Types of CB Microphones

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Types of CB Microphones

Post  Guest on Sun Nov 18, 2007 10:35 pm

CB Microphone Types

There are several features associated with CB microphones. Some are just for fun, but most have practical uses.

Power - Power, or pre-amplified, mic's are microphones that require a battery and amplify the audio before it gets to the radio. This is useful for those who speak softly, or may have a weaker signal.

Speaker - Speaker microphones are mic's with the speaker and microphone components in the handset. These types of microphones are typically used with radios developed to work with them.

Echo - Echo mic's, as the name would imply, produce an echo sound effect. Some have a dial to adjust the speed of the echo.

Noise Canceling - A noise canceling microphone helps filter out background noise while you talk.

Roger Beep - A microphone with roger beep will transmit a beep when you un-key the mic. This lets the listener know you have ended your transmission.

Dynamic - A dynamic microphone is a basic CB microphone with a ceramic cartridge inside.

Electret - An electret microphone is a basic CB microphone with an electric cartridge inside. These mic's can be smaller and less expensive than the dynamic mic's.

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Microphones with compressor circuits built in.

Post  brujo de la colonia on Fri Mar 07, 2008 5:26 am

These types of microphones have a compressor circuit in them. When we talk, we do not produce a constant sound pressure level. The audio power delivered to the microphone varies by several orders of magnitude depending on what we are saying, how loudly or softly we are talking, and how close we are to the microphone. This causes the modulation level of the carrier to vary considerably.

If we can manage to keep the modulation of the carrier to 95% all of the time, our radio will sound like it has more "punch" or power, and we will be heard more clearly over a longer distance.

A dynamic compressor circuit does this job for us. It acts as a level limiter to prevent modulation from exceeding 100% (excessive modulation causes distortion and reduces readability on the receiving end), as well as amplifying the quieter parts of our speech in order to not let modulation drop below 90-95%.

Compression is useful to us, it makes us sound louder, makes us appear to have more power. It is more usefull than a simple amplified microphone; an amplified microphone, if the volume is turned up too high, causes over-modulation, which reduces readability and sounds distorted.

You hear the results of a compressor circuit every day, if you, like most people, watch television. Ever wonder why those annoying commercials are so much louder than the regular programming? It's because the makers of the commercials run their audio tracks through a compressor circuit before recording it and sending it off to be broadcast.

Compressor circuits have a drawback though. They reduce fidelity. There is no such thing as a hi-fi audio track that has been run through a compressor circuit. This is not a concern with CB radio, as the audio circuits in the radio are not designed to be hi-fi (20hz to 20khz). The human ear best understands conversation in the frequency range of 300hz to 3,000hz. CB radio audio circuits are optimised to reproduce this frequency range, as are all communications radios including amateur tranceivers, aircraft tranceivers, police radios, etc. By not engineering hi-fi circuits into a CB radio, it is another way to keep costs down, yet another reason we can buy a CB tranceiver for $49.

For voice communications in the CB radio band, you can't go wrong with a microphone that includes compression. Some of the fancier, more expensive mobile and base CB radios include this feature in the radio itself, making a special microphone that incorporates compression unnecessary. The basic, cheap $49 mobile CB tranceiver will benefit greatly from the addition of a microphone that incorporates compression.

brujo de la colonia

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Re: Types of CB Microphones

Post  Reverend Bow on Sat Apr 27, 2013 1:33 pm

The listed audio specs on cab radios is often incorrect.

Most radios will transmit as low as 180 hz before the modulation transformer becomes saturated an distorts the waveform. Also, even low end radios can hear down as low as 100 hz...

If hi-fi audio on CB is your interest, no cb mic will get you there... at least not any stock mic...

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