Re: Basic question about phantom and sensitivity

Henk wrote:

Do you mean to say that although the max o/p level doubles when
applying 48V in stead of 12V the max SPL handling is also very likely
to increase by 6dB because of the additional powerhandling of the
preamp? And since a doubling of Voltage is equal to a 6dB difference
this "cancels" each other out when we speak about its sensitivity? You
could very well be right! It must be exactly 6dB though, otherwise the
sensitivity does change. Mmmm, thanks, I'll think about that

Hmm--no, actually, it's simpler. A condenser microphone's sensitivity
is determined by physical characteristics of its capsule, by the
voltage at which the capsule is polarized, and by the voltage gain of
the microphone's circuitry. With electrets (such as the lavalier
microphone which the original poster asked about) the polarization
voltage isn't a function of external powering, while with microphones
such as your Schoeps, the polarization voltage is kept constant by an
internal DC converter. Thus the sensitivity of the microphone is simply
not affected by the changeover from 12 V to 48 V.


[ ... ] I have been using schoeps microphones quite a bit and although I
love them on drums I have experienced some nasty clipping when I first
started using them. I've always assumed that this was the diaphragm for
in the recorded waveform you could see a very tipical and strange curve
that I could not otherwise explain. It's true though that I never experienced
this with other mics so maybe the preamp is indeed more often the
'weakest link' in that regard. Thanks again for making me rethink this.

Well, with Schoeps microphones, the capsules can handle far higher
sound pressure levels than the circuitry--but the circuitry can handle
levels of 130+ dB SPL (unless you have the blue dot version of the
amplifier, which has 5 dB greater sensitivity but a correspondingly
lower maximum SPL limit). So if you really are overloading the
capsule--a relatively rare occurrence--I would suspect that this may be
due to air motion rather than sound energy per se.

You might try a simple foam windscreen to see whether it makes the
distortion decrease or go away. If it remains, then I'd suggest trying
a resistive pad at the input of your preamp or mixer. A Schoeps
microphone can put out nearly a Volt without distorting, and some
preamp inputs can't handle such high signal levels.

Capacitive pads (Schoeps DZC 10 or DZC 20) can also be placed between
the capsule and amplifier of the microphone if the capsule's output is
overloading the amplifier, but they are normally needed only for sound
pressure levels so high that your hearing would be damaged by continued
exposure to them.

--best regards

.

Relevant Pages

  • Re: How do I find microphone output voltage?
    ... How can I calculate the output level of a microphone, ... I assume it is found from the Sensitivity, ... but at what SPL is that taken? ...
    (sci.electronics.basics)
  • Re: How do I find microphone output voltage?
    ... How can I calculate the output level of a microphone, ... I assume it is found from the Sensitivity, ... but at what SPL is that taken? ...
    (sci.electronics.basics)
  • How do I find microphone output voltage?
    ... How can I calculate the output level of a microphone, ... I assume it is found from the Sensitivity, ... but at what SPL is that taken? ...
    (sci.electronics.basics)
  • Re: Basic questions about microphones and mic preamp design...
    ... The output voltage of 1/4" diameter size is around 3 ... also musicians grade electrets with a built in transformer for balancing and ... > only used in differential microphone connections? ... Level vs. gain setting. ...
    (sci.electronics.design)
  • Re: Carbon microphone revitalization
    ... with the microphone. ... I have been told that carbon microphones can be ... output voltage with an oscilloscope while talking. ... Carbon mics are prone to "packing" which is when the ...
    (rec.radio.amateur.boatanchors)
Loading