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Title: Mic sensitivity vs gain
Post by: Aaron Kennedy on January 17, 2018, 08:43:38 pm
Can someone help me understand the difference between Mic Sensitivity and audio board gain. Is there any advantage between turning one down and the other up? I constantly battle feedback when running the board for our schools musical. We typically run 15 wireless sennheiser mics along with a few wired mics. We have two different sets of monitors and then the house. We also have about 15 pit instruments (not micd). When I first try setting everything up, I tone out all the mics, but after a few rehearsals I am battling everything again. I'm assuming that I just have things too sensitive. The biggest issue is ensuring the actors can be heard over the pit. Any advice is appreciated.

Thanks
Title: Re: Mic sensitivity vs gain
Post by: Ivan Beaver on January 17, 2018, 09:02:33 pm
Can someone help me understand the difference between Mic Sensitivity and audio board gain. Is there any advantage between turning one down and the other up? I constantly battle feedback when running the board for our schools musical. We typically run 15 wireless sennheiser mics along with a few wired mics. We have two different sets of monitors and then the house. We also have about 15 pit instruments (not micd). When I first try setting everything up, I tone out all the mics, but after a few rehearsals I am battling everything again. I'm assuming that I just have things too sensitive. The biggest issue is ensuring the actors can be heard over the pit. Any advice is appreciated.

Thanks
You can play all the "gain games" you want, but the real end result will not change.

Gain before feedback is based on many factors, NONE of which are mic gain, or any gain settings on the console.

Let's say your system has a maximum gain of 100dB before feedback. Let's say there are 4 gain stages.  It does not matter if 1 stage has 97dB and others each have 1 dB or each one has 25dB, the end result is 100dB.

If you work through various PAG-NAG equations, you will realize that the thing that makes the biggest difference in gain before feedback is getting the mic closer to the source.

There are other factors, location of speakers, pattern of speakers, response of the system, eq of the mic and so forth.
Title: Re: Mic sensitivity vs gain
Post by: Mac Kerr on January 17, 2018, 09:15:08 pm
Can someone help me understand the difference between Mic Sensitivity and audio board gain. Is there any advantage between turning one down and the other up? I constantly battle feedback when running the board for our schools musical. We typically run 15 wireless sennheiser mics along with a few wired mics. We have two different sets of monitors and then the house. We also have about 15 pit instruments (not micd). When I first try setting everything up, I tone out all the mics, but after a few rehearsals I am battling everything again. I'm assuming that I just have things too sensitive. The biggest issue is ensuring the actors can be heard over the pit. Any advice is appreciated.

Thanks

What are you talking about? Mic sensitivity refers to an intrinsic characteristic of a given microphone, how much voltage it puts out for a certain level of input. It is not something you can change. Input gain is the first stage of gain that raises the very small voltage that the mic puts out to a high enough level to overcome either the internal noise of the mixer electronics, or the digital resolution. To get a better signal to noise ration you run the mics with more input gain, to prevent overload you run them with less.

The other gain points you pass through would be the output levels of the mixer, and for balancing the levels of the performers and/or instruments, the input faders.

The biggest cause of feedback that you are probably running into is using stage monitors with lav type mics. It takes a pretty skilled operator to mix a musical with monitors, and it takes a lot of turning down mics that aren't active. In a Broadway musical the mics get mixed on a line by line basis. And there are minimal monitors that have the lav mics in them. Monitors are about letting the cast hear the important parts of the band, piano for pitch, snare and hat for timing, etc.

Ivan explained about how where in the signal chain the gain comes does not impact feedback, it is the total gain through the system, microphone to speaker.

Mac
Title: Re: Mic sensitivity vs gain
Post by: Corey Scogin on January 17, 2018, 11:47:06 pm
What are you talking about? Mic sensitivity refers to an intrinsic characteristic of a given microphone, how much voltage it puts out for a certain level of input. It is not something you can change.

He's referring to what most wireless mic manufacturers (if not all) call the input gain setting on the microphone transmitter. In Aaron's defense, they do call it "sensitivity".
Title: Re: Mic sensitivity vs gain
Post by: Len Zenith Jr on January 18, 2018, 12:03:37 am
Is there any advantage between turning one down and the other up?

