Option Sone low-noise microphone class 1 noise floor below 20dB

with this option you will get a high quality class 1 microphone for low noise measurements. You will need this option if you want to measure silent devices e.g. beamer, hard disks, ventilating systems etc. Please make sure that you have a special low noise room with low background level.   Listening tests You can easily compare these different classes of microphones with a short recording. We compare the  ECM8000 (1/4" capsule)  and DJD Type 1 (1/2" capsule).Microphone distance is 1m from a weak sound source from a loudspeaker.Both microphones are connected to the same pre-amplifier (M-Audio mobile pre).We adjusted the gain for the same level.Due to the low sound level noise occur and is intended.You can easily hear the difference. The ECM800 has a much higher noise floor of 12-15dB. Behringer ECM8000 https://www.dr-jordan-design.de/Download/ECM8000.mp3 1/2" Measurement microphone DJD Type 1 https://www.dr-jordan-design.de/Download/DJD_3x1.mp3   You can easily see the differnce from the construction of the capsule The left mic is our DJD Typ1 without protection grid. This allows watching the sensitive diaphragma directly. The right mic shows a ECM 8000. It's head basically allows connecting calibrators directly. The core capsule is much smaller. The diamater of the diaphragma is just 4.5mm compared to 10.5mm. Therefor the effective area is more than 4 times smaller. Specification 1/2-inch pre-polarized Fulfills IEC60651-class 1 low noise sound level  17-148dB frequency range 20-20kHz sensitivity 50mV/Pa Omnidirectional Connection via  XLR Requires phantom power 48V Capsule thread 60UNS Size: Length 165mm, Diameter capsule 13.2mm, pre-amplifier 19mm Individual frequency response Shipped with protective wooden box