CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => Headphone Measurements => Topic started by: kapanak on April 16, 2015, 09:07:16 PM
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Hello there :)
I am wondering if anybody here who does measurements is comfortable sharing some details or photos of what their baffle and coupler looks like, so I get a sense of where to start.
I have a miniDSP UMIK-1 for measurement microphone, and will be using REW V5.1 as the software. Just basic stuff.
I do have some headphones (HD800, Code-X soonish, Amperior, etc) that could be used to check generally where my measurement rig falls under.
I appreciate any and all inputs. I will use this thread to further develop my measurement rig.
Thank you!
Measurement Rigs
OJNeg: http://www.changstar.com/index.php/topic,2305.msg63430.html#msg63430 (http://www.changstar.com/index.php/topic,2305.msg63430.html#msg63430)
Marv: http://www.changstar.com/index.php/topic,2305.msg63273.html#msg63273 (http://www.changstar.com/index.php/topic,2305.msg63273.html#msg63273)
Stratocaster: http://www.changstar.com/index.php/topic,2305.msg63377.html#msg63377 (http://www.changstar.com/index.php/topic,2305.msg63377.html#msg63377)
Ultrabike: http://www.changstar.com/index.php/topic,2305.msg63270.html#msg63270 (http://www.changstar.com/index.php/topic,2305.msg63270.html#msg63270)
Why No Use of Ear / Pinna: http://www.changstar.com/index.php/topic,2305.msg63409.html#msg63409 (http://www.changstar.com/index.php/topic,2305.msg63409.html#msg63409)
Measurement FAQ: http://www.changstar.com/index.php/topic,2305.msg63865.html#msg63865 (http://www.changstar.com/index.php/topic,2305.msg63865.html#msg63865)
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foam --> plastic plate (with hole) --> creatology foam with hole cut in for microphone.
- In the middle of the foam later, a piece of felt about the size of an ear. Without this piece, I found measurements too ringy. Covered completely with felt, I found measurements too damped. The felt the size of an ear also serves another function. Proper measurement of supra-aurals that rest of the ear.
- I use a strip of felt to simulate hair and sometimes another strip to simulate imperfect seal of the nape of the neck. Knowing to get a properly simulated seal is crucial.
- The hard plastic plate (use a CD) is a good bone simulator.
photos in a bit...
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This thread is interesting, I've been building an anthropomorphic gear out of silicone and modelling hard clay for some tine now, it's almost done. The ear canal mass load is missing yet, other than that it is already great.
Ear and ear canal are based on straight silicone moulds of my own, modelling clay is hardened to simulate cheekbone and a bit of other bone in a roughly correct shape. Soft silicone skin. Silicone foam siluates cheeks.
Microphone is Dalton EMM-6, not the greatest SNR but otherwise great.
No compensation done yet, we'll see, but it is close to Marv's measurements at least on HE-6 and Parasox (new) - drops near 3-5kHz.
I'll start publishing once it's fully done.
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In all cases I cut a tight hole to pass the mic through. The mic should be flush.
sponge --> flat kitchen drawer liner --> thin foam padding (leaky headphones)
sponge --> flat kitched drawer liner --> small circle of foam padding (closed headphone) - foam padding must fit inside the cup
The sponge holds the mic in place and reinforces no leakage through the liner hole. This works:
Sponge: http://www.homedepot.com/p/QEP-7-1-2-in-x-5-1-2-in-x-2-in-Extra-Large-Grouting-Cleaning-and-Washing-Sponge-70005Q-144/100173109
Drawer liner maybe substituted by anything that provides a flat surface. This surface provides seal (like a CD or whatevs).
Foam Padding is used to absob reflections as much as possible. Will do photos later as well.
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pictures of my rig:
(http://www.changstar.com/index.php?action=dlattach;topic=2305.0;attach=9311;image)
(http://www.changstar.com/index.php?action=dlattach;topic=2305.0;attach=9313;image)
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LOL, nice! Can we get pics from the side to get a better look at the coupler?
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I know, I know, I should have posted pictures of my "semi-secret" measurement rig long ago. Many people, including Jude as recently at the Ann Arbor meet, have gone on rants regarding my not posting photos of my measurement rig or refusal to discuss my methods. I agree that this criticism is totally warranted. In my defense, I had my own myriad of reasons. Those close to me know exactly the reasons why I refused to post until now.
Quite a few Changstar members have figured out their own methods with great consistency and repeat-ability. The time is now right.
Here you go Hans:
(http://www.changstar.com/index.php?action=dlattach;topic=2305.0;attach=9315;image)
I actually have a newer coupler with pinna, et. al. but still using this old V2 for sake of comparability to existing measurements.