There is but it isn't gain before feedback. Having a weak signal that needs a lot of gain at the end of the signal chain increases noise in the system as the huge increase in gain at the end also increases the noise floor from all the components in the chain the same amount. A strong signal to begin with reduces that.
Title: Re: Mic sensitivity vs gain
Post by: Debbie Dunkley on January 18, 2018, 12:40:25 am
Speaking of such things.....
The singer in one of  Chris's bands uses a wireless Senny EW100. There is a local venue that they play with an in house PA which is one of the few places the band doesn't use me for sound. Each time they play there I have to turn her mic receiver sensitivity up at least 12db from what we normally use to get that board to even recognize the signal. The gain has to be way high on the channel input too.
I use a A & H QU-PAC and the venue uses a A & H GL ( 2400 I believe). That seems quite a difference.
Title: Re: Mic sensitivity vs gain
Post by: Len Zenith Jr on January 18, 2018, 01:02:14 am
^^ Sounds like a mic/line level issue. Look for a switch/push button on the board.
Title: Re: Mic sensitivity vs gain
Post by: Scott Holtzman on January 18, 2018, 01:45:47 am
^^ Sounds like a mic/line level issue. Look for a switch/push button on the board.

There is a line pad on the Gl2400 just above the input gain.

Title: Re: Mic sensitivity vs gain
Post by: Chris Grimshaw on January 18, 2018, 05:52:31 am
If they're going in on 1/4" jacks, the desk might be expecting line-level and will need plenty of boost to get it back up again if the receiver is putting out mic-level signals.


To the original poster, chances are things like mic positioning is changing, possibly without you knowing. Maybe you've got directional mics and someone's clipped them on upside-down or something silly like that.
However, stage monitors in a situation like this is just asking for trouble, IMO, unless you're extremely careful with what you send to them, and keep the volume low.

Chris
Title: Re: Mic sensitivity vs gain
Post by: Debbie Dunkley on January 18, 2018, 09:38:39 am
Unsure which position that channel pad switch is on the mixer - I assumed it was correctly set because all the other vocal mics and drum mics are fine. The guys who run the sound do it all the time and I didn't even consider the pad switch because it such basic thing.
I don't get to see the mixer - and I don't really involve myself too much in the sound. It's one of the rare occasions I get to  go as an audience member and I have a few drinks.
Title: Re: Mic sensitivity vs gain
Post by: Stephen Swaffer on January 18, 2018, 09:49:09 am
The first few rehearsals in situations like this -inexperienced actors ( its a school so they are learning) and even those who are unsure of their lines is that your source "signal" will (usually) be very weak and will naturally come up as they gain confidence in rehearsals.

Your (my) urge is to push everything up and get it perfect the second rehearsal.  I've learned it is better to work with the director and focus on projection and mic placement first.  Then as they gain confidence and project, you can manage your mic levels better- hopefully only having 1 or 2 challenging actors to try and maximize their volume.
Title: Re: Mic sensitivity vs gain
Post by: Aaron Kennedy on January 18, 2018, 11:59:38 am
I really appreciate all the advice. I've already learned quite a bit from this forum. I have no doubt that the mics are not placed in the same place each time, and you're right that they are students and learning (just as I am the teacher learning to operate a Pro board) I still don't know why a school has a Midas Pro 2 instead of something easier to use...  In any case. The mics, unfortunately are omni directional lavs placed at the hairline. The good news is that I have toned them out so the feedback issue isn't coming from the monitors. Surprisingly, most of my feedback at this point is low frequency coming from house speakers. 
Title: Re: Mic sensitivity vs gain
Post by: Dave Garoutte on January 18, 2018, 12:15:51 pm
I have some over ear wires that mount my lav mics (Senn MKE2).
It puts the mic right beside the mouth.
I don't remember where they came from, though.
Title: Re: Mic sensitivity vs gain
Post by: Tim McCulloch on January 18, 2018, 12:21:14 pm
I really appreciate all the advice. I've already learned quite a bit from this forum. I have no doubt that the mics are not placed in the same place each time, and you're right that they are students and learning (just as I am the teacher learning to operate a Pro board) I still don't know why a school has a Midas Pro 2 instead of something easier to use...  In any case. The mics, unfortunately are omni directional lavs placed at the hairline. The good news is that I have toned them out so the feedback issue isn't coming from the monitors. Surprisingly, most of my feedback at this point is low frequency coming from house speakers.

First - high pass filter the individual mics.  Except for a bass singer you can probably start around 150Hz for men and 200Hz for women.

Second, don't put body mics in monitors, especially ensemble performances.  It makes a big wash of vocals that don't time align to the mains and individual singers will never hear themselves so what's the point?  If your solos/duos/trios can't hear themselves ask yourself WHY?  Is the pit too loud?  That's a MUSIC DIRECTOR issue that needs to be addressed by the MD and and play director.  If the band/orchestra is that loud on stage, guess what the actors microphones are picking up?  Loudest sound at the mic is the winner...

Third, click on Kevin Maxwell's name* and from his profile, click on "show posts".  He's got lots of tips and suggestions for working in musical theatre and his writing is worth finding.

