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Re: Sennheiser omni absolute noise floor?

Subject: Re: Sennheiser omni absolute noise floor?
From: Walter Knapp <>
Date: Tue, 21 Jan 2003 15:07:33 -0500
Wild Sanctuary wrote:
> Anyone out there know the absolute noise floor specs of the best
> Sennheiser omni mic? Reason: We are interested in recording in
> natural habitats that are very nearly anechoic and are looking for
> references to the quietest production model professional mic
> system(s).

In Sennheiser it's going to be a choice between three MKH models if you
stick to omni, from Sennheiser's spec sheets:

MKH-20  Equivalent noise level 10dBA  Sensitivity 25mv/Pa
MKH-80  Equivalent noise level 10dBA  Sensitivity 45mv/Pa
MKH-800 Equivalent noise level 10dBA  Sensitivity 40mv/Pa

I've not seen a MKH-800, but do have a couple MKH-80's. I like the sound
from them better than my MKH-20's, although the difference is minimal.
I'm not sure if the MKH-80's are still in production, the MKH-800 is a
newer version of that mic with extended upper frequency range. I
currently have my MKH-80's set up in a suspension for M/S stereo. I
don't have quiet enough environments here to really push for the noise
floor of these mics, for practical purposes here it does not exist.

If you can move away from omni's, a couple other MKH are pretty low noise:

MKH-60  Equivalent noise level  6dBA  Sensitivity 40mv/Pa
MKH-70  Equivalent noise level  5dBA  Sensitivity 50mv/Pa

I've always taken those noise level ratings as a pretty close estimate
of the absolute noise floor. I've not seen any alternative reporting for
the noise floor. Of course to have any difference between self noise and
the noise you want, what you want has to be louder than that. And
everything past the mic has to be perfect.

I expect that if you need below the levels that these mics can record
you will have to get into measurement mics, some of the B&K measurement
mics are supposed to be usable as low as -40dBA. I don't know a lot
about them. I have some spec sheets on other brands, a quick scan
through those did not reveal anything that did as well as the MKH, but
my set of data is far from complete. A Schoeps MK/CCM 2 comes close with
a Equivalent noise level of 11dBA. Most high level pro omni mics seem to
come in the range of 15-25dBA for equivalent noise. At least of those
I've looked at.

Have you measured the habitats with a sound meter? From my experience
giving hearing tests to military draftees and volunteers I'd expect that
the average of even that group would not hear a 5-10dB level. And I know
my hearing is not that good. Your habitat could be louder than you
think. I also assume you are trying to record something there other than
the quietest level. How loud are the calls, or whatever?

Walt




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