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 Community Theater Green Room Discussion Board :Producing Theater :Lights and Sound |
 Topic: Setting mic levels on a mixer board |
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marlym
Walk-On 
Joined: 3/24/09 Location: United States Online Status: Offline Posts: 4 |
   Topic: Setting mic levels on a mixer boardPosted: 5/30/11 at 11:03pm |
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Hi all, does anyone know if the process for setting levels on a mixer board for laveliers is the same as setting levels for regular wired mics like SM58's? I followed the process of using the solo button and bringing up the trim on my board to make sure I've got a good signal before moving up the sliders. Got a lot of high frequency feedback and the mics generally seem to run hot. I'm missing something. Are there some special considerations when setting levels with wireless mics, specifically lavs and headsets. I have a Mackie mixer. Edited by marlym - 5/31/11 at 7:25am |
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PaulyWally
Player 
Joined: 2/03/11 Location: United States Online Status: Offline Posts: 28 |
Posted: 5/31/11 at 12:09am |
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I know some sound, but I'm not an total expert. That said, here's what I think:
You're doing the basic setting right, but you need to compensate for the fact that these aren't hand-helds (i.e. - not right up to your mouth) and they're wireless. First, try and backoff on the trim a little bit. If I recall correctly, Mackie suggests that you bring the trim up until the clip light begins flashing (because Mackie designs their clip lights to flash just BEFORE clipping occurs). Second, use the channel's EQ to tweak the frequencies where you are experiencing trouble. Third, don't forget that you (should) have some type of trim/gain on your wireless receiver module. Between that and your mixer's trim, you're running 2 pre-amps back-to-back. So you can try 2 different things with this: One, keep the trim/gain on the receivers as low as possible and use the trim on the mixer to boost the signal. Or keep the trim on your mixer as low as possible and use the trim/gain on the receivers to boost the signal. Every show and every theatre is different. Play with both, and see which works best for your situation. |
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marlym
Walk-On
Joined: 3/24/09 Location: United States Online Status: Offline Posts: 4 |
Posted: 5/31/11 at 2:54am |
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Thanks! I've looked on our receivers to see if there's some type of trim/gain and that's a negative. I do have 3 settings on the transmitters "-10dB", "0" and "mic". I'll try those.
Edited by marlym - 5/31/11 at 7:26am |
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David McCall
Celebrity 
Joined: 1/28/09 Location: United States Online Status: Offline Posts: 299 |
Posted: 5/31/11 at 1:14pm |
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I always start by setting the faders near full and then adjust the trims to a point just below feedback. Ideally you would do this when you are alone in the room, because feedback drive some people crazy. That gives you a maximum level for all of your inputs.
If you found that you were getting feedback at similar frequencies, then yo might want to dip those frequencies a little on your output EQ to see if you can improve your headroom.
Hopefully you will be able to back-off the individual trims once you get into rehearsal. There is usually a "0" marking toward the top of each fader. I like to set the individual trims so that the desired level for that mic is near that "0" mark. You may also want to adjust the individual EQs to improve the sound of each mic.
If this fails to be adequate on some channels and you still need more gain, then you will have to fiddle with the individual EQs to reduce the frequencies that are still feeding back.
A note of caution regarding EQ adjustment. You must always be aware that any EQ that you add is technically adding distortion to the signal. The less you can get away with the better. If you "ring out the room" by notching out all of the frequencies that are feeding back you will soon find that you have chopped up your bandwidth so bad that everything sounds strangely distorted. EQ is usually necessary, but try to keep it a subtle as possible.
What kind of mics are you using? We are using the over the ear mics with dual ear clips from www.microphonemadness.com and we like them a lot. They keep the mics near the actor's mouth, unlike clip-ons where the sound changes whenever the actor moves his head.
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David M
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museav
Lead 
Joined: 11/06/09 Location: United States Online Status: Offline Posts: 38 |
Posted: 5/31/11 at 3:31pm |
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Signal level is signal level so the process should generally be the same. That being said, output levels, gain before feedback, etc. may be quite different.
What are the wireless units? That might really help a lot as there are often concealed trim/gain controls on the transmitters and either selectable output levels or different levels on different connectors on the receivers.
In general, with a handheld or headset/boom the mic is usually fairly close to the mouth but with a lav it may be some distance away. That can mean both having to apply greater gain at the mixer in order to get the same level and it being more susceptible to feedback.
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Brad W.
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marlym
Walk-On
Joined: 3/24/09 Location: United States Online Status: Offline Posts: 4 |
Posted: 6/01/11 at 12:06am |
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We're using Countryman B3's with Shure transmitters and receivers. This year we tried the "halo" position, near the hairline and it worked well. Just a big hassle when your doing fast mic changes. Yep, my students share mics, which complicates everything.
Yeah, EQ is a mystery to me most times. I'm looking for anything online that would help train me in the proper EQ of a show, specifically musical theater. What should I be listening for? What should I be considering when setting the EQ for a bank of 12- 13 wireless mics? Am I even asking the right questions?
Still another problem is properly mic'ing the ensemble sound. Boundry mics and choral mics just feedback on me. I'm totally stumped there.
Starting with the faders near full huh? No fear! That's crazy awesome! Gonna try that for next year's show.
Edited by marlym - 6/01/11 at 12:18am |
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Marly M.
