AKG C747

[Andrew C]

I had heard that the 747 was prone to interference from mobiles, but until last week, I'd not personally had any problems. I'd put a note on the lectern and all the speakers had turned their phones off, but after the event and before I muted the system, someone walked past the podium and we had the "bip - bip - beeep" of the phone handshaking with the network.

 

Does anyone know where in the mic the weak point is, and whether there is anything that can be done to overcome the issue?

[mi-ul]

Does anyone know where in the mic the weak point is, and whether there is anything that can be done to overcome the issue?

 

Possibly useful answer: I think, but am probably wrong, that the cable is unbalanced up to the oversize XLR which would cause the problem

 

Probably less useful answer: Only let people in who are on Orange - don't know why but I've never had problems with any handset on orange. Vodaphone on the other hand gets switched off as soon as I get within 10 feet of a PA system

[Simon Lewis]

..........and whether there is anything that can be done to overcome the issue?

 

Not really too helpful - unless you are considering changing the 747s, but Audio Technica have spend quite a lot of time making their Engineered Sound range good at rejecting RF.

[Andrew C]

Possibly useful answer: I think, but am probably wrong, that the cable is unbalanced up to the oversize XLR which would cause the problem

Well, it is wired in a screened pair, I looked yesterday!

Don't know why but I've never had problems with any handset on orange.

Possibly the difference between 900mHz and 1800mHz networks.

 

And no I'm hoping not to replace them...

[Chappie]

My only suggestion would be to cut the cable as short as you can get away with. We have similar issues with Shure Beta 91s and 98s being slightly noisy until we shortened the reduced diameter cable.

[TAG1960]

Mobile phones will cut in to virtually any audio signal device including lectern mics, gooseneck mics, radio body packs but also DI boxes and mixing consoles themselves. I always try and brief speakers as I mic them to turn of phones and pda's. If you are running an open lectern event try taping a message to the lectern. At the end of the day this is more an education issue than a technical issue!

[Andrew C]

At the end of the day this is more an education issue than a technical issue!

Accepted. However, the 747s seem particularly bad in this respect, and I'd like to find out why!

[live]

I thought it was just me!!

I've set up ulx's, slx's and ew's in my workshop to see how they compare with "splashback" from mobiles and it's much of a muchness. The only mic's/recievers I've found to cut it down is my MiPro act 707's but it's still annoying, as Tag said any cable will act as an aerial, travel down into your system then get amplified. I usually sit with the organiser on conferences and when it happen's just say

"Do you think he should take that call?"

Doctor's and teacher's seem to be the worst offenders (imo)

[Bryson]

At the end of the day this is more an education issue than a technical issue!

Accepted. However, the 747s seem particularly bad in this respect, and I'd like to find out why!

 

 

From the other side, BlackBerrys seem particularly bad for creating the noise - which is a shame, as they are exceptionally common on corporate work!

[dbuckley]

The reason that Vodas make a racket and Orange don't is due to the differencing characteristics of the data exchanges; Voda (and O2) use GSM phones, which have the characteristic modulation pattern that breaks through electronics like the sound of a tambourine breaks through an anechoic chamber wall. Orange use the PCN modulation format, which is, well, different <_<

[pisquee]

Doctor's and teacher's seem to be the worst offenders (imo)

 

Doctors and other medical professional (oncall ones anyway) I can understand not being able to turn mobile phone and/or pagers off, teachers on the other hand I can't see any reason for them.