Solution for microphone sound distortion

I work as a teacher in a high school of arts in Romania and I created a mini-studio for my students that study music and want to record songs when they need. I bought a very good microphone but the problem is when singing, they tend to raise their voice intensity and the sounds distorts. Now, I learnt that in such cases we need what’s called a “compressor” or a “limiter” and luckily there’s “Chris’s Dynamic Compressor” which is a great tool and after I tried it I immediately noticed great improvements, namely it equalizes the partes with soft voice (it raises the volume of those parts) and decreases the ones with high volumes. This is 80% of what I needed. But there are still parts of the voice where I cannot make it sound good. I have just finished a recording with one of my students and I saved the project. Like I said, there are two places in the song where no matter what settings of the compressor I apply, I cannot lower the intensity and it really distorts. The sound of the voice is strong but not clear. Maybe I don’t know how to apply the exact settings or maybe I should do something else. Is it possible to send someone the project and find a solution that I can apply in the future again? That would be nice because we only have this problem left and it’s a pity as the microphone is a very good one.

You cannot recover from microphone overload in post production. Microphones have a limited ability to transform voices into signals and if the voice is too loud, the signal will be permanently damaged.

Turn on View > Show Clipping. If your show is a forest of red lines, then there is no recovery. The voice has gotten so loud that the tops and bottoms of the blue waves are missing – clipped off. There is a tool called Effect > Clip Fix that can help if you have only one or two red lines here and there, but even then, the tool tries to “cover up” the distortion, not restore the voice.

This is one of the guaranteed ways to destroy a show. Live recording is harder than everyone thinks.

You may get a little help with a pop and blast filter at the microphone. This prevents breathing damage to the sound and also keeps the performer from getting too close.

http://kozco.com/tech/audacity/wynonna2.jpg

http://www.amazon.com/s?ie=UTF8&page=1&rh=i%3Aaps%2Ck%3Apop%20filter%20microphone

Koz

In the illustration, Wynonna is wearing sealed headphones and listening to herself. That’s so she can judge her own volume and it helps prevent wild sound variations in the studio.

If you have a USB microphone without a headphone connection, you may not be able to do that because the headphone connection in the computer will probably be delayed too long to be useful.

http://www.kozco.com/tech/audacity/pix/samsonGTrackConnections.jpg

The other trick some studios use is they have a compressor and sound protection between the microphone and the mixing console – or they have a mixing console with live compressors built-in. Many microphones have the ability to manage voices better than the electronics in the mixer, so provision is made to “tame” volume variations ahead of time.

You can’t do that with a USB microphone because all the electronics are inside the microphone and cannot be changed.

Koz

Indeed, someone else gave me this feedback, too:

“Unfortunately, this kind of problem can’t be fixed. It’s a problem at the source—when you record. You would need extra audio hardware to completely prevent this from happening.”

If there is such an equipment that does this, I would try to buy it. I am using a Blue Yeti Pro mic and a Xenyx 802 Behringer. Can you tell me what that “extra audio hardware” that could go with these?

I will try this - luckily I have saved the project, and will let you know the result. I was delighted to see how much the compressor plug-in improves the quality of the recording since it equalizes the volume for the entire interpretation (it raises the volume for the soft parts) but still there are two places where it cannot do anything. The sound there is something like when someone screams into your ear - loud and unclear. I guess it has its limitations.

We are already using a pop-filter and we record in an insolated improvised studio. So we need to think of a different solution.

That is something we could try. I mean we have a pair of headphones with volume knob that we could use.

I think in the end this will be probably the best option. Can you recommend me something that would fit the microphone we are using?

Let’s do something else before we start throwing money around. I’m suspicions you may have something else wrong. Normal people make voice recordings every day without resorting to extra equipment.

All we know is you are using a Xenix analog sound mixer and an analog Blue Yeti microphone. I’ve done voice tracks very well with similar equipment and I didn’t have to write checks to do it.

How do you have the mixer connected to the computer, and which computer? This connection creates problems for many people.

Koz

I am using a a Behringer UCA-202 USB adaptor and the computer in a normal one, running Windows XP. I could write the computer’s configuration if that helps. I connect the mic to the mixer via XLR (this is a Blue Yeti Pro, the USB one does not have this type of connection).

Here’s a picture of the adaptor:

the picture is larger than this page, it seems. It only appears part of the mixer.

Thank you. I have it. You have the Main Out connections adapted to the Behringer UCA202 inputs and from there on to the computer.

The Xenix mixer is not as simple to run as you may think. Speak into the microphone so the first two Xenix green lights come on. Send Audacity into Monitor Mode:

Right click anywhere in the red recording meters > Start Monitoring.

