Rens Heijnis custom-built audio equipment - DPA/B&K 4003 4006 noise, hum problems. It's very unusual for me to write something about technical defects of microphones, but this time I will make an
4006 Omnidirectional Condenser Microphone
DPA 4006A | RecordingHacks.com
DC Audiovisuel - DPA 4006 paire stéréo
DPA 4006-TL, 2006A, 4090, 4011A, 2011C & Schoeps CMC64 on Yamaha Grand Piano | Microphone Comparison - YouTube