# Has anyone tried the IK Multimedia ARC 2 microphone with REW?



## misaer

Hi,

I bought the IK Multimedia ARC 2 system, which is a room correction plugin for use in music workstations. It works great, but I would like to use REW with the microphone that come with ARC 2 (it's the IK000008 version), because unfortunately the ARC 2 doesn't output detailed analysis that I can use to physically fix the room's acoustics.

However, I can't find the manufacturer or model of the mic.

Has anyone gotten hold of the calibration file for this mic, or calibrated theirs and would consider sharing their file?


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## Phillips

> However, I can't find the manufacturer or model of the mic.


Is the mic XLR requires phantom power or is it USB?



> Has anyone gotten hold of the calibration file for this mic, or calibrated theirs and would consider sharing their file?


Keep in mind that each mic has its own characteristics so someones else file or generic is not a good idea.

I don't recommend a generic file, most times you are better of without one, saying that i am not familiar with this mic.

You could look at getting calibrated by Cross - Spectrum if you don't want to buy a UMIK-1 or UMM-6 if you want a UBS mic.

The general way to look at it is if you are going to EQ etc buy a calibrated mic.

Hope this helps.


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## misaer

Phillips said:


> Is the mic XLR requires phantom power or is it USB?


It is a phantom powered condenser mic. (I.e. XLR)



Phillips said:


> Keep in mind that each mic has its own characteristics so someones else file or generic is not a good idea.
> 
> I don't recommend a generic file, most times you are better of without one, saying that i am not familiar with this mic.
> 
> You could look at getting calibrated by Cross - Spectrum if you don't want to buy a UMIK-1 or UMM-6 if you want a UBS mic.
> 
> The general way to look at it is if you are going to EQ etc buy a calibrated mic.


It is a calibrated mic, but the calibration file/info isn't supplied with the product (ARC 2, it's a room correction plugin for DAWs where the software and microphone comes bundled, therefor no need for them to supply the calibration data). That's why I was hoping someone here had used it with REW, and maybe calibrated it again or gotten hold of a file from someone, and would consider sharing.


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## Phillips

misaer said:


> It is a phantom powered condenser mic. (I.e. XLR)
> 
> 
> It is a calibrated mic, but the calibration file/info isn't supplied with the product (ARC 2, it's a room correction plugin for DAWs where the software and microphone comes bundled, therefor no need for them to supply the calibration data). That's why I was hoping someone here had used it with REW, and maybe calibrated it again or gotten hold of a file from someone, and would consider sharing.


I think you have missed my point, each mic has its own characteristics except the very expensive ones.
By getting another file except the your specific own mics one you could make things worse.


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## misaer

I haven't missed your point. The mics supplied with ARC 2 are calibrated, but the calibration data is built into the software and they don't supply the calibration file.


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## daffy

I have, and it works very nicely.

I also contacted IK Support and asked if they had a calibration file for the mic and they replied that they do not. I've put it in as an enhancement request. Maybe you could contact them and make the same request as well? If a few of us do it then they may put one together.

I 'kind of' disagree with the poster who said you need a calibration file for each mic. Their statement is absolutely correct - every single mic is slightly different due to tiny differences in component specs and build etc, and so if you want absolute accuracy in your sound measurement you should individually calibrate each and every single measurement mic.

However, general characteristics of each make and model of mic will be very similar, and for most mics the inaccuracies introduced by using a generic calibration file for a make and model are going to be completely swamped by the errors in mic positioning, calculation and other systemic factors. Also given that you are looking at macroscopic effects of a room and the changes you make, the minor differences between individual mics of the same make and model will not matter very much at all. This is why ARC2 doesn't ship and use individual calibration files themselves. The only thing you would want to make sure of is that you didn't have a dodgy mic that was completely off, but that should be able to be picked up pretty easily.

And let's face it - when you get to the point in your room measurements where you are worried about 0.25dB differences at a certain frequency, you'll go and get your mic professionally individually calibrated! and probably do it every few years as well!!

What I have found is that the ARC2 mic does have a high frequency rolloff that will skew your very HF results in REW. This is why I was keen to get a generic calibration file. I actually checked this out by plugging my monitor line out into my line in and doing an ARC run in an attempt to generate a generic cal file. Doing this will show you the cal curve they use in ARC.

Now if I could just work out the ARC calibration file format - I know it's a ZIP archive but the data format still eludes me!!


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## Wayne A. Pflughaupt

Here’s something Cross Spectrum supplied to the Forum sometime back, graphs showing deviations in response of numerous samples of two specific mics.



















Regards, 
Wayne


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## daffy

I stand corrected


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## Wayne A. Pflughaupt

Well, they are after all inexpensive mics... 

Regards, 
Wayne


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## daffy

Actually, I'd love to get my hands on the raw data in those graphs.

Judging by eye only it looks like my case is still valid if you used the average line as your cal file as most mics would only be a dB or so out across the entire range (you'd still have your bad mics thrown into the outlier population).

If you were looking at better than about 1dB resolution in your room measurements, you'd go and get the mic calibrated professionally.


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## djdanlib

I came here to check the same thing, and have empirically noticed the HF rolloff as well although I have not been able to measure it. How would you characterize the HF rolloff?


