Saturday, April 21, 2012

Mixing In The Theatre

Sooner or later you're going to find yourself behind the console in a theater and these are some things you're going to want to know.

Let's start with mics. Actors on lavalier mics are really the only way to go to capture a natural performance, it's not so easy though. Most typical is to go with an omnidirectional condenser. What? You mean with all those mics out on stage you want all omnis out there? Yes, they have better frequency response and a cardioid should only be used as a last resort, if at all. You'll find that it's well worth the tradeoff in signal bleed to have the most sound available, and you've also got the option to pick up adjacent actors with the actors that are miced.

So now you've got a troupe of actors, all wearing mics on stage and you start to mix, but holy cow is there a lot of feedback. Back up a bit and start with one mic, out at the mix. Keep turning it up and keep touching those graphic EQs on the house mix until you've got the channel gain up nice and high. But wait? You don't start by turning down a bunch of frequencies on the channel? Heck no! If you use up all your EQ fighting feedback you won't have any left to shape the sound of the individual actors. Since it's quite likely that if one mic feeds back at 250 Hz so will the rest of them, just notch it out once and move on. Also if you have a high pass filter of any sort, activate it on every lav channel. Most consoles have at least a button for roll off below 80 Hz and if you're lucky to have a sweepable low pass, get that sucker up to about 160 or 180. Except in the rarest of cases, those frequencies will never be needed to help the performance and with a host of mics open you're going to cut out a ton of rumble and room noise that comes from summing them, saving precious watts for intelligible vocals.

So now that you've got the room tuned for worst case scenario, a mic out in front of the mains, you need to further tune it on stage. Grab an actor and have them wear the mic on stage and say something. Any phrase will do, some lines from the show, their phone number or email if they're cute, whatever. Still not touching the channel EQ, get busy on the graphs again until you have even more gain at your disposal. A good tip to remember when on the graphs is that if you've touched more than half the faders you should flatten it out and start over.

Now you're ready to put the fleet out there and see how it sounds. Well, not quite. If you have any dynamic processing on hand you have to figure out where to use it. If you're lucky enough to be on a digital console and have full gating, parametric EQ, de-essing and coffee brewing at your fingertips you're set to go. If you've only got a couple channels of compressors from Guitar Center you have to decide where they'll do the most work for you.

If you've got an actor with a ton of dynamic range you could insert a comp on their channel, and really, compression-per-channel will get you the best results, if you've got the time and focus to get it done. But a little trick that will save you time, win you fame, fortune and the girl, here's what you do. Insert a comp on each sub-group that you have at your disposal and route the mics to them in groups. A common patch that I use is one sub each for male and female chorus members, and the same for male and female leads. This way when you've got one or two actors out there, you'll only compress if they really belt it. But when the whole cast piles on, you'll be compressing pretty much continuously to some extent, evening things way out and saving the audience from painful spikes. The only pitfall to avoid is too much compression which flattens out the mix. When comping on the groups it's good to go with a fairly low ratio, no higher than 3:1 and have it kick in pretty early (low threshold) so that you don't get pumping in the mix. But there's no juicy tidbit of knowledge here that will save your butts kids, use your ears, learn the box.

With that said you can finally hand those suckers out. But not just willy-nilly. First of all you will have conveniently hidden all the clips that come with the mics and armed yourself with medical tape, band-aids, barrettes, and a host of bobby pins. The actors will just loose the clips anyway. Have the actors square the body pack away somewhere and attach the pickup in the best possible location.

Top of the head is really good. It keeps the mic pointed away from reflections from the floor and walls and also helps a little with isolation between actors on stage. Place the pickup just at the hair line and hold it in place with a pair of bobby pins in an X or with a barrette. Add a couple more moving toward the back to secure the wire and finish up with a piece of transparent medical tape at the nape of the neck. If there's not enough hair to pin to up there or if the costume doesn't permit, then try to tape the element just behind their jaw. Both of these methods keep the distance from the element to the actors mouth the same so you don't get different levels as they move around. If all else fails, just pin it to their costume and pray.

Now that they're finally out on stage with their mics, the director will immediately start harassing you about how the show sounds. If you can't block them out then go have a nice conversation about how you need at least five minutes before you achieve perfection. After you tweak the trims you can finally touch those channel EQs. Note that you may have to reduce the gain setting on the pack itself if a particular actor is really belting and causing it to clip.

