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Comparing mic noise



 
 
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  #1  
Old July 13th 17, 11:28 PM posted to rec.audio.pro
Tobiah
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Posts: 616
Default Comparing mic noise

I have a pair of mics that claim Equivalent Noise Level of 5dB-A.
Another mic claims 70dB Signal to noise ratio. How can I compare
the noisiness of the two mics?


Thanks,

Tobiah
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  #2  
Old July 14th 17, 12:07 AM posted to rec.audio.pro
Scott Dorsey
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Posts: 16,655
Default Comparing mic noise

In article >, Tobiah > wrote:
>I have a pair of mics that claim Equivalent Noise Level of 5dB-A.
>Another mic claims 70dB Signal to noise ratio. How can I compare
>the noisiness of the two mics?


You cannot. The first number is actually a measurement of noise floor,
but because it's A-weighted it's going to ignore all the low frequency
noise (and that's primarily what you're going to have in a condenser
microphone).

The second number isn't a measurement of noise floor at all, but is a
measurement of the _difference_ between the noise floor and the overload
point at some unknown frequency.

Neither one of these measurements is measuring what you want to know.
They are measuring two different things, neither of which is what you want.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #3  
Old July 14th 17, 12:14 AM posted to rec.audio.pro
Mike Rivers[_2_]
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Posts: 2,078
Default Comparing mic noise

On 7/13/2017 6:28 PM, Tobiah wrote:
> I have a pair of mics that claim Equivalent Noise Level of 5dB-A.
> Another mic claims 70dB Signal to noise ratio. How can I compare
> the noisiness of the two mics?


Hook them up to two channels of a preamp, bundle them up in a pile of
pillows, put them in a quiet place, then listen to them. If you want to
be studious about it, record the noise and look at it with a spectrum
analyzer program. If you're going to do that, be sure to check the noise
of the preamp first, with its input terminated with a nice quiet 150 ohm
resistor.


--

For a good time, call http://mikeriversaudio.wordpress.com
  #4  
Old July 14th 17, 12:40 AM posted to rec.audio.pro
Tobiah
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Posts: 616
Default Comparing mic noise

On 7/13/17 4:07 PM, Scott Dorsey wrote:
> In article >, Tobiah > wrote:
>> I have a pair of mics that claim Equivalent Noise Level of 5dB-A.
>> Another mic claims 70dB Signal to noise ratio. How can I compare
>> the noisiness of the two mics?

>
> You cannot. The first number is actually a measurement of noise floor,
> but because it's A-weighted it's going to ignore all the low frequency
> noise (and that's primarily what you're going to have in a condenser
> microphone).
>
> The second number isn't a measurement of noise floor at all, but is a
> measurement of the _difference_ between the noise floor and the overload
> point at some unknown frequency.
>
> Neither one of these measurements is measuring what you want to know.
> They are measuring two different things, neither of which is what you want.
> --scott
>


>


Still, couldn't an experienced individual give me some idea, given these
incompatible statistics, what level of noise I might notice from one to
the other.

The one pair is Rode NT1-A, and the other is an Audio-Technica AT8010.

I don't yet have the AT8010. I was just considering it. I'm trying to
find any omni condenser that has a noise floor that is as close as I can
get to the NT1-A's. Any other suggestions?

Thanks,

Tobiah
  #5  
Old July 14th 17, 01:16 AM posted to rec.audio.pro
[email protected]
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Posts: 331
Default Comparing mic noise

On Thursday, July 13, 2017 at 7:40:23 PM UTC-4, Tobiah wrote:
> On 7/13/17 4:07 PM, Scott Dorsey wrote:
> > In article >, Tobiah > wrote:
> >> I have a pair of mics that claim Equivalent Noise Level of 5dB-A.
> >> Another mic claims 70dB Signal to noise ratio. How can I compare
> >> the noisiness of the two mics?

> >
> > You cannot. The first number is actually a measurement of noise floor,
> > but because it's A-weighted it's going to ignore all the low frequency
> > noise (and that's primarily what you're going to have in a condenser
> > microphone).
> >
> > The second number isn't a measurement of noise floor at all, but is a
> > measurement of the _difference_ between the noise floor and the overload
> > point at some unknown frequency.
> >
> > Neither one of these measurements is measuring what you want to know.
> > They are measuring two different things, neither of which is what you want.
> > --scott
> >

>
> >

>
> Still, couldn't an experienced individual give me some idea, given these
> incompatible statistics, what level of noise I might notice from one to
> the other.
>
> The one pair is Rode NT1-A, and the other is an Audio-Technica AT8010.
>
> I don't yet have the AT8010. I was just considering it. I'm trying to
> find any omni condenser that has a noise floor that is as close as I can
> get to the NT1-A's. Any other suggestions?
>
> Thanks,
>
> Tobiah


May I ask, why are you concerned with "noise"? I've listened to recordings from Pros and I hear magnetic tape and improper EMI shielding being the two MAJOR problems, not the microphones.

