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Microphone Calibration

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Microphone Calibration

Postby Elephone » Tue Sep 03, 2019 2:37 pm

Hi. I bought Sonarworks Reference 3 for my headphones and found the calibration did help.

Anyway, the Sonarworks Reference 4 Studio Edition claims to do the same for the room. I probably won't get the software, but I'm just wondering... since it is able to calibrate the supplied Sonarworks microphone so that it conveys a flat response, can it also calibrate other microphones? There is no mention of this on the website.

If not, is there any other software that calibrates specific microphones to record a flatter frequency response?

Thanks.
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Re: Microphone Calibration

Postby Hugh Robjohns » Tue Sep 03, 2019 4:10 pm

Elephone wrote:...is there any other software that calibrates specific microphones to record a flatter frequency response?

Kind of... There are plugins like Antares' Mic Mod EFX which aim to emulate the response of a 'desirable mic' by subtracting the response of a known source mic and then reimpose the characteristics of the wanted mic. So you basically tell the plugin what you're using and what you want, and it tries to sort it out...

https://www.antarestech.com/product/mic-mod-efx/

There are several other similar systems, some happy to start from any of a (small) collection of known third-party mics, and others (like the Slate VMS system) that can only work with their own reference mic.

However, while these systems can emulate the on-axis frequency and phase response of a desired mic reasonably well, they still can't change the laws of physics, so they can't match the off-axis response, proximity effect, and other specific acoustic/mechanical characteristics which are often quite important to the overall sound.

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Re: Microphone Calibration

Postby Wonks » Tue Sep 03, 2019 4:41 pm

If you buy the Sonarworks room package, you buy a microphone from them that has a downloadable calibration file for just that particular mic (the mics are all numbered) . They've done the calibration on the mic; the Sonarworks room software has nothing to do with that.

So no, you can't use it to get a flat response from other mics.
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Re: Microphone Calibration

Postby Elephone » Tue Sep 03, 2019 4:44 pm

Thanks. I also saw that Abbey Road "King's Microphones". I presume these sort of plugins work best with audio recorded with flat response microphone, such as a measurement microphone?
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Re: Microphone Calibration

Postby Elephone » Tue Sep 03, 2019 4:45 pm

Wonks wrote:If you buy the Sonarworks room package, you buy a microphone from them that has a downloadable calibration file for just that particular mic (the mics are all numbered) . They've done the calibration on the mic; the Sonarworks room software has nothing to do with that.

So no, you can't use it to get a flat response from other mics.

Yes that might be a good idea. They're not too expensive.
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Re: Microphone Calibration

Postby Sam Inglis » Tue Sep 03, 2019 4:53 pm

Elephone wrote:Thanks. I also saw that Abbey Road "King's Microphones". I presume these sort of plugins work best with audio recorded with flat response microphone, such as a measurement microphone?

To be honest The King's Microphones is sufficiently lo-fi that it really isn't worth worrying about the fidelity of what you put into it! It'll work fine with any vaguely high-quality studio mic.
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Re: Microphone Calibration

Postby Wonks » Tue Sep 03, 2019 4:55 pm

But I don't know if you can use the calibration file with any other software. You'd need something that worked as the first plug-in in your input chain and that used the same file format.
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Re: Microphone Calibration

Postby Elephone » Tue Sep 03, 2019 4:59 pm

Wonks wrote:But I don't know if you can use the calibration file with any other software. You'd need something that worked as the first plug-in in your input chain and that used the same file format.

Maybe it could be rendered with the calibration on. I've done that by accident with their headphone calibration on the master channel.
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Re: Microphone Calibration

Postby Wonks » Tue Sep 03, 2019 5:09 pm

But that contains the EQ for rendering the speakers and the room at your listening point (or headphones) to give a flat listening response. Which is very different from the mic calibration EQ which is only used on the initial set-up of the Sonarworks software.
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Re: Microphone Calibration

Postby Martin Walker » Wed Sep 04, 2019 8:22 am

Elephone wrote:Thanks. I also saw that Abbey Road "King's Microphones". I presume these sort of plugins work best with audio recorded with flat response microphone, such as a measurement microphone?

Sadly, until you get onto the more expensive measurement mics, you don't necessarily get a particularly flat response. Yes, cheap measurement mics are designed to be essentially 'flat', but in practice their frequency response may vary considerably from unit to unit. Here is a rather sobering web link that shows the variation in response of 55 Behringer ECM8000 mics:

http://www.cross-spectrum.com/weblog/2009/07/

For my own use with room acoustic and playback response measurements, I ended up ordering one of Sonarworks' own XREF20 microphones, which are individually calibrated against an ANSI certified measurement microphone so that their unique response is known exactly and can therefore be more accurately compensated for.


