Grounding issue with wireless lavaliers??

E

EdRicker

Active member
Hi all,
I recently bought 2 Sennheiser G3 EW112 wireless lavalier systems (A and B bands) and have been using them for weddings and interviews.
I've noticed that I'm getting a lot of seemingly random humming that doesn't seem to be related to frequency interference. I scan a new frequency list each time I turn the receiver on.

My situation: Say I need to interview 4 people separately, one after another. The mic sounds great with the first 3 people, and I have the transmitter sitting next to them for convenience since they're sitting. Then all of a sudden I'm getting bad humming when I connect the mic to the 4th. They don't have a cellphone anywhere near them or any other interfering devices. After scanning a new list just in case, I realize that the issue can be resolved by the person simply HOLDING the transmitter and essentially "grounding" it. Okay fine, but then why didn't the first 3 people have to do that too???

Other the weekend, I shot a wedding and was getting MAJOR humming from the lav on the pastor before the ceremony. On a whim, I switched out rechargeable AAs with some regular AAs and it fixed it...but why would rechargeable and regular AAs be different in that respect???

These things are being so temperamental, and I can't find a rhyme or reason for it because seemingly identical situations are producing different results. I've never once been able to duplicate the issue when testing alone, so it's frustrating to occasionally run into the problem when I'm actually working with people.

Shooting with a Panasonic AG-DVX200 if that makes any difference.

Anybody have any insight? Would be greatly appreciated.
Thanks!

Update: Here's a video of one occurrence of the problem.
https://www.youtube.com/watch?v=slQiFFQnN44
Sound was fine up until 0:05 when he raises his arm. As you see, I actually switch out the ME2 mic with another one at 0:55 and same issue.
 
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If you are SURE there are no cell phones nearby, it sounds like an intermittent connection between the thin wire and the lav mic. That is a very common place to have a wire break and cause intermittent symptoms as you describe.
 
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Radio mic's don't tend to like standard rechargeable batteries as they only put out 1.2v.

As for the grounding it could be that you have a faulty cable ?
 
GaryNattrass said:
Radio mic's don't tend to like standard rechargeable batteries as they only put out 1.2v.

As for the grounding it could be that you have a faulty cable ?
Click to expand...

Thanks for the replies so far guys.

Yes, it may be a faulty cable...I'm attaching a video of one specific time where I switched out one Sennheiser ME2 mic with another one.
https://www.youtube.com/watch?v=slQiFFQnN44

This was halfway through the interview, and I had just interviewed 3 people prior without problems. Everything was fine up until this point in the interview.
When he raises his arm 5 seconds into the video, a low and constant hum begins. I noticed it live in my headphones, so we stopped. We decided to switch mics at 0:35 (switched at 0:55) and the SAME PROBLEM occurred, but WORSE! After I cut the video, I asked him to simply hold the transmitter and that stopped the hum immediately.
Frequency was not an issue because I had literally just scanned a new list.

I might just send both ME2's into Sennheiser for a repair.
 
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Since there's no physical connection with other gear plugged into AC power, a ground loop (50/60Hz hum) issue can be ruled out when using a battery powered receiver. However a compromised cable from the mic element is common can cause intermittent noise. Interference can also come up w/o warning.
Yes, rechargeable AA batteries are 1.2 volts, however in my tenure using the G2/3 series, I've never had any issues with them. There are not for everyone though, and takes additional organization skills (and a reliable charger) with the two-battery sets. Aside from that, the battery meters cannot be a very accurate indication of remaining power with the inherent non-linear discharge characteristic.
 
The popping sounds like a bad wire. My guess would be the mic wire is damaged. They are very delicate, especially where they go into the mic.

Please note that, that is not really a radio issue but a lav issue.

This is, of course, just and educated guess based upon my own prior experience. Could be something else entirely.
 
