What Is Microphone “Gain” in Voice Over Recording?

This one goes to 11

There’s a term that has moved from the domain of electrical engineers to the everyday world of the home voice over studio. Unfortunately the “techie” baggage the term brings with it confuses or even frightens many aspiring audio engineer/voice talents.  And that term is “gain”, specifically microphone gain.

So what is gain and how do you control it to produce the best voice over recordings?

So what is “gain” anyway?

When you speak in front of a microphone, your voice creates tiny vibrations that the microphone converts to a very small voltage.  It’s actually too small to be usable. So this electrical “signal” has to be increased or “amplified”, often 1000 or more times greater.

Early on engineers wondered when the signal went through the amplifier “how much more voltage do we have now?”  Or how much voltage did we “gain” with this amplifier? And the term gain appeared in their vocabulary.

You could think of changing the gain as making the mic output louder or softer.  This will make purists cringe, but it’s a good analogy for us mortals. OK, so why do we care?

Your goal is to produce the best recording levels.

We talk into the mic, the sound is converted to electricity, then it’s digitized and then appears in your recording software as the squiggly waveform. And your mic gain will affect the level of that waveform.

First, remember William’s “Goldilocks” rule of recording: Not to cold, not too hot… ahh, just right.  Here’s a picture of how you want your waveforms to appear.

Not too cold – aah just right – not too hot

Now it’s a bit more obvious, isn’t it?  If your record levels are too low, turn up the mic gain. If the levels are too hot, turn it down. Adjust the gain until the loudest parts of your performance produce a waveform like the one in the center.

Do not adjust the level by talking softer or louder

Never change your performance to make your levels correct! Recording should capture whatever your artistic desire as a voice talent creates.  You SHOULD NOT have to change your artistic vision to make some piece of equipment (or engineer!) happy.  Capturing your   style is why they pay them (or you) the big bucks.

So if you’re shredding the vocal cords describing a theme park roller coaster or insane department store sale, GO FOR IT! Don’t dial it down to make the mic happy.

Do not adjust the gain by changing your mic distance

All cardioid mics have a proximity effect.  They get more bassy as you get closer to the mic.  So your distance from the mic will have an effect on your vocal tone. Close miking gives a more intimate sound, more distance gives a clearer, natural sound.

Find the tone that you like for the spot and then adjust the gain to get the recording levels correct.

This rule has some exceptions:

• If you are loud AND you’re close to the mic you may distort the actual mic input.  Move back until there is no distortion. (if your mic has a has a “pad” switch, turn it on. That’s what it’s for)
• If you have a spot with loud and quiet passages – you whisper and then scream – you may have to “work the mic”. Move closer for the quiet parts and back for the loud parts

You don’t need to be extreme in the distance changes. Every time you double the distance you reduce the level by 6dB.  So think 2 inches, 4 inches, 8 inches and 16 inches. That’s an 18 dB difference. Never go more than 16 inches or you pick up too much room echo.

If you can avoid it, don’t adjust gain in your software or control panel.

This doesn’t turn the analog part of the mic up and down. It turns the digital signal down.  So your 16 bit recording becomes a 14 bit recording, or 12… or 10.

Where is the GAIN adjustment anyway?

Once upon a time, maybe 10 years ago, the whole setup was different. The mic was analog and had a XLR connector. This went into a separate preamp or a mixing board. And there was a knob at the start of this chain that said “gain”… or “trim” or “level” or “drive” or… Something that adjusted the initial amplification of the mic signal.

If you have this setup, that’s the knob you want to turn.

You may also have an analog mic and an interface box (m-box, focusrite, etc.) The XLR connector plugs in the box and there’s a big knob that says – you guessed it!  “Gain”… or “trim” or “level” or “drive” or…

If you have a USB mic, things may be tricky.  The newer, better mics actually have a gain control knob. Some older mics may have a “level” switch: high or low, or high, medium and low.

And the oldest, least expensive mics have, well, nothing. For these your only recourse is to adjust the level in the computer control panel or in your recording software. And they can only turn the level down, not up. Sigh.

How to adjust the gain

Way back in the day, when we went to studios to record, the engineer would say “give me a little bit for levels.” Now you are the engineer. So give you a little bit for levels. Here’s what you do:

• Set the gain knob at about 2 o’clock.
• Hit record.
• Speak at the loudness you’re actually going to use at the mic distance you’re going to be at.
• If the recording level (the waveform) is to low, turn up the gain
• If the recording level is too high, turn down the gain.

There. The mystery of “gain” has disappeared.

Of course none of the above applies to my equipment… because it goes up to 11.

Happy recording and keep talking!

William