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Microphone tails/connbox less XLR metal casing (lighter for boom use) - problems?
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AdamAsnan
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#1
28th December 2012
Old 28th December 2012
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Microphone tails/connbox less XLR metal casing (lighter for boom use) - problems?

Hello all, quick question that I cannot seem to find any clear and cut info on; I'm thinking to remove the metal casing(s) from my my Rycote Connbox 3 and 4 XLR connectors (mic input stage - female) to reduce weight on a boom, might this cause a higher potential for RF noise being that the casing is no longer acting as the shield (is that right?).
I plan to keep the casing on the handle end (male) and thus all the way along to the recorder.

Also, might this be dependent upon the mics? I'm using a Sanken CSS-5 and am just about to acquire a Neumann KM-A + KK120 / KM184 Mid-Side rig

Any advice against?

Thanks!

Adam
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29th December 2012
Old 29th December 2012
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Against - you are removing the shield and making it more prone to RF interference.

I wouldn't do it.

In fact, I changed the bodies on my XLRs to the ones with "teeth" to make them more secure and get a better shell connection to the mic. As Neutrik's digital XLR has the same body but with teeth, I got a few bodies and swapped them over (no soldering involved).
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#3
29th December 2012
Old 29th December 2012
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Rolo 46 is offline
In to days nightmare world of RFI /EMI you need all the shields you can muster
Dont do it
Buy a CMIT 5U,its very light and the best shotgun yet.
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29th December 2012
Old 29th December 2012
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Quote:
Originally Posted by Rolo 46 View Post
In to days nightmare world of RFI /EMI you need all the shields you can muster
Dont do it
Buy a CMIT 5U,its very light and the best shotgun yet.
CMIT 5U is definitely *not* the best shotgun yet.

I would say that honour would probably have to go to the SuperCMIT - or the Sennheiser 8060 or 8070 if you include damp working.
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29th December 2012
Old 29th December 2012
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Have you tried em all on a boom Johnny boy ?
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29th December 2012
Old 29th December 2012
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Quote:
Originally Posted by Rolo 46 View Post
Have you tried em all on a boom Johnny boy ?
I use my MKH8060 on boom all the time and it is fantastic.
It's now my "middle" mic: Sanken CS-3e (the best shot gun ) for the difficult locations indeed, mkh8060 for the normal location and MKH50 or MK41 for internal recording.
Never tried a SuperCMIT though.

Ah..and yes you can remove the housing of XLR female if you really need. But I wouldn't do that because of the weight problem as it could be tolerated by a pro boom man. I removed them once only because of the space limitation.
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30th December 2012
Old 30th December 2012
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Have a look for plastic XLR connectors, they are around and seem to stand up to the ruff and tuff of OB productions. One of the OB companies I work for has been using them for a couple of years now and I've never seen a broken one yet.
I think they are made by ALCATEL .... and they are VERY light weight.

http://www.amphenolaudio.com/Ampheno...XLR_Cable.html
AdamAsnan
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30th December 2012
Old 30th December 2012
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Thanks all, now I know the risks; OzGizmo, surely plastic XLR casings are as good as none in terms of shielding?
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30th December 2012
Old 30th December 2012
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Quote:
Originally Posted by AdamAsnan View Post
Thanks all, now I know the risks; OzGizmo, surely plastic XLR casings are as good as none in terms of shielding?
Conductive plastic?
#10
1st January 2013
Old 1st January 2013
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What a great question!

Those shells can do all sorts of funny things. Most often, people like to have the "shells" not wired to the wire shield because of ground loops. The one at the mic usually contacts the mic housing. However, these arrangements can create some strange RF phenomena, where the shell to mic case measures 0 ohms, but at RF can behave very differently, even to the point of demodulating material to AF.

Out of curiosity, I have tried using completely unshielded twisted pair mic cables in very dense RF areas with no problems at all. The pairs were summed by a solid state device, not a transformer. I did this as an experiment, not for any potential sonic improvements.

At the other end of the continuum, I'm always amazed that a couple of large commercial concerns who employ people far more knowledgeable than I and who use transformer summing/decoupling have consistent RF problems on lines I use all of the time with no problem at all with no special treatments in place.

The point is that it's unpredictable, but even the tried and true is unpredictable. And there's a good chance what you're proposing will work. It could even improve matters.

You can also wire just the housing at the mic end to the braid w/o using the shell. Even when using the shell, there's an argument to be made for attaching housing to shield at the mic connection.

You'll have to try and see. And be sure to let us know.
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2nd January 2013
Old 2nd January 2013
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The metal casing for the XLR connectors is NOT connected on all of my mic cables, thus the only function they are performing is to keep the connectors from separating. They also protect the end of the cable when they get dragged across the stage.

I believe you could remove them and not have a problem.

We will be only guessing until you actually try it.
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2nd January 2013
Old 2nd January 2013
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Quote:
Originally Posted by JEGG View Post

Out of curiosity, I have tried using completely unshielded twisted pair mic cables in very dense RF areas with no problems at all. The pairs were summed by a solid state device, not a transformer. I did this as an experiment, not for any potential sonic improvements.
I had to run sound from one floor in an office building to another. I made an adapter and plugged into a CAT5 port and had it patched in the back room to a port on another floor. The sound went through 200-300 feet of unshielded CAT5 cable with no buzz or problems.

The twisted pair is essential, the shield does not usually do anything.
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2nd January 2013
Old 2nd January 2013
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That might work at line level
Not at mic level
As a star quad user I never had EMI/RFI induction on studio/location floors,only on locations under or opposite very powerful Radio Stations (Radio Belgrade and also high in an office block in Shanghai,China Radio)
Even dodgy Steadicam wireless controllers caused no problems, and they were next to the boom.
Motorola 5W walkies would click and that was it
My Micron radios were pin 1 to shell and were immune mostly
A brass MKH 416 was almost, but not quite ,impregnable to silly levels of RF
Every recordist should have one of those
Remember very light boom mics are difficult to mount compliantly
The Schoepes CCM 41L,a wonderful transducer, generate intense LF that is difficult to filter,as a boom on the move produces trouser flapping levels of LF.
Mics with mass are less trouble some
A proper ribbon, with huge mass,the RCA KU4 was also a weapon of choice, against especially recalcitrant actors..
#14
2nd January 2013
Old 2nd January 2013
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A good twisted pair is so that both legs pick-up the RF interference equally and cancel it out. Star-quad does this even better.

The screen is extra protection for when the two legs don't cancel completely.

Connecting the shell to pin-1 does give that extra RF protection, but can cause hum, which is why many people don't do it.

I use the Neutrik EMC connectors now, which have a ferrite bead on pin-1 and connect to the shell via a ring capacitor. This gives superb RF protection and prevents the hum problem.

With the increase in transmitted RF, more smart phones and G4 coming on line now, RF interference will only get worse and worse and we have to protect against it as much as possible.
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