The Stelberry M-90 omnidirectional miniature microphone has flexible sensitivity controls: at low / high frequencies and AGC response rates. The active microphone M-90 is designed for use as part of surveillance systems, and you can buy it from Videoglaz. AGC can be turned off, it is possible to attenuate 2 times by ten times.
Stelberry has released a digital microphone for the M-90 surveillance systems, which has unique features (for devices of this class). Innovations are aimed at maximum intelligibility when recording speech, so the M-90 is recommended to be used in classrooms, meeting rooms and reception rooms. This microphone, which is available from Videoglaz, has surprisingly flexible sensitivity settings - up to 36 dB. So, you can disable and enable AGC, set its response speed (there are three speeds) and attenuate the low / high frequency bands by a factor of ten. Such attenuation can be useful if you need to suppress noise from a working air conditioner, computer cooler, or other “noisy” equipment.
Another interesting option of the M-90 microphone (omnidirectional) is the possibility of attenuating (also 10 times) two fixed frequencies. Adjustments are made using a tiny joystick and an informative LED scale. At the end of the menu settings, the microphone M-90 can be blocked, so as not to accidentally knock down the adjustment. The M-90 microphone provides excellent sound quality with low noise, and the choice of the AGC response speed allows you to ignore car beeps and other short but sharp sounds. Often, installers have a difficult task - how to record conversations in a large room when the interlocutors go during negotiations. With the active M-90 omnidirectional microphone, it's easy! It is recommended that four M-90 microphones be placed around the perimeter at a distance of about one and a half meters from the floor - then the audio recordings will be clear when the interlocutors are located anywhere in the room. Of course, in this case, the sound channels need to be mixed.
The M-90 omnidirectional microphone weighs only 15 grams and has an acoustic range of 25 meters. The joystick and LED scale, despite its compactness, are very convenient. If it was not possible to deal with them intuitively - contact the managers of Videoglaz for help.