SETTING YOUR METER LEVELS
by Edwin J. Somers, CAS

Here is the question: I set tone on my mixer and the camera at -8 and the levels don't track. What gives? This is one of the most common misconceptions in mixing. Many people don't understand how to use a VU meter, or the relationship between the VU meter and the Peak Program meter.

Lets talk about how to read a VU meter first. It is very logical to set levels so that the average volume is around 0 dBm on the VU meter. One of the first things you notice, however, is that the loudest part of the program material goes into the red and very often goes off scale. Try as you might, you are unable to keep from going off scale under these conditions.

0 dBm
	The trick or solution is to set your levels so that the average signal is around -6 dBm. The peaks of the audio signal will magically come up to 0 dBm. With just a little practice, you will discover that you can precisely control your levels and stay out of the red.
Mixer

If you ever venture into a music studio where they are recording a session, the first thing you will notice is that all the VU meters on the big mixing board are peaking off scale. The reason is very simple. The sound recordest is using the VU meters for showmanship. It looks very boring to see the VU meter set properly, the meter needle is hardly moving. This is because the VU meter is logarithmic, and most of the scale is compressed at the left side. The recordest is probably mixing by ear, or he is relying on other meters for precise level information.

The VU meter is designed as an averaging meter. It does not give you any precise information about the peaks of the audio signal; however, there is a definite relationship. When the peak signal hits 0 dBm on the VU meter, the program peak is really about +6 dBm. With this little bit of information, we can figure out how to make the VU meter on the mixer and the peak meter on the camera or recorder track the same.

With a steady state tone, the reading on a VU meter and a peak meter will be exactly the same.

-6 dBm or -8 dBm
	The trick is to set the line up tone level with the VU meter on the mixer at 0 dBm, and set the level on the peak meter on the camera, or recorder at -6 dBm. Now when you feed in program audio, the meters will track very closely. This is called meter lead.
Camera or Recorder

There is another idea you might consider trying, adding some headroom to your signal. If you set the meter lead on the peak meter at -8 dBm, you will be adding 2 dBm of headroom. This means that you can come to +2 dBm which is quite a ways into the red on the VU meter, and you will still peak a 0 dBm on the peak meter.

A very important point to consider when using audio recording equipment is that it is designed to operate near 0 dBm. When you go significantly over that operating point you are increasing the harmonic distortion.

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