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Phone noise on cos-11's - probably stupid question.


chrisyking

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Hi. I have a couple of cos-11D with the battery barrel.

 

They seem to be picking up terrible mobile phone digadigas.

 

Just wondering if anyone has had this before? I'm using long xlr extensions into a SD633, and it's not the mixer cos it did it with my old 302.

 

It seems to do with using long 10m cables.  

 

I just checked my cables and they haven't put a small wire between the solder tag of the xlr socket and pin 1. Could this be the problem? It this totally necessary? I mean shouldn't pin 1 be earthed by the mixer anyway? I'll try some other cables when I can, but they seem much worse than ecm77's

 

Chris

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Thanks, yes that's what I've being doing, but with ECM77's I never had to do this (sometimes at sports gigs it's impossible). My radios, all with cos-11's have never ever picked up telephones, so to me it must be something to do with the mics or the cables. It's not the mixer for sure. 

 

I noticed Sanken bought out this 'D' model supposedly to stop phone noise, so it must be a known problem by them. Maybe I just got an early model as they had just released D when I got them.....

 

This thing with the earth tab on the XLR socket, what do you think?

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I use to work with a presenter that has always its mobile open...It surprised me :
 I never have had any radio noise coming from his mobile. Most of the time when I hear such a noise... it's coming directly on my headphones cable from my own mobile !
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Most of the time when I hear such a noise... it's coming directly on my headphones cable from my own mobile !

That's often my experience, too. It's usually a phone in my headphones rather than the mic. A quick listen back to the recording will confirm.

I don't think it will be the missing XLR mod. While Sound Devices is recommending this for use with their 7-series recorders, it is to stop rf leaking out of the recorder not so much into it. RF can enter your audio at various places, so you should check your components one by one. It's basic troubleshooting, really. And don't dismiss the recorder/mixer just because the old one did it, too. If it is the mic then talk to Sanken about it

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From their leaflet:
 
'Sanken has introduced the COS-11D, a new version of the popular lavalier which
overcomes digital transmitter RFI (radio frequency interference). '

 

 

...produced by digital transmitters like sony and zaxcom.

 

i prefer to have my XLRs with the tab connected (grounded shell) - all of the kit i'm using or plugged into is battery powered and i only encounter XLR screen issues with cables without continuous screen.

 

dan.

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From their leaflet:
 
'Sanken has introduced the COS-11D, a new version of the popular lavalier which
overcomes digital transmitter RFI (radio frequency interference). '

 

 

As far as Sanken are concerned, phones are phones, digital transmitters are something quite different, as Daniel says, see products from Zaxcom and Sony.

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I suspect the battery barrels too, though also imperfect shielding might let this GSM interference in.

My cables all have the connectors' housing connected to pin 1, no issues with RF. That way I ensure the shielding is complete.

Leaving the housings unconnected only helps against ground loops created by someone touching the connector. Big issue on a music stage with guitar amps and so on, non-issue in battery-powered and widely wireless movie world.

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CK: " Just wondering if anyone has had this before? "

YES, and it has been discussed here, though not recently...

 

" Could this be the problem? "

perhaps

It this totally necessary?  " 

some folks believe so, others think completely opposite!

" I mean shouldn't pin 1 be earthed by the mixer anyway? "

well, there may be both an audio common, and a different power earth...

" I think the D was D for digital. "  (and JG: " I could be wrong, but I don't think the D variant was... "

easy enough to find out instead of assuming...

" this 'D' model supposedly to stop phone noise," 

specifically

" so it must be a known problem by them. "

which this model should not suffer from

" I'm thinking it's probably that some of my cables don't have the tab linked up "

basic troubleshooting!

" Will do some troubleshooting later. "

maybe next time do the troubleshooting and some research yourself, first.

 

" Should it be connected both ends? Or just one end? "

or neither end..?

much discussion, much confusion, no complete agreements!

 

JG: " As far as Sanken are concerned, phones are phones, digital transmitters are something quite different, "

maybe...

portable telephones are portable digital transmitters, and for that matter, so are most modern tablets and computers...

plus all the digital emissions from the CPU's and other components like drives...

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Thanks Mike. I think they probably released the D version because of the increase in general RF. I guess the major increase is from 3G and 4G rather than radio mics, as I'm not aware of a major increase in the use of radio mics, but I imagine the D version is 'supposed' to counter all RF whatever the source. There are certainly more hard drives and general RF around. I meant 'supposed' as in my case their screening doesn't seem to have worked. 

 

The question about doing both ends is basically whether the mixer and the body of the mic should be electrically connected. My guess is that it should be, so I've just made sure if all my cables have this wiring and connected the ends which didn't. I'll report back if it cures the problem.....

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