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Audio Level recording questions

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Michael Moser
Audio Level recording questions
on Nov 18, 2009 at 10:53:24 pm

I'm using the updated firmware...
I'm not sure I'm getting an accurate reading on the VU meter as I'm recording audio separately through the XLR connectors. (Video in this case was coming from the component ports as an SD signal from a Betacam).

Even though tone was set properly, the final audio on playback seemed a bit low.
Also I noticed that when I turn down one or the other channel, it doesn't seem to go down completely.

Do I have a setting wrong? Input audio is set at -24, line in.

Are there plans to animate VU meters on the panel or as a screen super?

Thanks,
Michael Moser


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Jeremy Garchow
Re: Audio Level recording questions
on Nov 19, 2009 at 2:40:04 am

What level are you setting tone?


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Michael Moser
Re: Audio Level recording questions
on Nov 19, 2009 at 1:02:22 pm

Just at the place where the LED begins to go orange (-20?).



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Jeremy Garchow
Re: Audio Level recording questions
on Nov 19, 2009 at 4:38:43 pm

And during recording, are they getting up to that level? It's OK if they go in to the yellow a bit.

Jeremy


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Michael Moser
Re: Audio Level recording questions
on Nov 19, 2009 at 4:49:59 pm

Yes. They bite into that a bit. I monitored the sound and it didn't evidence any distortion.
Monitor setting was in the middle...not at max. I usually record mono feeds with one down slightly to take care of any surprises.
What I noticed in setting up, however, was that even though I would turn one channel completely down on the unit, it didn't go away. It seemed there is some agc at work here or I've got a setting wrong in the configuration.
Of course in previous shoots where I am feeding an image through SDI, sound is embedded and is controlled from the camera. In this case I was splitting the feed to the betacam (recording as a back up and the KiPro.



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Jeremy Garchow
Re: Audio Level recording questions
on Nov 19, 2009 at 5:07:04 pm

And then are you looking at the levels in FCP or some other application after words? Where are they hitting on the digital VU?


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Jeremy Garchow
Re: Audio Level recording questions
on Nov 20, 2009 at 2:28:22 pm

By the way, you can't turn the analog levels all the way down. It's a safety measure to minimize mistakes. Honestly, I think you may need to give it a bit more juice to get a more satisfactory level.


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Michael Moser
Re: Audio Level recording questions
on Nov 20, 2009 at 2:43:56 pm

Thanks Nanny AJA!!
I haven't been able to check the levels because I'm crashing another edit to get it out the door.
That'll be done soon so I'll be able to check the actual levels as I bring it in to FCP (I was looking at Quicktime on my client's computer when I noticed the low audio).
Some more accurate visual reference on the facer or as a super would be good though.



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gary adcock
Re: Audio Level recording questions
on Nov 20, 2009 at 4:13:07 pm

[Michael Moser] "I monitored the sound and it didn't evidence any distortion.
Monitor setting was in the middle...not at max. I usually record mono feeds with one down slightly to take care of any surprises. "


I was working on a 10 KiPro Capture project and could not answer.

if you are using the audio monitor metering you need to be above that to peak the peak on the VU meters, I have asked for the aja guys but to me it looks like the RED LED in the meters indicates something closer to -3db rather than 0db for the analog input.

for digital inputs they should run a touch lower.



gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Michael Moser
Re: Audio Level recording questions
on Nov 24, 2009 at 1:59:44 pm

Thanks.
I finally got a chance to import the material into FCP and it looks like I just was too careful. I recorded the material down a few dB's. The amazing thing is that there is plenty of bottom in the signal so that if it's too low it can easily be boosted with no noise problems.
Knowing that they are what they are helps, though it would be nice if they were full input control pots.
Thanks for your help.
Best,
mike



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Peter Gruden
Re: Audio Level recording questions
on Dec 12, 2009 at 8:59:06 am

The first yellow led lights up at approximately -20 to -22dBFS.
When the red led lights up there is still 6 dB of headroom available before clipping.

With 24 bit audio there is no need to go too hot. The KiPro converters are probably 19-20 bit in resolution, so at -20dBFS you still have the full quality of 16 bit resolution available.

Also, high levels may drive analog electronics in unconfortable zone and level matching with analog equipment is also lost.

Peter



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Michael Moser
Re: Audio Level recording questions
on Dec 12, 2009 at 7:31:05 pm

Thanks-
I've done more tests and have determined that one should set tone at that threshold. Noise is not an issue, so the big thing I need to avoid is clipping. Thanks for the information.
Michael Moser



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