This page informs about Microphones which can be used with Barix Annuncicom products.
The Annuncicom Microphone input is suitable for typical electret microphones, but other types work as well (dynamic microphones).
The input impedance depends on the configuration of the input gain, min. 8KOhm (at +43.5dB amp level), max. 94kOhm at +21dB. The input will clip at round 280mV. A third connection pin (on both 3.5mm connector as well as on the contact block) provides a "bias" voltage source of about 2.5V, perfectly suiting most electret microphones. If a microphone needs 12V, the voltage can typically also be taken from the Annuncicom power supply, provided it is a 12V regulated type.
Please make sure that if you use an electret microphone, the source voltage is also connected. A microphone not powered by the Annuncicom must be connected to pins 1 and 3 of the contact block, pin 2 provides the source voltage. The output impedance of the mic bias source is 5kOhm.