To "calibrate" my ECM-8000, I did almost like Dave.
I've got BMIdland's measurements from Seas, and built an test enclosure with the exact same dimensions. Then I measured both 27TDFC an d 27TFFC and compared it to Idland's measurements. My mic was very good up to 4000hz, at both 0 and 45 degrees. From 4000hz it peaked.
When I tried 90degree, it measured very closed from 4khz and up, but then it was about 2dB out at 2khz.
From those measurements I easily made my own calibration file in Speaker Workshop. I decided to use 45deg and removed all data below 1400hz, and used a 1/3 octave smoothing to remove the small variations from the cal file.
I also have tested and compared with CA18RNX, CA18RLY and new measurements of the tweeters. From 1khz and up its now better than 0,5dB matched to Idland's measurements.
I have also done the same thing to check my calibration of impedance measurements in Speaker Workshop.
So, like Dave said: buy a set of tweeters where you can copy the measurement setup from the vendor, and calibrate yourself.
I've got BMIdland's measurements from Seas, and built an test enclosure with the exact same dimensions. Then I measured both 27TDFC an d 27TFFC and compared it to Idland's measurements. My mic was very good up to 4000hz, at both 0 and 45 degrees. From 4000hz it peaked.
When I tried 90degree, it measured very closed from 4khz and up, but then it was about 2dB out at 2khz.
From those measurements I easily made my own calibration file in Speaker Workshop. I decided to use 45deg and removed all data below 1400hz, and used a 1/3 octave smoothing to remove the small variations from the cal file.
I also have tested and compared with CA18RNX, CA18RLY and new measurements of the tweeters. From 1khz and up its now better than 0,5dB matched to Idland's measurements.
I have also done the same thing to check my calibration of impedance measurements in Speaker Workshop.
So, like Dave said: buy a set of tweeters where you can copy the measurement setup from the vendor, and calibrate yourself.
At least for this mic, I think the point is that we trust the variance between good tweeters to be less than the variance between ECM8k's.
This mic has been proven to be a bit quirky from unit to unit in the top two octaves (although very good below that from unit to unit).
It's not a perfect solution, but it helps gain a ballpark estimate, which may be good enough for most people.
In my case, my mic was off over 6dB from the "standard" cal files at 16kHz, so I trust that my ribbon tweeters in the MG10.1s are flat enough to compensate for that. Again, not perfect, but it gets me closer without shelling out $120 for calibration.
Before I did not believe my measurements, now I can honestly say, I believe them as flat as my Magnepans
This mic has been proven to be a bit quirky from unit to unit in the top two octaves (although very good below that from unit to unit).
It's not a perfect solution, but it helps gain a ballpark estimate, which may be good enough for most people.
In my case, my mic was off over 6dB from the "standard" cal files at 16kHz, so I trust that my ribbon tweeters in the MG10.1s are flat enough to compensate for that. Again, not perfect, but it gets me closer without shelling out $120 for calibration.
Before I did not believe my measurements, now I can honestly say, I believe them as flat as my Magnepans
b_force said:
Like I said, BMIdland at Seas has measured all the tweeter and woofers in the same enclosure, without moving the mic. I have this measurements and the drawing for the enclosure. Temperature is "roomtemp" in both cases, so maybe I miss with one or two degrees celsius. Humidity I dont know. But do anyone know this when the mic is calibrated? And do you only measure your speakers when the climate is perfect?
And if the mic is one dB out, does it matter when building DIY speakers?
For me it doesnt, but is OK to know that the measurements you do, is very good, and not nearly 6dB off at 15khz.
I have compared a total of 15 Seas drivers with Idland's measurements, and it all came out within 0,5dB. So yes I'm sure thats better than no "calibration" at all. (I have bought all the drivers to build 5 speaker for my home theater.
Of course a calibrated mic is the best, and I would have done it, if there was anyone who could do it for me, at least in my home country.
ok, that wasn't really clear in your post(s).
I doesn't mather if you know exactly humidity, the point is that the calibration are done in the same circumstances.
I'm studying physics and we'v measured by coincidence some time ago some mic's and sensors with different temperatures and humidity.
There where quite some big differences.
But at the end, when you measure only 0,5dB difference form the original (calibrated) measurements, that's quite well.
It surprises me, but it's lucky for you
Here in Europe you can have your mic calibrated by a few companies in Germany for example. It costs around 30 euros. (without shipping)
I doesn't mather if you know exactly humidity, the point is that the calibration are done in the same circumstances.
I'm studying physics and we'v measured by coincidence some time ago some mic's and sensors with different temperatures and humidity.
There where quite some big differences.
But at the end, when you measure only 0,5dB difference form the original (calibrated) measurements, that's quite well.
It surprises me, but it's lucky for you
Here in Europe you can have your mic calibrated by a few companies in Germany for example. It costs around 30 euros. (without shipping)
Calibrating microphones is difficult and demanding. Most reports of microphone calibrations aren't! Most are casual frequency response checks with many errors. Earthworks Microphones wrote a white paper on how they test their calibration microphones:
How Earthworks Measures Microphones
http://www.earthworksaudio.com/tech/ew_measures_mics.pdf
How Earthworks Measures Microphones
http://www.earthworksaudio.com/tech/ew_measures_mics.pdf
b_force said:ok, that wasn't really clear in your post(s).
I doesn't mather if you know exactly humidity, the point is that the calibration are done in the same circumstances.
I'm studying physics and we'v measured by coincidence some time ago some mic's and sensors with different temperatures and humidity.
There where quite some big differences.
But at the end, when you measure only 0,5dB difference form the original (calibrated) measurements, that's quite well.
It surprises me, but it's lucky for you
Here in Europe you can have your mic calibrated by a few companies in Germany for example. It costs around 30 euros. (without shipping)
Nothing is clear in my posts, because my english sucks !
Lucky you, studying physics, that must be fun! But remember NOT to tell the highend gurus that sound is physics. It isnt you see, it just voodo and magic!
BTW; it is maybe wrong to say that my measurements was within 0,5dB? It was +/- 0,5 dB, then you say within 1dB I suppose.......?
Norcad said:But remember NOT to tell the highend gurus that sound is physics. It isnt you see, it just voodo and magic!
Sound is physics just to the medium. Part biology, part psychoacoustics, brain interpretation & brain state to the humans. Simple test: Smoke a joint and listen to same record.
Norcad said:So you ment to say that the highend gurus, do smokes before they listen to music?
Well for me its enough with a glas of cognac, after a while my DIY speakers are just perfect!
I meant to say that some THC proves that perceiving sound is much more than air vibrating the ear drum. If it alters, then much is in the brain.
Now do filter sonic perception through a mind of a guru that you never met out of a system that you have never seen or listened to, and see how important the personal experience is over reviews.
Congrats for your cognac tweak! Less expensive than special cables and always effective!
New ECM8000?
I just bought a ECM8000 for room correction.
However, found that its frequency response:
flat up to 22khz
Seems that they are selling new version of ECM8000 right?
I just bought a ECM8000 for room correction.
However, found that its frequency response:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
flat up to 22khz
Seems that they are selling new version of ECM8000 right?
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