What Is A Mic Activator: Giving Your Dynamic Microphone A Boost
The numerous advantages of dynamic microphones make them the unquestionable favorite for artists and sound engineers on stage and during live events. Their construction exposes one weakness though. Due to the robust diaphragm with which they operate, many dynamic microphones produce a very weak signal. In the past a high-gain preamp was required to provide a significant boost to make these microphones work efficiently in the studio. A relatively new development is making the process a lot easier. The mic activator.
To best understand why the dynamic microphone is so prone to producing such a weak audio signal in the first place, as well as the importance of boosting this signal, a brief look needs to be taken at the construction of the microphone.
Unlike the sensitive and easily moved diaphragm of the condenser microphone, the diaphragm of the dynamic microphone requires a much larger sound volume to move. As the amount of movement of the diaphragm produce the electrical signal, the smaller movement produce a weaker signal. (This is a very simplistic explanation, and much more complex in reality. You can read a much more comprehensive comparison between a dynamic and condenser microphones in this article.)
The reason why this weak signal is so significant, is the fact that most audio equipment communicate with each other at a certain signal strength. This standard signal strength is called line-level.
While most electronic audio input devices, as well as amplified condenser microphones produce a signal at line-level strength, the strength of the signal produced by a dynamic microphone is too weak to be directly connected to standard audio devices.
Traditionally some type of amplification, normally in the form of a high-gain preamps are used to strengthen the signal to line-level strength, enabling it to be used in other audio devices. It is this handicap that is being addressed by the mic activator. Compared to many other audio equipment, the mic activator is fairly recent development.
Simply put, a mic activator is a compact device inserted between your microphone and audio interface, boosting the microphone's signal strength substantially. The signal strength is now strong enough to be connected directly to an audio interface without any additional amplification.
In practice, the mic activator is a compact amplifier that draws its power from the phantom power provided by the audio interface. The dynamic microphone is connected via a normal XLR cable to the mic activator. The device amplifies the sound to line-level strength and connected directly through another XLR to the audio interface.
The result is a clean, amplified sound that can be directly connected to audio interfaces or mixers without the need for any additional cables or power sources.
This big advantage for us home owners, is the ability to connect dynamic and ribbon microphones directly to our audio interfaces without investing in a very expensive high-gain preamp. These amplifiers are fairly common in commercial studios, but are quite costly and take up a fair amount of desk space - 2 things the home user don't have a lot of.
The Cloudlifter CL-1 is probably the most well-known and popular example of a mic activator. With single input and output XLR ports, this device is ideal for a home recording studio where a single microphone needs a signal strength boost to connect to the rest of the recording setup.
Mic activators are not limited to single-input devices though. Devices like the Cloudlifter CL-4 are designed to cater for the expanded home studio and also make it appealing to the commercial recording industry.
The CL-4 allows up to four independent input sources. The versatility of this mic activator is further enhanced by adjustable gain and impedance controls. The impedance can be adjusted from 150 Ohms to 15 kOhms. The gain can be adjusted from 12 dB to 25dB.
Already other companies are producing competing products like the Radial McBoost and TritonAudio's Frethead. As the popularity of these devices grow, more companies will soon follow suite, and I am pretty sure it won't be long before established big names in the industry start to produce their own versions of this technology.
This is also good news for popular microphones traditionally used in broadcast studios. Well known models like Shure's SM7B, the Sennheiser MD 421-II and Electro-Voice RE20 are now within reach of the home user without the extra expense normally associated with these high-end dynamic microphones.
The mic activator is not just good news for the home user, but the recording industry as whole. New developments don't only allow previously unattainable technologies to become available to wider audiences, but allow the audio industry to stay on top of the latest technological advances.
We can be looking forward to many more new developments in the future that will help to keep revolutionizing technologies and equipment in the world of recording.
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Catch you in the next article and happy recording!