* Edit PS - use the member directory to find Kevin's name/profile.  I mistakenly thought he'd replied to this topic.
Title: Re: Mic sensitivity vs gain
Post by: Keith Broughton on January 18, 2018, 01:20:31 pm
Having re-read the OP, I have some thoughts. Get the system gain structure in  order to start with.
First, the mic gain or sensitivity on the wireless transmitter pack is set so you get a good solid audio level to the receiver (with that actor)but not so much as to overload the pack.
Then, set the input gain to the channel to get a solid level to that channel without clipping the channel input.
Neither of these will reduce feedback but this is a good place to start.
You mentioned low frequency feedback so don't be afraid to high pass those channels aggressively!
Now you can apply the needed channel fader gain to start mixing but, as indicated, don't get caught up in getting the "perfect" sound during rehearsals.
Audio like this can be tricky but remember this is supposed to sound natural and just "lift" the voices up enough to be heard....that's all.
The audience should have to listen and you can't beat them over the head with lavs.
Title: Re: Mic sensitivity vs gain
Post by: Jeremy Young on January 18, 2018, 03:26:50 pm
If the Pro2 is too much for you, I have a simpler mixer I'll trade you straight across for..... just kidding.

OMNI mics will have a hard time with monitors at the best of times so don't feel too down on yourself.  Good on you for seeking out advice, and those who have spoken before me have offered great advice already. 


If your primary issue is low frequencies from the backside of the mains (the lower the frequency, the longer the wavelength and the harder to control pattern) you might benefit from more aggressive high-pass filtering on the inputs (reducing sensitivity to those problematic frequencies) or (if possible, and it's probably not) changing the deployment strategy of the main speakers to reduce LF energy on stage. 

In your first post you said "two different sets of monitors".  Do you mean different locations, different brands, different configurations...?  In the world of gain-before-feedback, having all of your monitors match (brand/model) will give you a consistent pattern and frequency response on stage and makes your job of keeping feedback at bay a lot easier. 


When I went from a selection of hodge-podge mis-matched monitors to all matching models/brand wedges, I found it it was much easier to tame the feedback on stage for the work I do (which is not theatre, full disclosure, but the theory still applies).
Title: Re: Mic sensitivity vs gain
Post by: Aaron Kennedy on January 18, 2018, 05:59:43 pm
Once again. I really appreciate the replies. I can't tell you how helpful this forum has been. I've been on many other forums for various topics that aren't even 10% as helpful. Mostly, I appreciate that you didn't come on here and just slam me for being a novice.
Title: Re: Mic sensitivity vs gain
Post by: Debbie Dunkley on January 18, 2018, 06:15:43 pm
Regarding omnis vs cardioids in lavs.... I can get my cardioid WL185 WAY louder than my Shure CVL omni lav mic before feedback and tend to use it much more over the omni for that reason.
I agree with Jeremy that your job would be made much easier if you switched to cardioids where possible.  Even with my headset mics where the mic is literally touching my mouth, I can get the cardioid much louder than the omni before feedback.
Title: Re: Mic sensitivity vs gain
Post by: Tim McCulloch on January 18, 2018, 07:12:43 pm
Once again. I really appreciate the replies. I can't tell you how helpful this forum has been. I've been on many other forums for various topics that aren't even 10% as helpful. Mostly, I appreciate that you didn't come on here and just slam me for being a novice.

What, the Welcome Committee missed you?  They'll find you eventually!

Dave Stevens, the founder of the original Live Audio Board forums conceived of it as a community.  Like any real community there are folks you like having as neighbors and a few who don't get it, whatever "it" is.

Most of the folks here want to help but that help comes in different flavors and much of it comes with some schooling - hopefully you get more understanding instead of just an answer.  Stick around and meet the regulars, use the forum search (or use google with the " site:forums.prosoundweb.com " filter to find topics you're interested in.  Between the current forums and the archived, read-only FUD forums there are roughly 14 years of forum posts.  That's a whole lot of reading enjoyment/rabbit holes. ;)

And the memo to the Welcome Committee about missing your newbie abuse... 8)

Have fun, good luck.

Tim Mc
Title: Re: Mic sensitivity vs gain
Post by: Stephen Swaffer on January 18, 2018, 10:20:21 pm
Regarding omnis vs cardioids in lavs.... I can get my cardioid WL185 WAY louder than my Shure CVL omni lav mic before feedback and tend to use it much more over the omni for that reason.
I agree with Jeremy that your job would be made much easier if you switched to cardioids where possible.  Even with my headset mics where the mic is literally touching my mouth, I can get the cardioid much louder than the omni before feedback.

Provided you can control how the mic is positioned.  I tried a cardiod lavalier at our church a few years back,  with somewhat better results- until one speaker decided he liked it clipped sideways to his tie. :(
Title: Re: Mic sensitivity vs gain
Post by: Mike Locke on January 18, 2018, 10:44:27 pm
I find that the way the mics are mixed will go much further to have a great sounding, feedback free performance. 

