# Something better instead of ECM8000



## michael123 (Jul 26, 2008)

Hi

I am using REW for couple of years, but quite sporadically - when I change something in an audio chain or inside the room.

This week I ordered Vicoustic Veri Bass, hoping that it will help to flatten a bit the spikes (see attached)
http://www.vicoustic.com/vn/MusicBroadcast/ProdutoInfo.asp?Id=78

While it will take a month for these nice cylinders to arrive, I am thinking about replacing my stock ECM8000.
I am measuring basically only 20Hz-120Hz area, the question which calibrated microphone could you recommend with 1-2db of precision across this range?

Since I use REW only occasionally, I do not want to spend more than 100$
EarthWorks M23 looks good, but expensive... I mean it is not expensive (450$) if used on a daily basis, but for once a year I think it is a waste..


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## EarlK (Jan 1, 2010)

Buy a calibrated Dayton EMM-6 mic from  Cross-Spetcrum Labs with the custom calibration .

See this thread for more details .

<> EarlK


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## michael123 (Jul 26, 2008)

thanks
1) I do not see the specification though, is it really 1db precision?
2) It is possible to buy the mic here: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-801 for 48$, and then download the calibration file free of charge. Where is the difference?


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## EarlK (Jan 1, 2010)

Hi,

- I suggest that you ask those two questions in the thread to which I have provided a link .
- Eventually ( once there ), the owner of Cross-Spectrum will address your questions directly (within that thread ).

<> EarlK

ps ; ( I think the accuracy of a single unit calibration is better than 1 db / for the proscribed measuring axis )


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## lcaillo (May 2, 2006)

michael123 said:


> thanks
> 1) I do not see the specification though, is it really 1db precision?
> 2) It is possible to buy the mic here: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-801 for 48$, and then download the calibration file free of charge. Where is the difference?



The difference is that the calibration file you download may not be correct for the mic you buy. It really is not a calibration file but a set of data based on some other mic. A calibration file is specific to one mic at one point in time. There are variances between mics of the same brand and model. Units from the same or similar production runs may be close, but even then may vary considerably.


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## michael123 (Jul 26, 2008)

lcaillo said:


> The difference is that the calibration file you download may not be correct for the mic you buy. It really is not a calibration file but a set of data based on some other mic. A calibration file is specific to one mic at one point in time. There are variances between mics of the same brand and model. Units from the same or similar production runs may be close, but even then may vary considerably.


You enter the serial number of your mic on the Dayton website to download the calibration file.
Maybe they are cheating, yet..

Anyway, I ordered the calibrated Dayton EMM-6 as suggested above - because of the 90 deg and 5-25KHz range


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## Wayne A. Pflughaupt (Apr 13, 2006)

michael123 said:


> This week I ordered Vicoustic Veri Bass, hoping that it will help to flatten a bit the spikes (see attached)
> http://www.vicoustic.com/vn/MusicBroadcast/ProdutoInfo.asp?Id=78


I’ll be surprised if they do anything for the 40 Hz spike. Problems that low usually require equalization.




> While it will take a month for these nice cylinders to arrive, I am thinking about replacing my stock ECM8000.
> I am measuring basically only 20Hz-120Hz area, the question which calibrated microphone could you recommend with 1-2db of precision across this range?
> 
> Since I use REW only occasionally, I do not want to spend more than 100$
> EarthWorks M23 looks good, but expensive... I mean it is not expensive (450$) if used on a daily basis, but for once a year I think it is a waste..


The whole point of using a calibrated mic with a program like REW is that it doesn’t require an expensive mic. Calibration effectively gives you a mic with perfectly flat response. Herb at Cross Spectrum calibrates mics to _fractions of a decibel,_ so using a mic with ±1-2 dB “precision” is actually a step backwards.

Not that it matters; ±1-2 dB differences in subwoofer response are inaudible anyway. Then you have the issue of what might be termed “system instability.” While the measurement platform is stable enough (REW in this case), the transducers involved - the speakers and elements in the measurement microphones - are not. Their physical (and consequently electrical) properties are altered with changes in temperature, humidity, etc. As such, when you take a second REW reading six months or a year later you'll find it doesn't quite look like your original one. However, even though the measurements look different you haven’t noticed any audible change, because there isn't one.

Bottom line, fretting over a dB or two here or there with subwoofer measurements is unnecessary. Unless you were using our generic calibration file with your ECM800, I doubt you’re going to see (or more importantly, hear) any improvement with the EMM-6 unless you really need measurements down to 5 Hz (90˚ calibration is irrelevant for bass measurements, given that both the sound source and the measurement mic have omnidirectional characteristics down that low). Even that will depend on the particular sample you start with. As you can see from the chart of EMM-6 samples at our Downloads page, EMM-6 samples can vary more than 10 dB at 5 Hz. If your mic happens to be one of the poorer samples, the calibration file will merely be boosting noise. 

Regards,
Wayne


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## michael123 (Jul 26, 2008)

Wayne A. Pflughaupt said:


> I’ll be surprised if they do anything for the 40 Hz spike. Problems that low usually require equalization.


it will be a surprise for me as well, but they claim they do.
I do have DEQ2496 as well, but I want to resolve as much as possible using passive treatment, and then to 'finish' using EQ.
I will post my findings here for future generations, this Veri Bass looks like an interesting product.



Wayne A. Pflughaupt said:


> The whole point of using a calibrated mic with a program like REW is that it doesn’t require an expensive mic. Calibration effectively gives you a mic with perfectly flat response. Herb at Cross Spectrum calibrates mics to _fractions of a decibel,_ so using a mic with ±1-2 dB “precision” is actually a step backwards.
> 
> Not that it matters; ±1-2 dB differences in subwoofer response are inaudible anyway. Then you have the issue of what might be termed “system instability.” While the measurement platform is stable enough (REW in this case), the transducers involved - the speakers and elements in the measurement microphones - are not. Their physical (and consequently electrical) properties are altered with changes in temperature, humidity, etc. As such, when you take a second REW reading six months or a year later you'll find it doesn't quite look like your original one. However, even though the measurements look different you haven’t noticed any audible change
> 
> Bottom line, fretting over a dB or two here or there with subwoofer measurements is unnecessary. Unless you were using our generic calibration file with your ECM800, I doubt you’re going to see (or more importantly, hear) any improvement with the EMM-6 unless you really need measurements down to 5 Hz (90˚ calibration is irrelevant for bass measurements, given that both the sound source and the measurement mic have omnidirectional characteristics down that low). Even that will depend on the particular sample you start with. As you can see from the chart of EMM-6 samples at our Downloads page, EMM-6 samples can vary more than 10 dB at 5 Hz. If your mic happens to be one of the poorer samples, the calibration file will merely be boosting noise.


thanks, understood.
So, what is the usable range of calibrated EMM-6?
What is the real precision, taking humidity and other external factors into consideration?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Best to pose those questions to Herb, but (as noted) pinpoint accuracy is not necessary with subwoofer measurements.

Regards, 
Wayne


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## michael123 (Jul 26, 2008)

I am not using subwoofer


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## Wayne A. Pflughaupt (Apr 13, 2006)

Okay, I’ll rephrase: “Pinpoint accuracy is not necessary with bass measurements.” 

Regards,
Wayne


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