PRO TIPS: The Infamous Lavalier Microphone

Today I’d like to talk about a piece of gear that is one of the most difficult, yet common in the corporate audio world.

The Lav (Also know as a Lavalier, or a Lapel Mic).

It’s a rebellious little beast, that sometimes seems to be working against you by it’s very design. To understand how to utilize this thing properly, and actually make it work for you and not against, it’s design is the first thing you should understand. For todays post, I’ll be focusing on the most common lav mic that I have used, the Shure MX184.

The MX184 is a supercardioid electret condenser mic, with a frequency response of 50Hz-17kHz.

As you can see from the specs sheet here (if you don’t know what you’re looking at, I’ll be writing more basic audio posts, so stay tuned!), the mic is only truly accurate between 400Hz and about 6kHz, with a boost around 8kHz to about 15kHz. This curve is specifically tuned for spoken vocals, as these are the main frequencies of the human voice. Great right?

Well, it depends. Because of the response curve it has, it always sounds very mid-rangey (like speaking into a tin can) no matter how well you place it. The physical attributes of the mic (the fact that it needs to be small, and somewhat far from it’s source due to mounting) make it extremely tricky and sensitive to use. However, it is still one of the most popular mic options in the corporate realm, as it provides freedom of movement and attention for the presenter.

So, I’ve put together three big tips for using lav mics in the corporate audio environment, to hopefully enable you to get the best audio possible.

Tip 1: Mic Placement.

Now hopefully I’m not starting a little too basic here, but it all starts with placement. Let’s start with mic position:

You want your lav to be between 6-8 inches from the source (or their chin). This usually lands the mic above the “nipple” line by an inch or two (generally speaking).

 

Now, you want to be above the “nipple” line, but not above the shoulder line, as too far up will muffle the person’s voice due to the mic being shadowed by their neck. You also want to keep it within range of the presenter’s voice, so when mounting to either side of center, try and keep it around the “sweet spot” line (the thinner dotted line).

Because lavs are so sensitive, a difference of a few inches will drastically change the sound the mic will give you, so your goal is to land the mic right in the “sweet spot” every time.

Please note, this is primarily intended to be used as a general distance guide. In the field you will encounter many different types of clothing and physiques, so you will have to use your best judgment on how to place each time.

I have found (within the live corporate audio realm) that no matter how you have to mount the lav, as long as it’s stable (it won’t fall off during the show), within range, and pointing at the source, you will most likely be ok.

Mounting can be tricky though, especially for the ladies wearing dresses. Guys tend to have it easier as far as corporate clothing options (suit and tie is the easiest of them all!), but the ladies usually have a more difficult time.  When dealing with dresses, if possible, find a place to clamp on the hem or collar in the sweet spot (if there is a collar). Also watch out for dangling jewelry, as it will interfere by scratching and bumping the mic when the presenter moves. If you have to mount off to the side, try to determine which side the presenter will be speaking to the most, and mount it there. And always make sure it is pointed as directly toward the chin as possible!

Most ladies don’t wear belts with dresses (unless you know something i don’t??), so the transmitter pack is also difficult to place.  If there are absolutely no other options, either clip it upside-down on the top edge of the dress behind the presenters neck, or clip it (or have someone do it for you if you are a guy) on the bra strap in the back.

I’ll go into a complete “lav mounting guide” in another post, but this at least covers some general difficulties.

Tip 2: Speaker Placement.

Ok, so this tip precedes the placement of the mic as far as timeline goes, but if you have control of the setup, and know you will be mixing lavs during the show, optimizing speaker placement is your best defense against feedback.

If possible, always try and have your speakers as far forward and away from your lav-bearing-presenters as possible. Sometimes this takes a bit of creativity to also ensure proper room coverage, and as always, it takes proper knowledge of your gear. Here is a recent example of mine:

For this setup, we had a very wide seating arrangement, and a larger number of lavs. My best option was to go wide and straight with the main speakers, and then fill in the front-middle with front fills from the stage.  The goal here was not only coverage of the audience, but keeping the stage as clear as possible from potential feedback.  Most speakers will have a wider coverage area than you think, so always play it safe when it comes to lavs and keep the speakers pointed as far away from the stage as possible.

