Audio Measurements on a Headfi Budget

Would you buy an expensive headphone without hearing it or seeing any measurements for it?

  • No

  • Yes, I'd buy it on the spot if Steve Guttenberg says it sounds good. He is always right.


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Aug 11, 2022 at 2:09 PM Post #121 of 131

anli

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Hi!

Also have got the coupler from AE. A seller also has sent two mic calibration files, and one of them goes with 1/24 smoothing applied. Can not imagine the way such file can be useful.

Any ideas?
 
Aug 11, 2022 at 2:33 PM Post #122 of 131

csglinux

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Hi!

Also have got the coupler from AE. A seller also has sent two mic calibration files, and one of them goes with 1/24 smoothing applied. Can not imagine the way such file can be useful.

Any ideas?
Nothing intrinsically wrong with a 1/24th octave smoothing - it depends what it was smoothing.
If your coupler has significant narrowband peaks and troughs that need correcting, it's not likely that any calibration file is going to be universally applicable. At least, not very accurately.

There is a way to find out. We have a little project ongoing to help folks like you calibrate clone couplers to the GRAS standard: https://www.head-fi.org/threads/ety...r-ears-and-your-couplers.908512/post-17008210
 
Aug 11, 2022 at 3:54 PM Post #123 of 131

anli

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Nothing intrinsically wrong with a 1/24th octave smoothing - it depends what it was smoothing.
If your coupler has significant narrowband peaks and troughs that need correcting, it's not likely that any calibration file is going to be universally applicable. At least, not very accurately.

There is a way to find out. We have a little project ongoing to help folks like you calibrate clone couplers to the GRAS standard: https://www.head-fi.org/threads/ety...r-ears-and-your-couplers.908512/post-17008210
Yes, smoothing variant of mic calibrations file can be useful as long as it exists. Just I don't understand those use cases when calibration file with smoothing is preferable in comparison with raw calibration file.
 
Aug 11, 2022 at 6:07 PM Post #124 of 131

gordonli

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Yes, smoothing variant of mic calibrations file can be useful as long as it exists. Just I don't understand those use cases when calibration file with smoothing is preferable in comparison with raw calibration file.
one reason I can think of is it may have been calibrated in batches (though I dont know the process behind batch calibration but it happens like with umik1), so as cglinux said, a narrowband calibration may be less accurate than smoothed
 
Aug 11, 2022 at 6:38 PM Post #125 of 131

anli

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one reason I can think of is it may have been calibrated in batches (though I dont know the process behind batch calibration but it happens like with umik1), so as cglinux said, a narrowband calibration may be less accurate than smoothed
It is interesting. The thing is the seller has wrote do not use 1/24 smoothed variant as long as I don't understand why to use it, as far as deviation can be more on wrong use.
 
Aug 11, 2022 at 7:35 PM Post #126 of 131

csglinux

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Yes, smoothing variant of mic calibrations file can be useful as long as it exists. Just I don't understand those use cases when calibration file with smoothing is preferable in comparison with raw calibration file.
IMHO, smoothing is always preferable. Let's say you've compared measurements from an identical IEM. Your coupler gives a resonance peak at 7 kHz and the GRAS RA0045 gives a peak at 7.25 kHz for an identical insertion depth. If you just take the difference between those two curves and apply it as your calibration file, every other headphone you ever measure is going to present with a trough at 7 kHz and a peak at 7.25 kHz.

I think what @gordonli is alluding to is that you'll typically create a calibration file from an average over multiple headphones. An average of deltas from multiple headphone measurements is bound to be somewhat uneven. You really want to compensate for just the average error in the coupler, otherwise every measurement you take is going to have that unevenness in it. If your coupler is very different from the GRAS standard, there's no hope of finding a calibration file that will perfectly match GRAS results for all headphones measured. The hope is, if your coupler is close enough, with an averaged and smoothed calibration curve, your results will at least be reasonably close for any future measurements.
 
Aug 11, 2022 at 7:38 PM Post #127 of 131

csglinux

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It is interesting. The thing is the seller has wrote do not use 1/24 smoothed variant as long as I don't understand why to use it, as far as deviation can be more on wrong use.
In my experience, you'll find the calibration files offered by AE and Taobao sellers always fall into one of two categories: 1) completely useless or 2) non-existent.
 
Aug 13, 2022 at 11:30 AM Post #128 of 131

anli

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In my experience, you'll find the calibration files offered by AE and Taobao sellers always fall into one of two categories: 1) completely useless or 2) non-existent.
Probably you are right. At any case resulting FRs look similar to those found around. So these files don't seem to be too harmful. mix-five.jpg
 
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Aug 13, 2022 at 12:56 PM Post #129 of 131

csglinux

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Probably you are right. At any case resulting FRs look similar to those found around. So these files don't seem to be too harmful.

The test would be to compare your measurements, with and without the calibration file, against those from a GRAS coupler. Your measurements could easily be off several dB here and there. That matters if you want to compare your measurements against those from external databases, because these errors could be larger than the differences between two headphone models.

If you don't plan on making external comparisons and you only want to see the rough shape of the curve for internal comparison purposes, then you don't need to worry about calibration.
 
Aug 13, 2022 at 2:00 PM Post #130 of 131

anli

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The test would be to compare your measurements, with and without the calibration file, against those from a GRAS coupler. Your measurements could easily be off several dB here and there. That matters if you want to compare your measurements against those from external databases, because these errors could be larger than the differences between two headphone models.

If you don't plan on making external comparisons and you only want to see the rough shape of the curve for internal comparison purposes, then you don't need to worry about calibration.
Absolutely agree. Unfortunately there isn't anybody around me interested in measurements. It there a place where measurement maniacs share their mdat files?
 

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