This will run the sound meters for testing without making a recording. You should make the meters very much bigger. The standard Audacity meter size is not useful. Click the right-hand edge of the meters and pull sideways.

http://kozco.com/tech/audacity/Audacity1_playback.jpg

Where do the red meters bounce when you have the two green lights on the mixer flashing? What happens if you flash a yellow light occasionally? Keep going back and forth until you know what the mixer lights look like when the Audacity red meters hit the top. That’s the forbidden point. Let us know if the meters never hit the top.

Now you don’t have to look at Audacity any more. You can do the whole thing at the mixer’s sound meter.

There are three ways to set the sound level on this mixer. The little Trim control next to the microphone, the Level control on the bottom down from that, and Main Mix. They have to be tuned and they effect each other.

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If you use the whole mixer for production, this is what’s supposed to happen:

If you want to make the whole show louder or softer or fade in or fade out, you do that with Main Mix. Main Mix affects the whole show at once. Main Mix knob generally lives around 2 o’clock or 3 o’clock.

If you want to change the balance between voice or instruments within the show, that’s done with the Level controls. “I need to bring the background music up just a little.” Reach for the Level control that does music and touch it up a little. All the Level knobs live around 2 o’clock or 3 o’clock.

These controls live between 2:00 and 3:00 to give enough range and swing room to adjust the volume for a pleasing show. During the show you may decide that the knobs need to change to make up for show sound problems, but this is the starting point.

If you find yourself pushing Level and Mix up as far as they will go and the show isn’t loud enough – you fail to get the green mixer lights, then the Trim controls are set wrong. Push them up until Level and Mix controls are comfortable. If you get red clip lights, then the Trim and maybe Level controls are set too high. Reduce the Trim until the red clip lights go away when the performance is as loud as it can get.


As you found, you can recover from having a low volume performance, but if it’s too high, it can create permanent damage. Perfect recording levels are remarkable hard to get.

http://kozco.com/tech/audacity/Audacity1_record.jpg

You probably can’t set the mixer and forget it with non-professional performers. Keep trimming down until the red mixer lights stop flashing and the Audacity sound meter never hits top. Then use Audacity effects to rebalance the show in post production before delivery. Note that nobody can record a show where the performer whispers into a pillow across the room and then runs over and screams into the microphone. Special provision must be made for shows like that, such as multiple microphones set individually as the performer travels across the room, or a microphone that moves with the performer.

Some microphone systems like on consumer camcorders have Auto Level. They try to guess what a good sound level is and automatically raise and lower as the room sound comes and goes. The problem is they don’t “know” what the show is, and if someone bumps the camera of makes a loud noise, the rest of the show vanishes until the camera recovers. If nobody makes any noise for a long time, the camera will go looking for sound. …ssssssFFFFFFFFFFF.

That’s the air conditioner in the room. The camera thinks that’s the show.

So it pays to get the mixer running and maybe make proper volume during a presentation a part of the class.

Koz

Sorry about the detail, but this is a little like writing a book on how to ride a bicycle.

Koz

:slight_smile: There is a lot of information for me to process here, as I am still a beginner with mixers, but I think I will be able to try, at least, all the steps you mentioned. Thank you for your patience to write so much. I liked your comparison with the air conditioner :slight_smile: Someone else also told me that the problem could be in the mixer’s configuration. So I guess there’s a big chance this is the case. I will follow your indications and come back with the result.

Microphone amplifiers are hard. Microphone signals are the butterfly wings of the electrical world. People complain all the time trying to get rid of hiss in their performance. That hiss is usually the tiny atomic-level noise of the microphone amplifier competing with the performer. One of the amplifier design problems is to intentionally choose parts not only the right value, but that don’t make a lot of noise.

Cool, so all we have to do is make a super sensitive, well behaved, quiet amplifier and we can go home, right? Of course not. If you walk up to a dynamic (moving coil) microphone and scream into it like these guys are doing (illustration), then it’s not butterfly wings any more. Now there’s a very significant powerful signal and it will rip your sensitive microphone amplifier to shreds.

The Trim control is how you get between those two extremes. The Clip light is the guide.

Koz
Screen shot 2013-09-23 at 4.07.49 PM.png

Looks like this conversation is long over but I didn’t notice anyone mention that cross-talking into the mic could help. If the kids are singing directly into it’s center, it may be helpful to position the mic or the kids so they are singing “past it” instead of into it. Re-positioning made a big difference for me. I think this may be specific to large diaphragm condenser mics.