Tip 3: Ringing Out The Room.

Ok, now we’re on to a more advanced, and yet, very critical subject.

Ringing the room is the process of equalizing the mic to the specific room/setup of the event. It requires someone to be on stage (another tech) wearing the lav properly, and speaking while the engineer works the console.

First though, this requires the right gear. You at least need one graphic EQ (such as THIS) in addition to the channel strip EQ of your console (I usually use an Ashly Protea Graphic). If you are working a smaller event with a small board (such as a Mackie 1402), you will need an in-line graphic EQ to use either as an insert, or as a final stage EQ. Example:

Final Stage EQ:

Inserted EQ:

I put the Ashley Graphic EQ in the second example because it has four different channels to choose from. If you wanted, you could even run your mono output to the PA through the last channel, and have an added layer of EQ!

Hopefully in your setup, you’ll have the flexibility of a digital console, such as an LS9, or one that I use often, the QL5, which has multiple layers of routing and EQ available internally. This is especially useful, as you can EQ each set of speakers differently based on their proximity to the stage. You can also set groups of mics, and EQ each group collectively and independently. This allows you to leave pre-produced inputs (such as music or video audio) untouched, so they won’t be “chopped up” by your work on the lavs (That also goes for the insert EQ setup above). Whichever of the three situations, the technique is very similar to ringing out the room.

One note: You want to mimic how the show is going to run as closely as possible, so you can tune the room accordingly. Ringing out the room with the mic in a different place than it will be during the show will give you a false representation, and ultimately bad results.

Once your assistant (or presenter, if you have a rehearsal and it’s the appropriate time) is on stage with the lav on, start bringing up the volume.

To start, make sure your levels are up enough to get signal, and you have your EQ’s ready. I generally start each lav with a high-pass filter engaged to about 160Hz, and a general deep mid-range scoop around 1kHz.  Your first goal is to get the lav to sound as natural as possible using the channel strip on your console.

My general rule of thumb is to use the channel strip to get the lav sounding as natural as possible, and then use the graphic EQ to eliminate problematic frequencies.

Once you’ve got a fairly natural sound, it’s time to move on the dangerous part. In order to find the problematic frequencies, you have to crank up the volume to the brink of feedback. BE CAREFUL!!  Feedback can get out of control very quickly! Try raising the gain very slowly, and only until you just start to hear some ringing. The moment it starts, you have enough gain!

Once you hear the ring, try and identify what frequency it is, then gently attenuate that frequency on the graphic EQ (try no more than -3dB to -5dB to start with.) You can also “search” for what frequency by gently boosting one frequency at a time on the graphic (just until slight ringing) until you find the frequency you are looking for.

Continue with this process until you are either satisfied with the stability of the lav, or you are having to push the gain to unreasonable levels in order to attain a ring.  There will always be ringing at some level, you will not be able to eliminate all of them. The goal here is to stabilize the performance of the mic during the show. Remember what your show volume level is. If you are pushing the volume past that without feedback, then you are safe.

If you find that you are attenuating a large amount of frequencies across the spectrum, I would urge you to flatten everything, and start over. It’s all too easy to work yourself into a corner doing this, as once you attenuate one frequency, the balance shifts to higher level of gain in the spectrum, so other frequencies become more apparent. Attenuating on a majority of frequencies only results in an overall loss in gain, which you will have to make up elsewhere, and it turn, will raise your noise floor.

Questions?

I hope you found these three basic pro tips useful and informative. Please feel free to comment with any questions or topic requests. I’ll be sharing more of my experience and knowledge in various forms in the future, so stay tuned!

Peace & Happy Mixing

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