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Re: AudioTechnica AT4022

Subject: Re: AudioTechnica AT4022
From: "Paul Jacobson" thebrunswicktwitcher
Date: Thu Nov 19, 2009 3:34 pm ((PST))
On 20/11/2009, at 9:21 AM, Eric Benjamin wrote:

> Uh oh!  Someone used my name
> 
> The basis for my original statement of 8 dB self noise for an AT3032 was that 
> I had measured one as having 8 dB self noise.  I have very good facilities 
> for measuring microphone self noise and I can generally do a pretty accurate 
> job down to about 5 dB or so.  Below that, the impact of environmental noise 
> may limit my ability to measure the true self noise of the device.  Note that 
> the usual sort of errors work in the direction of causing the measurement 
> result to be high, not low.
> 
> Could I have been in error in my measurement?  Of course I could!  But I 
> don't think so.  I was so surprised by the result that I did the measurements 
> over again, and then I did a listening test to confirm.  As it happens, the 
> Schoeps Mk2 microphones are very consistent in terms of their self noise.  I 
> have measured three of them and they were all within a fraction of a dB of 
> the specified 11 dBA.  The reason for this is that a particular resistor in 
> the circuit limits the self noise, not the FET.  And the AT3032 was 
> noticeably quieter than the Schoeps Mk2.
> 
> Could other samples of the AT3032 have different self noise?  Of course.  I 
> haven't analyzed the AT3032 circuit so I don't know what limits the 
> performance.  It could be pretty variable.  That could explain why AT chose 
> to rate the microphone as having 16 dBA.  I dunno.  I only measured the one 
> sample.  I do have access to about a half dozen of these microphones so I 
> could sit down and measure the whole crop.
> 
> But that doesn't answer the question about the AT4022.  Lack of funds 
> prohibits my purchasing one just out of curiosity.  But if there is someone 
> in the SF bay area who has one and would like to have it measured, I would be 
> happy to make the comparison.
> 
> Eric
> 

Hi Eric,


Sorry to use your name in vain, and thanks for taking the time to respond and 
clarify your tests. 

I have three of the AT3032 two purchased from a US online retailer and one old 
stock from an Australian music retailer.   I'm currently using a the "old 
stock" mike and one of the newer production mics as a pair because they are a 
fairly close match.  The second newer production mike was substantially 
mis-matched to the other two and I was having to adjust gain to L-9 R-9.25 on a 
scale of 10 get a reasonable match on levels.  The "odd" mic also seemed to 
have a tonal balance that was tilted in respect to the other two. I think this 
points to a reasonable level of sample to sample variability between the 
AT3032's  so I wouldn't discount the possibility that your 8dB sample was an 
"outlier".  If you had the time and interest I'd be more than happy to send my 
3 AT3032 to you to test.

cheers
Paul







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