Tips for Buying a Camcorder by Bill Olson

Note: this article will be most useful if the equipment you are using is right in front of you as you read this.

Novice audio technicians are often intimidated by the complexity of the studio audio mixer board. Whether small or large, it’s a board with levers and dials with cryptic notations like “Trim” and “EQ.”

It would be misleading to say that using the audio board is not complicated, but there are some basic principles to setting the sound levels that will help demystify some of the process.

While this article assumes an audio mixer is connected to a Video tape recorder as the final audio output. Beware the equipment and setup you face might be different. Also keep in mind that some equipment might have peculiarities because of age, wear or different settings.

At the bottom of each input is a slider lever, often called a pot (short for potentiometer). Set this at U or 0.

To the far right of most audio mixer boards is another pot, called the Master or Main Mix. This should also be set for U or 0.

The last audio controls are on the video tape recorder (VTR). There’s usually a meter for each of two channels. Below each meter is a level control labeled Norm, for Normal audio. This article will ignore the Hi-Fi knobs.

Set each Norm dial to the center position, pointing up.

Now you are ready to adjust the audio level.

If your audio source is a person in the studio, ask him or her to talk until you indicate that you’re finished. If the person is inexperienced at doing mike tests, you may ask the person to count up to 50 (see my article on Mic Checks).

Looking at most audio mixer boards, you will see a dial at the top of each audio input. This is labeled Trim, but you will often hear it called Gain. Adjust it until the audio needles on the VTR peak at no higher than 0 and no lower than –3. If the audio level is too low it will be difficult to hear the completed show. If it’s into the red, the sound will distort and will be either difficult to understand or unpleasant to listen to. Some audio experts advise peaking at –3; low audio can be increased in post but audio that is too high might “clip.” This is a form of distortion, and there is no way to fix it.

Adjusting for good audio is basically an exercise in avoiding the red, not just on the VTR, but on the mixer as well.

There are a number of LEDs on the mixer board. The first one to look for is at or near the top range of each input slider. Make sure that this does not light up red. If it does, the Trim must be turned down.

Now bring your attention to the Main Mix or Master pot to the far right of the mixer board. Above this pot is an audiometer that might be either LEDs or needles. Again, you want to avoid the red. If the meter enters the red, lower the level on the input slider for that person. I recommend that you not adjust the Main Mix.

Finally, look again at the meters on the Record VTR. The needles should not enter the red. This is more complicated than it might seem.

If the VTR’s audio limiter is activated, the needles will not enter the red; they will not peak above 0. I never-the-less recommend attempting to lower the input slider to make sure that it’s as low as possible so that the VTR needles still peaks between 0 and –3. This will help ensure that the sound does not distort and that lower-end noise is not amplified.

The VTR needles should average between about –7 and -2.

If, after adjusting the Trim and the input slider to avoid red LEDs, you find the VTR needles to be too low, turn the VTR Norm dials clockwise until the level is correct.

The needles will normally be moving in unison. If they are not, there’s one more control to adjust – the Pan.

The Pan is typically at the bottom of all the dials. It adjusts how much of the audio signal goes to the left and right channels. Usually, we want it in the center position. But if the VTR audio needles are not in unison, adjust the pan either left or right.

If taking these steps does not result in the desired audio level, there are additional steps that can be taken, but that subject is for another time.

good luck in all your audio-video pursuits!

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