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Zoom H6 RF Interference
Set up the new Zoom H6 for recording a podcast in downtown Seattle. I fired it up and put the headphones on to find that I was listening to a local radio station! I was finally able to kill the RFI by turning on the -20 pads for the mic inputs. However, I had to crank up the gain knobs all the way in order to compensate and get a good signal.
I was there the week before with a small mixer feeding into a Marantz PMD661 MK2 and there wasn’t a hint of RFI. Any advice on dealing with this?
Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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18 Replies
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Where there any mics plugged in?
If so what sort of mics were they?
Were the mics balanced or an unbalanced audio output? -
Both times I was using some inexpensive radio shack lavs. They run on button batteries and terminate with a 1/8″ plug. This last time I also had a nice $250 Rode lav with a little built-in xlr pre-amp that runs on phantom power. I had to remove the Rode and replace it with a Radio Shack lav because the RFI was worse on the Rode.
Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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Hello Jason and welcome to the Cow Audio Forum.
It would be interesting to experiment at that problematic location with balanced XLR terminated lavalier mics. I’m guessing you’d have better results.
Regards,
Ty Ford
Cow Audio Forum LeaderWant better production audio?: Ty Ford’s Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford’s Blog -
[Ty Ford] “It would be interesting to experiment at that problematic location with balanced XLR terminated lavalier mics. I’m guessing you’d have better results.”
One mic that I tried was this: https://www.dvestore.com/guy-says-gear-reviews/audio/microphones-audio-adaptors/rode-lavalier-microphone/
with this: https://www.dvestore.com/audio/connectors/rode-micon-5-connector/
Does that meet your description?Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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Hi Again Jason,
You would think so, but it’s still a slightly unconventional connector. Finding the problem requires a simple process of elimination. Were you using the XLR connector? Was it plugged right into the recorder or did you have an XLR cable to plug into? Try a regular XLR mic and see if the RF is still there.
Do you know which station and how far away the transmitter is? Radio Station RF can get into audio in a variety of ways, including funky cables. Do you have any other XLR mics or hardwired lavs to experiment with?
Regards,
Ty Ford
Cow Audio Forum LeaderWant better production audio?: Ty Ford’s Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford’s Blog -
Are the microphone extension cables correct?
I once worked in a small suburban theatre with bad RF problems, ALL XLR wall plates, patch bays and the mixing desk were wired in phase reverse. (pin 3 hot)
Even the mic cables were wired incorrectly, yes it was pin1>1, 2>2 and 3>3 but they put the cable braiding onto pin 3……. Yes it was RF hell working there.
It gave me just over a month of work to rewire the whole place, so shouldn’t complain to much. -
[Ty Ford] “Do you have any other XLR mics or hardwired lavs to experiment with?”
I’ll definitely take some extra gear in this coming week and try to isolate the problem. Thanks for the ideas!
Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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Following up on this situation. I went in today with some extra gear and some extra time. I found that anything with an unbalanced cable is trouble, unless I run it through a mixer first. For whatever reason, that seems to cut out most of the RFI. However, in this situation, I need to get a setup working without a mixer, which means using xlr mics on small desk stands, feeding into the Zoom H6. This will sound way better than the lav mics as long as I can get them to stay within a good pickup boundary.
Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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Hey Jason,
Thanks for confirming that science works! 🙂
The extra shielding of a balanced circuit and the double conductors of a truly balanced circuit were designed for just this reason.
Several other thoughts. Were you using the same mics that were susceptible to RF? If so, the mixer probably has some RF draining circuitry. You could try getting some Iron Ferrite RF chokes and wrapping the mic cord around and/or through them as an experiment to see if they will scrape off the RF.
I have not tried this, but you may find it helpful. I does require an XLR connection.
https://tinyurl.com/lhkdnowHere are some simple clip-on beads: https://tinyurl.com/prs4ymb
You may need more than one. Even several may not help. Just a suggestion. Are you up to it? 🙂Regards,
Ty Ford
Cow Audio Forum LeaderWant better production audio?: Ty Ford’s Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford’s Blog -
[Ty Ford] “You could try getting some Iron Ferrite RF chokes and wrapping the mic cord around and/or through them as an experiment to see if they will scrape off the RF. “
Ty, I was ahead of you on this one! I had picked up some RF chokes at Radio Shack to test, but they had no effect in this scenario.
Jason Jenkins
Flowmotion Media
Video production… with style!Check out my Mormon.org profile.
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