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Old June 24th, 2003, 07:59 AM   #1
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Audio Levels and Distortion?

Maybe someone on here can clue me in to what is happening in my situation. I'm shooting with a DVX100 using a Sennhiesser ME66. I have everything set up on the camera for phantom power.
Here's my problem: When shooting at a wedding gig or what have you- during loud noises like the crowd cheering during the formal entrances at the reception I can't avoid distortion. I adjust the levels in such a way that it doesn't spike. Yet the audio becomes incredibly shrill and crackly when a loud event happens. I monitor the levels closely and according to the levels there should be no distortion at all?!

As far as I know I don't have this problem if I simply use the onboard mic and adjust the levels- only when I use the Sennheisser ME66. I've heard it's an extremely powerfull mic- could it be that it's feeding the camera a decible level thats beyond it's threshold?! Either way I would think adjusting the levels would remedy that- corrrect?!
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Old June 24th, 2003, 02:29 PM   #2
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Often, the microphone itself overloads. The only thing you
can do is move the camera away from the source,
UP if not to the side. You can also use a limiter, but I haven't
seen anything too portable.
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Old June 24th, 2003, 03:26 PM   #3
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Shotguns in general and especially the Sennheiser overload very easily. It's the nature of the beast.

I much prefer the Sony microphone that came with my DSR-300. It isn't as directional but it can handle gun shots that previously I had to record using a Shure SM81C.

It is my opinion that shotguns are great for dialog and miserable for most other applications.
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Old June 24th, 2003, 04:43 PM   #4
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So my problem is "mic overload"? I thought it was a problem with the DVX, thank gosh thats not the problem. I purposely shelled out the extra cash to get the Sennheisser because of it's fidelity- little did I know it would cause a problem in wedding videography. Most of the time during the reception I have to run my auido off of my secondary cam (GL-1). Ugh, what's the point. I should have purchased a wireless lav mic and called it a day!

So there is nothing short of getting further away from the noise? No amount of audio level tweaking will help? UGH!
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Old June 24th, 2003, 05:31 PM   #5
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Some microphones have a 10 or 20 db attenuator. You could try an in-line attenuator but I don't think it is going to help much.

The Sennheiser is so 'hot' that we VX2000/PD150 folks have to purchase a version of the K6 module that has been turned down at the factory.

Still, a shotgun works by timing the arrival of sound to the microphone element such that sound, at the right frequency range and coming from the sides is cancelled. This works unless the sound is low frequency or the sound is very loud. The acusical-mechanical tuning that leads to the directionality can be overloaded and is transparent to low frequencies.

My AT835B, which is not as hot as the Senn, has the same problem in high sound levels. I switch to the Sony, the Shure SM81C which for sure will not overload (it works very well with cymbals which are the worst thing, I'm told, to mic.) or the ole Sure Beta58. If fact, I favor placing a plug-on transmitter on the Beta58 and taping it to the top of the DJ's speaker so the top of the microphone (with a fuzzy wind sock on it) just peaks over the front of the speaker.

Great sound every time, no reverb problems since the speaker swamps them out.

There have been times when I've put a dynamic lavaliere on my hat bill and used that for sound. Dynamic microphones are really good in these loud environments.
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Old June 24th, 2003, 06:00 PM   #6
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Yeah your right about the cymbals- I can tell it's the high frequencies that do it. Anytime the DJ's voice gets to almost a yell or some girls in the crowd scream the audio goes totaly "shrill". That's what was throwing me off because the levels indicated no distortion.

How can you get this version of the Senn (the one that is turned "down" at the factory)? Hmm, lol, wonder if the kind folks at Sennheisser would let me do a trade! *yeah right*

It's ashame too- other than it not being capable of picking up loud sounds- it's great for low to medium volumed sounds/vocals. It's so rich and lifelike. The onboard mic on the DVX sounds tinny in comparison.
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Old June 24th, 2003, 06:53 PM   #7
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If you're microphone is overloading at its diaphragm, attenuation of the electrical signal at *any*point, be it with a built-in attenuator or a limiter, will not undo distortion already done.

