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Author Topic: Mic sensitivity vs gain  (Read 12200 times)

Ivan Beaver

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Re: Mic sensitivity vs gain
« Reply #30 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.
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Ivan Beaver
Danley Sound Labs

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Kevin Maxwell

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Re: Mic sensitivity vs gain
« Reply #31 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.
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Keith Broughton

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Re: Mic sensitivity vs gain
« Reply #32 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
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Kevin Maxwell

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Re: Mic sensitivity vs gain
« Reply #33 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)
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Ivan Beaver

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Re: Mic sensitivity vs gain
« Reply #34 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".
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Scott Bolt

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Re: Mic sensitivity vs gain
« Reply #35 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.
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Mike Caldwell

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Re: Mic sensitivity vs gain
« Reply #36 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!!

Peter Morris

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Re: Mic sensitivity vs gain
« Reply #37 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
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Kevin Maxwell

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Re: Mic sensitivity vs gain
« Reply #38 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.
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Ivan Beaver

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Re: Mic sensitivity vs gain
« Reply #39 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.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

ProSoundWeb Community

Re: Mic sensitivity vs gain
« Reply #39 on: January 21, 2018, 09:23:47 am »


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