Over the next few months I'll be trying to learn how to record my band. I have a few newbie questions on some condenser microphone concepts. I just want to make sure I understand this all correctly. Specifically I was looking at the spec for a CAD M179 microphone. I noticed the spec states the following for the Max SPL.

Max SPL: 143dB, 1% THD, attenuator engaged

And this got me thinking about a few things. I want to know if it is correct to say the following?

1) I probably won't see 143dB in a studio setting unless I was recording a gun shot or something, in which case I wouldn't be in a studio.

2) Inside the Mic itself is a diaphragm which is connected to a pre-amp circuit. The -10dB attenuator is located between the diaphragm and the pre-amp.

3) If the attenuator was not engaged, the Max SPL would be 133dB.

3) The 1% THD that would occur at 143dB SPL is due the the preamplifier distorting and not the diaphragm.

4) If I were to raise the SPL beyond 143dB not only would the pre-amp distort the signal from the diaphragm, but the diaphragm would itself start to generate a distorted signal. If I continued to raise the SPL even further the SPL would be so high as to cause permanent physical damage to the diaphragm.

5) Generally speaking. If the sound source were to momentarily (on the order of milliseconds) peak above 143dB, would the microphone incur any damage? Alternatively if the sound source were to momentarily peak above 143dB for say 1-2 seconds, would the microphone incur any damage?

6) Is blowing into a condenser Mic enough to cause damage to the diaphragm? Would dropping the mic on the ground be enough to damage the diaphragm?

1 Answer 1


If you can achieve 143dBSPL in a studio, I would be very seriously more concerned about your own ears than the microphone. 130dBSPL is the estimated threshold of pain, roughly 4.34 times quieter than 143dBSPL (if my math is correct).

If you take Inverse Square Law into consideration, if you feel the mic is being subjected to too much level, move it further back. I would suggest you will be fine in a studio with that microphone, if you take standard precautions. Test everything at a reasonable level, and start raising the gain until the mic distorts, then pull it back.

Dropping a condensor is a solid way to destroy it (in most cases), though I do not know if blowing into it causes damage. I would suggest blowing into it while it is turned on, could cause damage.

All about dbSPL

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