Clarinet Notes

Odds and ends of clarinet tech and training

Setting the pre-amp gain on your mic


This specific example talks about setting the gain on a USB mic in Windows. However, the same principle applies when using a tablet or phone. The key factors are:

  • The reason you do this adjustment is to make sure your clarinet is loud enough to be heard, without being too loud and causing distortion. Too loud is both worse (in terms of quality) and more likely to happen.
  • High-end external mics have a pre-amp gain adjustments. Built-in mics typically don’t. If you don’t have a gain adjustment, you address the problem by moving further away from the mic when you play.
  • When you “fix” your gain to be good for clarinet, your voice on a zoom call can sound quite soft. I am constantly switching mics depending on whether I am talking or playing.
  • Zoom has a setting called “auto-adjust volume”. If you do that there is better balance between clarinet and voice, but you may lose some of the dynamics in your playing.

I am reloading from a computer crash, a new version of Windows, and a mic firmware update, so I’m having to remember all the hassle I went through when I set this mic up initially. What I have is a PreSonus Revelator, but the more popular Blue Yeti has a similar setting. In Windows there seem to be endless places where you can set volumes with no idea of whether they are conflicting with each other or not.

High-end mics have a setting called pre-amp gain, that controls the volume range that gets recorded. If you think of those wave forms that you see when you watch your sound, what you want is a block of sound running right in the middle of the channel.  If it goes off the top, or is too close to the center line, you are losing dynamic range. In particular, going off the top is called “clipping” and it seriously distorts the sound. If you ever see a sound wave that looks like the top was sliced off with a razor blade, that’s clipping.  A high-end mic usually has a flashing light that shows clipping as you record.

So if you have a good mic you adjust your pre-amp gain to make sure your loudest sounds aren’t clipped. I like to set it once, then never touch it again.  The optimal adjustment will depend my mic placement, and also how loud I play.  If you don’t have this kind of dial on your mic, you have to move further away from your mic to avoid clipping.

In the attached video I kept everything constant except my pre-amp mic gain. I tried 40, 30, 20, and 10 dB. I will probably set it at 20, or maybe 25. The way I did these, you will notice that the result sounds softer as the mic gain gets lower.  A more meaningful comparison would have been to normalize the loudness of the four recordings. Then they would have all sounded similarly loud, but the distortion would still be audible in the 40db case.

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