Yes, cardioids can be less prone to feedback.  If their positioning is correct and they're not turned up too much.  But any variation in placement will cause a large sonic difference, something that's less of an issue with omnis. 

Having mics closer to the sound source does let you run them at a lower gain.  But hairline placement is so often done because the sound quality of the hard bone of the forehead (or cheek bone, just in front of the ear) is much better than on the fleshy part of the cheek.  I find much less EQ is required.  And there's aesthetics as well. 

And no voices in monitors, if you can at all prevent it. 

Only having mics on for actors that are speaking is the real key.  Mac mentioned line by line mixing, which means there's not a bunch of extra inputs summing into your mix.  It takes practice, but the rewards make all the difference.  You might find yourself in a middle ground with a school show: not quite line by line, but off in an actor doesn't speak for a handful of lines.  This also helps with the unpredictability of non-professional actors jumping or dropping lines. 

There are a few youtube videos showing an operator mixing line by line.  Les Mis and Legally Blond (https://www.youtube.com/watch?v=2_d--J8z92I) I believe  A good place to start to understand the technique.

Mike
Title: Re: Mic sensitivity vs gain
Post by: Steve M Smith on January 19, 2018, 03:08:12 am
You can play all the "gain games" you want, but the real end result will not change.

Gain before feedback is based on many factors, NONE of which are mic gain, or any gain settings on the console.

Let's say your system has a maximum gain of 100dB before feedback. Let's say there are 4 gain stages.  It does not matter if 1 stage has 97dB and others each have 1 dB or each one has 25dB, the end result is 100dB.

If you work through various PAG-NAG equations, you will realize that the thing that makes the biggest difference in gain before feedback is getting the mic closer to the source.

There are other factors, location of speakers, pattern of speakers, response of the system, eq of the mic and so forth.

I am amazed by the number of people I have found who don't believe this.


Steve.
Title: Re: Mic sensitivity vs gain
Post by: Ivan Beaver on January 19, 2018, 07:28:05 am
I am amazed by the number of people I have found who don't believe this.


Steve.
It is yet another audio myth.  And you can detailed explanations of how to "adjust it".

But yet the end result never changes-just the physical position of faders, which makes people "think" they are getting more gain.

Oh well--------
Title: Re: Mic sensitivity vs gain
Post by: Aaron Kennedy on January 19, 2018, 08:39:39 am
Thanks again. I will say that the mics and monitors we have are what we are stuck with for now, but the feedback I was receiving was coming from house anyway. I made a few adjustments and last nights final dress rehearsal was much better.

I do program the board so my scenes only have mics on for characters onstage/speaking. Our typical show will have somewhere around 80-100 cues. I learned that very quickly after my first show many years ago. (That was a real nightmare).
Title: Re: Mic sensitivity vs gain
Post by: Keith Broughton on January 19, 2018, 09:02:04 am
. I made a few adjustments and last nights final dress rehearsal was much better.


Please give us some details on what "few adjustments" helped.
Title: Re: Mic sensitivity vs gain
Post by: Joseph D. Macry on January 19, 2018, 10:59:55 am
I really appreciate all the advice. I've already learned quite a bit from this forum. I have no doubt that the mics are not placed in the same place each time, and you're right that they are students and learning (just as I am the teacher learning to operate a Pro board) I still don't know why a school has a Midas Pro 2 instead of something easier to use...  In any case. The mics, unfortunately are omni directional lavs placed at the hairline. The good news is that I have toned them out so the feedback issue isn't coming from the monitors. Surprisingly, most of my feedback at this point is low frequency coming from house speakers.
The educational advantage to having the Midas is that your tech theater students can learn the workflow of a modern, professional digital mixer. I maintain five PACs in a local district, the newer ones got Roland V-mixers, the older ones got Soundcraft "digi-log" mixer which emulates analog workflow and was easy swap-out with old analog board. So depending on which school a student goes to, he/she gets to learn the old or the new way of working the board.
Title: Re: Mic sensitivity vs gain
Post by: Keith Broughton on January 19, 2018, 11:43:53 am
The educational advantage to having the Midas is that your tech theater students can learn the workflow of a modern, professional digital mixer. I maintain five PACs in a local district, the newer ones got Roland V-mixers, the older ones got Soundcraft "digi-log" mixer which emulates analog workflow and was easy swap-out with old analog board. So depending on which school a student goes to, he/she gets to learn the old or the new way of working the board.
It helps having a nice cup of tea and a bisquit when figuring out the Midas ;D
Title: Re: Mic sensitivity vs gain
Post by: Tim McCulloch on January 19, 2018, 12:02:51 pm
It helps having a nice cup of tea and a bisquit when figuring out the Midas ;D
Bisquit = Xanax bar to deal with the frustration.

