JVC HD250 audio levels

[Baker Park]

I was working with a JVC hd250 yesterday. Fairly calm sit down interviews. Levels looked good on the 442. Pushed line out to line in on 250. I sent tone out and matched index notch on the JVC. Auto off. Peaks ( PPM) running +8 to +10. I also did a quick check of levels on auto to double check where the camera seemed to want things running. Op wouldn't let me double check real time. Now I am told that on playback audio is usable but low (+/_8 db). I got on line manual this morning and noticed there is a menu setting for signal to tape at 12 or 20db. Other than that I am lost. All my experiance is with Sony D-30. Where did I screw up??

 

[Alex H.]

Were you listening through headphones off the camera during recording? That's the first and most important safeguard, since what you hear from the camera is what's going to tape. You can't rely on the meters to tell you that the sound is good... only that it's hitting the right amplitude in that particular point in the chain.

As far as the op not letting you check levels in real time... terribly sorry, but my first rule with DPs is that the audio section of the camera is mine and mine alone. I don't back down, though I rarely have any resistance since most DPs who are concerned about the project know not to mess with audio when there's a recordist in the room.

And I wouldn't trust what the camera says it wants in AGC mode. AGC compresses the poop out of the signal and doesn't care what your 442 says is going on.

As for the signal to tape menu setting... -12dB is the reference level standard for DV material. -20dB conforms to professional production formats like DBeta. I think this changes the reference mark on the dB scale but does not actually affect the audio level. It's just a scale setting. Stay with -12dB reference and peak.

You need to be able both to listen off-camera (headphone return channel on your mixer>cam snake) and to watch the meters on the camera. Like I said, this is a non-negotiable for me and I haven't worked with a DP who didn't understand.

 

[Baker Park]

A good lesson, thanks. I did listen to return and though it was clear it seemed to have the characteristics of a low signal jacked up. Unfortunately the Op knew I am on the learning curve and insisted that no else he had worked with ever needed to check back after setting reference. Like I said... lesson learned.

Would you expand on the 12 db reference standard. How does that apply to me, especially if it requires a different tone setting and/or peak control. The Sony D-30 has always been a "set tone on 20 and run" experience for me.

Finally, would you remind me where you tend to max your peaks when working with the pro-sumer cameras. I usually set my limiter around 16-17 and light up with the occasional loud hit. ( Not often)



Thanks again for the help.

 

[Alex H.]

Would you expand on the 12 db reference standard. How does that apply to me, especially if it requires a different tone setting and/or peak control. The Sony D-30 has always been a "set tone on 20 and run" experience for me.

Which dock were you using with the Sony DXC-D30?

The higher broadcast formats such as DBeta use a dB scale that references at -20dB. In all my days with DBeta, I always set tone at -20dB in the camera, and my audio would peak at -10dB.

The -20dB standard is also what's used when mastering tape for broacast/cable facilities on higher formats.

But with the dawn of DV, audio rules were adapted to the new "prosumer" technology and a scale closer to that used by DAT was conformed to DV. This sets -12dB as both the reference and peak levels. In the field, sudden and extreme peaks may cross that by 3 or even 6dB, but you should keep audio as close to -12dB as possible without crossing.

The reason the JVC has the selectable scale is that it is designed to be used either as a DV/HDV camcorder (-12dB) or as a studio cam that feeds a high-end deck (-20dB). So if you're using the SDI out to something like HDCAM or DBeta, go with -20dB. But if recording in-camera to HDV, use -12dB.

Finally, would you remind me where you tend to max your peaks when working with the pro-sumer cameras. I usually set my limiter around 16-17 and light up with the occasional loud hit. ( Not often)

On the mixer: Since you're using PPM meters, peak right at 0 with the occasional journey into +3dB land. When you're using an averaging meter (such as on the Shure FP33), you want the meters to average between -7dB and -3dB. Set the limiter to catch peaks beyond 0dB (usually kicking in at about +3dB or +6dB).

If you've properly calibrated your tone between mixer and camera, the above info will keep you in the safe zone with camera audio.