How do I adjust sound level on the fly during a video recording?

kwkeirstead

kwkeirstead

Well-known member
The other day I did sound check with a signal from a sound board, set my Mic Gain to -60db to get the volume dial near the mid point.

About 5 mins into a stage event, the sound board signal increased dramatically and I had to throttle back the volume dials to close to the "1" setting.

How do I get wider control over incoming sound?

Would it help, for instance, to insert a Behringer XENYX 802 (just an example) mixer between the sound board and the camera?

I would set and leave the camera mic gain at -50 then take a fairly high signal from the sound board at sound check time.

Hopefully the dials on the pre-mix would let me filter the signal down over a wider range than I currently am able to get on the camera volume dials.

Clearly running signals through extra black boxes is going to negatively impact quality? By how much?

I have never understood on the AG-AC160A why you can be at 2 and hardly hear anything but if you go to 3, then it's too loud.
 
What kind of performance was this, just out of curiosity?

From what I get out of your setup: you were taking a board feed from a house sound console in a performance venue. Pre-show check seemed to be okay, but once the performance started it was too hot coming into the camera. How did you check your signal pre-show, or, what did the house engineer send you as a signal test (voice, pre-recorded, something else)?

My guess is that you got something like a talkback mic with a quick "Check, 1, 2" muttered into it. That means you calibrated to a signal that is MUCH too low. Once the show started, you were actually getting the full mix and were not ready for it. Further, I'm wondering if you were getting a line-level signal from the house feed (very likely), but it sounds like you were set to a mic-level input. Always, always, always check your nominal signal levels (mic, -10dB line, +4dB line) and adjust accordingly.

A mixer in front can help, but the problem would have been the same if you were using a mic-level input with a line-level source.
 
Thanks, Alex..

This was a Phd exam for a pro musician - the concert was held in a university concert hall. The sound check featured the performer at five separate clusters of percussion instruments so we did 5 sound checks over one hour.

My board feed came to ch 2 (line) and I had a Rode VideoMic plugged into Ch 1 (mic).

I do about 30 of these events a year and I cannot recall ever taking anything in on Ch2 other than a sound console feed so I cannot figure out how I could moved Line to Mic or have made my connections backwards. But, you never know.

The thing was the concert started off with normal volume (same as the sound check volume) but then, around the 5 minute mark, the feed went through the roof and almost blew my headphones off. I waved frantically to the sound engineer to lower the signal but he indicated there was nothing he could do.

I may be able to verify this by digging up and playing the Ch2 signal.

Anyway, we had a separate Tascam DF100 MII recording so I had three signals to choose from.

My general question, possibly specific to the Ag-AC160A remains - why are the sound dials so sensitive to small adjustments? .

It could be that it is the Level Meter that is not faithfully indicating the actual sound level (I make sure I am 3-4 dots below the red line indicator). Barry's book says each dot represents 2 db of signal strength.

I find during many music events where one moment you have two or three people almost whispering, then the next minute 20 singers come on stage, that i am constantly tweaking the sound dials.

I suppose I should borrow a sound generator and check the linearity of the both the dials and the level meter.
 
The signal from the board is almost certainly line level. On the camera handle upper left side make sure you have the appropriate channel switch is set to LINE.
 
It actually sounds like you or the FOH mixer bumped a switch but?

As a post mixer it's a real PITA when folks start riding gain in production unless they are VERY skilled at it.
With decent equipment and digital recordings there isn't a lot of reason to ride gain. When you were always fighting the noise floor of tape there was more of a reason to do it.

In your case specifically I would say you need an external mixer. The little knobs on a camera or a hand held recorder are not designed for mixing and are likely to bring lots of grief if you try to use them that way.
 
Many prefer a pre-fader feed from the board, if the house eng. kicks the level up/down it would not a affect the pre fader send.. however.. if the musicians play louder or the house person changes the preamp gain, it would change the aux. send level. Generally and especially with musical performances, there's 99.999% chance the performance will be louder than the sound check.
 