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museav
Lead
Joined: 11/06/09 Location: United States Online Status: Offline Posts: 38 |
Posted: 6/01/11 at 9:00am |
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What model transmitters and receivers, e.g. PG, PGX, SLX, ULXS, ULXP, etc.? The output signal format and level could vary and some of the issue might be as simple as having a much 'hotter' output from a wireless mic receiver than you get from wired mics.
Equalization can have several purposes, for FOH probably the most common are to try to increase gain before feedback or to create some desired subjective/artistic result. The latter is purely what sounds right. EQ for feedback should really be a last step, a common situation is to try to use EQ to compensate for issues best addressed in other ways and that can lead to the problems David noted.
A simple example relates to boundary and choir mics. Keeping in mind that any increase in level applied will apply to everything the mic picks up, the more you can increase the level of the desired source, the less gain you then have to apply for that source. Each time you halve the distance the mic is from the source you effectively create a 6dB increase in the source level at the mic, which translates to 6dB less gain required for the mic input and thus 6dB more resistance to feedback. A handheld or headset/boom mic may be a couple of inches from someone's mouth but a boundary or choir mic many feet away. That alone can make boundary and choir mics much more susceptible to feedback, for example changing from a mic being 3" away to 10' away could be up to a 32dB difference in the gain before feedback.
It might also be that you are encountering issues with sources being picked up by multiple mics. If multiple mics picking up the same sounds are mixed together this can both increase the resulting overall level and alter the resulting frequency response. So for that tender duet between the leads where they face each other, approaches such as dropping the level or even muting one mic are common.
Another factor in this can be the relationship of the mic location and it's directionality or pattern to the location of the speaker and it's directionality or pattern. Many times simply moving a mic or aiming it slightly differently can provide much more gain before feedback than can be achieved via EQ and do so without incurring the negative aspects of extreme equalization. I have seen cases where aiming hanging or choir mics to maximize the rejection of the sound from the speakers actually provided better results than aiming the mics to maximize the pickup of the vocals. These types of issues are always best directly addressed rather than by trying to compensate with EQ.
I'm guessing the reason for that is simply a safety factor that you then can't exceed that level. But what is more important, and where I have to differ with David a bit, is that addressing EQ and feedback is best done with as close to the actual conditions as possible. Not only can the acoustical environment of the space change, but there are a multitude of stories out there of factors such as cupping the mic, wide brimmed hats, etc. affecting feedback as a result of either modifying the pattern of the microphone or producing reflections of sound into the microphone.
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Brad W.
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David McCall
Celebrity
Joined: 1/28/09 Location: United States Online Status: Offline Posts: 299 |
Posted: 6/01/11 at 9:41am |
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Well, you wouldn't just start out with the fader at the top`the trim/gain would be all of the way down and you would ease the fader up, just in case :-)
99% of the problem with sound systems start before you even turn on the power. If you are getting nothing but feedback from hanging or boundary mics, it is probably because there isn't much to get. It is getting so bad that I've heard of actors asking for monitors on stage because they can't hear each other. What do you suppose would be the problem there? The actors need to learn to speak up and speak clearly.
In fairness, there can be issues with the orchestra being too loud especially if they are sitting in front of the stage. A good orchestra can get quiet enough to hear good actors without a sound system, and weak but decent actors to be heard with a good sound system. I've even heard a piano drown out the actors by playing too loud. One group that I work with has taken to putting the orchestra backstage with great success.
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David M
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David McCall
Celebrity
Joined: 1/28/09 Location: United States Online Status: Offline Posts: 299 |
Posted: 6/01/11 at 10:20am |
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Mr. Lowell (Dana) made an excelent post in the topic "mic feedback" well worth a read/
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David M
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marlym
Walk-On
Joined: 3/24/09 Location: United States Online Status: Offline Posts: 4 |
Posted: 6/04/11 at 12:09am |
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Hi all, we’re running Shure SLX transmitters/receivers. Sounds like what you’re all saying is to use EQ sparingly for feedback, if at all. Feedback sounds more like a physical issue of placement, costumes, and actors after you’ve learned how to set your knobs correctly. We’ve worked over the years on finding good placement for our mics on the actors, diction/projection of our actors and muting as many mics as possible, especially between two actors who are close together. Orchestra is not an issue because we use a CD accompaniment. I just want to know that I’m setting my gear correctly and that my level settings are not the reason for the feedback. I’ve always thought that primary purpose of EQ was to assist in reproducing a person’s voice/ instrument as accurately as possible, so I often wonder how sound engineers are able to address both. I guess you could use the 2 knobs that control the mid-range sweep (is that it’s term?) on the Mackie, but finding the mic that’s feeding back is a challenge let alone the correct frequency that's feeding back. I run 12 – 13 mics most times and I can’t imagine running the 15 mentioned in the Mr. Lowell’s brilliant post. “A sound system is only intended for 20% ENHANCEMENT of acoustical voices – for clarity sake – not for delivering 100% of the singing. It’s theater, not radio!” I love that! We’ve already implemented a lot of Mr. Lowell’s suggestions: mic checks before the show, multiple mic runners, prompters, the script marked with mic cues and mic plots which include the mic switches during the show. I’ll trying placing the boundary mics differently, and setting the levels then bringing them down a little. Or if I’m feeling brave, I’ll try David’s way. Thanks guys! : ) |
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Marly M.
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