It is using a transistor type of low noise types: BC 650 C, but it was hard to find transistors can be replaced degan 109 BC which is just as good. EMC electret condenser mic or in which there is a very sensitive micriphone element and an internal FET preamp circuit, so any 'voltage to the EMC is between 20-10 volts, for that we can love resistor 1 K-10 K ohms for the EMS mesuplay.
