Mobile phone speaker interference

Arnold

Arnold

www.alanarnold.co.uk
Moderator
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Hello people

This isnt a car related question but it is speaker related.

At our work conferences, we have 100+ people in the room with mobile phones switch on. When someone gets a call, the speakers kick off with there buzzing tone and from where i sit at my control desk, i have no way of controlling the speaker to shut it up. The only solution is killing the power to it. It obviously causes some disruption and i need a way to prevent it from happening.

Is there anything i can buy to fix this? Possibly purchase speakers which dont have this problem? Different cabling? a shield to go around the speaker etc etc, anything along those lines.

Our next event is in early March and i need a solution purchased and tested before this date!

Cheers people!
 
Well, the only phones that do this are the ones that operate on the GSM900 band, which is Vodafone and O2, so the cheeky solution would be to get everyone to switch to Orange or T-Mobile which use GSM1800 ;)

How thick is the speaker wire you use? To be honest I don't think there's much you can do except for asking people to turn their phones off or building a faraday cage around the room so they can't get signal!
 
James said:
Well, the only phones that do this are the ones that operate on the GSM900 band, which is Vodafone and O2, so the cheeky solution would be to get everyone to switch to Orange or T-Mobile which use GSM1800 ;)

How thick is the speaker wire you use? To be honest I don't think there's much you can do except for asking people to turn their phones off or building a faraday cage around the room so they can't get signal!
Click to expand...

Could we get one of these faraday cages made up just to go round the speaker? would that work?

The cable is a Musiflex professional microphone cable. 1/2 cm thick. We have loads of it daisy chained together going round the room.
 
its low quality poorly shielded audio cables/amps/mikes etc that do this.

Ed
 
Ed said:
its low quality poorly shielded audio cables/amps/mikes etc that do this.

Ed
Click to expand...

Ed,

i think i've said to you before we use Trantec microphones. 2 Hand held, 3 lapels. Would these be an issue?

Also, can you recommend any cables that would would be suitable for us? or at least recommend a decent thickness which would prevent these problems. I can at least then contact our supplier and discuss costs etc. I have to get this problem sorted!!

Cheers
 
Orange do it too, not just vodaphone and 02. I think one2one do it as well.

Simple solution - At the start of the conference, remind everyone over the mic (once all r seated) that mobiles are not allowed to be left on, and explain why obv!! A lot cheaper :)
 
Ems said:
Simple solution - At the start of the conference, remind everyone over the mic (once all r seated) that mobiles are not allowed to b left on, and explain y obv!! A lot cheaper :)
Click to expand...

We do! lol, but people just put them on silent thinking that'l solve everything when it doesnt.
 
So explain then. The reason people put them on silent is coz they think your moanin about the noise, not the interferience (sp!). Tell them they have to actually turn the phone off, and explain y, otherwise they'll get deaffened (sp again lol)!! It only takes 2 mins to do this!!
 
We do but people dont listen.. Anyway, apart from explainations, i need a technical solution so if anyone can help, that'd be apprechiated.
 
The course of action first of all is to find at which point the interference is getting into the system. Only then can you take action to stop it. The most likely source are the mikes, however this doesn't mean they are at fault, as it can be that there is inadequate filtering elsewhere in the system that is allowing this to happen. (i.e. within the mixer) example does the noise go away if you turn the mixer off? do you hear the noise on headphones on the mixer?
 
I think the speakers still have interference even if the mixer is switched off. Im not 100% certain on this but i believe they do.

It always seems to be speakers on one side of the room (near a reception area) and you can see people walking around with phones outside. When they go, the noise stops. I can turn the volume off on the mixer for that channel but it still makes a noise. The other side of the room (using a different channel) works fine without a fuss, so i've always put it down to the speakers themselves being the problem.

I'l try do a very quick diagram of the setup and see if you can spot any weak areas

6.audio.jpg
 
Can't you put the two speakers at the back of the room in the corners, not near the doors. At least you have a wall in the way then. Obv angle them out towards the audience.
 
I've edited the image to include the door at the top of the room. the reception area runs parallel to the room the function is held in. To get to the door, walk off the top, and across and enter the room at the back

Ed... there are no amps at all anywhere, apart from whatever is built into the mixer! I guess thats not very good! Everything connects to the mixer direct instead. The only other wires are where they plug into the wall socket electrically.

Cheers for that link, may get some of those! better than nothing :)
 
Wrap them around the wires that go into the amp/mixer particulary the speaker and mike wires. It may help.
 
Ok cheers, i'l get a load and do that.

Any other suggestions? Upgraded cabling, speakers or other equipment that may help?
 

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