We can say that this Multidirectional microphone circuit consists one side of electret four modules, each of them provide power to the capsule through 10K resistor, DC blocked through 1μF capacitor and the resulting AF signal is received at the end of the potentiometer which serves as a reception setting. 100K resistors and transistors form a network FET preamp and summing several signals, which can be applied without any problems on the line input as the microphone channel of the console.

The circuit is powered by a 9V and consumption is very low, so it can be safely operated by a power source or standard 9V battery. In the latter case, remember that proper filtering is the key to good audio quality.

Output cables must be shielded types (mesh) to prevent interference or noise from the sound produced.

It is recommended to mount it in a cabinet or in a circular or pyramidal. Although the first is what gives best results and has a nice aesthetic.

Another recommendation that is not in the scheme is to put a 100nF capacitor between + V and mass within the printed circuit of the apparatus.

The potentiometer allows to adjust the sensitivity of each microphone. This is useful when there are more people on one side than another, or when someone is talking too loudly than others.

The post Multidirectional microphone amplifier appeared first on Amplifier Circuit Design.

The op amp provides an amplification of about 30 dB (which is sufficient for the relatively high output level of an electret microphone), this gain depends on the value of resistors R3 and R4. If you want to be able to vary the gain, simply replace the resistor R4 to 120K a 470K potentiometer in series with a resistance of 10K. The overall gain in this way can vary from 10 to 45 dB.

It is sufficient for a single power supply (not balanced), a single 9V battery work fine. To increase the independence of assembly, you can replace the NE5532 with less energy op amp. AC power can be used, but must be perfectly stable.

The post Electret Microphone Pre-amp based NE5532 appeared first on Amplifier Circuit Design.