A couple quick tips about channel EQ. First, roll off the bass. Just do it. You probably don't need it in 99% of cases and it'll still be there if you want to put it back. But don't. The low mids can be tricky but this is where you'll earn the right to say “that's why they pay me the big bucks” (or nothing and misspell my name in the program but hey, it's not about the money). You'll be tempted when things don't sound clear to grab some highs and turn them up. If you do this a team of audio specialists will come around and smack you, there is no escape so get this through your head. When you can't hear something it's usually because there's something else in the way.

For guys, take a real hard look between 160 Hz and 300 Hz. This is the mud room. If you don't know exactly what to take out then turn down the gain on your low mids about 6 dB and sweep the frequency back and forth until they sound the clearest. Then slowly turn the gain back up until they don't sound tinny. For girls, you want to look a little higher, from 600 Hz up to about 1.5 kHz and do the same thing to take care of any harshness.

You'll want to stick at this for quite a while, until you're absolutely positive that you can do nothing else to improve the sound. Then and only then can you start to add just a little low mid to the girls to fill them out a little and maybe put a little of the low end back on the guys so they sound nice and manly. If at any time you feel like you're having trouble deciding what frequencies to touch there's a little trick where instead of cutting the gain and sweeping around, you raise it and sweep. When it sounds the worst you then cut that frequency. You may need to warn people that you're doing this as it can be quite disconcerting to listen to. You may even need to find some down time to spend with each problem actor to get it right when nobody else is around.

That's about it for the lavs. Now let's talk about area mics a little. A lot of schools have a pair of hanging mics that a director will want you to use. They're not as common in other venues because what they're really intended for is getting a decent recording of the Christmas concert. They should never ever be routed to the main mix and if you do those same guys will be around to administer a smack or two. I may be one of them. Those are usually omnidirectional and by putting them in the mix to try and catch a line or two from upstage you're just going to get room noise or Uncle Ed coughing in the twelfth row or the pit band. Do. Not. Do. It.

Instead go for a row of pencil condenser mics, or some PZMs if you can get your hands on them, across the front of the stage. These are directional mics and will serve to help keep room noise, the pit band and Uncle Ed out of your mix. The Three To One rule states that the distance between two mics should be at lest three times the distance from the object being miced. Chances are you have what you have and you'll be working around pit musicians so just do the best you can. Most PZMs are basically omnidirectional though so instead of placing them flat on the floor, which basically turns the floor into a big mic, try mounting them on a smaller vertical surface like a piece of plexi or a music stand. I've had good results and bad doing that so try some things out. Keep in mind that the size of the plane it's mounted to will affect the frequency response.

EQ the heck out of them, insert graphs on their group if you're able, and keep cranking the gain. The more you can get out of them the better chance you have of picking up that stray line, or saving a scene when a lav goes dead. If you're able to hang some up stage, or mount them on the set then that will help as well and you can pick and choose as fits the scene. In general though you're not going to use them much unless a lav dies and you're left grasping at straws. You can help out a big choral number some, but with a bunch of lavs on stage you can usually get a pretty good blend.

Well, that's about it for the basics. You're now ready to venture out into the world of theatre and deal with all this stuff on a nightly basis for your bread. Oh yeah, and also all the attitudes, cranky directors, back stage drama, stage parents, bomb scares, pregnancy scares and fire alarms you can handle. Good lu- er... break a leg.


  1. I should mention that I have had success with choir mics for reenforcement. It was either on systems that were designed specifically for that theater, or only for large group number with lots of people far upstage. In all cases the mics were not omni.

    First, the theatre that I'm talking about is a 3/4 thrust, and they have an array of 5 small speakers hanging from the ceiling addressing each section of their audience so they never really have to get very loud. These speakers are specifically for the 5 Shure MX202s hanging from the ceiling to pick up dialogue. All of the other audio that happens in the show is pumped out of a pair of clusters hanging stage back stage left and stage right.

    They hang 5 Shure MX202's around the stage to cover it evenly. Then they only use the wireless for soloists when it's needed. The pit is hidden back stage which helps too. I should mention that this paticular theatre doesn't do musicals all that often, but in the hands of the right engineer and sound designer, they sound great.

    Also, I use a pair of AT Pro45s for one of my shows every year to catch the large group vocals when the stage is full. It's a very deep stage so the upstage mics are far away enough away from the mains to make a difference with feeding back.

    Anyways, that's my $.02.

    Great posts as usual.


  2. I should have specified that I wrote that article about a year ago for kids that mix in the high school theaters in my area. They've all got omnis hanging up for some reason, probably because the chorus teacher mentioned in the planning meetings that they'd like to be able to record the Christmas concert.


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