CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => IEM Measurements => Topic started by: Kunlun on August 25, 2014, 03:27:53 AM
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http://diy-ciem.blogspot.jp/2014/03/blog-post_10.html
Thanks, google translate... :-\
First and maybe more interestingly, the guy did some measurements:
(http://4.bp.blogspot.com/-QXHAIv0Ethc/Ux1C3sGJWzI/AAAAAAAACzM/PjEnFcYV8lc/s1600/IE800-%E6%AF%94%E8%BC%831.png)
So, one of the neat things about the IE800 is that it uses two helmholtz resonators to get rid of ear canal occlusion resonance at something like 7 and 8khz, which you can kinda see in the two little bumps at those spots in the blue line. Meanwhile, the shelled version (red line) has a big peak at 5.5khz.
For comparison, here's rin choi's FR chart (yeah, I know, the guy tends to huff his own farts and fails to see his limitations): Here's his diffuse-field measurement with the raw FR in grey
(http://www.picturevip.com/x/images/2014/08/25/AlDne.jpg)
Okay, here are some pictures of the shell: They are big:
(http://cymbacavum.files.wordpress.com/2014/03/3fb2f-dsc_0126.jpg?w=1158&h=777)
(http://2.bp.blogspot.com/-lHHxqciB9nE/Ux1B72UGNAI/AAAAAAAACzE/cYaH4X5ywsU/s1600/DSC_0129.jpg)
GIS reveals where Sennheiser spent its marketing dollars overseas:
(http://assets.hardwarezone.com/img/2013/03/Sennheiser_IE_800_resized.jpg)
Kunlun Note: OMG
(http://www.stereosound.co.jp/review/article/2012/10/28/P1020344.JPG)
Etc...
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Terrible place to develop a spike, though perhaps not so bad based on the minimal transient valleys fore and aft respectively speaking. That's bass response is just ridiculous custom or otherwise.
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That really is an awful lot of bass. The shell version makes the IE800 more like a deep insertion IEM I think, which might explain why it behaves/gets close to rinchoi's measurements.
Edit: Omg the Japanese lady is really cute.
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It seems like they were really tuned around the assumption that they would be a very shallow fitting iem (which the shell design forces).
In terms of real life bass performance, people have been saying, here and there, that the shure 846 has more bass, which I think is clearly a function of people having a poor fit. Because dang.
I'm thinking of picking up a pair again and playing with further limiting the vents, although not totally occluding them, plus adding a filter at the nozzle to thicken the treble and reduce the bass just a little. Think it'll work?
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Kumitate's measurement rig is not IEC60318-4 (711), so his and Rin's measurements are not at all comparable.
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846 does have more upper to mid bass. Of course it has different filters so....
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Kumitate's measurement rig is not IEC60318-4 (711), so his and Rin's measurements are not at all comparable.
How do you think limiting but not totally occluding the vents will effect the sound for the bass and treble?
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Aren't the vents just for treble EQ? In this case, you could argue that the Helmholtz resonators are actually "anti-resonators", and introduce diffraction-induced nulls in the back wave of the transducer.
BTW, the placement of the "remolded" IE800 is such that the equivalent insertion depth (port head is still distal to the first bend) is still relatively shallow, so it has "correct" placement that replicates Sennheiser/Axel Grell's intended design characteristics. At the same time, the pathway from port to ear drum is substantially different because the canal portion from first to second bend is now essentially a curved regular cylinder. While this makes "tuning" more predictable, it also changes the dynamic of the IE800 interacting with the residual canal volume of the ear. For CIEMs, it's "supposed" that because everything is molded up to the second bend, then residual canal volume is ~0.5 cc, and usually takes on a regular cylindrical shape, so the "standing wave" argument for predicting ear canal resonances works, at least partly, and in this case, an industry standard IEC60318-4 ear simulator can be used in a controlled fashion. Sennheiser with the IE800 switched up the game. They use the entire 1.5cc volume from the first bend to the ear drum, and while ear simulators still work in limited fashion, their reproducible data is limited. That's why Tyll had such a hard time trying to measure the IE800 (in addition to it not fitting correctly in the fake ear). IME, ear simulators have problems with off-axis (pitch/yaw) measurements (because they introduce the most asymmetries in a compression wave, leading to resonances/nulls), but real ears and real people often wear their earphones off-axis and their ear canals are irregular in concavity. Ear simulator measurements should be at best a reference of a singular wear scenario.