Are you using an automatic gain control option on your camcorder? You may want to try turning it down. I notice
that I have similar problems with my VX-2000 and its built-on
microphone. I've noticed that this happens when there is a major difference between the speaking levels of the camera
operator and the subject, or when the subject speaks quietly,
then laughs. I would guess that this happens because the
attack and release times of the AGC are too long. This prevents
reduces "pumping" at the expense of distortion of loud sounds that follow soft ones.
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Old June 24th, 2003, 08:09 PM   #8
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I understand that you can send your K6 in and it will be modified for a small sum. That said, it may not be appropriate for your camera. The underlying problem is that microphone is just not the correct choice for that venue.

It is somewhat difficult to overload a diaphram as you can see by the absolute SPLs most microphones will handle. Well into hurt-the-ears levels.

But shotguns are special animals and I think it is possible to have side sounds reinforce the front sound and cause significant diaphram overload, the exact opposite of what they normally do.

I normally only use a shotgun at a wedding if I cannot get two recording devices onto the groom and officiant. Then I'll set it on a stand and feed my MD recorder.
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Old June 24th, 2003, 08:33 PM   #9
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I use the MM-1 mic-preamp (I know I kind of repeating this but I love it).

Beside being a very quiet preamp it also includes an active limiter that will limit the output signal to avoid clipping (which is very bad when recording digital).

Dany
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Old June 24th, 2003, 10:35 PM   #10
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<<<-- Originally posted by Vince Denali :

Are you using an automatic gain control option on your camcorder? You may want to try turning it down. I notice
that I have similar problems with my VX-2000 and its built-on
microphone. I've noticed that this happens when there is a major difference between the speaking levels of the camera
operator and the subject, or when the subject speaks quietly,
then laughs. I would guess that this happens because the
attack and release times of the AGC are too long. This prevents
reduces "pumping" at the expense of distortion of loud sounds that follow soft ones. -->>>

The DVX has a "mic alc" which I turned off on the last wedding. It did seem to help a bit but didn't eliminate the distortion. It's gotta be overload at the diaphram level. Does this do any damage to the mic?
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Old June 27th, 2003, 01:30 PM   #11
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one thing which has been mentioned in another thread is to turn one channel lower (about 10-20db) than the other.. this way, most of what u pick up will be caught by the higher end mic, but the loud fluctuations wont be distorted on the lower gained mic.

In post these can be chopped and changed and normalised to suit... each channel

Personaly i dont have any probs with the DVX.. mind you im using the MC100 Pana mic, which is prolly set a lil lower than the senn...

Dont run the AGC its useless as it does not allow you to set configurations for different environments.

The gain trick mentioned above can be run from the internal mics at the same time as the shotgun.
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Old June 27th, 2003, 02:00 PM   #12
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<<<-- Originally posted by Peter Jefferson :
The gain trick mentioned above can be run from the internal mics at the same time as the shotgun. -->>>

Ya know what- I've heard of that first trick, turning one channel up and leaving one lower...however, I never even thought to use my ME66 and onboard mic simultaneously. Good idea- just not sure how to set it up. I'd have to connect the ME 66 into input one instead and behind the LCD switch input one to the mic and keep input 2 as the R-channel. The only problem with that is the fact that the onboard mic is stereo and will pick up audio primarily from the right side of the camera. Correct?
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Old June 30th, 2003, 06:44 PM   #13
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Have you ever tried using ME62/K6, the omni capsule? If you remove the ME66 capsule and cover the K6 with a foam, should that make an omni mic? Just a thought.
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Old June 30th, 2003, 08:43 PM   #14
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The K6 is just the amp. Has no microphone elements. Have to have a microphone capsule to get any sound.
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Old June 30th, 2003, 10:22 PM   #15
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Try using it with a battery. I noticed yesterday that when I replaced my battery with a fresh cell I had to lower my gain. less voltage may = less sensitivety. If that works you could even try using a nicad, they have even less output voltage than an alkaline.
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