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Static sound issue with Sennheiser ew 100 g3 and Zoom h4n

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inanc tekguc
Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 4, 2015 at 4:00:51 pm

Hi,
I have been experiencing occasional, loud static sounds in my recordings using Sennheiser ew 100 g3 set, coupled with a Zoom H4n.
The Sennheiser lavalier mic is clipped on around the speaker's neck and the transmitter part is either hand-held, in a pocket, or hanging from the belt, while the receiver is attached to Zoom H4n.

I recently recorded about 22 presentations this way and a few of them have this static noise that I cannot explain. I had the same problem last year and I couldn't figure out why. I changed frequencies thinking perhaps some electronic device interfered, but it did not solve the problem.
I end up having to go through all the videos and find a way to cut out the noise if it's not in the middle of a word, or find a way to reduce it.

I am attaching two samples to help me explain better.
https://copy.com/8UKnZVOfcFxYGb80
https://copy.com/PmVOpfpfKNinFUcy

Any ideas how I end up getting this problem?

Thanks

Inanc
Visual Anthropologist 'n photographer


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Bruce Watson
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 4, 2015 at 5:04:16 pm

First sample, it sounds like an RF hit of some kind. Interestingly isolated. You did do a frequency scan before picking a frequency, yes?

Second sample sounds like a similar RF hit, but since it's a sibilant which already has a fair amount of energy in it, your speaker might just be overloading the mic/transmitter. But that should sound more like clipping than this does. Still, you might want to check your gain staging to make sure you aren't clipping something in the chain.

There are myriad sources of RFI in any environment, from fluorescent lighting fixtures to cell phones and pagers. And myriad ways for said RFI to get into your signal chain. Connectors, unbalanced cables, even the microphone itself can all provide paths for RFI.

That said, I sorta discount the idea of bad connectors here since your speaker is hardly moving when these sounds hit. I also discount the idea of clothing rustle being a part of this since the mic is above the cloths and the speaker is hardly moving -- what's to rustle?

What about battery levels? Fresh batteries in both the transmitter and receiver? I'm not talking rechargeables either. Only a few rechargeable brands can deliver sufficient power for radio mics. When in doubt, use fresh alkalines.


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Peter Groom
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 5, 2015 at 10:19:07 am

Sounds to me a bit like your right on the edge of either transmitter input overload, or input of the recorder camera overload. It seems to occur on peak transients. If the cameras I can see in the picture are the recorders then they look like DSLRs and so id be looking there (as I have a very LOW opinion of DSLR audio capability in general).

Are you going into cameras as XLR or are you converting down to something horrible like a 3.5mm jack?
Peter

Post Production Dubbing Mixer


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Craig Alan
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 6, 2015 at 2:05:48 am

He said he's recording on a Zoom H4n.

Mac Pro, macbook pro, Imacs (i7); Canon 5D Mark III/70D, Panasonic AG-HPX170/AG-HPX250P, Canon HV40, Sony Z7U/VX2000/PD170; FCP 6 certified; FCP X write professionally for a variety of media; teach video production in L.A.


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Ty Ford
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 6, 2015 at 2:45:44 am

Hello Inanc and welcome to the Cow Audio Forum.

Sounds are similar. The first one sounds like an RF hit.

The second on happens on a sibilant syllable.

How to reduce these? For RF, Move the receivers closer to the transmitters and cable back to the mixer or camera.

If your speaker is overly sibilant, try hanging the mic upside down on them. so the mic is aimed away from their face.
Try a different mic, Try a different speaker. Some people have very sibilant voices and they are extremely difficult to record without artifacts.

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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Rob Neidig
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 6, 2015 at 4:16:09 pm

Just as another idea, I know I have worked with some of the Sennheiser units in the past that were very sensitive if you touched the receiver's antenna. That would create just the sort of RF crackle you have. That is easy to have happen if you have several units all crammed into a sound bag and you have fat fingers like mine. You can touch one of the antennas while trying to reach to turn a gain knob. Just another idea... good luck!

Rob Neidig
R&R Media Productions
Eugene, Oregon


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inanc tekguc
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 10, 2015 at 1:49:34 pm

Thank everyone for all your responses.

These sounds are happening in 3-4 of about 20 talks given in the same room. I don't know if it eliminates some of the potential culprits.

