Sennheiser wireless lav kit popping/cracking noise...

S

Shaunmlavery

Member
Let me preface this with, I don't have a ton of experience with field recorders and wireless systems. I have recorded in a "studio-like" environment but that was always for fun.

My issue with my current setup is as follows: I have been renting a Sennheiser EW112P3 kit with a ME2 lav. Thus is being recorded directly into a Roland R26.

Now, this has been far better than my experience with the zoom line as far as the interface and knobs. I had an issue with noise but I dealt with it and the second time out was better prepared.

The second time I rented it, everything was going smooth, I was monitoring the audio with headphones. Next thing I know, cracking and static. Ok, made sure the batteries were fresh, the mic wasn't rubbing any clothing and the transmitter antenna wasn't damaged. Everything looked good.

I proceeded lightly and it was still there. I had to do multiple takes in case I was screwed once I started editing. It nearly happened but I was able to save it.

My question, does this sound like a broken mic wire, are these transmitters/receivers cheaply made? I'm a firm believer in "you get what you pay for."

Below is a sample of the cracking noise. It's towards the end of the audio file.

https://www.dropbox.com/s/mf56pu8544edavu/R2600042.WAV

Thanks for your advice.
 
Sounds like radio interference... could be anything from someone using an intercom to a passing truck with a CB radio. Doesn't sound like a damaged mic or receiver wire (but of course that doesn't rule it out).

Any chance you were using rechargeable AA batteries? An audio engineer friend had pointed to that as a possible source of interference issues I had with my G's last year after I swapped over to rechargeables, as their nominal voltage is lower than alkalines. FWIW, rarely had problems after swapping back to even the cheapest alkalines.
 
RF noise. Did you do a frequency scan to find clear-ish channels before you started? What kind of batteries? Did you make sure the transmitter antenna wasn't touching any skin?

In any case, good on ya for monitoring the audio with headphones -- this, is why you do it.
 
Guys/Gals, thanks for the prompt help and advice.

As as far as batteries go, just regular alkalines. I quit using rechargeables after having issues during something else.

Radio frequency/ interference: I did swap he channel once but that was before I noticed this issue. I was unaware of the "scan" feature. These are still new to me.

Touching skin...I was thinking this but I felt crazy! The talent is wearing a dress. I feel his is going to be an art in itself, hiding the body pack and lav. Any suggestions there to eliminate that? I was going to suggest the talent wear a "belt" of some sort with the dress so I could clip it there. This isn't going to be a fix for everything though. Haha

Again, thank you for your knowledge you are offering me so far! I just want to make sure I'm on the right track before I purchase these. I feel like everyone saying "RF" kind of points at operator error. That should be a quick fix by hitting the scan button. Needles to say, I didn't have a user manual. YouTube got me off and running.
 
Shaunmlavery said:
Radio frequency/ interference: I did swap he channel once but that was before I noticed this issue. I was unaware of the "scan" feature. These are still new to me.
Click to expand...

Now that you know, it's a crucial step. These systems are never set-it-once. If the location changes, the RF usage may also change. And even from day-to-day, depending on what other portable/mobile RF sources are moving through the area, things can change.

Shaunmlavery said:
Touching skin...I was thinking this but I felt crazy! The talent is wearing a dress. I feel his is going to be an art in itself, hiding the body pack and lav. Any suggestions there to eliminate that? I was going to suggest the talent wear a "belt" of some sort with the dress so I could clip it there. This isn't going to be a fix for everything though. Haha
Click to expand...

It is absolutely an art form, but there are lots of tools out there to help! As far as the transmitter pack is concerned, there are belts made specifically for this purpose. For an actor wearing a dress, there are small belts that allow the pack to be strapped to the thigh... potentially awkward, but a very effective way to hide a pack in a dress and to keep the antenna away from the skin.

There's a really good resource out there called "Down to the Wire" that walks the reader through all sorts of methods for hiding both the transmitters and the lavalieres. I know it's available on iPad through the iTunes books store. Google it for other platforms. It's well worth the read. The other good resource to look at, which covers a broader spectrum of production sound, is the Sound for Film and Television tutorial video available on DVXUser. Not focused on dealing with wireless systems, but as you are learning more about production sound it is a handy resource.

Shaunmlavery said:
I feel like everyone saying "RF" kind of points at operator error. That should be a quick fix by hitting the scan button. Needles to say, I didn't have a user manual. YouTube got me off and running.
Click to expand...

It is and it isn't operator error. It is insofar as you do need to go through a proper setup of the system every time you use it, which includes scanning for a clear frequency. It isn't due to the fact that any wireless unit is vulnerable to RF interference by its very nature. It uses Radio Frequency transmission, and the airwaves are cluttered just about everywhere you go.
 
Last edited:
Alex H., thank you for your in-depth reply. I know there is a huge learning curve for me. Being around audio in different aspects, I knew this was going to be tough to tackle out of the gate. Nonetheless, I had to give it a shot to get my feet wet and have a base where I could begin improving.