A nice cup of tea = large rum-bearing beverage to celebrate with.

8)
Title: Re: Mic sensitivity vs gain
Post by: Roland Clarke on January 20, 2018, 05:35:16 am
Regarding omnis vs cardioids in lavs.... I can get my cardioid WL185 WAY louder than my Shure CVL omni lav mic before feedback and tend to use it much more over the omni for that reason.
I agree with Jeremy that your job would be made much easier if you switched to cardioids where possible.  Even with my headset mics where the mic is literally touching my mouth, I can get the cardioid much louder than the omni before feedback.

In theatre applications cardioid microphones on the talent are rare, take any west end or broadway show and the actors mics are almost exclusively omni dpa’s.  Depending on the theatres set up this can be a problem, not so much in the mainstream theatres these days as sound systems are generally of the “zoned” variety.
Title: Re: Mic sensitivity vs gain
Post by: Scott Bolt on January 20, 2018, 10:11:05 am
You can play all the "gain games" you want, but the real end result will not change.

Gain before feedback is based on many factors, NONE of which are mic gain, or any gain settings on the console.

Let's say your system has a maximum gain of 100dB before feedback. Let's say there are 4 gain stages.  It does not matter if 1 stage has 97dB and others each have 1 dB or each one has 25dB, the end result is 100dB.

If you work through various PAG-NAG equations, you will realize that the thing that makes the biggest difference in gain before feedback is getting the mic closer to the source.

There are other factors, location of speakers, pattern of speakers, response of the system, eq of the mic and so forth.
Wow!  Well said.  I can't even count the number of forum discussions I have had to argue this point with people. 

The best way to determine how well a mic responds to real life, is to put the mic in the real-life situation and compare it to how other mic's do in that same environment.

All supercardioids are NOT created equal when it comes to GBF.

It has been my experience that lav mics tend to be the worst offenders in the GBF realm.  Not really sure why and YMMV.
Title: Re: Mic sensitivity vs gain
Post by: Ivan Beaver on January 20, 2018, 10:25:19 am


All supercardioids are NOT created equal when it comes to GBF.


People "assume" that a directional mic will get them more gain, due to the rejection.

But that ONLY happens in the areas of the directivity.  In many cases, the null of the mic is NOT pointed at the speaker, so it is not doing any good.

And since the pattern is tighter, any movement of the mic or the head of the talker will greatly affect the direct (intended) sound arriving at the mic to change, so the levels go up and down with natural movements of the head.

I agree that in certain situations a directional lav mic might give more gain, but THE WHOLE picture needs to be looked at, NOT just one little part.
Title: Re: Mic sensitivity vs gain
Post by: Kevin Maxwell on January 20, 2018, 01:50:24 pm
Wow!  Well said.  I can't even count the number of forum discussions I have had to argue this point with people. 

The best way to determine how well a mic responds to real life, is to put the mic in the real-life situation and compare it to how other mic's do in that same environment.

All supercardioids are NOT created equal when it comes to GBF.

It has been my experience that lav mics tend to be the worst offenders in the GBF realm.  Not really sure why and YMMV.

Really long reply as usual. You should see how long winded I am if you ever talk to me.

Are the “Lav” mics really the “worst offenders in the GBF realm”? Take a standard vocal mic and put it in the same place that the “Lav” is and you will most likely find that you have very similar gain before feedback with both mics. If you put a vocal mic on the chest of someone you won’t get as good a result as you will if they were to talk right into it. Or take the vocal mic and hold it on your forehead facing down to simulate a hair worn mic. It isn’t the same as when you use the vocal mic as it was intended. I like to say to some people using a vocal mic whether for talking or singing “Swallow the mic”. But I actually really just want them to be consistent. Most “Lavs” don’t have very good rejection of wind noises like your breath. If you have ever tried to talk directly into a “Lav” you will find that it is very intolerant of being used that way. The “Lavs” are always used in a way that isn’t ideal for gain before feedback for any mic. But if you set things up right and use proper techniques you can get pretty good results. I have had 30 wireless mics on people on stage with a pit band playing pretty loud and I also have apron mics and hanging mics all on and have no problems at all with gain before feedback. This is for the big numbers. Someone recently told me that the mics might be too loud and I told them the director likes it loud. I have also thought that it was a little too loud. I might try and drop the next show a little bit.

As with any show the placement and configuration of the sound system is critical. Also the linearity of the sound system makes a big difference. So you are already at a disadvantage in theater because of the mics and you want it as good as it can be. I wouldn’t want to do a show in the places I usually do them without having the delay speakers that we do.