Jack
  #6  
Old July 14th 17, 02:45 AM posted to rec.audio.pro
Mike Rivers[_2_]
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Posts: 2,078
Default Comparing mic noise

On 7/13/2017 7:40 PM, Tobiah wrote:
> Still, couldn't an experienced individual give me some idea, given these
> incompatible statistics, what level of noise I might notice from one to
> the other.
>
> The one pair is Rode NT1-A, and the other is an Audio-Technica AT8010.
>
> I don't yet have the AT8010.


Oh, so you want to compare them based on published information, not
actual performance. You should read my series about specifications
published in Recording. The gist of the introduction is that
manufacturers measure products any way they want to, and publish numbers
that they think will look good to the customer even though they're
relatively meaningless out of their own context. Neither of those
specifications can tell you how many milivolts of noise you get out of
the microphone when there's there's no sound going into it.

What you want is a specification that says something like "Self-noise:
-72 dBu (or 0.2 mV). But that's too simple and honest.


--

For a good time, call http://mikeriversaudio.wordpress.com
  #7  
Old July 14th 17, 02:59 AM posted to rec.audio.pro
Scott Dorsey
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Posts: 16,655
Default Comparing mic noise

In article >, Mike Rivers > wrote:
>What you want is a specification that says something like "Self-noise:
>-72 dBu (or 0.2 mV). But that's too simple and honest.


There is in fact a push on the part of the AES standards committee SC-04-04
to actually create such a specification with a standard measurement method
that would allow consistency between vendors. AT is one of those vendors,
and their microphones among others were passed around the group comparing
measurements.

So, it IS possible that someday soon we'll have a standardized method that
can be used for comparison.

In the meantime, if you want a quiet mike, try the MKH-20.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #8  
Old July 14th 17, 04:54 AM posted to rec.audio.pro
Don Pearce[_3_]
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Posts: 2,269
Default Comparing mic noise

On Thu, 13 Jul 2017 21:45:31 -0400, Mike Rivers >
wrote:

>On 7/13/2017 7:40 PM, Tobiah wrote:
>> Still, couldn't an experienced individual give me some idea, given these
>> incompatible statistics, what level of noise I might notice from one to
>> the other.
>>
>> The one pair is Rode NT1-A, and the other is an Audio-Technica AT8010.
>>
>> I don't yet have the AT8010.

>
>Oh, so you want to compare them based on published information, not
>actual performance. You should read my series about specifications
>published in Recording. The gist of the introduction is that
>manufacturers measure products any way they want to, and publish numbers
>that they think will look good to the customer even though they're
>relatively meaningless out of their own context. Neither of those
>specifications can tell you how many milivolts of noise you get out of
>the microphone when there's there's no sound going into it.
>
>What you want is a specification that says something like "Self-noise:
>-72 dBu (or 0.2 mV). But that's too simple and honest.


That isn't what you want either. The 5dBA figure is much more valuable
than a simple level with no sensitivity reference to compare it to.

What I do know is that it is a long time since mic noise was actually
an issue. Noisy preamps like RNP are much more where the problem lies.
I use an NT1-A and I can confirm that it is an extremely quiet mic.
What noise it is, as Scott says, is at the bottom end, and most
situations where you need the low noise figure are going to be ones
where you are in any case going to roll the bottom end back because
you are up close.

d

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  #9  
Old July 14th 17, 05:37 AM posted to rec.audio.pro
Phil Allison[_4_]
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Posts: 457
Default Comparing mic noise

Tobiah wrote:


>
> Still, couldn't an experienced individual give me some idea, given these
> incompatible statistics, what level of noise I might notice from one to
> the other.
>
> The one pair is Rode NT1-A, and the other is an Audio-Technica AT8010.
>


** The AT8010 has a noise spec of " 70dB, 1kHz at 1 Pa"

1 Pascal = 94dB SPL.

So the self noise of the AT is 24dB at 1kHz.

Pretty poor, even for an electret mic.



...... Phil
  #10  
Old July 14th 17, 09:14 AM posted to rec.audio.pro
Adrian Tuddenham[_2_]
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Posts: 502
Default Comparing mic noise

Don Pearce > wrote:

> On Thu, 13 Jul 2017 21:45:31 -0400, Mike Rivers >
> wrote:

....
> >What you want is a specification that says something like "Self-noise:
> >-72 dBu (or 0.2 mV). But that's too simple and honest.

>
> That isn't what you want either. The 5dBA figure is much more valuable
> than a simple level with no sensitivity reference to compare it to.


Perhaps a figure for the equivalent noise in dBC, so it takes account of
the L.F. noise too?


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
 




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