Microphone tuning

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The choice of some frequency-dependent properties when designing a microphone is known as microphone tuning. In particular, the resonance frequency and resonance damping of the membrane are important for the correct function of a microphone. They must be matched to the type of microphone ( dynamic microphone or condenser microphone ) and the directional characteristic to be generated (omnidirectional, cardioid, figure eight).

Resonance tuning of the membrane in microphones

The tuning is intended to achieve a desired frequency response of the microphone, for example as linear a course as possible. The membrane adjustment necessary for this takes into account the respective type of sound transducer and is listed for pressure receivers and pressure gradient receivers in the following table. See Figure 12 in the web link "Mutual position of membrane resonance and transmission range for dynamic and condenser microphones".

Receiver / converter Condenser microphone dynamic microphone
Pressure receiver
(omnidirectional) 		Highly tuned membrane Center tuned membrane
Pressure gradient receiver
(kidney or figure eight characteristics) 		Diaphragm center-tuned, friction-inhibited Membrane deeply tuned

The terms “high” or “low tuned” mean that the membrane resonance was placed at the upper or lower end of the transmission range . Center-tuned means that the membrane resonance is in the middle of the transmission range (500 to 1000 Hz). These adjustments are intended to compensate for the principle-related frequency responses of the respective receiver and transducer, for example the low reproduction of lower bass frequencies of a pressure gradient receiver outside the near field of a sound source.

It can be seen that a microphone with cardioid characteristics cannot be converted into a usable microphone with omnidirectional characteristics by closing the cardioid holes on the back of the diaphragm, since the unsuitable diaphragm tuning would lead to an undesirable change in the frequency response. This sound distortion is only occasionally used in so-called “cupping” (encircling the back of the microphone basket with your hands) as an effect for “grunting” , while accepting an increased risk of feedback from the omnidirectional characteristics generated.

The deep membrane tuning required with ribbon microphones leads to greater sensitivity to disruptive structure-borne noise (impact noise and wind noise). In this regard, omnidirectional condenser microphones are superior to all microphones because of their tuning.

literature

  • Thomas Görne: Microphones in theory and practice. 8th edition. Elektor-Verlag, Aachen 2007, ISBN 978-3-89576-189-8 .
  • Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.): Manual of the recording studio technology . 2 volumes. 8th, revised and expanded edition. Verlag Walter de Gruyter, Berlin / Boston 2014, ISBN 978-3-11-028978-7 or e- ISBN 978-3-11-031650-6 .
  • Norbert Pawera: Microphone Practice . 4th edition. Franzis Verlag, Munich 1993, ISBN 3-932275-54-3 .

Web links