issue. The rack is sending out white noise which is being heard in the desk, even with the channel down and muted, when all mics are off, and then hears a flick in of frequency and we get signal for half a second sends and then it goes back to white noise, its perhaps happening every few seconds. What is odder is that the white noise is by passing the channel and mute on 2 different desks (not the master), in 3 different locations on 3 different forms of power. Any clue what might be the issue? I am going for an earth loop of sorts but its a rack we have used quite a bit before with no issues. The rack is built as power in, and each unit plugged in to a power strip. The aerials are combined passive and sent out to 2 aerials. Its take a while to craft how to even describe the issue so if it makes not much sense I will try and rephrase it Link to comment Share on other sites More sharing options...
Albatross Posted August 20, 2015 Share Posted August 20, 2015 I had a re-read of your post & realized that I'd misread.I was going to suggest that it was a desk issue. Could it be cabling between mics & the 2 different desks?I struggle to understand how 2 desks could both have the signal bypassing the mutes though. Link to comment Share on other sites More sharing options...
the kid Posted August 20, 2015 Author Share Posted August 20, 2015 We did think that at 1st but having tried other desks we have it still. I just checked out yes it is with the mutes on as well. Cables have been changed several times on site and here. Link to comment Share on other sites More sharing options...
Shez Posted August 20, 2015 Share Posted August 20, 2015 Have you tried bypassing as much of the rack as possible (i.e. internal power distribution, any wiring to a connection panel, just using a single direct-connected antenna etc) to eliminate as many variables as you can? If that behaves, then add the common components back in one at a time to see at what point the problem manifests again. Link to comment Share on other sites More sharing options...
themadhippy Posted August 20, 2015 Share Posted August 20, 2015 how close is the rack to the desk,could it be some sort of rf break through Link to comment Share on other sites More sharing options...
the kid Posted August 20, 2015 Author Share Posted August 20, 2015 We have just done power from the wall in to a unit, and aerials straight on to the RF in, still same issue. on the units Link to comment Share on other sites More sharing options...
paulears Posted August 20, 2015 Share Posted August 20, 2015 an input to the desk that is muted with cable down shouldn't make any noise at all. Does it vanish if you physically pull the plug out? Can you isolate the receiver(s) that are doing this from the ones that behave? If every output from the rack is misbehaving, then you need to remove all the connections, aerial, DC and audio, and reconnect each one, one at a time until the problem breaks out again. If you have tried two desks and they both refuse to mute, then something unusual is happening, and frankly, it sounds 'wrong'. Something else is causing the problem. If you turn down the mixer output and PFL the inputs that has the noise on it - is it mega loud and the gains unable to bring the level down. Depending on the desks, some off switches are really mutes, and might not be muting a direct out, or something like that - that somebody may have patched in? It's going to be a silly one. So you need to physically check the input first with an ordinary mic, and check it's stable and working fine. Then connect just one receiver - with every other one powered off and probably disconnected - then build it up. If the fault suddenly happens again, you can report back. Link to comment Share on other sites More sharing options...
john deans Posted August 20, 2015 Share Posted August 20, 2015 Seem like some kind of conducted RF issue similar to the noise from some laptop computers when connected to mixer. try connecting one of the receivers via a DI box with the earth lifted Link to comment Share on other sites More sharing options...
cedd Posted August 20, 2015 Share Posted August 20, 2015 Seem like some kind of conducted RF issue similar to the noise from some laptop computers when connected to mixer. try connecting one of the receivers via a DI box with the earth liftedMy thoughts too. It'd also be interesting to see what happened if you connected just pin 1 (would involve some surgery on a cable) without pins 2 and 3. I suspect it'd still occur. I doubt very strongly that it'd be all of the receivers. I know you've tried singling out single points of failure, but perhaps it's one rogue receiver that's putting noise on the ground and in to the others. I've had a Sennheiser receiver go rogue and start transmitting (well, emitting low level RF sproggies) that got in to the other receivers - not the same fault as here, but I'm trying to say that just because it's a receiver doesn't mean it isn't capable of still producing some RF. Link to comment Share on other sites More sharing options...
Christopher Evans Posted August 20, 2015 Share Posted August 20, 2015 Could this be because you are using G2 packs? and some of the frequencies you are tuning to are no longer usable? Link to comment Share on other sites More sharing options...
paulears Posted August 21, 2015 Share Posted August 21, 2015 I was going to say I doubt it, but then thought that maybe very strong digital signals could be the cause. I've not tried looking for an old channel 69 newly occupied channel, as I didn't think any were active in my area, but I suspect they'd certain cause a full strength very nasty sounding to be produced at the output, if the pilot tone was off? As to getting through the mutes? no idea? Link to comment Share on other sites More sharing options...
Electrolytic Posted August 22, 2015 Share Posted August 22, 2015 what are the mixing desks you have tried this phenomena on?digital and analog? Link to comment Share on other sites More sharing options...
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