NEED HELP WITH DAYTON iMM-6 MICROPHONE

[Stash]

So, I caved and ordered the iMM-6 mic. I wish to know that my measurements are accurate. It's my bd gift to myself lol. Its my hobby. I like messing with the electronics when no one is around and its nice and quiet.

In the meantime..I need help with the following:

The mic comes with a calibration file. If I printout this file, it will indicate each individual frequency with a +/- dB compensation value. How do I interpret this file?

For example, if the file indicates "-1.0dB at 1kHz", does this mean the mic response is '-1dB' and I should add 1dB to my measurement?
or, does it mean I should subtract 1dB from my measurement?

I know most of you feed the calibration file into a simulator program, but, I am, as yet, not so advanced. And I'd like to know how to properly read the file.

Which simulator programs, if any, are safe to install? And free? I'm using Windows 10. If I have to buy a program, I will consider suggestions made here, at a future date. If I consider any programs outside of Microsoft, I am warned not to download. So I am dubious as to what I can download safely.

Currently, I have a free version of Fricture on laptop. It serves its purpose. I downloaded it years ago. I can read 20-20kHz FFT spectrum plus other basic features including simple oscilloscope readings, spectrum analyzer and up to 1/6th and 1/9th octaves plus adjustable dynamic ranges, etc. No annoying ads. Never had an issue with this program.
I have Sheffield Labs My Disc, which contains many test freqs, some warbled or pink noise. Since it is CD quality, I am certain of its bandwith, unlike online sources which may be compressed files.
I also may be able to generate test freqs via my Fricture program. I've never really played with that option.


I will use the iMM-6 with my laptop, bypassing the internal mic. I should obtain full audio bandwith. I fashioned a length of cable with a TRRS plug, to allow flexibility of placement of the iMM6 and tested the setup using my YPAO mic I have on hand. Seems to work fine. Should be accurate with iMM-6.

Any suggestions/advice welcome. For now, just knowing my mic reads will be accurate will suffice. Gives me something to do in my spare time.

Also, I happened to run across a MOVO mic, for about $8 online, which is exactly a copy of the Dayton iMM-6, without calibration of course. Idk if PE is aware of this Chinese knockoff, or if it tramples on patent rights. Should I bring this up with PE? Who might I contact?

[Stash]

[a4eaudio]

I am not sure about the calibration file, but I assume that -1db means you need to subtract 1db from the raw/uncalibrated measurement you take to have an accurately adjusted measurement.

The reason I think this, is because a program like REW asks if you have a calibration file in which case you tell it where the file is located and then it applies the adjustments for you. I bring this up because REW is super easy to use and free.

[wogg]

The calibration file is the adjustment to get to reference flat, so -1dB at 1kHz means the mic is hot 1dB right there.

+1 on REW, powerful and pretty simple. I use ARTA for crossover design files, but either works.

These programs are likely to give you Windows warnings when you install. That's because it costs money to certify, and these things are often produced by tiny companies or single engineers in their spare time. If you're getting it for free, there's no money to certify in the Microsoft store. They are perfectly clean though. I've used these: REW, ARTA, WinPCD, Tolvan Edge, and probably a few others I can't think of ;)

[DeZZar]

There's really no need to even look at this file. Any decent measurement software you use to take your frequency measurements will ask for the mic calibration file (REW, ARTA, Holm). You load it up and forget about it. Compensation for the microphones errors is factored into the measurements by the software.

I also create a calibration file for the soundcard/amplifier combo (easy to do in REW) without the mic calibration so that any anomalies from the amp and soundcard are compensated for as well. Final measurements then include both the mic and soundcard calibration file.

[Stash]

Ok. Thanks to all for your quick responses. I'm expecting the mic tomorrow. I'll look up REW and ARTA tonight, and, if free, download one or the other. Then I can really get into the audio, when no one is around.
thanks again

[Stash]

Btw, my Friture app does not ask for a calibration file. But, that may be due to it being the free version and somewhat limited.

[DeZZar]

REW and Holm are free (donations accepted). ARTA requires a license.

[Stash]

Good to know

[Chris Roemer]

MANY (most? - like 99%?) of the guys on here who use ARTA (for making .frd files w/calibrated mics) use the "free" (non-"licensed" / limited version) software. The license lets you save out certain kinds of "design" files, but it's not needed simply for making measurements and cranking out .frds to use in xover sim programs.

Also (if you're careful), once you've got your "cal'd" iMM-6, YOU should be able to create a cal file for any (your $8 MOVO) mic by using the cal'd mic as your standard.
You'll know if you made your (MOVO) cal file properly if you can make a (cal file loaded) measurement w/the MOVO that matches a measurement w/the iMM-6 (w/cal file loaded).

