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Strange electronic buzzing with Sennheiser ew 100 g3

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Jacob Dean
Strange electronic buzzing with Sennheiser ew 100 g3
on Jan 18, 2017 at 7:26:43 pm

I've chronically have a strange buzzing while using my Sennheiser ew 100 g3 wireless microphones. I own sets for both frequency bands and it's present in both. I always scan for open frequencies, and it doesn't sound at all like interference or squelching. It's present using both cameras and field audio recording units. Also, this is definitely not noise associated with phantom power - I've experimented with both +48 volts active and passive. The buzzing is present on all usable channels, is both unpredictable and noticeably audible - I can't even really find a good way to reproduce it. Sometimes it's a low underlying hum, and sometimes it phases in and out, often reaching levels that are quite present in the track.

My thoughts are it has something to do with grounding, maybe a ground loop or cable interference, but like I said, I've had a hard time reproducing it. The one thing I've found that helps is if I literally hold the receiver, as if I'm grounding the unit. However, quite often in the field this just isn't and option. I scrub takes and toss footage all the time because it makes the audio track quite unusable. I can't really believe that this is an acceptable take away for the price of these mics. While relatively inexpensive, they're still over $600 for a set.

Any thoughts? I've uploaded a sample of the noise for your listening puzzlement.

Audio Samples - https://vimeo.com/200056783


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Bruce Watson
Re: Strange electronic buzzing with Sennheiser ew 100 g3
on Jan 18, 2017 at 11:21:23 pm

[Jacob Dean] "Also, this is definitely not noise associated with phantom power - I've experimented with both +48 volts active and passive."

You do know that these are battery powered units that should not be fed phantom power at all, right? Turn your phantom power completely off for any channel being fed by a Sennheiser EK 100 receiver.

As to buzzing, I don't actually hear any in your sample. Oh, wait. I went back and cranked the volume way up. There are a couple of tiny short duration wide bandwidth "sparks" at very low levels. Could be a number of things, from a mic cable problem to some level of RF interference to maybe a static discharge (unlikely). I don't hear anything else untoward -- I'm not hearing any kind of hum or any kind of phasing issues (unless the fade up / fade downs in the clip are the doing of some unknown poltergeist).

If all your recording gear records whatever problems you're experiencing, then the problem more or less has to be upstream from the recording gear. That is, the G3s and the cable that connects them to the recorders. The most common things that cause problems are the mic cables, the connectors where they plug into the units, and the most notorious is the batteries used to power the units. Wireless systems are well known to not like rechargeable batteries. They respond much better to very fresh alkalines. If you have to use rechargeables, the only brand I know of that people don't constantly complain about are the Panny eneloops (and even then you have to use an excellent charger).

Personally I've been using Sennheiser G3s for a number of years. I've never had anything but good results. I did have problems once from a Sennheiser "G0" set that got swamped by a cell phone or cell phone tower once. But nothing like that from my own or anyone elses G3s. Highly reliable for me.


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Jacob Dean
Re: Strange electronic buzzing with Sennheiser ew 100 g3
on Jan 18, 2017 at 11:36:25 pm

I'm well aware that phantom power isn't necessary, but I've read enough to know that many people assume that to be the problem immediately - I wanted to eliminate that from the discussion. I don't mean to say the channels are phasing, but that the level of the buzz intermittently dips in and out like phasing. Sometimes the buzz cuts in and out suddenly, as if some circuit was activated. While the levels seem minimal in the previously posted example, that's because I've been battling it for some time.

To clarify the noise, I was able to expose it more clearly using a greater AF Out signal level from the receiver -

To also clarify, I have no doubt the issue lies north of the recording gear. I don't think it's cables because I can observe the problem using both systems (different cables). I never use rechargeable batteries and I've had this problem with an expansive array of battery brands - same result.

And yes, it is like a poltergeist. That's exactly my point. I can't pin it down and I can't eliminate it. That's why I'm trying to see if anyone else has observed it or if I have a hardware problem.


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Bruce Watson
Re: Strange electronic buzzing with Sennheiser ew 100 g3
on Jan 18, 2017 at 11:46:53 pm
Last Edited By Bruce Watson on Jan 18, 2017 at 11:49:34 pm

Better example. That sounds like RF, and digital to me. Might be a cell phone talking to a tower. No doubt you've turned off (airplane mode) the cell phones and pagers, etc. as much as possible. What Sennheiser blocks are you using? In an "RF hell" like Manhattan or downtown LA, or someplace with less RF? Doesn't really sound like broadcast interference.

Mr. Crowley can probably nail this. I'm such an amateur troubleshooter by comparison.


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Jacob Dean
Re: Strange electronic buzzing with Sennheiser ew 100 g3
on Jan 18, 2017 at 11:57:37 pm

I've done those same tests. Woodlands shoots, cabin shoots, I've tried to eliminate all radiation possible. Comes to the surface regardless. Diving into this further, I have been able to accentuate the noise with the receiver close (in proximity) to my camera. It's kind of frustrating considering the logical place to mount the receiver is on the camera. That being said, I still observe the buzz using field recorders separate from the camera.

In what circumstances do you use your G3's?

I've also extended a line of questioning to Sennheiser. Hopefully someone there has observed it before.


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Ty Ford
Re: Strange electronic buzzing with Sennheiser ew 100 g3
on Jan 20, 2017 at 8:52:41 pm

Hello Jacob and welcome to the Cow Audio Forum.

As Bruce says, I also think it's an EMF issue. Was your talent wearing a smart phone during the recording?

Where are you geographically?

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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