I didn't know about the batteries, mentioned by Bruce Watson. I tend to use rechargeable batteries that have at least 2/3 on them (mainly because I want to make an environmentally less damaging choice). I didn't know they could be bad choices for transmitters/receivers. I mostly use Ansmann or Eneloop pro, which tend to have very good reviews.

I did the frequency check once, so I guess I should do it more often? (the talks lasted two full days).

Ty Ford, I carry the receiver, Zoom H4n and headphones on me. I move around the room with a 4th camera to get reaction shots and creative angles on the speaker, while also double checking that the other 3 cameras are recording well on their tripods. So, the Zoom is the "mixer" and I listen to the audio to ensure all is well. I guess to keep the receiver closer to the transmitter, I could set it up in a nearer place and maybe ask someone to keep the headphones on. However, I don't always have this luxury.
Oh, and I use the XLR cable provided by Zoom H4n.

Your point about sibilant syllable makes sense. I notice that on some speakers even though the static noise is not as disturbing as the ones here.

Someone also suggested that it could be my transmitter's volume is too high and it causes overmodulation (new concept to me) by the time it reaches to Zoom, which brings the peaks down to a safe level but keeps the distortion. When I checked the transmitter settings it was at -6Db. I moved it to -18Db. Will keep an ear on the device with these settings.

I am adding another short piece that has the same distortion even when the person is not speaking or moving much. In one instance, there is no contact with the antenna either.
On the other hand, I think she is overly sibilant as Ty Ford mentioned and you can hear a bit of distortion at the end of her words too.

video sample with static sound distortion



(i hope the embed works!)

Inanc
Visual Anthropologist 'n photographer


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Ty Ford
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 10, 2015 at 2:27:12 pm

Hello Inanc,

Ty Ford, I carry the receiver, Zoom H4n and headphones on me. I move around the room with a 4th camera to get reaction shots and creative angles on the speaker, while also double checking that the other 3 cameras are recording well on their tripods. So, the Zoom is the "mixer" and I listen to the audio to ensure all is well. I guess to keep the receiver closer to the transmitter, I could set it up in a nearer place and maybe ask someone to keep the headphones on. However, I don't always have this luxury.

If you are walking around the room and it's full of people, many of whom have smart phones, they can be causing the problem. In addition, your body may be blocking the signal from getting to the receiver.

Anytime the path between transmitter and receiver changes, something bad may happen. If the person walks around on stage and you're walking at the same time past someone who has a particularly problematic cell phone. You might hear drop outs and fitzes.

The problem can be worsened by the presenter also wearing their phone, unless it's completely off.

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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Bruce Watson
Re: Static sound issue with Sennheiser ew 100 g3 and Zoom h4n
on Nov 11, 2015 at 12:05:06 am

[inanc tekguc] "I tend to use rechargeable batteries that have at least 2/3 on them (mainly because I want to make an environmentally less damaging choice). I didn't know they could be bad choices for transmitters/receivers. I mostly use Ansmann or Eneloop pro..."

The Eneloops are OK, but they should be fully charged every time you use them. The problem with rechargeables is that they don't offer the same voltage level as a fresh alkaline. But the Eneloops do get good reviews and are used by professional sound mixers.

[inanc tekguc] "I did the frequency check once, so I guess I should do it more often?"

You absolutely should. Things change.

[inanc tekguc] "Someone also suggested that it could be my transmitter's volume is too high and it causes overmodulation (new concept to me) by the time it reaches to Zoom, which brings the peaks down to a safe level but keeps the distortion. When I checked the transmitter settings it was at -6Db. I moved it to -18Db."

This is probably part of your problem. Look up the concept of gain staging. Clipping anywhere in the chain stays in the chain, no matter what your recording levels are. You are probably clipping the transmitter on the high-energy sibilants at the higher settings. That said, you don't want to set it too low either, because of the corollary of the above: noise anywhere in the chain stays in the chain. I'm just sayin' don't guess at the settings. Spend the time to learn what works in your workflow.

[inanc tekguc] "I am adding another short piece that has the same distortion even when the person is not speaking or moving much."

What Mr. Ford said about blocking and walking around people with cellphones. It's always best if you can avoid moving the receiver, and can prevent anything from blocking line-of-sight between transmitter and receiver.

Everything we are talking about here is why I continually advise people that wireless is a last resort. Not a first. Last. Because it's full of problems, and the laws of physics aren't ever on the side of wireless. A cheap XLR cable is always going to sound better, be infinitely cheaper, and be way more reliable.


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