[Stash]

FYI...I did not purchase the MOVO knockoff mic. I was simply making others aware of its existance.

[ernperkins]

The calibration file is the adjustment to get to reference flat, so -1dB at 1kHz means the mic is hot 1dB right there.

I believe the calibration file should be the actual response. From the REW help file (my bolding):

"The calibration file is a plain text file which by default has the extension .cal, though other extensions are also accepted. It should contain the actual gain (and optionally phase) response of the interface at the frequencies given, these will then be subtracted from subsequent measurements."

[Stash]

I received the iMM-6 mic. I downloaded its file to my laptop for the time being. Yes, it includes the corrective adjustments for each respective frequency.

I will hold off on the apps. I did download the REW app onto my laptop no problem. But, it is a bit much. And I am not certain I can use my mic as-is. According to the app directions, I may need a USB converter/adapter, which does not thrill me.

The directions also show a separate SPL meter. That also turned me off. I assumed such an app has a built-in measuring device of some sort.

Lastly, I cannot stand the butchering of the English language by the author. He spells words, such as equalize, with an "s" (equalise). This spelling atrocity repeats so often, to the point I could not read any more. I uninstalled the program. It is a shame. A person who is obviously well educated.

My Friture app works with this mic. I am able to use the built-in FFT spectrum, oscilloscope and other means to measure response. Plus, it does indeed include a signal generator with various options. Good enough for now.

It I decide to look into another analyzer program, I will consider Holmes or ARTA.

Again, thanks to everyone for your comments and suggestions.

[wogg]

I will hold off on the apps. I did download the REW app onto my laptop no problem. But, it is a bit much. And I am not certain I can use my mic as-is. According to the app directions, I may need a USB converter/adapter, which does not thrill me.

The directions also show a separate SPL meter. That also turned me off. I assumed such an app has a built-in measuring device of some sort.

Lastly, I cannot stand the butchering of the English language by the author. He spells words, such as equalize, with an "s" (equalise). This spelling atrocity repeats so often, to the point I could not read any more. I uninstalled the program. It is a shame. A person who is obviously well educated.

No USB converter needed - it will read just fine from your laptop headset port. You (and myself) are in a very, very small group of people doing this poor man measurement method with these iMM6's, the general assumption is that you'll have a mic that needs an interface.

The separate SPL meter would be required to get or verify actual SPL you're measuring at. That is also not required, but the "85dB" in REW may not actually be 85dB. There's no way for the program to know exactly what input level = real world SPL. This is not important for measuring relative frequency response.

REW is developed out of Europe, they spell some words differently and the engineer may not even be a native English speaker. That's a silly reason to dismiss a well regarded program.

FFT real time spectrums are OK for spot checks, but a real impulse response with gating capability is what you'll need to get deeper.

I have a bunch of ARTA instructions with the iMM6 in my speaker build published on my site here.

[Stash]

Good to know, regarding the spelling. Maybe I jumped the gun.
If I do not need a USB adapter, then I'll look into the apps, again. I've read a little on gating. I understand the idea of ruling out reflections.

[a4eaudio]

Lastly, I cannot stand the butchering of the English language by the author. He spells words, such as equalize, with an "s" (equalise). This spelling atrocity...

Not to sidetrack too much, but... The English language comes from England. Those of us in America are fine that Americans butchered the English language by arbitrarily replacing s's with z's.

[DeZZar]

Lol. I was about to chime in with the same thing. Oh boy what a golden example of a typically American thing to say...the real atrocity being the genuinely innocent ignorance of who the real butchers are...hahahaha

[Stash]

Well, I wouldn't go so far. According to Webster's, "Z" is the correct spelling, here. If you were in a foreign country and misspelled, mispronounced or used poor grammar, natives would take notice. It is what it is, and. I'm afraid "equalise" is not correct, here.

[DeZZar]

Its ok, it was just a harsh critique of a well respected piece of software where the internationally located author has done no wrong by electing to use original English. Often reflective of our own frustrations that a new item of software doesn't come with an instantaneous learning curve and requires a little effort and some patience to become proficient. Such is the iPhone age.

[DeZZar]

The directions also show a separate SPL meter. That also turned me off. I assumed such an app has a built-in measuring device of some sort.

You don't need to worry about that until you really want to be able to validate the sensitivity of your speakers. Otherwise you just need to know (which by the way applies to any software like this) that 70db on the graph may not actually be 70db specifically until you configure the spl.