Was there only one mic? From the clip it's hard to tell. If you're confident of your switchology then either something went awry in the camera (unlikely) or the board op did something which drastically changed the level. If you were fed from the board's mix bus then I would think you would have heard the level change in the house, also. I could easily envision a scenario where your feed came from an aux send and the board op accidentally adjusted it. That doesn't explain his inability to fix it but maybe he didn't realize his error. I did hear some (digital overs?) noise at one point. You MAY be able to address those with something like Sound Forge or Izotope Rx.

Maybe instead of an outboard mixer you need a compressor set as a limiter. Better to have clamped peaks than distorted audio. Trying to manually ride audio gains - either on the camera or an external mixer - is difficult to accomplish while also paying attention to picture!
 
@zjrt02 . . thank you for your input

I think one mic per instrument cluster.

I agree with you the probable cause was "the board op did something which drastically changed the level" and yes, I did get a loud noise at the headset about 5 mins into the 1st number.

I looked up "compressor set" - what I need is to keep away from the little volume dials so the following sounds right.

"Compression is the process of lessening the dynamic range between the loudest and quietest parts of an audio signal. This is done by boosting the quieter signals and attenuating the louder signals",

This sounds EXACTLY what I need (ie. in the theatre/music recordings I do, one moment you have two people almost whispering, then suddenly a chorus of 10 opera singers appears).

The camera has an audio limiter - I read somewhere not to use it because it lobs off the top which presumably would mess up the recording.

My events are all amateur theatre. Never the same sound folks from one event to the next, even at the same venue. Some of the boards are 30 years old, others just out of the box.

You are right it is enough for a one-trick pony like me to worry about the camera and not be messing around with audio dials. The only assistant I have ever had is a German Shepherd who did a fantastic job over the years protecting my gear when I have to make several trips to/from the concert hall to my car.

Stage events are challenging enough for me if you want to zoom in ona solo./duet, follow them across the stage, pick up actors appearing from several entrances, zoom out for groups and suffer the lighting changes that the lighting folks program in to set what they feel are the right moods. During all of this I am typically 65 feet from the stage trying to do a recording.

Now, what about something like this ?

http://www.humbuckermusic.com/1001.html

The price is affordable, do you figure it would help me with my problem?
 
I'm told many camera AGC circuits do tend to mangle the audio. I have used the AGC in my HPX-250 at times and didn't notice anything horrible but the 160 has different insides so I can't speak to its effectiveness. You should turn it on and experiment. Maybe that's all you need! Again, a little bad is better than all bad!

A compressor can be set to more gently limit the input. This would be a bit of an unorthodox use of a compressor but might be just what you need. While it will be inconvenient to throw down and connect an extra box it might be the simplest solution if AGC is too objectionable. If you want to try this be sure to buy from a dealer with a good return policy in case things don't work out. I would recommend something with balanced I/O to keep your signal as clean as possible. The unit you mentioned appears to be unbalanced while its bigger brother:

http://www.humbuckermusic.com/fmraupbco.html

has balanced I/O but is pricier. You might also consider something like this:

http://www.bhphotovideo.com/c/product/1069102-REG/art_scl2_dual_stereo.html

even though you might only need one channel. The price for this one is good but some don't like ART. I can't vouch for either one. Make sure whatever you get has a "bypass" button in case you need to quickly take it out of the circuit.

If you decide to go that route please experiment with the device before taking it on a paying job! Compressors can greatly assist - or mangle - your audio. I'm sure you can find plenty of tutorials on the web.
 
An unbalanced connection is usually fine as long as the cable runs are short. I wouldn't use the expander/gate at all for acquisition.
It's also possible to daisy chain two comp. channels in dual mono mode, the first with light 'over easy' type compression, the second a peak limit setting. However this should not be attempted by inexperienced folks.. even one maladjusted channel can muck up the sound.
 
Let us know how things work out. Take it slowly until you're confident of the results. Yes, short runs of unbalanced cable should be OK and that's not an uncommon setup for studio compressors; I'm just a big fan of not taking unnecessary risks - especially in remote situations - plus, with XLR connectors on all devices, you don't have to rummage through your kit looking for those special cables.

(An aside: not all XLR connectors carry balanced circuits so caveat emptor, but most do. The specs on the ART say its connections are balanced.)
 
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