This is the "cliche" sound of someone tapping on a public address microphone before speaking. This has a bit more feedback than (1)
I used an EV635 microphone hooked up to an amp. The PA speaker is positioned incorrectly behind the microphone, the volume is too loud, the EQ is off and the room is live - so there's a ringing or feedback.
I took the AKG condenser microphone out of the audio booth and brought it into the studio to record the amp set-up. Encoded with M-Audio Delta AP