RFI/hash solutions at location recording

PlugHead · 17th July 2008, 02:39 AM

So,

I'm wondering who has had problems with mics and RFI when recording (remotes in particular)?

I just completed a couple of days in a lovely space, but had a couple of instances of RFI creep into my TM-1, which could not be quickly terminated. The other (Beyer M260) was resolved, but got me thinking - this could really be a problem if swapping mics doesn't solve it.

I know cables can act as antennae, and there are ways to reduce hash from entering the lines, but in a quick and dirty setup and record situation, what do you use to keep RFI from contaminating a line?

BTW - no other mics exhibited this problem - any one else with a TM-1 experience this?!?

thanks!

**Remoteness** · 17th July 2008, 05:07 AM

Just trying to narrow it down...

Did the TM-1 exhibit the same problem when it was plugged into another channel or attached to another mic cable?

Did you patch a clean mic into the channel that the Pearlman was in?

If so, what did you experience?

PlugHead · 17th July 2008, 01:00 PM

Quote:

Originally Posted by Remoteness

Just trying to narrow it down...

Did the TM-1 exhibit the same problem when it was plugged into another channel or attached to another mic cable?

Did you patch a clean mic into the channel that the Pearlman was in?

If so, what did you experience?

Steve,

I didn't try swapping the Pearlman with another (adjacent) channel: However, I did patch another mic (57) to test that particular channel/cabling: no noise. Time being short, I had to shelve the TM-1 for a better option...

NorseHorse · 17th July 2008, 02:38 PM

Aluminum foil hats keep aliens from reading your mind.

Probably works with RF waves as well.

Heck, just hang an aluminum foil canvas over the whole building, and you'll probably be fine.

Right?

David Rick · 18th July 2008, 12:28 AM

Most modern professional microphones are designed with some attention to RF susceptibility. In theory, you have to pass susceptibility testing before you can put a CE mark on the product. That doesn't mean you won't have problems with GPRS interference, but at least you have a fighting chance.

It's a different case with far east microphones for sale to the US prosumer market. CE marking is not required, and FCC only cares about RF emissions. So there's probably no testing done, and even if they did find a problem, nobody is going to spend a dime (or a dime-sized ceramic disk capacitor) to solve it.

In your case, what you've got is something that's a clone of a microphone designed fifty years ago when there was less understanding of RF immunity, and certainly no testing requirements. One might catch the problem in testing, if boutique audio companies ever did such tests. But since the mic is probably only offered for sale in the US, no tests are required.

David L. Rick

JoeyM · 18th July 2008, 01:00 AM

If my memory is correct, copper shields against RFI and ferrite-based (iron) shields against EMI.

As for what Mu Metal will shield and why, well that's just pretty close to getting out of control.

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17th July 2008, 02:39 AM	#1
PlugHead Lives for gear Join Date: Jan 2003 Location: steeltown Posts: 1,714	RFI/hash solutions at location recording So, I'm wondering who has had problems with mics and RFI when recording (remotes in particular)? I just completed a couple of days in a lovely space, but had a couple of instances of RFI creep into my TM-1, which could not be quickly terminated. The other (Beyer M260) was resolved, but got me thinking - this could really be a problem if swapping mics doesn't solve it. I know cables can act as antennae, and there are ways to reduce hash from entering the lines, but in a quick and dirty setup and record situation, what do you use to keep RFI from contaminating a line? BTW - no other mics exhibited this problem - any one else with a TM-1 experience this?!? thanks! __________________ Jay PlugHead Productions

17th July 2008, 05:07 AM	#2
Remoteness Super Moderator Join Date: Aug 2002 Location: NYC Posts: 4,880	Just trying to narrow it down... Did the TM-1 exhibit the same problem when it was plugged into another channel or attached to another mic cable? Did you patch a clean mic into the channel that the Pearlman was in? If so, what did you experience? __________________ Steve Remote AuraSonicLtd.com the home of ASL Mobile & Location Production Remoteness on the Linkedin Network Remoteness on Myspace

17th July 2008, 02:38 PM	#4
NorseHorse Lives for gear Join Date: Jul 2008 Location: Virginia Posts: 512	Aliens Aluminum foil hats keep aliens from reading your mind. Probably works with RF waves as well. Heck, just hang an aluminum foil canvas over the whole building, and you'll probably be fine. Right? __________________ Williamsburg, VA 23186

18th July 2008, 12:28 AM	#5
David Rick Gear addict Join Date: Mar 2004 Posts: 366	Their design problem is now your location problem Most modern professional microphones are designed with some attention to RF susceptibility. In theory, you have to pass susceptibility testing before you can put a CE mark on the product. That doesn't mean you won't have problems with GPRS interference, but at least you have a fighting chance. It's a different case with far east microphones for sale to the US prosumer market. CE marking is not required, and FCC only cares about RF emissions. So there's probably no testing done, and even if they did find a problem, nobody is going to spend a dime (or a dime-sized ceramic disk capacitor) to solve it. In your case, what you've got is something that's a clone of a microphone designed fifty years ago when there was less understanding of RF immunity, and certainly no testing requirements. One might catch the problem in testing, if boutique audio companies ever did such tests. But since the mic is probably only offered for sale in the US, no tests are required. David L. Rick

18th July 2008, 01:00 AM	#6
JoeyM Gear nut Join Date: Dec 2007 Location: Audioland Posts: 111	If my memory is correct, copper shields against RFI and ferrite-based (iron) shields against EMI. As for what Mu Metal will shield and why, well that's just pretty close to getting out of control.

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