EdRicker said:
I might just send both ME2's into Sennheiser for a repair.
Click to expand...
If your ME2 is broken at the cable that can be easily repaired, Most any locations aound shop can fix the connector endif it's broken at the element, repair is usually not an option and must be replaced.. it that's the case, it would be more economical to purchase a third party mic with the locking 3.5mm plug. OST mics are a good choice, (search this forum for opinions) they're affordable and sound very good. (about $120USD) Basically the ME2 is a POS.
 
EdRicker said:
I might just send both ME2's into Sennheiser for a repair.
Click to expand...
If your ME2 is broken at the plug end, that can be easily repaired and most any location sound shop can fix it. If broken at the element end, repair is usually not an option and must be replaced.. it that's the case, it would be more economical to purchase a third party mic with the locking 3.5mm plug. OST mics are a good choice, (search this forum for opinions) they're affordable and sound very good. (about $120USD) FWIW, the ME2 is a POS.
 
Rick R said:
If your ME2 is broken at the cable that can be easily repaired, Most any locations aound shop can fix the connector endif it's broken at the element, repair is usually not an option and must be replaced.. it that's the case, it would be more economical to purchase a third party mic with the locking 3.5mm plug. OST mics are a good choice, (search this forum for opinions) they're affordable and sound very good. (about $120USD) Basically the ME2 is a POS.
Click to expand...

Agreed, Oscar SoundTech lavs would not just be a great replacement but they're even a smart upgrade to get before your stock lavs wear out. I've ordered a set of them myself.
 
Rick R said:
If your ME2 is broken at the plug end, that can be easily repaired and most any location sound shop can fix it. If broken at the element end, repair is usually not an option and must be replaced.. it that's the case, it would be more economical to purchase a third party mic with the locking 3.5mm plug. OST mics are a good choice, (search this forum for opinions) they're affordable and sound very good. (about $120USD) FWIW, the ME2 is a POS.
Click to expand...


Thanks for your help everyone. Instead of repairing, I decided to purchase a new lav and see if that's the cause. If it is, then I'll purchase a second new one as well. Taking this in stages just to make sure.
 
I had a similar issue with these same units and it drove me crazy for a while. It was the cable. I went for a pair of Countryman B3's and wow(!) better mic, better cable & hardware, better sound, easier to hide, all around worth the additional money. I liked the B3's so much I bought a pair of B6's with XLR direct connect (not for wireless) and they are even better. I have no scientific proof, but I believe that the Coutrymans may last better because they come in a fancy travel case that holds the mic capsule and plug securely in place in the case so that they are not banging around in the same box as the wireless unit, the way I was keeping the gear previously. Human nature is such that when you pay a lot of money for something you may be more prone to treating it better.
 
After a year or two of use both my ME2 lavs were giving me varying degrees of noise on movement. I bought a pair of Countryman B3's and never looked back. Better sound, easier to hide, less handling noise. After seeing what a difference a good mic makes I bought some B6's that are even easier to hide. Better mics are usually really worth the money.
 
I had a similar issue with one of my three Sennheiser G3 sets. Narrowed it down to one of the lavs. It was dirt cheap to get a local tech to replace the 3.5mm plug assembly; I just lost a couple of inches off the cable to facilitate that.

I don't really need top of the range lavs for the work I do so at the same time I bought several lavs from Aspen Mics.

http://aspenmics.com/

I bought the versions without the securing screws so that they are a better fit when going straight into the likes of a Zoom H1 or a 3.5mm cam socket. I've stuck very small cable clips to the relevant gear to ensure the cables can't be accidentally yanked out.

The Sennheiser lavs clips fit the Aspen mics fine and are more practical than the ones that come with the Aspen lavs, so I bought a few more of those.

Pete
 
"I bought the versions without the securing screws so that they are a better fit when going straight into the likes of a Zoom H1 or a 3.5mm cam socket."
- FWIW, the collar on the TecNec M-3.5S locking plug retracts enough to be fully inserted into a flush mounted 3.5mm jack. If the jack is recessed, as is the case on my portable IFB transmitter, it may not..
 
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