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Re: AT822 Microphone Noise Floor

Subject: Re: AT822 Microphone Noise Floor
From: "bbystrek" <>
Date: Tue, 30 Jul 2002 23:18:15 -0000
Rudy,

Thanks for the comments.  This sounds like an easy way for me 
reference comparisons going forward.  Normalizing makes sense to me.  
Otherwise, the individual gains of each mic would make it difficult 
to make an equal comparison.

My first thought on reading your response was why not just record 
silence on each mic and look at the levels after importing the 
samples into the computer - but then I realized, that this would 
ignore sensitivity.  Therefore, it's possible for a mic which 
generates the most noise amplitude without a signal, to actually 
provide the best signal to noise ratio if the sensitivity was such 
that it produced high sensitivity under low SPLs.

Reading many of this group's archives, I see that equipment generated 
electronic noise can have different qualities - I read some posts 
talking about the noise of some mic not sounding as "smooth" as 
others.  I guess I have to get a feel for what's out there.

Brian Bystrek


--- In  Rudy Trubitt <> wrote:
> 
> I did a three-way comparison with the AT825 (the balanced version 
of 
> the same mic), a Shure VP88 and a pair of Schopes with CMC-6 
> multipattern capsules. The AT was the noisiest, followed by the 
VP88. 
> The Schopes were the quietest by a rather wide margin. All three 
mics 
> were connected to the same pre-amp, a Mackie MS1202 mixer, and I 
> recorded a quiet pocket watch ticking. Then I normalized all the 
> example files so that the watch ticks reached the same peak level 
and 
> compared the noise floor in each recording.
> 
> rudy
> 
> >
> >Message: 7
> >    Date: Sun, 28 Jul 2002 23:13:53 -0000
> >    From: "bbystrek" <>
> >Subject: AT822 Microphone Noise Floor
> >
> >Does anyone have any experience with the Audio Technica AT822 
stereo
> >condenser mic?  How does it stack up against other mics in terms of
> >background noise?  It's the only mic I own and I don't really have
> >much perspective.  I was pleased with the results recording frogs 
and
> >various water sounds this past spring.  It seems a little tricker 
to
> >capture lower level sounds like a meadow of insects.  Close miking
> >helps improve signal relative to noise, but this can also throw
> >things out of perspective where I'm really trying to capture a
> >broader image.
> >
> >Datasheet:  
http://www.audiotechnica.com/prodpro/profiles/AT822.html
> >
> >Open Circuit Sensitivity: -45 dB (5.6 mV) re 1V at 1 Pa
> >Signal to Noise Ratio: 70 dB, 1 kHz at 1 Pa
> >
> >Reading various manufacturers datasheets and app notes, it appears
> >that quiet recordings at low SPLs are related to both Sensitivity 
and
> >SNR.  How does one compare two mics, when neither value is equal?  
Is
> >it always subjective?
> >
> >Another reason I'm asking about noise - I'm thinking of getting 
into
> >one of the more robust stereo imaging techniques like M-S or
> >boundry.  
> >
> >By the way, I'm recording with a Sony walkman style DAT, and
> >presently editing with Magix's Samplitude on a 90 day demo basis.  
My
> >objective is for playback via CD and loudspeakers and of couse for
> >optimal imaging, using headphones.
> >
> >Brian Bystrek
> >
> >
> -- 
>       *--------------------------------------------------*
>       *    ...  http://www.trubitt.com   *
>       *--------------------------------------------------*



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