One of the more difficult decisions that must be made when specifying acoustic measurement systems concerns microphone selection. An error in this important component can throw doubt on every measurement made and the design decisions that follow. On the other hand, not everyone can drop $2,000 on a high end metal diaphragm measurement microphone system. Even for those who can afford this, there are circumstances where accuracy remains critical but the operational environment is such that there's a risk that delicate equipment could be damaged. Examples include on-site sound system tuning, loudspeaker production lines and FOH setups for concert touring. Audiomatica offers an ideal and cost effective solution to these needs with the MIC-Ox series of measurement microphones.
The MIC-01, MIC-02 and MIC-03 are precision prepolarized electret microphones that perform far beyond their modest cost. Each of these microphones have identical specifications other than length. The 3" MIC-03 is perfect for production line use in tight spaces, the 5" MIC-02 is by far the most popular size for general use and the 10" MIC-01 is the best choice for high resolution measurements where you want the mic stand assembly as far from the transducer capsule as possible. Each microphone is individually tested and the sensitivity value is supplied. Each are perfectly suited for CLIO 12 and CLIO Pocket (the latter comes with MIC-02 at no extra cost).
The MIC-04 uses the same transducer assembly, but is installed in a 90˚ aluminum body with 3mm threaded mounting points for production lines and small test jigs. Specifications are similar to the 01-03 series.
A second type of transducer that Audiomatica has made available for loudspeaker designers is a similarly rugged and cost effective accelerometer; the ACH-01. This is a small piezoelectric polymer film device that transforms the motion of the surfaces it is attached to into an analogous electrical signal. A typical application for an accelerometer is the observation of cabinet resonances generated sympathetically by the attached loudspeaker drivers. Ideally, we only want to hear the output of the drivers themselves, but poorly designed cabinets add later arrivals to this output that can result in an otherwise excellent design that sounds mediocre. I strongly recommend that you add this type of vibration testing to your design procedure.
The ACH-01 comes with a Mogami 3’ shielded cable terminated to a Pomona female RCA plug and requires 3V - 40V DC (phantom) powering on the center contact. Factory calibration in mV/g is included for each unit. Both CLIO Pocket and CLIO 12 are ideally suited for this application. A 10’ or 25’ Canare coax RCA cable is a recommended accessory.
All microphones come with a calibration certificate that includes a measured sensitivity rating. This is quite satisfactory in many cases, but for those who want the very best accuracy and the ability to verify their measurement microphone inventory over time, a calibrator is required. The selection of a microphone calibrator shares many of the same decisions that must be made when buying a microphone. Metal diaphragms can survive environmental extremes and have a longer useful lifespan, but are very expensive. The same is true of calibrators, but just like microphones there are some very well made and reasonably priced plastic diaphragm designs and the sturdy Extech 407744 is one of the best. When purchasing from Soundscapes, each Extech mic calibrator is calibrated to 1/10th of the factory specified errors in both frequency and level using CLIO with Brüel & Kjær's Type 4231 calibrator and Type 4007 microphone. Distortion is also less than 1/10th factory specification due to Extech's very conservative rating in this area. Be sure to purchase an AA-001 calibrator adapter for the MIC-0x series if you plan on using these microphones.
Extech 407744 Specifications