There are other reasons, aside from S/N, to favor Sennheisers. They
seem to be less sensitive to humidity than, say, standard Schoeps, or
Neuman systems. When tested by the AES (I forget which models the AES
Journal checked), the noise floor was reported to be about 3dB
quieter than any of the other dozen or so mic models evaluated. Since
then, new mic systems have come onto the market, but I have yet to
find systems quite as reliable and durable in the field. My MKH 30s
and 40s (3 complete M-S systems in all) range from 12 to about 2
years old. There is no measurable difference between them when tested
for sensitivity or noise.
Bernie Krause
>richpeet wrote:
>>
>> I have now spendt way to much time trying to get up to speed in the
>> data given by manufacturers of microphones to figure out what is good
>> and what is not, for natural sound. I am either missing a few
>> building blocks in my knowledge or we simply are not given the
>> information.
>>
>> It seems to me:
>>
>> 1. Sensitivity of a condenser mic is only determined by the after
>> element electronics that determine how "hot" the output is and only
>> lets you know if you need another preamp that already exsists in all
>> condensers.
>
>Sensitivity is also a function of the element design and does vary quite
>a bit.
>
>Sensitivity is a tricky business since so many parameters can effect it.
>The measures given are normally sound chamber measures. They can be used
>to compare, though it's complicated in that different specifications are
>given by different manufacturers. You have to research just what the
>spec means, it's some specific test and often you can find at least a
>general description of what it means either from the manufacturer, or
>searching the internet.
>
>For nature recording one thing to note is that sensitivity tests are
>actually done at pretty high noise levels. When, in fact we are
>recording much quieter stuff. It would be nice to see, say, sensitivity
>tests done at 40 dBA or even lower. The numbers provided are designed
>much more for studio or concert recording.
>
>> 2. Self noise is not represented as a AC voltage within the audio
>> range by any manufacturer and therefore we have no tool to evaluate
>> the specs given.
>
>This all depends on the specs given, you don't need a voltage. Signal to
>noise, usually given in dB is against 94 dB most times. The other way,
>generally used by Sennheiser is to give equivalent self noise. This is
>usually the S/N subtracted from the reference level. For instance the
>MKH-20 lists it's A weighted inherent noise as 10 dB. That means the S/N
>is 84 dBA. Sennheiser, as many manufacturers do lists a code with this
>rating, which is the particular test done to determine the rating. You
>can hunt up those codes on the internet if you want to examine the protocol.
>
>Note A weighted means exactly what it says, the sound measurements are
>in the A weighted sound profile that more or less represents human
>hearing. Different profiles will give quite different results, and
>Sennheiser also reports the CCIR weighted version, which is less
>influenced by human hearing profiles and typically results in a higher
>self noise measurement.
>
>And the measure of self noise in dB as Sennheiser gives it relates very
>well to the actual recording environment. In the case of the MKH-20 this
>means that the environment has to approach a 10 dBA level as measured by
>a noise meter before mic self noise will be much of a problem. Note this
>is not the averaging dBA measure, but the fast measure.
>
>It would be nice if all manufacturers would use the same measures and
>provide all the info necessary, converting measures can be tricky.
>
>> 3. db is a bad measure and should be tossed when comparing condensers.
>
>Depends on what you are used to and what you are doing. Since I own and
>use a noise meter, I can easily relate to a noise floor given in dB. I
>prefer it to the voltage related measures. What I'd like to see is a
>standardization on dB for all manufacturers for the mic noise, giving
>the equivalent mic noise. It would probably be nice to have sensitivity
>in the form of dB or dB related too. So, for instance if I go out and
>measure the calls with the noise meter and get, say 50 dBA, I have some
>idea what sort of signal I'll get from the mic.
>
>> It seems to me what we need is two AC sonographs of the audio
>> spectrum, at silence and when the sensitivity is brought to a
>> constant output voltage, such as a constant of say 20 mv/pa when
>> exposed to a white noise. The sonograph then needs a
>> voltage/frequency view both at the constant full white noise output
>> and at the silence levels.
>
>Sonographs are not necessarily all that precise, and would certainly
>introduce more chance of error. I also doubt they would be that
>informative vs numeric measures.
>
>> Without something like this I don't have a clue how to evaluate any
>> one mic to another. Am I missing something or are condenser
>> microphones currently impossible to evaluate against each other?
>
>They can be evaluated, but the use of different measures by different
>manufacturers does complicate it. Keep digging, in particular study how
>the tests are done for better understanding. Condenser mics are really
>no harder to evaluate than any other type. I hardly claim to be a
>expert, and I've been digging in it for quite a while. I'm slowly
>getting better at this arcane art. It does take a lot more time than
>it should.
>
>Of course the cheating way is to come in the group and ask. For most of
>the common mics used in nature recording someone will be able to provide
>a comparison.
>
>Walt
>
>
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