# Galaxy CM-140 Calibration File Info Thread



## Sonnie

I stated that I would provide a calibration file for the CM-140 and I plan on doing just that. However, it may be a couple of weeks before I actually post it. Some of you will no doubt ask why. There are a couple of reasons for this that I will explain below. 

First of all, I am having my ECM8000 re-calibrated at West Caldwell Calibration Lab. These guys are the real deal. The cost for calibration is $150. I could provide you with a calibration file today, but once my mic has been re-calibrated, the .cal file may be slightly different than it is now. While more than likely it will be very close, I prefer to make absolutely sure and not be releasing a .cal file today and then in two weeks be releasing another .cal file telling you the first one is no good. 

Secondly and most assuredly something that will excite several of you... my ECM8000 is going to be calibrated down to at least 5Hz. Once it is returned, I will hopefully be able to provide you with a calibration file to 5Hz or lower for the CM-140.

In the meantime you can use the CM-140 as is and be fairly close.

Once the .cal file is ready... it will be available for download on the Downloads page.


----------



## brucek

> In the meantime you can use the CM-140 as is and be fairly close.


By checking the C-Weight box in REW of course....... 

brucek


----------



## Ilkka

brucek said:


> By checking the C-Weight box in REW of course.......
> 
> brucek


Well actually...it was ~7 dB high @ 10 Hz with the C-weighting checked, and ~7 dB low without it. Pick your poison. :surrender:


----------



## Sonnie

You could use the ECM8000 .cal file with no C-Weighting and be almost there.

ecm8000.cal


----------



## Ilkka

Sonnie said:


> You could use the ECM8000 .cal file with no C-Weighting and be almost there.
> 
> ecm8000.cal


True. Assuming your current calibration for the ECM8k is accurate, you'd be less than 2 dB off @ 10 Hz which is more than enough accurate for most in-room measurements.


----------



## Sonnie

> Assuming your current calibration for the ECM8k is accurate


Yeah... I hope it is because we've been using it for quite a while to calibrate against. I think Kim does a good job from what I've been told... and if you remember yours and my mic are almost spot on. But we will know for sure here pretty soon... either way.


----------



## Ilkka

Sonnie said:


> Yeah... I hope it is because we've been using it for quite a while to calibrate against. I think Kim does a good job from what I've been told...


I don't doubt that at all. 



> and if you remember yours and my mic are almost spot on. But we will know for sure here pretty soon... either way.


My mic? I've never had an ECM8000. My mic is recommended by the ETF Acoustics and it's only ~0.6 dB off at 10 Hz without a calibration file. :bigsmile:


----------



## Sonnie

Exactly... but when we both provided calibration files for one of the RS meters a while back... you might remember we were spot on, except at one frequency I believe. This would indicate that mine must be pretty accurate.


----------



## Geoff Gunnell

Thanks for taking your time and money to re-reference your mic to a physical standard before calibrating others' equipment from it, Sonnie. It's the right thing to do. It's also kind of an honor, I think, to transfer a standard of measurement. We know in advance that we cannot get it exactly right, but we have the courage to try anyway


----------



## tweakophyte

Hi-

Yes, thanks for spending the extra bucks to make sure your mic is "perfect" so _our_ mics will be.  I'm glad I got in on the buy. It's laying the groundwork for my next investment into my HT, too.


----------



## Sonnie

It is my honor to do so... I want nothing less than as good as I can provide for everyone... :T


----------



## Eric_RP

Sonnie said:


> Secondly and most assuredly something that will excite several of you... my ECM8000 is going to be calibrated down to at least 5Hz. Once it is returned, I will hopefully be able to provide you with a calibration file to 5Hz or lower for the CM-140.


 This is awesome Sonnie. :T Thanks much for doing this! Can't wait to get it and put it to use.

Eric


----------



## ifeliciano

Thanks Sonnie !!


----------



## nerdful1

Are you having the high end done, and above 8khz? Now I think I should have bought a 140 instead of getting my RS charted...Jim


----------



## Sonnie

The initial plans are to provide a calibration file for the bass region. I will provide some measurements full range, but I'm not sure anyone is going to be up to the task to complete a calibration file for it. It would be a fairly gruesome task IMO.


----------



## Vader

Sonnie,

I have always read that the Rat Shack meter is 2 to 3 dB low when using the pink noise on DVE to calibrate (ie. when the meter reads 72 dB it is actually about 75 dB). Does the Galaxy meter need a similar correction factor?


----------



## Sonnie

I'm not sure how anyone could qualify that correction. Your response is not perfectly flat and the SPL meter is going to read the highest peak in your response when that pink noise is playing. If that peak is at 500Hz, then neither meter is really going to need any correction, yet if it were at 20Hz it would... but with pink noise how can you tell where the peak is unless you have an RTA. I think most of the time we see peaks down low in the 30Hz to 60Hz region. With the old RS meters it could mean anywhere from 2db - 7db of correction, with the newer RS meters it could mean from .5db - 2db and with the CM-140, it would not need any at all in that region. So ultimately, I would say you would not need to perform any corrections to the CM-140 for pink noise.


