Xlr agc level.Separate or linked?

[Marcus Martell]

Hi on the audio menu when i find xlr agc level,what does it stand for?
thx

[Philip Howells]

I don't have a camera in front of me but isn't this the sensivity setting of the XLR inputs - adjustable from -18dB to +12dB (or the other way around) - basically Marcus it's to cater for a wide range of mic level inputs.

[John Cline]

Originally Posted by Marcus Martell

Hi on the audio menu when i find xlr agc level,what does it stand for?
thx

AGC stands for "automatic gain control." Like the name implies, it is used to set the audio levels automatically. Even though the two interact, it has a different purpose than setting the microphone sensitivity.

[Philip Howells]

OK I have the camera in front of me and Marcus both John and I are wrong. The specific control you refer to allows you to decide whether the agc (which John correctly states means Automatic Gain Control) works on each channel independently or if they are linked. It does not enable you to set the actual agc level. The mic sensitivity which I referred to is known as input trim and is the only way you can make any difference to the way the agc works but it is not strictly the agc level. AFAIK the Z1 agc is precisely what it says ie it is not merely a limiter, but raises and lowers the input level around a fixed optimum. It would make no sense to give the user the choice of this optimum setting.

The specific application of the control you queried would normally be separate since if you're using separate mics in each channel it makes sense for the agc to operate on each separately.

However, I can envisage the occasional situation when for example you have one mic very near to a highly variable sound source and the other further away, when it might be prudent to choose to have the agc's linked - it might possible avoid the second channel catching the change in sensitivity as the agc closes. This is pretty extreme situation and normally I'd leave it on separate.

Frankly the agc is so much better these days compared with years ago when the breathing or hunting was so noticeable it was virtually useless (I'm thinking of the BVW507 but others will know of better/worse examples). If event people like wedding video people had to have a sound man monitoring the levels on an outboard mixer like the SQN the business would be even less profitable than it is now.

Incidentally, if you choose channel A input to be sent to both channels on the tape, the agc setting for the input channel will apply to both recorded channels.

[Boyd Ostroff]

Originally Posted by Philip Howells

ncidentally, if you choose channel A input to be sent to both channels on the tape, the agc setting for the input channel will apply to both recorded channels.

Don't think that's true. I get really confused by those audio menus and switches myself! I use a mono feed from the house sound board when I record our operas. I plug the XLR line into channel A and have AGC operating on channel A with manual control of level on channel B. I find that I can get a little higher levels using the manual control, but I also have the other channel in case it gets over-driven.

In fact, I think this is what the OP is talking about with "linked" in the thread title.

[Philip Howells]

I can see that would be useful Boyd. In fact that application would argue for keeping the separate. The manual says the linked option is there to cover situations in which the two xlr inputs are serving a stereo mic or a psuedo stereo situation.

[Marcus Martell]

So,if i wanna record a good audio @ an airshow, what do u suggest to set on audio settings?AGC on right?What about the volume meters?Trim?I 'd like to cop good engine sound without clipping the audio....

[Philip Howells]

Originally Posted by Marcus Martell

So,if i wanna record a good audio @ an airshow, what do u suggest to set on audio settings?AGC on right?What about the volume meters?Trim?I 'd like to cop good engine sound without clipping the audio....

Unless you've been at the dress rehearsal and therefore know exactly what will happen and when, my recommendation would be to put both channels on AGC. The potential sudden variation in levels would demand it. As long as it was out of any wind I'd also replace the gun with an AT825 stereo mic to maximise any big stereo effects.

[Tom Hardwick]

I agree - use AGC when you're not at all sure what will happen next. I might add that the Z1's AGC is much more sophisticated than AGCs of a few years ago, when gentle birdsong was raised to ludicrous levels along with preamp hiss, and exploding cars were no louder than casual speech. The Z1 acts far more like a limiter than an AGC, and can be safely used in situations of very high sound pressure levels.

tom.

[Philip Howells]

Originally Posted by Tom Hardwick

I agree - use AGC when you're not at all sure what will happen next. I might add that the Z1's AGC is much more sophisticated than AGCs of a few years ago, when gentle birdsong was raised to ludicrous levels along with preamp hiss, and exploding cars were no louder than casual speech. The Z1 acts far more like a limiter than an AGC, and can be safely used in situations of very high sound pressure levels.

tom.

Tom's point is absolutely right - the Z1's agc is almost as good as any auto function could be, though of course, the camera also has limiters.

[Tom Hardwick]

As a one-man-band it's the audio that I'm happiest to leave to the AGC. I keep a tight grip on the shutter speed, gain and iris, a slightly less tight grip on the focus and white balance and as I say, leave the audio in auto 95% of the time.

[Philip Howells]

Originally Posted by Tom Hardwick

As a one-man-band it's the audio that I'm happiest to leave to the AGC. I keep a tight grip on the shutter speed, gain and iris, a slightly less tight grip on the focus and white balance and as I say, leave the audio in auto 95% of the time.

Interesting priorities. Assuming we're both talking about weddings, like Tom, I have to rely on intelligent settings, multiple mics and the agc for the sound.

Since the z1 does so well in terms of exposure consistency (I use some of the the PP settings mentioned in this forum) my main concentration is on focus and framing, then lighting - the backlight boost is invaluable). If they can see and hear the subject clearly most of my clients' needs are fulfilled.