Sennheiser MKH 416 The MKH Story - Page 3

The MKH Story No problems with humidity There is another important benefit of the RF principle for practical use. The low electrical impedance of the capsule provides outstanding immunity against detrimental effects due to humidity, because even then the leak resistance is very much larger than the capsule impedance. Thus MKH microphones are well-suited for outdoor use. In normal AF condensers the stored charge on the high-impedance capsule finds it easy to leak away across the insulation on water molecules, which can cause noise and 'crackling' effects. This is why outdoor recording became an important domain of the MKH microphones; especially as interference-tube microphones ('shotguns') with increased directivity and good suppression of ambient noise were available. The short shotguns MKH 415 and MKH 416 soon became the industry standard. The MKH 415 short gun microphone New MKH models for phantom powering Besides AB powering, phantom powering was also introduced and became the standard microphone powering over the course of time. Nowadays nearly all microphone inputs provide this powering. With phantom powering the supply current is equally conducted via both signal leads of the microphone cable and returned via the cable screen. This powering does no harm to dynamic microphones, as the DC potential is the same at both microphone terminals; this prevents current flowing through the moving coil. So phantom powering need not be switched off when using dynamic microphones. The MKH line was extended by microphones for 12V and 48V phantom powering (P12, P48), which received the model code '6' (MKH 106 P12, MKH 106 P48 etc.). Again, the RF operation facilitated a transformerless balanced and floating output. Associated with this development was a circuit redesign of the AB models, which then also received the model code '6' (MKH 106 T, etc.). In the mid 1970s for each method of powering there was an omnidirectional microphone (MKH 106), a cardioid (MKH 406), a short shotgun (MKH 416) and a long shotgun (MKH 816). Later the microphones' quartz crystal was replaced by an LC circuit which made them even more rugged. After phantom powering had become the de-facto standard, the production of the AB microphones declined successively. Only the MKH 416 T survived because recording equipment that provides only this powering is still in use. At the end of the 1990s the shotguns MKH 416 T and MKH 416 P48 were completely redesigned without altering the essential acoustic properties of the microphones. The goal was, besides the implementation of new production technologies, the tightening of production tolerances. Measuring set-up for the MKH 110 low-frequency microphone Microphones detect subsonic sound As the RF technique operates down to 0 Hz without limitations, special microphones for subsonic measurement applications were developed. The subsonic microphones MKH 110 and MKH 110-1 featured lower limiting frequencies of 1 Hz and 0.1 Hz, respectively. Apart from this special application the frequency response of conventional transducers is limited at low frequencies by a pressure equalising port in order to suppress subsonic signals in normal recordings. Page 3