Excellent suggestion, John. I'm Sorry I overlooked that.

Why use lavs at all? A PZM boundary layer "conference table" mic or two on the table itself might work better as the mic itself would be farther away from the phones in the participants' pockets than would be the case when they're wearing lavs. The inverse square law can be your friend.

I assume you're feeding the mics via the mixer directly into the camera (my understanding of the requirements of deposition work is that courts get suspicious of edited tapes and double system sound, preferring unaltered originals). Are you also feeding a backup audio recorder? How about outlining your entire recording chain for us from start to finish. I'm wondering if the interference might be finding its way in AFTER the mixer, either in the connection between the mixer and the camera or perhaps even in the camera or recorder itself. Are you sending balanced or unbalanced audio from the mixer to the camera, ie, are the camera audio inputs XLR or are you using a miniplug 'external mic' input on the camera?

Thanks to this thread, I bought three Tascam PR-10 recorders. I'll keep them handy for those times when I have more people on camera than I have wireless mics, or when I need the talent far enough away that the Sennheiser wireless setup won't work (seems to be 40 to 50 yards).

Thanks for the tip!

Okay, bit of an update!

I'm pleased (and somewhat embarrassed!) to report that I was wrong! The Shure SM11 mic does not pick up the GSM interference. I believe the reason for my mistake was I didn't allow enough distance between the Shure and the Audio Technica mic. After I separated them farther from each other, I could tell for sure that the SM11 IS impervious to the noise. My apologies for the false alarm...

Anyway, a couple of thoughts on the SM11:

* This thing is surprisingly large. Not a deal-breaker, but it is big. For video depos, it shouldn't matter, as I don't need to hide them.
* The sound quality on it is okay, but not great. It's not as rich or full as the AT803B mics that I normally use, but I think it would get the job done.

For what it's worth, I DID get a slight bit of interference when I placed the phone right on the head of the SM11 microphone. It wasn't a huge amount of interference, and obviously that's not going to be a problem in the real world.

For those who asked, here's my setup: Microphones (Audio Technica AT803B or Shure SM11) via XLR to the SignVideo ENG-44 mixer. That outputs via XLR to the camera, Sony PD-150.

In my testing, I did also try bypassing the mixer, and connected the mics directly to the camera. No real difference in interference. I did notice, though, if I placed the phone directly on top of the mixer, I would get a little buzz. Aside from that, it doesn't look like the mixer affects things at all, positively or negatively.

As an aside: When my phone was on a call and I brought it within a foot or two of the camera, the camera itself started shaking/vibrating a little bit! Kind of amazing the signal could be that powerful.

Steve: I have actually been thinking about that myself, using a few boundary mics, shotgun mics, or gooseneck mics. I wonder how the audio quality would compare if I used something like that. My AT803Bs sound great by and large, but maybe I can match their quality by using a few boundaries or something.

This is huge progress, and I want to thank everybody for all of their input up to this point! I now know that I can get rid of the interference if I use these SM11s. This is exciting!

Luke,

That's great news! Based on your previous reports, I was pretty sure the SM11 would solve the problem... I'm glad it did so.

As to the size... the specs clearly state the dimensions... it's roughly twice as long as the AT803B. Really, it's about the size of one joint of your middle finger, right? The problem is perception: you're accustomed to pea-size electrets and even Cheerios are big by comparison. Nobody is going to cancel a deposition job because the SM11 is too big. But you might get some complaints about GSM interference. C'mon, be a man, deal with it. ;-)

Two drastically different mics, like the AT803B and the SM11, will certainly sound different. You may be able to somewhat mediate that using some EQ.

For example, I note that the SM11 has about a 4dB peak centered around 9 kHz and extending down to around 7 kHz. The A-T also has a HF peak, but it extends down lower, so that mic might sound as if it has a little more presence. More notably the SM11 low end rolls off notably, starting around 500 Hz; it's down around -9dB at 100 Hz; the A-T is relatively flat down to around 50 Hz, so it will have a lot more balls. You could try applying an inverse curve to the SM11, to make the sound "theoretically flat." However, I'd be careful with that much bass boost, as it will increase room noise and also "thumps" when the talent moves around.

If you wanted to get really involved, you could do a free air test of the two mics, side by side, recording pink noise played through a speaker that's 3 or 4 feet away. Then compare the curves, and apply EQ to the SM11 so that its final response is an approximate match for the AT803B.