With everyone's advice and the two resources you listed, I think I will be well on my way. All that is needed now is the investment from me in myself.

Again, thank you for your replies and time you have taken to read my posts, listen to the audio and offer your knowledge.
 
The clip exhibits typical RF interference or a reception issue.
As Alex stated wireless are never set-it-once-and-forget it.. no matter how expensive the system.
Search this and the DVinfo forum for my postings on frequency selection. The receiver's scan function is a good place to start. However it only IDs significant RF. For optimum RF performance, most pros use an external RF scanner and/or the Sennheiser on-line Frequency Finder ( http://en-us.sennheiser.com/service-support-frequency-finder ) or Spectrum Bridge ( http://whitespaces.spectrumbridge.com/whitespaces/home.aspx ) to find vacant or low level frequencies/channels in a given area.
 
Rick R., those links prove to be invaluable! The Spectrum Bridge link was very fast and efficient. I can't wait to compare this with the G3 packs next time I have them in hand! The way it looks, it will be another week before I start on another project.
 
Also, if anyone cares to offer there opinion on the price point of the Roland R26 I'm using. Is that the best "bang for the buck" for what I'm doing. 1-2 sources and mainly the lav and possibly a shotgun in the future. I still have a ton to learn but I don't want to "outgrow" this in a year or so.

I know money is a factor for this... Just curious.
 
Shaunmlavery said:
Also, if anyone cares to offer there opinion on the price point of the Roland R26 I'm using. Is that the best "bang for the buck" for what I'm doing. 1-2 sources and mainly the lav and possibly a shotgun in the future. I still have a ton to learn but I don't want to "outgrow" this in a year or so.

I know money is a factor for this... Just curious.
Click to expand...

There's a sticky that talks about the various benefits and challenges of different recorder designs. That's a good starting place.

In short, though, you will outgrow any handheld recorder eventually, and likely sooner rather than later. A more "bag-friendly" machine that is a bit more future-proofed to go with any other surrounding kit you may acquire is going to be your best bet.
 
For the G2/3, the Sennheiser/FCC site shows the relative RF strengths. A frequency(s) within a vacant TV channel is preferred, or a far away/low power with the lowest level strength channel. (for instance, a Prx of -80dBm is good -90dBm is better)
At the location, always manually check for extraneous RF as well. Transmitter off, pilot tone mode temporarily deactivated.
When using multiple units, stay within one frequency bank to avoid inter-modulation issues.
 
Another source of noise like this is the 1/8 plugs on both the transmitter and receiver. Of course both have the little mini nuts to secure them, but if left slightly loose and allowed to rotate or wiggle, can make some similar noise. This is most likely to happen with the transmitter located on the talent. Not saying this is the case, but this hadn't been mentioned and illustrates one of the weaknesses of those damn little plugs. In particular, I always carry a spare 1/8 to xlr since they are pretty hard to find short of BH or an audio store.

Grant
 
Rick/Grantly, again, thank you guys so much for the time spent replying to the thread and offering the links and advice. I will take this with me on the next time out.

I knew the recorder topic was touchy...If it were me and I were spending the money, I would put it out there and just grab a nice one but that's not the case...
 
Just a short update for those that offered their time and advice to me. I took the gear back to the rental company and informed him of the issues. We talked about it and he took care of me, Dodd Camera and Hal in Cincinnati have been great.

I went back last week to grab the same gear to shoot some more footage regarding this project. When I arrived, he informed me that the mic did in fact have a short and he ordered a replacement for that kit.

So, with that said, what a learning experience with these wireless lavs! As soon as I got to the recording location, I found that SCAN feature to eliminate that issue. Haha

Again, thanks to all that offered their knowledge and advice. I'm considering myself lucky this time for being able to salvage the audio files.
 
Just a warning...everyone seems to say the scan on these systems only detects significant rf, not everything on location. You might look into a standalone rf scanner because i think stuff that the unit cant detect can still ruin your day.
 
Also, if it's a beltpack receiver, do the scan outdoors. The building you're in might turn a steady interference into an intermittent one that the scan might miss. I had that problem with my Sennheiser wireless. Scanning outside took care of it.
 
This is probably gonna sound stupid, especially with such great advice and info from the good folks on this thread. But there was a moment when I had some issues with my g3's and we boiled it down to the iPhone. For some reason with all the iPhones in the room caused some interference and static. Like I said it sounds dumb, I'm not a sound guy but I shoot a lot, my 2 cents. Thanks :)
 
Smart phones, and the iPhone is the worst at this, "call home" periodically and will cause all manner of audio problems. I used to leave mine next to the mixer for class presentations so in the middle of the lecture you would get this ungodly "modem" like modulation through the speakers. Then I would point out that is what will be on you production tracks if you do not make all your crew AND actors turn off their cell phones. Helped drive the point home.

Not stupid at all, it's a problem even with all wired systems.
 
You must log in or register to reply here.
Back
Top