You are here

Q. Which modular mic parts are matched?

By Hugh Robjohns

I often wonder exactly what gets matched when microphones with interchangeable capsules are bought as a stereo pair. Is it the bodies, the capsules, or both? My Rode NT55s have serial numbers on the bodies but not the capsules, and I sometimes lie awake, fretting that I may inadvertently have swapped them over at some point!

Many small-diaphragm mics are sold with interchangeable capsules. When selecting pairs of such mics, it’s the capsules that need to be matched — the preamp ‘bodies’ of such mics are usually quite closely matched in any case, and not only on high-end models such as those pictured.Many small-diaphragm mics are sold with interchangeable capsules. When selecting pairs of such mics, it’s the capsules that need to be matched — the preamp ‘bodies’ of such mics are usually quite closely matched in any case, and not only on high-end models such as those pictured.

SOS Forum post

SOS Technical Editor Hugh Robjohns replies: The capsules are the critical elements insofar as matching is concerned. The mechanical construction tolerances affect the overall sensitivity, the precision of the polar response, and the on- and off-axis frequency responses (as described in my answer to the previous question). The bodies, though, only provide an impedance converter and output driver, and the electronic bandwidth should be massively wider than that of the capsule — and thus not a limiting factor in the combined mics’ performance. The only possible tolerance variation in a mic body is of the gain, which is very easy to set quite precisely by design, and any remaining tolerance variations are easily corrected by the preamp/mixer it’s plugged into.

So swapping capsules between bodies shouldn’t affect the stereo matching at all... You can sleep soundly!

Published August 2015