Of course too much EQ can cause various problems. But you might consider the above as a starting point if you are really concerned about the sound quality.

Boundary mics can sound quite good for the right application. But of course they will be more susceptible to room noise, paper shuffling, coughs, HVAC, plumbing noise... all things that can detract from the clarity and intelligibility of the deposition. What's your goal?

But just think... now that the GSM problem is solved, you have lots of free time to devote to these other experiments. And you won't need to confiscate phones or hold a gun to anyone's head. ;-)

Happy Trails!

THANKS again for all of the great info in regards to the microphones.

If I'm understanding correctly, the reason the SM11 is "special" is because it's a balanced dynamic mic as opposed to an electret? I was sifting through this thread, and I couldn't see any mention of any other mics like the SM11, but I was wondering if such a thing exists. For instance, Pete mentioned he uses the same mixer I use but with an Audio-Technica AT899 microphone, and he has no problems.

I guess I'm just wondering if the SM11 is a one-of-a-kind, or if there is a collection of such mics that I could choose from. A quick search on B&H for "dynamic lavalier" returned just the SM11 and some $464 Electro-Voice lavalier (Electro-Voice 649B Dynamic Lavalier Microphone F.01U.118.092 B&H).

Anyway, now that I know it's possible to find a lav that is balanced, it's now a matter of finding the best one. The SM11 looks like it will suffice; I'm just wondering what other options there are before I buy anything else.

Also, the idea of the ferrite beads intrigues me too. I might order a few and try them with my existing mics, to see if there's any improvement. Is there any specific type of ferrite bead I should be looking for? Richard mentioned a ferrite torroid, but was saying I would need a large one that would allow the microphone's head to pass through it.

Thanks again, gentlemen! Your expertise, experience, and patience have been a huge help.

There are also ferrite filters that are cut in half so you can snap them around the cable. If you have much of a cable collection for your computer(s) you may already have a cable or two with this kind of thing around it. Either a clip-on version (which can be removed and tested with your microphone) or the molded-on kind (which are not "hackable").

I just did a search on eBay for "snap around ferrite" and got 230 hits.

Remember that you can significantly increase the effectiveness by looping the cable back around through the ferrite bead.

If I'm understanding correctly, the reason the SM11 is "special" is because it's a balanced dynamic mic as opposed to an electret?
That's correct. A dynamic element is just a coil of wire, so it is balanced by default (although you can ground one terminal if you really want unbalanced). An electret element, by its very nature, is unbalanced. Most small electret mics also include a FET impedance converter, which is also unbalanced. They then feed the unbalanced signal down an unbalanced cable to the "power pack" which usually converts to balanced at that point. But there is a lot of unbalanced circuitry in an electret mic.

I was sifting through this thread, and I couldn't see any mention of any other mics like the SM11, but I was wondering if such a thing exists.
I had never given it any thought until I read about your problems. At that point I said to myself, "what Luke needs is a balanced lav, which would have to be dynamic. A few minutes on Google found the SM11, but I've looked since then and have not found any other dynamics that are comparable size.

The SM11 looks like it will suffice; I'm just wondering what other options there are before I buy anything else.
It sounds as if you've already researched that and have found the answer: essentially none.

Is there any specific type of ferrite bead I should be looking for? Richard mentioned a ferrite torroid, but was saying I would need a large one that would allow the microphone's head to pass through it.
The previous suggestions were good ones. If the RF is traveling down the shield of the [thin] cable and getting into the "power pack" then ferrite might help you. I suspect, though, that that's not the modality of the problem. I suspect that the [thin] cable is acting like an antenna, so there is RF voltage at the capsule end, relative to the power pack ground. Since the capsule is unbalanced, that RF voltage then becomes superimposed on the audio output from the capsule, travels down the center conductor of the [thin] cable, and enters the "power pack" on the hot lead. If that's the case, ferrite will not do much good.

Apparently you're not happy with the sound of the SM11, or you wouldn't be looking at $500 E-V microphones. Have you tried my previous suggestions about equalizing the SM11? I think you should try that before doing (or buying!) anything else. Let us know exactly what you do, and how it sounds.

Okey dokey. More news.

I did get my hands on a few snap-on ferrite beads from different cables. I tried putting three of them on a mic, wrapping the thin mic cable around each one a few times, but unfortunately that didn't make any difference.

