Cannot be said in short:
Microphone Preamplifier
Even among engineers, the discussion of microphone preamps can be confusing and lead to misunderstandings. Especially in the context of measurement microphones, the term "preamp" can refer to two different devices.
(1) Generally, a preamp is the unit to which a microphone is connected, which amplifies the microphone signal so that a computer or mixing console can process it.
(2) Another type of amplifier is meant, when we are talking about the microphone body the detachable microphone capsule is connected to and having a built-in buffer amplifier with no or low gain and an output stage that can drive the preamp mentioned under (1).
iSEMcon will use the nomenclature microphone capsule - microphone body/preamp - microphone preamplifier in this manual to express things more clearly.
Open Circuit Microphone Capsule Sensitivity
Open-circuit sensitivity in microphones refers to the voltage generated by the microphone capsule when exposed to a sound pressure level of 94dBspl, measured without any load or preamplifier connected . It's a crucial specification for comparing microphone capsules and understanding their inherent ability to convert sound to an electrical signal.
At a glance:
|
Small signal |
Selfnoise
to 130 dBspl
|
|
Large
Signal |
114dB
to AOL |
|
Phantom,
nominal, open circuit |
48V,
6.8k, Rload > 100K, Input Impedance 6.8k |
|
Phantom
nominal, loaded |
48V.
6.8k, Rload=1.2k, Input Impedance 1k |
|
Phantom,
high voltage, open circuit |
60V,
6.8k, Rload > 100k, Input Impedance 6.8k |
|
|
|
|
Nominal
Environmental Conditions |
23
deg Celsius, 1013mbar, 50% r.H. |
|
|
|
|
AOL |
Acoustic
Obverload Point (10% distortion) |
|
SPL |
Sound
Pressure Level |