Tired of riding the audio

E

Ethan Turpin

New member
The mic level control on my 100B seems really sensitive. There isn't much margin between no bars and hitting red. I usually use an attached shotgun mic. What's up?

Is there any way to set an auto suppressor? Cameras I've had in the past have had that option. I didn't see anything in the menu.

thanks
 
Yeah... there isn't one, and it does seem VERY sensitive. Why wouldn't they put an auto option here? Every other camera I've shot with has this feature.
 
There is a menu setting to reduce the gain from -50dB to -60dB. You may want to try that and see if it helps.

And one of the first things I did when I got this camera was to see if there was an AGC feature so that I could turn it off. Basically, AGC's don't give you professional sound. You get all kinds of pumping that really turns out awful. It's not what I would use on a pro camera. I suppose that was the view the engineers shared when designing this thing. For me there never was much of a problem with the gain at all. It could be something to do with the microphone you're using which may be running too hot.

Daniel
 
Ethan,

Hitting RED is not a "bad" thing. Hitting 0 db at the top of the scale is.

The demarcation between white and red happens at -12db. The problem is that if you adjust to always be in the "red" zone and if the dynamics of the sound you're capturing go from a whisper to mega scream you'll probably hit 0db and go into digital clipping, which means it will sound awful.

One of the things you can do to help keep you off 0db is to buy an outboard mic preamp with a limiter or compressor built-in. Adjusted properly, that should keep you off 0db.

You could also double mic the shot or plug into "input 2" and set the signal to go to both channels (selector switches behind the LCD) on the "B" with one adusted about 6db lower than the other. The reason to do this is you can cut out (or mute) a "bad" section (one that goes into distortion) and still have the other channel that should be sounding good.

All that not withstanding, if it's possible, it's always best to check levels BEFORE you shoot to get an idea of what the normal volume range is going to be and set accordingly. It's OK to have levels vary to some degree, remember, you can always balance them in post to your liking.

Ethan, Daniel & rcbrown,

There is "AGC" (auto gain control) in the menu system. It is called "ALC" (auto level control) on the DVX100B. Go to the recording setup menu and in its list you will see "MIC ALC". It can be switched on or off.

Like everthing else in life, there are pro's and con's for using or not using "ALC" or "AGC". It can act, in certain circumstances, as a sound engineer "riding the faders" , but it can produce pumping IF the levels are jumping all over the place.

If "perfect" audio control is desired, there's a sound crew near you that you can hire (perfection is a difficult thing to achieve in an imperfect world).

If you want the best without hiring sound crew, get an outboard mic preamp with or in combination with a limiter or compressor.

If you don't want to spend the money for that, then double mic or split the signal and run 2 channels.

There are always many ways to skin the cat, it's just that some are "better" than others, depending on your perspective of what "better" is.

Ken :)
 
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Unless your subject is going from a normal tone of voice to screaming you should be able to set the level manually, with peaking into the red, without problems. I'd also look for ways to get that shotgun off the camera and closer to your subject. And finally, changing the menu setting from -50 to -60dB actually increases the sensitivity of the input. :)
 
Hi kenackr,

With respect to the ALC, my understanding is that it is more of a limiter than a gain control. With the AGC, what happens is that your have an integrator that averages the temporary signal strength and will adjust the gain automatically. In units where there is AGC, what you will hear is that when the room is soft, the background will increase in volume and when there is some foreground noise, it will automatically reduce in volume. Testing the DVX102B shows that this isn't the behaviour.

The DVX does have an AGC setting but that's for the video gain, not the audio gain. In fact, there is no need for an external pre-amp with a limiter because the DVX already has a limiter circuit, or a compressor if you like. Normally I would leave the ALC on to deal with the really loud bursts so that it doesn't clip, or at least not so badly. This is why it is called MIC ALC and not MIC AGC. Again, don't confuse the video AGC with the MIC ALC. (See page 83 of Barry Green's "THE DVX BOOK", and page 72 of the manual. The book explains it in no uncertain terms but the manual isn't nearly as explicit.)

Ethan, perhaps you can tell us what kind of shotgun mic you're using. Maybe it's just running too hot and you need to use the -50dB option instead of the -60dB setting if somehow it got changed from default. Again, it may be that your mic is running too hot. I say this because with my onboard mic and with my externals, R0DE NTG-2 as well as the Senheisser G2 lavaliers, I don't have this problem. I had this problem initially with the G2 when I had the gain set too high but now that I've adjusted it all, it's running perfectly.

Daniel Wee

Checklist:-

Menu
MIC GAIN 1/2 setting (normally -50dB)
MIC ALC setting (normally ON)

Switches
Phantom power on/off as required
MIC/LINE switch selected correctly
Channel input switch selected correctly

Others
Headphone volume set correctly
 
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All,

I stand corrected, ALC is an auto limiter only.

My mistake was from too much past baggage in the audio world where limiters were almost always called limiters to my recollection and some audio marketing folks called AGC "ALC" just to have something "new" to hype about.

Sorry, my mistake.

Ken
 
hi guys, on the weekend i'll be shooting an event with about 1000 people, i'll be interviewing anybody that comes my way,my problem is i don't hav any other mic but the on board one, my question is can the on board mic do justice,?intend making a dvd for resale so sound quality is important. please note i can't afford an out board mic at the mo.
 
For one thing you have to be very close to the person to separate his/her voice from the (considerable) background noise.

Even then the sound will be just passable. Not good.
 
If you can get your interviewee to a relatively quiet spot, the on-board mic will do just fine. It's not really that bad a mic except that you have to get as close as you can. The issue is not so much quality per se as in the isolation of subject from the background. If you can't find a nice quieter spot, just hook up a microphone and have someone hold it up to their mouth.

Daniel
 
Basically, AGC's don't give you professional sound. You get all kinds of pumping that really turns out awful. It's not what I would use on a pro camera.
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Pro camcorders usually have a really good AGC in my opinion. We are using it all the time on our Sony DXC D30 dvcams for atmo and interviews because in most situations you wouldn't be better off with manual control. Plus the AGC adds some compression to an interview so that you don't have to do it on editing (saves some time).
We sometimes use an SQN3 for certain situations, but mostly it's for the professional looks, not because the sound is so much better ;)


We also have 2 DVX 100As and the audio controls are a real problem for quick tv shots. You have to look at the audio all the time because the limiter in the DVX 100A doesn't seem to work at all.

i'll be interviewing anybody that comes my way,my problem is i don't hav any other mic but the on board one, my question is can the on board mic do justice,?
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The onboard mic on the DVX 100A is horrible, doing interviews in a noisy situation should be almost impossible. Maybe you can rent a good mic for a day? I used a Sennheiser ME 66 on our DVX recently for shooting a wedding - the sound was perfect.
 
If it sounds good it is good, if it doesnt, it isnt. That is the rule of thumb for all things I would say. Listen in your headphones and if it sounds like crap there it will likely sound like that in post. Same goes if it sounds good. Make sure you have good sealed phones as well
 
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