Two videographers (Pete and another fellow I know) have told me they use Audio-Technica's AT899 mics (Audio-Technica AT899 - Condenser Lavalier Microphone AT899 B&H) for depos with no problems, so those look like real possibilities.

What is interesting, though, is that Audio-Technica has a feature they call UniGuard (Audio-Technica - Microphones, headphones, wireless microphone systems, noise-cancelling headphones & more : Audio-Technica’s UniGuard® technology (http://www.audio-technica.com/cms/features/c7c8449a8a90ba58/index.html)) that seems to do just what I am asking. However, the ES943C (Audio-Technica - Microphones, headphones, wireless microphone systems, noise-cancelling headphones & more : ES943C Cardioid Condenser Lavalier Microphone (http://www.audio-technica.com/cms/wired_mics/c008d27ad2e507b1/index.html)) is the only lavalier mic of theirs that I could find which has UniGuard... leading me to believe that the AT899s do not have it. As an aside, I can't even find any site that sells that ES943C.

Now, naturally if the AT899s are impervious to the cell phone buzz, I don't care what they call the technology. I'm just curious if somebody who knows more about this stuff than I do can read the specs of the AT899s and understand how they could be possibly built/shielded differently to keep out the interference.

By the way, the Shure SM11s aren't BAD. I'm just looking at my different options.

By the way, the Shure SM11s aren't BAD. I'm just looking at my different options.

Did you try equalizing them as suggested, to restore some of the missing bottom end?

I have not tried equalizing, as it would take up a lot of time to equalize each video after the fact so I don't think it would be practical.

As of now, I'm thinking of trying an AT899. Will report back if I do or if I come across some other mic.

Luke,

I'm surprised that it would take more than a few minutes to EQ an entire track (before editing).

What is the total length of one shoot that you're talking about?

The total length varies from 30 minutes to several hours, depending on the length of the deposition.

I don't know that the EQ itself would necessarily take a while, but it would require a few more steps in the process. Instead of simply having a master DVD that is good to go, I would have to rip it, EQ it, render it, and burn it.

I thought we were talking about DEPOSITION recordings here? Why are we worrying about EQ? Speech intelligibility is the #1 requirement for the sound track here. Certainly absence of interference noise (including cell phones) is a significant factor. But I fail to see how subtle tonal changes is even worth discussing.

Now if we were talking about a big-time dramatic production that would be a different matter.

Richard,

I'm inclined to agree with you. As I see it, there are two important issues for deposition recordings: they should be noise free, and the intelligibility should be good. The mic in question solves the first issue. The mic's LF rolloff will not have any adverse effect on intelligibility; in fact it might improve intelligibility because it will reduce pickup of LF room noise (air handlers and the like) as well as bumps and thumps when the person moves around and bumps the mic. The problem is solved (assuming the OP is really recording depositions, and not doing something else).

Yet now the OP is unhappy because this mic's response is not the same as a mic which he was unable to use because of cellphone interference. [extraneous blather removed]

Luke,

As I see it, if you really want more LF but are unwilling to devote any time to achieving that, you have two choices at this point in time.

First: go on an unending quest for another -- different -- better -- more super deluxe -- microphone.

Second: use a mixer like the Mackie 802-VLZ3 which has some analog equalization. Crank up the LF boost about half way and that will restore a lot of the bottom end to the Shure mic, so it sounds more like the [useless] electret that you like. (Remember that the LF boost by itself will add to room noise and LF thumping noises, but the Mackie also has a LF cut switch to get rid of the really low end.)

Of course you will probably find something you don't like about the Mackie. And, indeed, we haven't tested it for GSM/RF immunity so I can't speak to that point.

FWIW, I've been given to understand that ANY post-production manipulation of the recording - editing of any sort, sound sweetening, whatever - can get the testimony in a video deposition invalidated and tossed out of court. I've been told the only thing acceptable as evidence is the original camera raw footage and the only "editing" allowed being in-camera editing, stopping tape when the attorneys agree to go off the record and resuming recording before going back on the record. Even an exact duplicate copy of the original recording is unacceptable in some courts - the only valid evidence being the actual camera original media.

Interesting, Steve, and that may be valid.

If that is the case, would it be acceptable to use some analog EQ as part of the recording process? Or would that also be taboo?

Interesting, Steve, and that may be valid.

If that is the case, would it be acceptable to use some analog EQ as part of the recording process? Or would that also be taboo?Just guessing but I would think EQ during recording would be acceptable as its use would be clearly known by the attorneys for both sides.