You may have noticed that I was putting Lav in quotes. I did that because I think we use the term “Lav” when it would be better to explain more what exactly we are referring to. So I want to try and define Lav mics. Lav is short for Lavalier which has to do with something that is hanging around your neck. The first Lavs were on a string hanging around a person’s neck and they were big (HUGE) by today’s standards.

What is commonly called a Lav today is a very small mic with a clip, to clip it on a tie or other piece of clothing. It is usually used for things like talking head on air talent. It is also used for people during a panel discussion for a more relaxed look, whether that be live or video.

For theatrical presentations it is more common today to use a head worn mic. Which is usually just a Lav type of mic without the clip. The advantage is that the relationship of the mic to the mouth stays the same. Sometimes the mic is worn thru the hair and it come out on the forehead and sometimes it is an ear worn mic, narrowing down the definitions to exactly where the mic is. Some ear worn mics are very short and only come to just past the ear. Some are long and come down by the mouth. And a lot of those are too long and then you have problems picking up the breath sounds. I don’t understand why they insist on making them so long. I have been lucky in that the directors I work the most with don’t care about the mic being hidden they want the sound to be the best it can be.

As with any other mics the loudest thing wins, as someone already said. This comes to shows with a loud band and if one of the other actors is a lot louder than the others. Especially if there is lot of fast interactive stuff with the actors really close to each other. When I say close I mean they are face to face and sometimes shouting. I did a show recently where one of the actors was going to get shaving cream on their face to simulate getting shaved. So the director wanted him to not have the mic down by his mouth. I tried to tell him if he watched the video of the Broadway production of the show he would have seen that they don’t put shaving cream on that side of his face. So we had the mic up by his ear. The director wasn’t happy with the sound but the main cause wasn’t so much with how the actor himself sounded but all that was going on around him. So the director then said they will fake it with the shaving cream and put the mic like it was on everyone else. And he said if he ever told me to do something like that again to remind him about this show. And this brings up the consistency issue, I want all the mics on the actors to be worn the same way. When you have some hair worn mics and some mics really close to the mouth on other actors it makes for one more complications. I also like the mics to be consistently placed on each actor from performance to performance.

One of the problems that I have noticed is vocal projection it seems to have become a lost art. I recently said that I think the actors aren’t being trained for stage acting but for TV or film where they will most likely go in and redub the vocals.

Just some thought and ramblings.
Title: Re: Mic sensitivity vs gain
Post by: Keith Broughton on January 20, 2018, 03:41:05 pm

One of the problems that I have noticed is vocal projection it seems to have become a lost art.


There you have it!
I had to make a coffee to get through that post ;D
Title: Re: Mic sensitivity vs gain
Post by: Kevin Maxwell on January 20, 2018, 05:02:02 pm
There you have it!
I had to make a coffee to get through that post ;D

I don’t write posts I write novelettes.  8)
Title: Re: Mic sensitivity vs gain
Post by: Ivan Beaver on January 20, 2018, 06:30:03 pm
I don’t write posts I write novelettes.  8)
The "problem" is that complicated topics don't have easy, simple answers.

There are a lot of "depends", and variables.

Where people become "better", is understanding all of the issues, NOT just one or two that they get "locked onto".

BTW, I totally agree that performers simply don't project anymore, they way they HAD to in the past.

My opinion is, If you want a group of people to hear what you have to say, SAY IT LOUD so as to address them.  Physical conditions being the exception.

If you whisper, I assume you don't have any confidence in what you are saying/performing, and trying to "hide".
Title: Re: Mic sensitivity vs gain
Post by: Scott Bolt on January 20, 2018, 08:31:18 pm
Kevin,

Thanks for the novelette ;)

Perhaps you are right.  If you clipped the capsule of a normal mic onto your tie clip, then turned the gain up enough so that you could work with the signal the mic was getting from that distance, you would absolutely have more feedback problems that the same exact microphone capsule being used 1" from the lips of the performer singing into it.

I really hate lavs ;)  I understand the need for such a device (I have used them for wedding ceremonies mostly), but they are a real test of my nerves sometimes.
Title: Re: Mic sensitivity vs gain
Post by: Mike Caldwell on January 20, 2018, 10:37:52 pm

If you whisper, I assume you don't have any confidence in what you are saying/performing, and trying to "hide".

And those are the people who are chosen to be the MC or keynote speaker at events!!
Title: Re: Mic sensitivity vs gain
Post by: Peter Morris on January 20, 2018, 11:38:40 pm
You can play all the "gain games" you want, but the real end result will not change.

Gain before feedback is based on many factors, NONE of which are mic gain, or any gain settings on the console.

Let's say your system has a maximum gain of 100dB before feedback. Let's say there are 4 gain stages.  It does not matter if 1 stage has 97dB and others each have 1 dB or each one has 25dB, the end result is 100dB.