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Re: Microphone Calibration

Postby cyrano.mac » Thu Sep 05, 2019 3:49 pm

It's just a marketing ploy...

A real measurement mic comes with a frequency chart, on paper and as a txt file. And it's also SPL calibrated individually. That's why these are several thousands, usually.

If you want the cheapest that comes close, look at the MiniDSP's UMIK MKI.
https://www.minidsp.com/products/acoust ... ent/umik-1

It is individually calibrated. Don't expect it to be precise under lesser conditions (very humid air, very cold...), but it's perfectly fine for most measurements.

Other stuff, like the Behringer ECM8000, is just globally "calibrated". And since the ECM8000 has seen at least five revisions (and Behringer didn't care to update the calibration file) it's less precise. It'll still do for acoustic measurements, as long as they are relative. Relative to other measurements with the same mic/setup. So for those who are measuring their home studio and don't need to exchange data with other, it's still fine.

When it comes to "calibrating" a mic, forget it. The character of the mic is defined by much more than the frequency chart. Hugh already pointed that out.

And when it comes to emulate let's say a Neumann with a 60 € Chinese mic, I'll start laughing. Loudly. What isn't there, will not be added by the emulation. Impossible.

Now, if you like how the emulation sounds, please go ahead. But that's taste. And taste has nothing to do with calibration. Quite the opposite, in fact. That's also why most measurement mics aren't really suited to record music...
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Re: Microphone Calibration

Postby Elephone » Sat Sep 14, 2019 7:06 pm

Wonks wrote:But that contains the EQ for rendering the speakers and the room at your listening point (or headphones) to give a flat listening response. Which is very different from the mic calibration EQ which is only used on the initial set-up of the Sonarworks software.

Damn! That's really unfortunate. So they only allow you to use the calibration for the set up and not to use the mic for other projects? That's a bit short-sighted considering how easy it would be to let you use the software to calibrate the mic for recording, and also offer it as a another selling point.
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Re: Microphone Calibration

Postby Wonks » Sat Sep 14, 2019 7:08 pm

Not with the calibration file, no. But that's how it works.
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Re: Microphone Calibration

Postby cyrano.mac » Sun Sep 15, 2019 11:20 am

A mic calibration file is just a text file, with some numbers in it. First column is frequency, second column is gain in dB. An EQ file should be the same, but it can contain more finely grained settings. You might need to strip out some to use it with other EQ software.

Unless they've "invented" some custom format, they can't prevent you from using the calibration file with any other software. And if they did, it's just another company to avoid at all cost...
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Re: Microphone Calibration

Postby Martin Walker » Sun Sep 15, 2019 1:13 pm

cyrano.mac wrote:A mic calibration file is just a text file, with some numbers in it. First column is frequency, second column is gain in dB. An EQ file should be the same, but it can contain more finely grained settings. You might need to strip out some to use it with other EQ software.

Unless they've "invented" some custom format, they can't prevent you from using the calibration file with any other software. And if they did, it's just another company to avoid at all cost...

Each Sonarworks XREF20 measurement mic has its own calibration file, which by default is supplied in its own SWMIC format to be directly loaded into the Reference 4 Measure software, where it displays the response (here's mine for instance):

Image1.jpg


However, the calibration files can also be downloaded from this page, where they are supplied as a zip file containing both the .SWMIC and standard. txt format for inclusion into other software e.g. Room EQ Wizard etc.)

https://www.sonarworks.com/reference/downloads

Hope this helps!


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Re: Microphone Calibration

Postby cyrano.mac » Tue Sep 17, 2019 9:01 pm

That sure helps, Martin!

Does it also work in the other direction? Can SonarWorks read a .txt cal file for another mic?

BTW. The internet has never heard of "SWMIC format"...
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Re: Microphone Calibration

Postby Wonks » Tue Sep 17, 2019 10:13 pm

.SWMIC = Sonarworks mic format I presume.
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Re: Microphone Calibration

Postby Martin Walker » Wed Sep 18, 2019 10:03 am

cyrano.mac wrote:That sure helps, Martin!

Does it also work in the other direction? Can SonarWorks read a .txt cal file for another mic?

Yes, it can, as long as it only contains a basic table of frequency and level information. Any other data must be stripped out, as described here:

https://support.sonarworks.com/hc/en-us ... /207211709

Essentially:

"You can also use your own omnidirectional measurement microphone with a calibration.

To do so, you will need to convert your calibration file so our measurement software can import it.

Calibration files are usually supplied in formats like .cal or .txt

Open up this file with any text editor and remove anything that is not the values for Frequency Response and Magnitude."



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