A common question is:
How come the audio is so soft when I record on a professional camera in auto mode?

The majority of digital audio recorders, including DV cameras, use the dBFS scale, that is, “decibels full scale.” So, 0dBFS is the maximum audio level the equipment can record without distortion. Anything above that mark in a digital recorder like miniDV will result in digital distortion, which sounds horrific.

But, 0dBFS does not equal 0 VU. Volume Unit (VU) meters, found commonly on North American analog equipment, equates to 8dB below the point at which the analog device will produce 3% third-harmonic distortion given a 400Hz sine wave signal. Analog devices do not “clip” and produce complete distortion like digital devices. Therefore, analog equipment cannot use the dbFS scale.

Anyway, what you have to keep in mind is, professional DV recorders like the JVC GY-DV500 or the Sony PD150 use the scale of –20dBFS = 0VU, while consumer DV recorders like the Canon XL-1 and Sony VX-2000 and use the scale of -12dBFS = 0VU.

As you can see, -20dBFS gives you more headroom for audio transients before distortion, which is useful when utilizing better-quality, cleaner-sounding professonal audio equipment that do not require higher input levels to mask the noise underneath the sound (inherent in all devices, just depends on the amount.)

So, when you play back a tape recorded at –20dBFS = 0VU on a device that expects –12dBFS = 0VU, the output is noticably softer. In this case, you should raise the gain or recording level +8dB on your recorder to compensate for this loss.

Some equipment like the JVC GY-DV5000 allows a switch between the -12dBFS and -20dBFS reference level. Keep in mind, however, that this does not change anything digitally except for the reference level that the device uses to gauge the "ideal level" of audio. However, it may change audio playback characteristics in that the specified level becomes 0VU. With pro-level equipment like the DV5000, I would recommend staying at the pro level of -20dBFS, as the audio circuitry is built to higher (and quieter) standards than consumer audio. It simply gives you more headroom before distortion.

This is why it is important to have the “bars and tone” at the beginning of each tape, even for digital tapes. On playback where digital audio is converted to analog, the operator needs to calibrate the input of the analog device to meet the standard operating level of your camcorder’s output.