If you work through various PAG-NAG equations, you will realize that the thing that makes the biggest difference in gain before feedback is getting the mic closer to the source.

There are other factors, location of speakers, pattern of speakers, response of the system, eq of the mic and so forth.

Absolutely - BUT -  I often see people using hand held radio mics with the gain set too high on the transmitter. This often results in the mic compressing the signal as it overloads the companding circuit.  When they stop singing the gain effectively increases and feedback occurs.

The solution is to have the gain set correctly as indicated by the meters on the receiver (apologies if someone else has covered this)

 https://en.wikipedia.org/wiki/Companding
Title: Re: Mic sensitivity vs gain
Post by: Kevin Maxwell on January 21, 2018, 12:39:32 am
Kevin,

Thanks for the novelette ;)

Perhaps you are right.  If you clipped the capsule of a normal mic onto your tie clip, then turned the gain up enough so that you could work with the signal the mic was getting from that distance, you would absolutely have more feedback problems that the same exact microphone capsule being used 1" from the lips of the performer singing into it.

I really hate lavs ;)  I understand the need for such a device (I have used them for wedding ceremonies mostly), but they are a real test of my nerves sometimes.

It is getting late for me tonight where I live, USA east coast near NYC. If I have some time tomorrow I will write what may be another novelette this time about how I get the best gain before feedback on Lavs. It actually works on any vocal mics. But part of it involves using Smaart. Or at least that is the easiest way to do it. I can try to explain how to do it without Smaart.
Title: Re: Mic sensitivity vs gain
Post by: Ivan Beaver on January 21, 2018, 09:23:47 am
Absolutely - BUT -  I often see people using hand held radio mics with the gain set too high on the transmitter. This often results in the mic compressing the signal as it overloads the companding circuit.  When they stop singing the gain effectively increases and feedback occurs.

The solution is to have the gain set correctly as indicated by the meters on the receiver (apologies if someone else has covered this)

 https://en.wikipedia.org/wiki/Companding
But that is getting into non linear operation.  You can really assume linear operation.  All sorts of things change in non linear mode, and not in a good way.

The same thing happens with some compressor settings, the "make up gain" can send it into feedback.  But again, this is non linear operation.
Title: Re: Mic sensitivity vs gain
Post by: Kevin Maxwell on January 21, 2018, 11:27:00 pm
It is getting late for me tonight where I live, USA east coast near NYC. If I have some time tomorrow I will write what may be another novelette this time about how I get the best gain before feedback on Lavs. It actually works on any vocal mics. But part of it involves using Smaart. Or at least that is the easiest way to do it. I can try to explain how to do it without Smaart.

Some of this I have posted before so I am copying, editing a little bit and pasting it here. There will be some parts that seem to be repeated when talking about a slightly different EQing method.

One trick to getting a good amount of gain before feedback with lavs or actually any mics is in how you setup the sound system. I like to get the main left and right (L/R) speakers far enough away from the stage towards the audience. Far enough out that the mics aren’t too close to them will help a lot. And if there are also delay speakers you don’t need the front L/R to be too loud to reach the back of the room. You will usually need to have Front Fill (FF) speakers to cover the area lost due to the placement of the L/R. This all give you better coverage and more control then just L/R speakers.

I used to do a lot of corporate conferences and when we had breakout rooms with ceiling speakers and presenters with Lavs on, one of the tricks was to tape over the ceiling speakers over the stage. I even had in the traveling kit some covers I would use over these speakers. It was pieces of magnetic vinyl sign material cut into circles. This is the stuff that they make the removable signs that you can put on a truck of van. If the speaker covers were made of a material that these would stick to we could cover them and then just pop them off when we were done.     

The other is the trick I use when setting this kind of thing up. I EQ the system for linearity, what goes in is what comes out. Then I insert a good quality EQ in a subgroup of like mics. So all MKE2 mics get the same inserted EQ. And the way that I EQ them is a put one out in front of the speakers (or just a little bit in front of where the mic would usually be used) using it as a measurement mic into SMAART and I EQ it for gain before feedback. The routing is pink noise into the console and into the SMAART input and then take a per-fader send from the board routing the MKE2 on the wireless to your other input on your measurement system. I play pink noise thru the system and take out the problem frequencies. I usually find I also need to pull down around 200hz to have good gain before feedback. Sometimes when I am all done and I check how it sounds if I am not happy I have to do it all over again. But that isn’t usually much of a problem because this method is so quick. I seem to get the best results when EQing if I start with the lower frequencies and work my way up to the higher ones. I also only cut frequencies I never boost.   

What works for me may not work for others but if you have the time to tune and test you might find it works for you also.

