Auto gain audio pre-amps

[julienjarry]

Unless I am shooting an interview where I need to dial in a very specific audio level and babysit the knob, I am almost always running my audio gains on AUTO. For doc work capturing ambient, scratch, and environmental in-camera audio, it simply works - really well. Give it a shot sometime. What do you think?

 

 

[DougJensen]

I agree completely.   I would say that I run my audio on automatic about 95% of the time when I don't have an audio tech working with me, and not once can I remember being burned.  I even run all my audio on automatic for interviews because that is one of the easiest things for the camera to handle. I sold all my Sennheiser and Lectrosonics gear a few years ago and now use Sony branded audio gear exclusively -- including several shotgun microphones and four wireless mic systems. A major advantage of the Sony ecosystem is having a single manufacturer build the camera and the audio gear, which are designed to work seamlessly together .  I can't think of any other camera manufacturer who also builds wireless audio systems, shotgun mics, lavs, and everything in-between.

I use Sony's wireless UWP-D wireless transmitters and receivers with my cameras that have an MI-SHOE, such as the FX6, FS7, and Z280.  And I use Sony's very sophisticated DWX wireless transmitters receivers with my Z750 and F55. I trust my camera/audio gear to provide flawless performance, and that greatly reduces the things I have to concern myself with on a shoot.

The money I've saved on not having to hire audio techs for shoots where I really don't need that level of service has more than paid for my audio gear.  If we are on the verge of having self-driving cars, why should it be so surprising that we can flip the camera to automatic gain control and let it do the work for us?

The fact that my wife was an audio tech (we met on a shoot) and I have basically put her out of business, doesn't bother me  . . . or her.  She has gone on to find more creative endeavors than holding boom pole or turning knobs on a mixer.   No offense to audio techs intended!  🙂

[alisterchapman]

I do use auto a lot, and generally it works well, but I hate those quiet moments in the audio where the auto gain creeps up and the background noise increases, then someone speaks and the background noise abruptly changes as the auto compensates for the louder voice. So for interviews or other situations where the audio won't vary that much I make use of the limiter. The limiter is a variable slope soft limiter, so they will almost never hard clip doing their thing, which is to prevent audio peaks from clipping or distorting. Instead once the audio level goes above the limiter set point it is very gradually compressed, much like a video highlight roll off. The further into the compressor range it goes the more it is compressed. The greater the limiter range, the softer the effect.

 

So, as an example, I will set the limiter level to -9dB, this means that the soft limiter will start to kick in at the -9dB level on the audio meters, which is approx 3/4 of the way up the scale. Then set the manual audio level so that the loudest normal audio peaks just reach 3/4 of the way up the scale. If the audio then suddenly becomes much louder (for example the person you are interviewing raises their voice) the peaks will start to go into the limiter and will be gently compressed preventing them from distorting, the person will sound louder as the average sound energy will increase (as it should) but there won't be any pumping of the audio level as there can be with auto gain.

 

Obviously there will eventually be a point where the compression becomes audible if the sound level significantly increases but with a -9dB limiter the sound has to become 8 times louder before you'll start to notice anything. -12dB and you need a 16x increase before the limiter is even detectable, let alone objectionable.