----------



## Vader

Sonnie,

Ron had me use that correction when we were trouble-shooting my first cylinder last year. He had me run several tests using both my AVR test tones and DVE (which is 10dB hot on the sub test). When I reported the results of the sub tests, I thought they were all 2-3 dB low, but Ron said they were spot-on, because of this correction. Based on this, I calibrated the subs to "flat" with respect to the meter, so it would really be 2-3 dB hot (or so I understood).

Edit: My wife just called and said that my meter came today, so I guess I'm gonna be re-calibrating tonight. It will be interesting to see how far off my old Rat Shack meter really is (I bought it when I was in college - 1991 - and have never re-calibrated it...). Thanks so much, Sonnie!


----------



## Ilkka

Vader said:


> Sonnie,
> 
> I have always read that the Rat Shack meter is 2 to 3 dB low when using the pink noise on DVE to calibrate (ie. when the meter reads 72 dB it is actually about 75 dB). Does the Galaxy meter need a similar correction factor?


DVE's pink noise is not good for setting up the subwoofer level. It's too wide band to be accurate if your frequency response isn't close to dead flat. Especially any amount of "room curve" can cause one very interesting results. AVIA and pretty much all receivers have band limited pink noise for setting up the subwoofer and speaker levels. Usually the noise for subwoofer is limited in ~40-80 Hz range. Since normal C-weighting reads around 1-2 dB low in that range, the same amount of correction is needed for the CM-140 too. So adjust your subwoofer to output around 73-74 dB on the CM-140 when using your receiver as the source. With DVE it's much more difficult to define the correct compensation but around 2 dB is a good starting point. Your ears should always be the final judge, don't just blindly trust on the SPL meter. If the subwoofer sounds too loud, turn it down.


----------



## Vader

Ilkka,

So you would recommend that I use the AVR's TT instead of DVE? I had always heard that DVE was the better way to go because it tests the entire signal path (from DVD player --> AVR to Speakers --> SPL meter). What you say makes perfect sense too. What about the other channels? Would it be better to simply calibrate all of them to keep consistancy, or use DVE for everything _except_ the LFE channel? I know, I need to get AVIA.... just haven't gotten around to it yet.:innocent:


----------



## Ilkka

Vader said:


> Ilkka,
> 
> So you would recommend that I use the AVR's TT instead of DVE? I had always heard that DVE was the better way to go because it tests the entire signal path (from DVD player --> AVR to Speakers --> SPL meter). What you say makes perfect sense too. What about the other channels? Would it be better to simply calibrate all of them to keep consistancy, or use DVE for everything _except_ the LFE channel? I know, I need to get AVIA.... just haven't gotten around to it yet.:innocent:


The signal path doesn't really matter at all in this case. I would use the AVR's test tones instead of DVE for all channels.


----------



## Sonnie

Ilkka, you can still have quite a variance in response from 40Hz to 80Hz, so how do you account for it? I realize the CM-140 is pretty accurate in that range, other than maybe reading a db or so low on C-Weighting, which on an SPL meter 1db is pretty hard to adjust for, but on those who still have RS meters, that could be anywhere from 1db to 4db, with the C-Weighting reading low... 2db to 5db from 80-40Hz respectively. :scratch:


----------



## Vader

Thanx, Ilkka!

Up to now, I have been using the auto-cal for the Denon (AVR-2105) to get a rough starting point, then fine-tuning with DVE. I will re-fine-tune using the manual speaker trim in the Denon (much easier, too!). Oh, well.... at least there are those fantastic intro videos on DVE......


----------



## Ilkka

Sonnie said:


> Ilkka, you can still have quite a variance in response from 40Hz to 80Hz, so how do you account for it? I realize the CM-140 is pretty accurate in that range, other than maybe reading a db or so low on C-Weighting, which on an SPL meter 1db is pretty hard to adjust for, but on those who still have RS meters, that could be anywhere from 1db to 4db, with the C-Weighting reading low... 2db to 5db from 80-40Hz respectively. :scratch:


Varying frequency response is a bad thing when trying to adjust your subwoofer level with any kind of noise (band limited or not). The SPL meter measures the total energy, it can not tell if the frequency response is flat or not (unless we plug it into our computer). Depending on how flat frequency response you have, the noise method can give you good or really bad results. A major peak or wide null in 40-80 Hz range can throw off the readings big time. That's why I will always recommend taking an accurate frequency response measurement instead.


----------



## SteveCallas

Vader said:


> I had always heard that DVE was the better way to go because it tests the entire signal path (from DVD player --> AVR to Speakers --> SPL meter).


