Audio Limiter within the AG-AF100

L

Luc Desjardins

Member
Hi there!

Last night I was asked to shoot a live show which had a lot of dynamic range sound wise. Therefore, I was constantly fighting with the audio levels to hear people talk and avoid peaking when it became too loud.

What would be a great help is if the AF100 had some way to switching on an internal audio limiter to avoid peaks that I got lots of time during the show.

I looked around the menus and multiple forum but could not find a clear / direct answer.

Is there any way of enabling an audio limiter from within the AF100? If not, is there a way to get a portable battery powered limiter between the mics and the AF100 inputs?

Thank you very much for all your help!

Luc Desjardins
 
You could turn the onboard ALC on in the AF100.

I use a Sound Devices field mixer as a front end which has high quality limiters.
 
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The camera's limiter is called mic alc, or auto level control. Check out page 56 of pt 2 of your camera's manual for how to turn it on and off.
 
kwoff said:
The camera's limiter is called mic alc, or auto level control. Check out page 56 of pt 2 of your camera's manual for how to turn it on and off.
Click to expand...

This is true .. it tries to auto-compensate the audio level .. not like a limiter which will keep the audio from
pegging a certain DBU level.

In quiet moments, the ALC will raise the level .. including room tone .. to sometimes unacceptable levels. If
there is a quick transient, you can still peg the meter .. followed by a quick (and very noticeable) clamp down.

I would advise using an external mixer that has a limiter / compressor (SoundDevices, Shure, PSC, etc.).

I'm not a big fan of ALC....

[[ EDIT ]] I was corrected, on the AF100 it's a limiter ... but I still hate ALC :-)


jeff
 
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jmarkham said:
This is true .. it tries to auto-compensate the audio level .. not like a limiter which will keep the audio from
pegging a certain DBU level.

In quiet moments, the ALC will raise the level .. including room tone .. to sometimes unacceptable levels. If
there is a quick transient, you can still peg the meter .. followed by a quick (and very noticeable) clamp down.

I would advise using an external mixer that has a limiter / compressor (SoundDevices, Shure, PSC, etc.).

I'm not a big fan of ALC....

jeff
Click to expand...

This is incorrect. The ALC on the AF100 is a limiter, not automatic gain control or automatic level control. it just clamps down on excessive levels to prevent clipping. See page 148 of Barry Green's AF100 book on this function of the camera. I did get the acronym wrong--it stands for automatic limiter control, not automatic level control.

Kevin
 
kwoff said:
This is incorrect. The ALC on the AF100 is a limiter, not automatic gain control or automatic level control. it just clamps down on excessive levels to prevent clipping. See page 148 of Barry Green's AF100 book on this function of the camera. I did get the acronym wrong--it stands for automatic limiter control, not automatic level control.

Kevin
Click to expand...

Sorry bout that. What camera was I thinking of :-)
 
Hi guys, thanks for the answers!

ALC was on, but I think my mistake was that I had lines in, but left the switches to MIC. But still, when I used a Shotgun Mic instead, it still peaked pretty easily even with ALC on.

What would be a good external/portable mixer? Would the Zoom H4N do the job? Does it have a good limiter? Would it be correct to assume I would get a better audio dynamic range by recording in 24 bits instead of 16?
 
Hi David,

You are right indeed, this sound business can get confusing pretty fast for a newbie such as myself.

This brings an interesting question: Would I be better with an external recorder? Considering that the in-camera recorder is limited to 16/44, would I see an noticeable improvement in sound and features using for example a Tascam DR100MKII recorder as oppose to use a MixPre-D routed to the AF100 directly?
 
The AF100 can record audio at 16bit 48k. Is 24bit audio better? Maybe, maybe not. There are plenty of low end recording devices out there which record 24bit audio, but are built to a price level with less than stellar A/D converters and electronics. Ask yourself if any of the CDs you have listened to have sounded all that bad? And they are 16bit 44k. If I were you, I would worry less about your AF100 recording audio at 16bit 48k, and more about doing what you can to provide the camera with the proper signal, like switching to mic level when using microphones, and switching to line level when using line level sources, as you seem to admit that was your problem in an earlier post. Also wear headphones and monitor when recording with sound.

Once you master this, then yes... a nice field mixer can add to the overall quality of your productions, whether feeding into your AF100 or an external field recorder.

All the Best!

Dave
 
Hi again David,

Mostly, I was thinking of 24 bits in terms of wider audio dynamic range, thus I thought it would help me with managing peaks in a widely varied sound environment (Very low and very high volumes).

I understand that 24 bits is mostly a "mastering" bit rate, that I would in the end convert back to 16 bits, since I am pretty sure I would not hear the difference (Thus, CD quality is more than plenty as a playback bit rate as oppose to a recording bit rate).

Of course, next time I will try out the line levels with lines inputs, but as I also mentioned, even when I switch to my shotgun mic, I still had great difficulty managing peaking and clipping, which is why I was wondering if a wider dynamic range, provided by 24 bits recording, would have helped.
 
Barry_Green said:
Not on an AF100. The AF100 doesn't have automatic "level" control (which would, of course, behave exactly as jmarkham says). The AF100 has an automatic "limiter" control. The ALC only refers to the limiter, not to level control.
Click to expand...

Very succinct answer to the query. I have been searching around to find out that very thing. I even posted a bit of a thread highjack when it had come up in that other thread. Thank you for sharing this important fact, as the difference between the two systems is enormous.
 
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