For quality assurance purposes, Schoeps measures the frequency response and sensitivity of each capsule that we produce. Deviations are accepted only within narrow limits. For the sensitivity of a microphone capsule, i.e. the level at 1 kHz, we allow deviations of ±1 dB relative to the standard sensitivity specified on the Web site. In the frequency range between 200 and 6000 Hz, deviations of more than ca. 1 dB from the normalized 0° frequency response are not allowed. The off-axis curves of some microphone types are also measured and—depending on the microphone type—must adhere to various other strict limits.
If microphone capsules are shipped as matched pairs, particularly strict criteria apply. We always look for the best pairs from a large batch of microphone capsules. In this way, we actually achieve an overall match in the entire mid-frequency range between 200 and 10000 Hz with deviations of less than 0.1 to 0.5 dB, depending on the microphone type. Especially the sensitivity, i.e. the level at 1 kHz, has to match exactly in order to achieve a perfect stereo image with a fixed, common gain setting at the preamplifier.