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Old October 24th, 2009, 06:44 AM   #1
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Did I misunderstand?

I was videotaping a band and got a direct line-level feed from the sound guy. For setting the level he gave me a -12db white noise signal. I set the recording level on the camera to -12 and left it. I now have audio that is overdriven and distorted. Did I misunderstand what he was doing? My thinking was that if the levels were matched I would stay out of trouble. I used a Sony PD170 with line input.

Any ideas/suggestions on what went wrong?

Regards,
Jerry
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Old October 24th, 2009, 07:16 AM   #2
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A -12 1khz line up tone would have been a better check than white noise, it would also have been good to check the levels coming in with the band playing. It may be that he gave you a line up but then drove his mixer a lot harder than the max for your inputs.

Also was -12 his max level or was that his zero level? -18 is more usually the zerp level with -12 being the max.

It may also be that the input amplifiers on your camera were being overloaded, it is possible for the metering to look OK but for the audio to still be distorted, it is also advisable to always have some headphones plugged into your camera so you can hear what is going to tape.
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Old October 24th, 2009, 07:29 AM   #3
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Quote:
Originally Posted by Gary Nattrass View Post
It may be that he gave you a line up but then drove his mixer a lot harder than the max for your inputs.
That is my guess.

Quote:
Also was -12 his max level or was that his zero level? -18 is more usually the zerp level with -12 being the max.
This is exactly what I assumed. (I'm sure you know the old saw about assume!) I probably should have made sure exactly what he was sending to me.

Quote:
It may also be that the input amplifiers on your camera were being overloaded, it is possible for the metering to look OK but for the audio to still be distorted, it is also advisable to always have some headphones plugged into your camera so you can hear what is going to tape.
This camera was a lockdown and I did not get a chance to check it when the band was playing. Oh well, it was a spur of the moment setup at best.

Regards,
Jerry
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Old October 24th, 2009, 11:07 AM   #4
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A more standard approach would be for him to give you tone at 0 on his console, you set your cam to somewhere between -18 and -12, then he runs his peaks to 0. Transient peaks to above 0.

The idea here is that a little overdrive on an analog circuit (his mixer) tends to be not as bad as a little overdrive on a digital device (your camcorder). Once you're overmodulating on the camera, it's all over - digital overmod sounds really bad. Although there are some peak restoration tools, SoundForge comes to mind.

So this 0db analog = -18db digital is designed with some headroom. -18=-18 is equivalant to 0=0, no headroom at all. That's how you might set up an analog recorder, where tape saturation is warm. If he gave you something at -18, you'd probably want that down at -30 on your camcorder: But you'd want to have a little discussion with him as to where he'll run his peaks during the show.

However, even if the house soundie thoughtfully provides you with 0db tone, it pays to give some attention to your meters. Bless them, many have no idea what sort of gain structure will help you, and most are going to be primarily concerned with sound in the house, doing the things they did yesterday to make it good.
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Old October 24th, 2009, 02:11 PM   #5
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One word: Headphones.

I had this problem just last weekend. I set tone on my XL1s from my field mixer and monitored at my mixer. Sounded fine during rehearsal and on a lark, I monitored from the camera and heard the attached. The meters on the XL1s were perfect at -18 but you can hear it's all overdriven. The left channel is a Studio Projects B1 and the right is from the mixer. I switched the camera <-> field mixer lines to mic level and it came out fine.

Unless it's a hardware failure of the MA-100 XLR inputs at line level, its a mystery to me. Your mileage may vary.
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