MiniSonic Measuring MicrophonesLindos miniature electret microphones are calibrated to UniSon-Mic standard and fitted with Minijacks for plugging directly into the MiniSonic MS1/MS10/MS20 test set. This allows precision measurement of loud speakers, room responses and other microphones. The MM1 and MM3 are both classed as "1/4 inch" mics (standard 7mm external diameter).
We favour the use of quarter inch mics, because, being small compared to the wavelength even at 20kHz (wavelength 18mm) they do not need to be pointed accurately at the source (omnidirectional), and do not disturb the propagating waves in free-field measurement as bigger microphones can.
The fact that calibrated mics can be plugged directly into the MiniSonic unit, without the need for a pre-amplifier or phantom power source, makes instant speaker measurements possible at last.
The MiniSonic units have dual (stereo) mic inputs for two reasons. Firstly, it is very easy to compare miniature mics (using the difference plot facility on Lin4Win) and even to compare traditional mics (using the line input too). Secondly, using two Lindos miniature mics, the MiniSonic becomes a 'purist' recording front end (spaced omni technique), or camcorder adaptor for interviews, with precision 1dB gain setting facility and PPM level monitoring.
The Calibration ProcessLindos mics are all calibrated using a pressure calibrator, which consists of a sealed tube with a tone generator at one end and the mic under test well sealed at the other. This provides a tight coupling between the tone generator and the mic's diaphragm that ensures a constant energy transfer independant of any reverberant sound in the room. While generating a 1kHz tone the output voltage/level is measured and this reading is used to select appropriate resistors for a potential divider (arranged inside a gold plated minijack) to attenuate the output voltage such that -30dBu (24.5mV) is output for 100dBSPL (2 Pa) i.e. our microphones are calibrated to a sensitivity of 12.25mV/Pa. Our calibrator operates at a fixed level of 114dBSPL.
Click here to see best case test results for the MM3s.
Click here to see worst case test results for the MM3.
Click here to view test results.
AccessoriesThese accessories are supplied with both the MM1 but not with the MM3.