I agree in that I trust using the exact signal path my music and movies will follow for the final calibration. I use my receiver's built in tones as a starting point and then finish up with Avia's tones. I usually find a 1db variance on my right front channel and a couple db difference for the surrounds. I believe Avia has you set the surrounds a little hot :scratch:


----------



## Sonnie

Ilkka said:


> Varying frequency response is a bad thing when trying to adjust your subwoofer level with any kind of noise (band limited or not). The SPL meter measures the total energy, it can not tell if the frequency response is flat or not (unless we plug it into our computer). Depending on how flat frequency response you have, the noise method can give you good or really bad results. A major peak or wide null in 40-80 Hz range can throw off the readings big time. That's why I will always recommend taking an accurate frequency response measurement instead.


That's exactly what I was thinking and somewhat stated, but in a different way of course. :dumbcrazy:


----------



## PeteD

Hi Sonnie:

Did you get your mic back, yet? I am curious to see how the CM-140 performs (accuracy and precision between meters) since I don't have a clue what my RS correction factors should be...I have the 33-4050 with a 04A04 code, which puts me squarely in limbo.

Thanks,
Pete


----------



## brucek

> accuracy and precision between meters


Precision between meters has already been established. They're all tested identical....

brucek


----------



## Sonnie

I will call the lab on Monday and see where they stand on getting it calibrated. It's getting close to the time that should have called me for payment anyway.


----------



## PeteD

brucek said:


> Precision between meters has already been established. They're all tested identical....


That is great news.

Thanks for the update Sonnie.


----------



## Sonnie

I just spoke with Felix at West Caldwell Calibration Lab and he stated he has my mic scheduled to calibrate today. Maybe by the end of the week I'll have it back in my hands.


----------



## Sonnie

The lab called today and they are shipping the mic back via UPS today with the cal file on disc. I should have it by Thursday or Friday... :T


----------



## Sonnie

brucek has completed the necessary and very time consuming task of creating the .cal file for the Galaxy CM-140... much appreciation for his work on this!

The GALAXY140.cal is now available via the Downloads page.

The file is from 5Hz - 200Hz... therefore C-Weighting in REW does not have to be checked.

When measuring with the CM-140, be sure to set the meter to dBC, FAST and set the level to the 50-100 range.


----------



## tweakophyte

Hi-

This is great. Any chance we get a file that does the whole spectrum?


...or should we assume zero correction above 200hz and call it a day?


----------



## brucek

> Any chance we get a file that does the whole spectrum?


No chance. We don't have the capability or equipment to do so. REW automatically assumes zero past 200Hz. I wouldn't trust it beyond 10KHz......

brucek


----------



## koiman

Sonnie,
I tried to down load the GALAXY 140 Cal. file to desktop and I get (WINDOWS CANNOT OPEN THIIS FILE) What do I do.
Thanks,
Leon


----------



## Sonnie

Downloading and opening are two different tasks. Apparently you are not trying to download it, but rather you are trying to open it from the Downloads page. You need to download it first (save it) and then load it in REW. No reason to open the file unless you just wanna see the values... in that case, open Notepad and then open the file.


----------



## koiman

Sonnie,
Thanks this is all new to me.
Leon


----------



## koiman

Sonnie,
I have another question.. do you open the cal. file for both the Soundcard Screen and the Mic/Meter screens.
Thanks,
Leon


----------



## Sonnie

No, you need a soundcard.cal file to open on the Soundcard tab. You will only open the GALAXY140.cal on the Mic/Meter tab.

You may want to read up on the REW Help files... it will explain how to make you soundcard calibration file. Then of course there are several threads pertaining to the same if you wanna scan down through them.


----------



## JimP

brucek said:


> No chance. We don't have the capability or equipment to do so. REW automatically assumes zero past 200Hz. I wouldn't trust it beyond 10KHz......
> 
> brucek



I've been reading like a madman trying to get up to speed on testing microphones and came across your post.

Please correct me if I'm wrong.

Are you saying that above 200hz, REW isn't going to factor in adjustments from the microphone calibration file?


----------



## brucek

REW reverts to the standard C-weight curve outside the limits of the calibration file....

If the cal file stops at 200 Hz, then C-Weight curve takes over after that (same as for the bottom end limit).

brucek


----------



## JimP

So, is the C-Weight curve basically there for those without a calibration file as most calibration files go up to 20K?


----------



## brucek

> So, is the C-Weight curve basically there for those without a calibration file as most calibration files go up to 20K?


Whatever the lower and upper limits of the calibration file is, determines the point that the C-Weight curve will take over (if C-Weight is checked in REW)....

brucek


----------



## calderes

I know this thread is super old but in January of 2017 it is still the first result when googling "galaxy cm-140 calibration file" and it might be worth pointing out that although in 2007 the .cal file for the galaxy CM-140 that was provided only went up to 200hz, the file that is now available goes all the way to 20khz (and as before, down to 5hz).

Love this site and thanks for the hard work (the downloads page referenced where you can find the mic .cal files was last updated in February 2015).


----------