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## daffy

djdanlib said:


> I came here to check the same thing, and have empirically noticed the HF rolloff as well although I have not been able to measure it. How would you characterize the HF rolloff?


The best way to see it for yourself is to simply plug either side of your monitor outputs into a line input on your interface unit (doesn't matter which side L or R).

Then run through a calibration in ARC - you don't need to move mics or anything just keep clicking "next". The resulting graph on both sides will be the inverse of the built in calibration curve they apply. 

This is what I got from a very quick run just now.


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## Saddle

I've used my ARC mic with REW and had good results. I also use it with my new DBX Driverack PA2 and have good results. 

I thought about having it sent in and having a calibration done, but I figured I might as well just buy a calibrated mic for $75 or so and then have two laying around.

BTW, ARC 2.x has helped me. I use it after putting as much treatment in my small room as I have room for...


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## Owl

*Applied diffuse field equalization*

Hi everyone,
I just ordered a measurement mic and while I was collecting info on the net for room measurement, I found this nice forum. Maybe my infos are useful for others (and hopefully correct):

A friend told me, the mic that is used with IK Multimedia's ARC2 was the Superlux ECM999.
It was very similar to the Behringer ECM8000 but with one difference:
The Behringer ECM8k was already diffuse field equalized (diffusfeldentzerrt), while the Superlux was not!
Therefore the Superlux misses the boost of high frequencies the ECM8k is containing.

As I understand it, this is critically important, because in the diffuse field (Diffusfeld) the high frequencies roll off and the ECM8k is compensating for that effect by artificially boosting the treble of the recorded signal.

But in the direct field (Direktfeld) there is no treble-rolloff occuring like in the reflections of the diffuse field and therefore the ECM8k signal contains way too much treble if it is used for direct field recording. 
The different options I see:



Software expects: *flat mic*, recording taking place in *diffuse field* 
real useage: *flat mic*, recording in *diffuse field*

I guess this is the standard ARC2-setup.

The measurement software expects a flat response from the mic which the mic delivers.
The software expects a diffuse field monitoring position, which translates it expects a signal with too less treble/too much mids - therefore it compensates for it, by boosting the high frequencies.

Result: ok. Depending on how well the from the SW expected diffused sound matches the real world situation.




Software expects: *flat mic*, recording taking place in *diffuse field* 
real useage: a diffuse field *compensated mic*, like the Behringer ECM8000, recording in *diffuse field*.

Software expects recording/monitoring in a diffuse field and therefore boosts the treble to compensate for this effect.
But it also expects a flat mic response. Since the mic's signal contains much more treble because of the mic's internal compensation, and the SW doesn't know that and tries to compensate to achieve a flat response, it sees much more treble content in the signal and therefore boosts treble much less, or even reduces them.

Result: too dull (because of compensated mic)




Software expects: *flat mic*, recording taking place in *diffuse field* 
real useage: *flat mic*, recording in *direct field*

Software boosts high treble because it expects listening/recording in diffuse field (flat mic) and the recording contains relatively more treble because of recording in direct field (instead of the expected diffuse field). Correct mic compensation, but believing the signal contains too much treble. The more direct the signal, the better the signal, the more the SW removes treble. Ouch!

Result: too dull (because of a too good direct field sound recording)




Software expects: *flat mic*, recording taking place in *diffuse field* 
real useage: *compensated mic*, recording in *direct field*
The recorded signal contains less reflections and relatively more treble, because of the direct field, while SW expects lacking treble. Therefore SW compensates with a reduction of treble. Like above.
But the mic additionally delivers a treble boosted (compensated) signal, while the software thinks this is a flat signal. Therefore the SW compensates with reduction of treble, while it applies internally a second diffuse field compensation.

Result: probably too bright (two times diffuse field compensation [once by mic, once by SW], but a reduction of the "good" treble: the better and more direct the sound, the stronger the reduction of the "good" treble)


I think this also fits quite nicely to the picture posted by _daffy_ showing the internal compensation curve of the ARC2-software, when no mic is applied:
no mic applied could be interpreted as the case of a flat mic applied, and the recording taking place in a perfect direct field with a perfect LS delivering white noise.
The resulting curve shows the software's compensation for the expected diffuse field recording of the expected quite flat mic resulting in a boost of the treble.

It's not easy to get around these inverse results. It's similar to mixing on bright monitors: the mixes tend to be too dull. Or hifi-like monitors with lacking midrange: mixes tend to sound boxy.


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## fletch44

Hi everyone, I know this is very late to the party, but I've had the ARC2 mic identified by a noise & vibration specialist calibration service, as a Casella CEL-252 element mounted on a phantom powered pre-amp body. It is a free-field microphone with a frequency range 20 Hz to 12.5 kHz ± 2 dB.



http://site.jjstech.com/pdf/Casella-pdf/CEL-252-0.50-Measurement-Microphone-Capsule_Datasheet.pdf



I hope this information helps anybody seeking more detail on how this mic behaves and what its frequency response characteristics are.

Here is a sample of calibration data for one of these microphones, which are typically used on noise dosimeters in industrial noise surveys:


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## jon9

Thank you! I was looking for this info!


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