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Recording with Measurement Mics



 
 
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  #31  
Old August 1st 18, 09:25 PM posted to rec.audio.pro
[email protected]
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Default Recording with Measurement Mics

"FWIW, In the early '70s I was visiting a top level R&D lab in
Nashville. A tech was showing me some of their projects. One
was using a measurement mic. I was very small, about the size of a
cigarette filter. He said the freq response was very good but it was
worthless for audio recording. "

So this begs the question: When and where(within the recording
and playback of music) is 'flat' important??
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  #32  
Old August 1st 18, 10:39 PM posted to rec.audio.pro
Mike Rivers[_2_]
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Default Recording with Measurement Mics

On 8/1/2018 4:25 PM, wrote:
> "FWIW, In the early '70s I was visiting a top level R&D lab in
> Nashville. A tech was showing me some of their projects. One
> was using a measurement mic. I was very small, about the size of a
> cigarette filter. He said the freq response was very good but it was
> worthless for audio recording. "


He could have been using one of these, or something similar from another
manufacturer:

http://www.mic-w.com/products.php?cid=46

As it's been pointed out here, small measurement mics typically have low
sensitivity, that is, significantly less output than a typical recording
mic for a given SPL. Recording mics need to work satisfactorily over a
very wide dynamic range (you want to capture the stick hitting the snare
drum and the tail end of the reverberation decay, a range of 80 to 90
dB), while a measurement mic is usually used over a much smaller dynamic
range, or at a single level for a single measurement. You wouldn't use
the same measurement mic to measure noise on an airport runway as you
would in a field on a quiet night.

> So this begs the question: When and where(within the recording
> and playback of music) is 'flat' important??


It's important in the signal chain, so that you can modify it
predictably if you choose to do so. Recording microphones are usually
designed with known frequency response peaks and dips that have proven
to be flattering or useful for particular sound sources. This is why a
mic that sounds good on a snare drum has a different frequency response
curve than a mic that sounds good on a male vocal. There's no reason why
you couldn't use a dead flat mic on either of those sources but it
wouldn't sound like you're accustomed to hearing those sources miked
with the usual mics.

You could make it sound more or less like a "sounds good on...." mic by
applying EQ, but since most of the "sounds good on..." mics are
directional, they have their unique off-axis frequency response curves,
and a measurement mic, which is typically omni, wouldn't be able to
accurately reproduce the off-axis response with simple EQ.

There's been a fair amount of work in microphone modeling in the past
few years, so now we have mics from, for example, Antelope Audio and
Steven Slate, that start out with a pretty flat, pretty omni mic and DSP
is used to create the phase shifts and resonances within a particular
"sounds good on..." mic to provide a reasonably good faith model.

But that's more than you want to know.
--

For a good time, call http://mikeriversaudio.wordpress.com
  #34  
Old August 1st 18, 11:48 PM posted to rec.audio.pro
geoff
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Default Recording with Measurement Mics

On 2/08/2018 9:39 AM, Mike Rivers wrote:

>
> There's been a fair amount of work in microphone modeling in the past
> few years, so now we have mics from, for example, Antelope Audio and
> Steven Slate, that start out with a pretty flat, pretty omni mic and DSP
> is used to create the phase shifts and resonances within a particular
> "sounds good on..." mic to provide a reasonably good faith model.
>
> But that's more than you want to know.


Remember Antares Mic Modeller ? Those are my Tannoy ribbon mics as one
of their presets on there. In recompense got a copy of the plug-in. Have
never used it ....

geoff

  #35  
Old August 2nd 18, 02:38 AM posted to rec.audio.pro
Phil Allison[_4_]
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Posts: 338
Default Recording with Measurement Mics

wrote:
>
>
> "FWIW, In the early '70s I was visiting a top level R&D lab in
> Nashville. A tech was showing me some of their projects. One
> was using a measurement mic. I was very small, about the size of a
> cigarette filter. He said the freq response was very good but it was
> worthless for audio recording. "
>
>
> So this begs the question: When and where(within the recording
> and playback of music) is 'flat' important??
>


** The tech's comment implies wide, flat response is important to music recording, the tiny mic has that but is compromised in other ways - like having limited dynamic range. IOW it's too noisy for low level audio.

Classical and Jazz musicians care a lot about the tonal qualities of their instruments, often paying big money to get desired qualities. The mistake is in thinking it takes a "measurement mic" to capture sound quality accurately when judged by human ears or that using one would do a better job.




..... Phil







  #36  
Old August 2nd 18, 01:49 PM posted to rec.audio.pro
Scott Dorsey
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Posts: 16,417
Default Recording with Measurement Mics

Just for a quick example I put this up:
http://www.panix.com/~kludge/bk_examp.wav

This is recorded with a pair of B&K 4155 microphones with homebrew electronics
behind them, into a Tascam HS-P82. Microphones are on a Jecklin baffle about
thirty feet forward of the brass, ten feet forward of the soloist. The choir
is way in the back and there's a minor flutter echo above them that you might
hear.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #37  
Old August 2nd 18, 02:57 PM posted to rec.audio.pro
Dieter Michel
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Posts: 15
Default Recording with Measurement Mics

Hi Tobiah,

>> If the goal of a live recording is to record the instruments as
>> faithfully as possible to the source audio, wouldn't a measurement
>> mic with a flat response be preferred over a mic with a response
>> that's not flat?


> I posted a similar question some time ago, and one person brought
> up the idea that low self noise may not be a primary objective when
> designing a measurement mic. That's important to me because I
> often record quieter sounds.


I actually made that very experience like 30 years ago
when I attempted to make speech recordings in a very
quiet and acoustically dry environment.

The first trial using B&K measurement mics and
corresponding (pre)amplifiers resulted in too noisy
recordings.

After I bought a John Hardy M1 mic preamp and used
a Neumann U87 or AKG C414 mic, everything was fine.

Best regards

Dieter Michel

 




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