soundspider Posted October 25, 2012 Share Posted October 25, 2012 Hey, Quick question cos I haven't experienced it before - I tried using a DVD player (Toshiba SD1010) to play CD's through an old mixer amp, basically cos its cheaper than a proper CD player, and it seems to be causing serious interference with the radio mics that also go through. They are old VHF Audio Technicas (ATW R-11, I think) on 175.0 and 173.8 MHz. With the DVD player unplugged, no interference, with it in, really loud kinda pink noise/static coming through the radio mic receivers, mostly the 173.8, but a bit on the other as well. Once you switch the beltpacks on it goes, cos the signal from them is stronger than the one that seems to come from the DVD player. Is it a fault with the DVD player? Is there some way of switching any RF off from it? Its not a DVD recorder, so its not like it has the capability of receiving TV signal. Do I just bite the bullet and get a proper CD player? Any other suggestions? Thanks, Alan Link to comment Share on other sites More sharing options...
timsabre Posted October 25, 2012 Share Posted October 25, 2012 Short answer: yes they can do, and it's probably just noise from the power supply rather than any intended RF output (i.e. the TV aerial output if it has one). Get the DVD player as far away as you can from the radio mic receivers. A different DVD player may or may not be better. Link to comment Share on other sites More sharing options...
Shez Posted October 25, 2012 Share Posted October 25, 2012 Do the receivers have a variable squelch setting? Link to comment Share on other sites More sharing options...
soundspider Posted October 25, 2012 Author Share Posted October 25, 2012 Do the receivers have a variable squelch setting? No, no squelch control unfortunately :( Woulda been handy. Do CDs players do the same thing or would they be safe enough in this setting? Short answer: yes they can do, and it's probably just noise from the power supply rather than any intended RF output (i.e. the TV aerial output if it has one). Get the DVD player as far away as you can from the radio mic receivers. A different DVD player may or may not be better. They are currently stacked on top of one another - hardly the best idea I suppose, then! Any way of isolating the noise from the power supply? Safely (I'm not gonna drag the earth out or anything)? Alan. Link to comment Share on other sites More sharing options...
timsabre Posted October 25, 2012 Share Posted October 25, 2012 They are currently stacked on top of one another - hardly the best idea I suppose, then! Any way of isolating the noise from the power supply? Safely (I'm not gonna drag the earth out or anything)? Even 12 inches separation will help a lot. The noise is probably radiated interference so not easy to stop. All electronic devices do it to some extent, it's why a lot of things have big ferrite lumps on all their cabling. Link to comment Share on other sites More sharing options...
Simon Lewis Posted October 25, 2012 Share Posted October 25, 2012 I've had exactly this issue with Trantec VHF radios and a CD player (in the 1990s). Separating the devices did the trick. It is possible that a newer DVD / CD player may have fewer emissions, but I wouldn't count on it. Link to comment Share on other sites More sharing options...
paulears Posted October 25, 2012 Share Posted October 25, 2012 Older gizmos with the old RF modulators designed to give an output on channel 37 or so often have a low level sproggie because their output device is a pretty crude and cheap multiplier device, and weren't filtered very well. Just a bit of distance, as is suggested above usually fixes it. Link to comment Share on other sites More sharing options...
soundspider Posted October 25, 2012 Author Share Posted October 25, 2012 Will try tomorrow - as usual, thanks for all the advice. Alan. Link to comment Share on other sites More sharing options...
JimWebber Posted October 25, 2012 Share Posted October 25, 2012 As others have hinted, anything electronic will give off a degree of RF Interference - Paul and others have suggested physical separation - Thanks to a little gem called the Inverse Square Law, if you can double the distance between the DVD and the receiver, only a quarter of that nasty RF will get through... Three times the distance - one ninth of the power will hit the microphone receiver.... Jim Or something like that, maths never was my strong point! Link to comment Share on other sites More sharing options...
laolu Posted October 26, 2012 Share Posted October 26, 2012 I had a similar problem with an FX unit and a VHF mic, when I took them out of the rack at one occasion. Screwed tightly in the rack the problem was gone. So I connected the two (metal-) boxes of the VHF mic and the FX-unit, and additionally grounded them and voila!, the interference was gone. Different, I know, but maybe it works with your DVD player as well. Norbert Link to comment Share on other sites More sharing options...
soundspider Posted October 26, 2012 Author Share Posted October 26, 2012 Jus a wee update - the DVD player was sitting on top of the radio recievers. I swapped them round, put the DVD player under, separated with a bit of cardboard, and hey presto, interference gone. Thanks again, problem solved! Link to comment Share on other sites More sharing options...
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