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Zoom H6 RF Interference

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Jason Jenkins
Zoom H6 RF Interference
on Feb 2, 2015 at 11:24:51 pm

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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Brian Reynolds
Re: Zoom H6 RF Interference
on Feb 3, 2015 at 3:29:14 am

Where there any mics plugged in?
If so what sort of mics were they?
Were the mics balanced or an unbalanced audio output?


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Jason Jenkins
Re: Zoom H6 RF Interference
on Feb 3, 2015 at 5:07:00 pm

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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Ty Ford
Re: Zoom H6 RF Interference
on Feb 3, 2015 at 7:55:07 pm

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 Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Jason Jenkins
Re: Zoom H6 RF Interference
on Feb 3, 2015 at 8:50:14 pm

[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: http://www.dvestore.com/guy-says-gear-reviews/audio/microphones-audio-adapt...
with this: http://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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Ty Ford
Re: Zoom H6 RF Interference
on Feb 3, 2015 at 9:31:57 pm

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 Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Brian Reynolds
Re: Zoom H6 RF Interference
on Feb 3, 2015 at 10:23:28 pm

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.


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Jason Jenkins
Re: Zoom H6 RF Interference
on Feb 5, 2015 at 4:51:37 pm

[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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Jason Jenkins
Re: Zoom H6 RF Interference
on Feb 10, 2015 at 4:16:25 am

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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Ty Ford
Re: Zoom H6 RF Interference
on Feb 10, 2015 at 3:09:23 pm

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.
http://tinyurl.com/lhkdnow

Here are some simple clip-on beads: http://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 Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Jason Jenkins
Re: Zoom H6 RF Interference
on Feb 11, 2015 at 5:04:01 am

[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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William Guth
Re: Zoom H6 RF Interference
on Nov 29, 2017 at 4:51:10 am

Did you actually get good signal? Or just something decent enough to work with?

This happened to me today for the first time in downtown Chicago. I was 26 floors up on Michigan Ave in a sleek modern building of metal and glass, so basically inside of a giant antenna, stones throw from two radio stations and a TV station.

In my situation, the RF interference was actually slightly amusing. In all of my 15 years of AV experience, and countless wireless transmitters/receivers I never anticipated my first RF interference would occur in a wired system. I didn't think to switch on the -db pad, and I don't know if that would've helped, but I'll consider it next time it happens.

Your initial post was a while ago, and I've learned today that Zoom has acknowledged the issue. No idea if any design updates have been implemented. Too late in both our cases.

I was able to mitigate it a little in post-production. The recorded radio sounds were extremely faint. Much more faint then they were when I was listening to them live through the headphones.

That said, I still plan to conduct continuity tests of all my XLR before I take any of it out in the field again.


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Tom Strand
Re: Zoom H6 RF Interference
on May 7, 2018 at 3:24:58 pm

This happened to me today.

Zoom H6 - (4) XLR cables + Sennheiser microphones.

I'm using the Zoom to add more microphones to a conference room with a built-in videoconference system. So I use the line out (TRS 3.5mm M/M cable to a Rhodes 3.5 to XLR adapter) then XLR into a room XLR jack in the wall.

The line out is set to -20dB so the Zoom output doesn't over-drive the room audio system.

We picked up a radio station with varying intensity. Loud enough to be distracting during a videoconference.

Solution 1: Use the microphone out (instead of line out) turned down to Volume 50. So far so good.

Next attempt: Set the line out to -40db or more, hoping to get low enough not to propogate the interference.


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Ty Ford
Re: Zoom H6 RF Interference
on May 7, 2018 at 6:20:56 pm

Hello Tom and welcome to the Cow Audio Forum.

1. Any time you go unbalanced, you grossly increase your probability of interference.

2. What's a Rhodes? I know Rode, but not Rhodes. Rode makes an adapter, but it is not clear if the adapter is wired to convert an unbalanced stereo input to a balanced XLR output or not. Your RF problem could be happening right there.
I've asked Rode to comment.

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Tom Strand
Re: Zoom H6 RF Interference
on May 9, 2018 at 10:44:58 pm

Ty,

Thank you for the quick response.

re: Rode. It's a Rode VLXR as described https://www.amazon.com/Rode-VXLR-Adapter-VideoMic-Mini-Jack/dp/B000Y021NA/r....

I assumed the M<>M 3.5 TRS connection between the Zoom H6 line out and the Rode 3.5 F <> XLR M was balanced. But that may be the only unbalanced link in the chain. Does a balanced 3.5<>3.5 M cable exist? Or maybe a 3.5mm M <> XLR F single cable would work. I thought the VLXR would do the magic to prevent AM radio interference.


WORKAROUND: Yesterday I was able to use the MIC out and reduce the volume to 10 so that online people wouldn't hear the interference. I'll try that again tomorrow. I tried the LINE out, but the miximum reduction is -30 dB which wasn't enough to hide the radio interference.


Tom


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Ty Ford
Re: Zoom H6 RF Interference
on May 9, 2018 at 11:21:11 pm

I have an email in to Rode. I t seems it's an unbalanced stereo input (3.5mm) to an XLR male. Questions remains about the stereo/mono balanced/unbalanced thing. Normally, this unbalanced to balanced thing results in problems. Yes, you can hear the audio in balanced audio land, but when you play it back in mono the sound source disappears because you putting positive peaks on one half of the waveform and negative peaks on the lower half of the waveform.

"Does a balanced 3.5<>3.5 M cable exist? " Sure, but everything depends on the sending and receiving circuitry. It's a plumbing issue. A 3.5mm TRS has three conductors. If the cable is properly made those three conductors can pass a balanced mono signal. If the cable is plugged into a stereo output, it carries the unbalanced stereo signal. Plug that into a mono input 3.5mm input and you may have problems unless the tip and ring of the cable are tied together, making the signal mono. It's still not balanced, but it will combine the two track into mono.

Questions?

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Ty Ford
Re: Zoom H6 RF Interference
on May 10, 2018 at 2:05:00 am

Tom,

I heard back from Rode. The adapter is setup to combine unbalanced stereo to mono. The XLR carries unbalanced Mono.

If you wanted to balance it, use really short unbalanced cables and put it through one of these.

https://bhpho.to/2rvvMJE

After balancing, you'll have a much better chance of not hearing the AM.

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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Tom Strand
Re: Zoom H6 RF Interference
on May 10, 2018 at 11:30:56 pm

Ty,

Thank you for the guidance.

I would guess that what I need is a Hum Eliminator for only the 3.5 mm leads.

As you can tell, my beginner brain thought that a TRS cable (vs TS) took care of interference, but of course, the intelligence isn't in the mechanical presentation of the cable, but in the circuitry and physical wiring of the cable.

For now, I will keep the microphone output at 10 (or less) or move closer to the XLR jack that links to the room system.

But game for any adapter options pre-wired to help remove the AM radio.

Tom


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Ty Ford
Re: Zoom H6 RF Interference
on May 11, 2018 at 2:43:55 am

Hi Tom,

You could get a 3.5mm TRS to two Male 1/4" Y-cord and plug that in to the box
Keep that cord short.

" the intelligence isn't in the mechanical presentation of the cable, but in the circuitry and physical wiring of the cable."

yup, you got it!!! There are transformers in the box to create a balanced circuit. The balanced circuit is he intelligence that will allow the radio station to be cancelled out.

Regards,

Ty Ford
Cow Audio Forum Leader

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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