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Thanks Tomscy, that's very interesting!
For the "anti-resonators", one vent is said to also adjust the bass and the other is said to correct pressure in the ear canal--just going on rin choi here... :/
But, given as a likely case that at least one vent also effects bass, do you think limiting the airflow will both reduce bass (as we can see with set ups like the Senn ie8 or Aurisonics ASG-2) but also have an effect on how these anti resonators work and the treble will change?
Is it reasonable that some of the thinness in the treble I hear is due to the anti-resonators? They might reduce decay or something?
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The D2CA seems to work on treble only:
(http://2.bp.blogspot.com/-JJNvBhtpdKk/UVGyHOaAHxI/AAAAAAAAFjA/QzIMMAWvgZE/s1600/d2ca.png)
But I take it you mean the vents:
(http://3.bp.blogspot.com/-AcqJzQDdQCQ/UVG1FsePweI/AAAAAAAAFjY/sJrsSv7WTZw/s1600/damping.png)
It's not really possible to know what the "thin treble" is due to. More likely, it's a property of the "XWB" driver and whatever material/construction it's made of. Just like loudspeakers, I find that mass-driven excursion and surface treatment of the diaphragm/("cone") strongly influences "timbre" and the driver's breakup nodes. With respect to bass, I always find that closing/limiting bass vents makes drivers sound "less good". The FR gets corrected, but the driver always sounds "off".
We'd have to look at Sennheiser's internal data to really know what effect these resonators and vents have on decay, and that's not really possible; there's no "WikiLeaks" for hi-fi.
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Thanks, much appreciated.
I'm going to figure out Axel Grell's email and ask him about this sometime.
Yeah, I'm not really sure how rin manipulated the d2ca without futzing with the vents.
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I'm going to figure out Axel Grell's email and ask him about this sometime.
Go for it. He's head of marketing now.
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ut not totally occluding the vents will effect the sound for the bass and treble?
once you covers vent at the back, ie800's bass quantity will reduce by 10db
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ut not totally occluding the vents will effect the sound for the bass and treble?
once you covers vent at the back, ie800's bass quantity will reduce by 10db
Thank you, that's good to know.
what is the effect on the treble from the d2ca when the vents are covered?
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ut not totally occluding the vents will effect the sound for the bass and treble?
once you covers vent at the back, ie800's bass quantity will reduce by 10db
Thank you, that's good to know.
what is the effect on the treble from the d2ca when the vents are covered?
two port at the back is helping dynamic driver to move easily. when dynamic driver runs, it moves air in both front and back of the driver. If enclosure is sealed, dynamic driver will having hard time to move because vacuumed air will against the movement of the driver. Simply, physical impedance will be increasing at the back of dynamic driver when enclosure is sealed.
Then What will happen is driver is suffering to move back and forth causing lose of extension on bass.
Also driver makes peak at the high frequency due to under damping of driver or you can say Acoustic resonance.
Acoustic Resonance can be reduced, or moved to higher FR range that is not really sensitive to human hearing.
This is a reason why you always see air vent on dynamic driver iem.
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That's a good explanation, thanks again!
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It's not really possible to know what the "thin treble" is due to.
Rin also measured quite a bit of ringing in the treble. Can that contribute to the "thin treble" ?
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There are likely more factors than just the ringing. I haven't listened to the IE800 in a while, but whilst the ringing was audible, it didn't define the treble and overall timbre.