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Jason Davidson - CB Radio Specialist

Jason Davidson

Over 18 years of hands-on experience with CB radios and installations.

Mic Gain / Dynamike
Full Name Microphone Gain
What it does Adjusts your modulation
Where to set it Varies, commonly 12:00 to full right

So what does the Mic Gain or Dynamike control do?

Your Mic Gain control, which is short for "microphone gain" is in essence, a level control for your modulated audio. Or a much easier explanation: the Mic Gain controls how loud you are to everyone else. It's a volume control for your voice. If you want to know where to put this control, normally, turn it all the way up (to the right). However, there are reasons to not always to do this. Keep reading to better understand this control.

Voice Volume

Having worked in the communications business for almost 2 decades, I can tell you the Mic Gain control along with the RF gain control are the most common to be positioned incorrectly. I have had many, many people bring their radio in to have it repaired because they "can't get out". After inspecting their radio, I find their Mic Gain is turned down. And voila, with the twist of a control, now everyone can hear them talking again. One of the reasons the Mic Gain control is not well understood by casual CB'ers has to do with the name, "Mic Gain". The name of this control makes it sound like you're boosting something beyond what it would normally be set at, sort of like turning turning your volume to 11 (thanks Spinal Tap!). In reality the Mic Gain allows you to turn down your voice, rather than turning it up.

Why your microphone affects your Mic Gain

Here's where this control can get tricky. You now understand that your Mic Gain controls how loud your voice is. It is normally turned all the way up. So why would you want to turn it down? The answer is usually related to which type of microphone you are using.

  1. Dynamic / Stock Mics: Most CB's come with a dynamic microphone --which is essentially a speaker, in reverse-- the issue is that these types of mics are so loud that you may sound over-modulated, or distorted if your run your Mic Gain turned all the way up (to the right). So with any dynamic mic, or any mic that comes with your radio, you may need to back your Mic Gain down to sound clear.
  2. Amplified / Power Mics: Amplified mics like the Astatic D104M6B require a battery, this battery powers the microphone element and makes your voice even louder. If the Mic Gain on your radio is turned all the way up, and the amplified microphone is up too high, you will sound like a distorted, squealing, hard to understand mess to everyone else. If you're going to use an amplified mic, you will need to spend some time getting both the gain on the microphone itself, and the Mic Gain on your CB set properly where you are loud, but clear.
  3. Noise Canceling Mics: The most common CB microphone, the one we suggest for most mobile installations, is a noise canceling mic like the Astatic 636L or the RoadKing RK56. These types of microphones are not as loud as the stock mics, or amplified mics, but they are almost always the clearest and cut out all the background noise. Since these mics are somewhat less loud, your Mic Gain will almost always need to be turned far the right, all the way up, for that clear and loud audio.
There are some variations on the above, like echo mics, or electret element mics. But for most people the above 3 microphone categories will comprise what you are using.

Talkback and reasons you may have transmit squeal

Talkback is a special function found in some CB's and some external speakers, it is a circuit that allows you to monitor what you sound like to other people, by hearing your own voice through your CB's internal or external speaker. Everyone has heard what happens when someone at a concert gets metal too close to a microphone, and a loud high pitched sound is produced. You can have a similar problem with any CB system that has built-in talkback. The problem is this. With talkback enabled, your speaker echos what you say, if your microphone is too close to your speaker, it picks up your echo, then your echo comes through the speaker, and it's again picked up through your mic. Etc etc. A feedback loop is created and you will hear transmit feedback, or a squealing sound. This is where your microphone gain can come in to help. To reduce your transmit squealing, the first step is to turn down the talkback level if your setup has a dedicated control for it. If you don't have a way to turn down the talkback level, your microphone gain will produce the same effect. Turn down your Mic Gain until the talkback stops squealing. Just make sure to keep your Mic Gain as high as you can get it. Normally you won't start to see a reduction in your transmit audio level (aka modulation) as long as your Mic Gain is at the 12:00 position or higher.

Modulated power output control

Your Mic Gain control actually affects how much AM modulation your radio has. It can be easiest to think of this control as a volume for your voice, but you need to understand it's also a power level control. CB radios in the US all operate primarily on the AM mode. This mode consists of modulating an RF carrier. The amount of modulation is directly affected by where you have the Mic Gain control set. Your CB radio has a maximum of a 4 watt AM carrier, when measuring the peak envelope power, or PeP, most CB's have between 9 to 18 watts modulation. Your Mic Gain affects this latter number. The more you turn down your Mic Gain from the maximum position, the less peak power you will have, and the more quiet your voice will be. If you want to be heard over longer distances, and if you want to be loud, always run your Mic Gain as high (far to the right) as you can.

Modified / Peaked Radios

An important last note. If you have had your radio modified, specifically any modification having to do with your power output, then you may need to back your mic gain down more than this guide suggests.

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