CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => IEM Measurements => Topic started by: speakerphone on February 09, 2015, 05:34:12 PM
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(http://i.imgur.com/qr8eyF1.jpg?1)
(http://3.bp.blogspot.com/-ZwgoQHns52k/VIhMVA2J9vI/AAAAAAAAAHU/A4MYvFH5F2Y/s1600/DF.JPG)
(http://1.bp.blogspot.com/-ri7NDN-f5h4/VIhMWmk6QBI/AAAAAAAAAHw/qLuXrSnsBzM/s1600/ow.JPG)
(http://1.bp.blogspot.com/-B6FFhwzwFis/VIhMVKcJfmI/AAAAAAAAAHM/mk4DABUgHEI/s1600/csd.JPG)
(http://2.bp.blogspot.com/-qQIXpRfnVjc/VIhMWFhj86I/AAAAAAAAAHg/K1LCuEawFkA/s1600/ditn.JPG)
(http://4.bp.blogspot.com/-wyY5pLpei5Q/VIhQLCqG61I/AAAAAAAAAIA/80F9IatAw6s/s1600/phase.JPG)
(http://4.bp.blogspot.com/-wCzzJbnDv04/VIhMWmcDv0I/AAAAAAAAAHo/YSsEkc6OW8Q/s1600/impe.JPG)
I didn't uploaded CSD and Distortions of right channel. Because both channels are almost the same.
My artificial Ear (Coupler) follows IEC 60318-4 (former IEC 60711), ITU-T Recommendation P.57, ANSI S3.25 standards.
About the measuring standards
I mostly follow the IEC 60268-7 standard. I use O2 Amp for Lower the output impedance close to 0ohm. (In IEC standard, amplifier output impedance should be 120ohm.)
Also I use [1/24 octave smoothed Pink periodic noise] for frequency response analysis, and [1/6 octave stepped sine] for harmonic distortion analysis.
Diffuse Field Compensation Target follows the ISO 11904-2 standard, and Olive-Welti Target follows latest In-Room research. (Olive, Sean; Welti, Todd; McMullin, Elisabeth at AES).
But, as we know, frequency range of ISO 11904-2 standard is 20~10000Hz. So I dealt [-6dB/Oct.] at 10000Hz~20000Hz.
References
IEC 60318-4 : Electroacoustics - Simulators of human head and ear - Part 4: Occluded-ear simulator for the measurement of earphones coupled to the ear by means of ear inserts
http://webstore.iec.ch/webstore/webstore.nsf/artnum/043703!opendocument
ITU-T Rec. P.57 : Series P: Telephone transmission quality, Objective measuring apparatus : Artificial ears
http://www.itu.int/rec/T-REC-P.57
ANSI/ASA S3.25 : Occluded Ear Simulator
http://webstore.ansi.org/FindStandards.aspx?SearchString=s3.25&SearchOption=0&PageNum=0&SearchTermsArray=null%7cs3.25%7cnull
IEC 60268-7 : Corrigendum 1- Sound system equipment - Part 7: Headphones and earphones
http://webstore.iec.ch/webstore/webstore.nsf/artnum/043714!opendocument
ISO 11904-2 : Determination of sound immission from sound sources placed close to the ear
http://www.iso.org/iso/catalogue_detail.htm?csnumber=32439
Olive-Welti Target : Listener Preferences for In-Room Loudspeaker and Headphone Target Responses
http://www.aes.org/e-lib/browse.cfm?elib=17042
Feel free to ask a question about this!
But I'm not native English speaker, so I'm not very good at English.
And anyone who knows how to use 'attachment'? I don't know how to, so I'm using my blog http to upload a file.
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Thanks for the measurements. I would say I relate to the ER-4S measurements for diffuse filed compensation for frequencies 5k and above, and relate more to the Olive-Welti compensation for everything below 5k.
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Looks pretty typical of the ER-4S into the 60711. I find my taste closer to the conventional diffuse field here.
I don't know what IEC 60268-7 specifies for measurement level and reference frequency, can you describe it in detail?
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Looks pretty typical of the ER-4S into the 60711. I find my taste closer to the conventional diffuse field here.
I don't know what IEC 60268-7 specifies for measurement level and reference frequency, can you describe it in detail?
IEC (International Electronical Committee) 60268-7 is international standard about way of measuring Headphones and earphones.
That specified article about HATS(coupler) as a frequency response, measuring impedance, harmonic distortions and so on.
Reference frequency in standard is 94dB @ 500Hz or 1mW output for that headphone. I'm using 94dB @ 500Hz.
And In standard, only thing that we could trust in harmonic distortion is just THD, 2nd, 3rd harmonic.
And according to IEC 60318-4, my coupler's reliable frequency range is ~16kHz.
So 16kHz~20kHz is not that accurate.
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Cool to know someone has a real IEM coupler. +1 for you
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I think you were supposed to reference ISO 11904-1 past 10kHz, which is about a -9dB/oct slope past 10kHz. It's probably the source of the 16kHz limit in the revised IEC standard.
I don't see the reason to cut out the higher order harmonics if you have the data. These are bound to be lower in level than the 2nd and 3rd order and not clearly identified in THD, but more noticeable than the lower order harmonics.
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I think you were supposed to reference ISO 11904-1 past 10kHz, which is about a -9dB/oct slope past 10kHz. It's probably the source of the 16kHz limit in the revised IEC standard.
I don't see the reason to cut out the higher order harmonics if you have the data. These are bound to be lower in level than the 2nd and 3rd order and not clearly identified in THD, but more noticeable than the lower order harmonics.
ISO 11904-1 is DF for the real human head. But ISO 11904-2 is DF for HATS(dummy head) reponse. So I just judged that 11904-2 is more accurate than -1 for measuring headphones with coupler, not a human. (Actually, both targets are very similar.)
ISO 11904-1: technique using a Microphon In a Real Ear, ISO 11904-2: MIRE technique using a manikin
And about the high order harmonics, those are not visible in normal coupler. high order harmonics can audible easliy, but these energy is very small, so it's hard to notice on measurement data. Therefore, higher harmonics more than 5th in my measurement data would ,, maybe noises in my room.
You should use Klippel GMbh to clearly see the higher harmonics.
(http://i.imgur.com/C22mSXN.png)
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How to add diffuse field compensation in ARTA?
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How to add diffuse field compensation in ARTA?
There is no DF option on this program. You should make a compensation file with offered target.Then you can compensate this.
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Is it possible to share this file ?
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Is it possible to share this file ?
Yes I can share this, but maybe you can't use this unless you have artificial ears, because of impedance mismatch.
You have to compensate acoustical impedance mismatch between a 2-cc coupler and an occluded ear simulator, first.
You can reference
http://rinchoi.blogspot.kr/2012/09/akg-k3003-part3-in-depth-analysis.html?m=1
Measurement data difference between そのべ's and Rin's.
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Plus,
http://goldenears.net/board/1506729
Article about acoustical impedance mismatch {RECD (Real Ear to Coupler Difference)} compensation. You should use Translator to read this.
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Can you check measurements for W4 and VSD5 and see if DF compensation is correct? I would like to try with your file too.
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Can you check measurements for W4 and VSD5 and see if DF compensation is correct? I would like to try with your file too.
Actually, there is many varieties of DF file,
because Diffuse Field is not a specific target, it is just a way to get a Target.
Can you explain more about your measurement condition?