One other little trick that someone showed me a while ago. When using a lav for reinforcement on a male always try to put the lav on their tie. You want it centered to minimize the movement created distance changes when they move their head. Also have the person look down almost touching their chin to their chest and move the mic slowly up the tie, have them tell you when they can no longer see the mic. You then put the mic at the position it was just before they couldn’t see it anymore. Then be sure to dress the cable very neatly, I would usually put a piece of gaffers tape on the back of the tie to keep the wire and mic in place. And for some reason this doesn’t apply to women, I find with them I can clip a mic right up at their neck just under their chin and it works just fine.

So to do (EQ) this by ear - I would usually play a bunch of different tacks from different CDs that I am very familiar with the way they sound. What you are trying to do here is to get the system to accurately reproduce the way the CD sounds. While playing the CD I then would listen for the things that don’t sound quite right. I like to only cut frequencies when doing system EQing. To pinpoint the offending frequency sometimes it helps to boost the suspected offending frequency when hunting for the right one. So boosting the frequencies to make the bad sound stick out more. Sometimes you find that it isn’t the one you thought and you need to try another one. This means bring up the control of that frequency and if it’s not the right one bring it back down, when you find the frequency you are looking for you would then cut that frequency, how much depends on what it sounds like. I like to be conservative but you can get the feel rather quickly as to how much of a cut to make. When you are all done using this method you should hopefully find that you haven’t hacked the EQ to death. Also try hitting the bypass switch to see the difference with the EQ in or out of the system. It may be a very minimal difference.

I then insert (on the vocal subgroup) an EQ and EQ that subgroup for gain before feedback. The way I do that by ear is to have a vocal mic on stage that is on thru the system (thru the vocal subgroup) and I put another mic into another channel thru the vocal subgroup back at the mixer. I then, while using my voice at a decent level, slowly bring up the mic on stage till it starts to slightly ring (while I am making various noises and talking) I then find that frequency and cut it a bit and continue this till I start to get multiple frequencies ringing at the same time. This is usually the point at which you can’t get any farther without hacking the EQ to death and screwing up the sound. All this while I am paying attention to how my voice sounds. This is to give your vocal mics the best GBF (Gain Before Feedback) that you can reasonably expect. If you do this without exciting the system with your voice you will be surprised at the frequencies that pop up when a person gets on stage and talks into the mic. I find most mic’ed instruments don’t usually have a problem with gain before feedback and playback (CD) and instruments don’t need the additional EQ that the vocals do.  When more EQs are available you can breakup what needs to be EQed for GBF and do them separately (or in subgroups).  If you try to do a best gain before feedback EQ on the whole system you take the life out of playback and a lot of instruments. Now of course this is assuming you have that kind of flexibility to the system.

(For church)
If you were doing the church system using lavaliere mics on the preacher/speaker and handheld or in stand mics like the SM58 for the singers, I would route each of these types of mics to its own sub group. In other words you would have a wireless lav sub group and a SM58 sub group, and the other instruments in whatever sub groups you have leftover. It depends on how many sub groups that you have. I then EQ each vocal sub group separately. Then the channel EQ on the mixer can be used for tonal shaping for each mic.

(for theater)
If you were doing the traditional theater system using mics on the apron of the stage (apron mics) and mics hanging over the stage (overhead mic) I would route each of these types of mics to its own sub group. The Apron and Overhead mics aren’t for picking up individuals they are for chorus number when you have a lot of people on stage and a bunch of them aren’t wearing mics. In other words you would have a wireless sub group, an apron sub group, an electrics (overheads) sub group etc.. It depends on how many sub groups that you have. I then EQ each sub group separately. Then the channel EQ on the mixer can be used for tonal shaping for each actor.

-----------------------------------

I find that when I EQ a system with SMAART I can do it quicker than I can with just my ears and I think I get a more consistent sound.


In my opinion pink noise with an RTA is useless no matter how flat you might think it is. Years ago before Smaart existed I used to use an RTA and I never used pick noise with it. When I had one to use I used it to confirm or tell me what frequency I was hearing by seeing it react on the RTA. And using the techniques I wrote above.

With a program like Smaart there is a learning curve so it isn’t a quick program to learn. But with Smaart you compare what you are feeding to the system (pink noise is good for that) and what you are getting on your measurement mic or mics. And what you are going for is linearity, what goes in is what comes out. At least that is how I do it. I have been using Smaart since Version 2 and have been paying for upgrades all along. It is now up to version 8.2.1.1. I am not an expert in Smaart but it have helped me a lot I just recently got into using multiple mic at the same time for the measurements.

I know this is long but I hope there is something in here that will have helped someone.
Title: Re: Mic sensitivity vs gain
Post by: brian maddox on January 22, 2018, 10:41:55 am
Bisquit = Xanax bar to deal with the frustration.

A nice cup of tea = large rum-bearing beverage to celebrate with.

8)

^^this