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I highly appreciate all the great information and photos Marv and Ultra! I think I can use these as my reference in approaching a solution for my rig as well! :)p1
And absolutely hilarious naming XD :)p13
Out of curiosity, is the inside of the enclosure filled with anything? Cotton wool or similar material? Would that even have any effect on the measurement?
Thank you all so much :D
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I filled the inside with medium density open cell foam - to simulate brains. Use something squishy to avoid interactions between L and R.
Really, you could just put the felt / foam layer on top of a CD on top of a foam brick. I just made it look nicer and named it C.U.N.T. to establish "cred". We all know that stuff that looks nice, that is shiny white, and has a euro kind of acronym like G.R.A.S. or C.U.N.T. must be good.
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If you replace the word technology with machine, the abbreviation makes more sense... :D
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If you replace the word technology with machine, the abbreviation makes more sense... :D
I assume you associate HF with the Death Star. I can understand that with a chuckle...
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AHHHHH GREAT thread ! thks popcorn
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Nice ideas. I have been using a CD with felt over it.
But some of 318 couplers or Gras artificial head dont have any damping material on it.
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FYI, an easy to use measurement microphone.
http://www.amazon.com/Dayton-Audio-UMM-6-Measurement-Microphone/dp/B00ADR2E68/ref=sr_1_1?ie=UTF8&qid=1429254678&sr=8-1&keywords=UMM-6+USB+Measurement+Microphone
(http://ecx.images-amazon.com/images/I/61vWels1FeL._SL1500_.jpg)
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But some of 318 couplers or Gras artificial head dont have any damping material on it.
I feel damping material is necessary to simulate effects of skin, fat, muscle, blood, which seem to have some absorbing properties. I've had access to artificial ears, shoved a microphone through a large piece of pork belly, coated surfaces with sriracha sauce, etc. until I came up with this V2 version (small ear size piece of felt over a sheet of high-density construction foam).
Without damping material, I feel that peaks and ringing in CSD tend to be overemphasized, at least with what I was working with. Finally, my V2 rig as seen here, uses absolutely no compensation. The whole thing was about doing it fast / uncompensated jointly on an unbiased device for evaluating headphones.
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I think I was wrong seems they use some special material.
"is equipped with a pair of removable pinnae (the outer visible section of the ear), molded from a soft rubber-like compound, and mechanical couplers called Occluded Ear Simulators at the locations of the inner ears, to simulate the mechanical impedance of the ear to incoming sound. Measurement microphones are situated at the location of the eardrum."
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Tnx for the info Marv.
Have you tested ballistic gelatin in conjunction with other materials?
Are there any particular settings for REW?
edit: I am seriously considering this dummy head from epay, it has a decent pinna. Some damping-felt can be easily added. (If more members would make the same dummy head model we could have a uniformed standard and cross-evaluate measurements)
http://www.ebay.com/itm/Extensions-Mannequin-Soft-Head-Eyelash-Extensions-Male-Dummy-Display-Stand-Q-/251734683480?pt=LH_DefaultDomain_3&hash=item3a9c8e6f58
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Nice for positioning the headphones right.
purr1n looking at the headphone on your rig, isnt it too stretched and too much pressure?
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I am using this ... Wood construction lined with creatology foam, calibrated Dayton EMM-6 mic and Steinberg UR22 audio interface.
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I think the distance should same like head size right?
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I think the distance should same like head size right?
No reason for that as long as you get a good seal. Also, where would you fit the mic unless you were doing 90 degrees measurements.
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The measurement changes drastically with clamping force.
Same like with different pads.
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In radiology and rad-onc, we use dummy heads that simulate tissue densities all the time, in order to measure penetrance of our therapeutic rigs. The dummy heads themselves range from really rudimentary ones made from plastic and different densities of liquids and foams, to realistic ones that use very true-to-life silicone that simulates the absolute density of epidermal/dermal, and then musclular tissue, as well as skeletal tissue.
(http://www.studentvoiceonline.com/wp-content/uploads/2014/10/b851c7ce-7714-4b07-a0d8-a8bc945229e5.jpg)
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The important part is to make sure to keep Snell's Law in mind as sound energy converts from media of air to tissue to bone and back to air before it gets to the "eardrum" or rather, the capsule of the pressure mic. The refracted energy needs to undergo an appropriate amount of overall loss.
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Dunno why it never occured to me to make it out of a biscuit tin rather than just a CD. Much more convenient and easier to build.
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Totally misread that as "biscuit" and not "biscuit tin"...
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Here in
Totally misread that as "biscuit" and not "biscuit tin"...
Here in France we're used to use cheese in our measurements rigs. does wonder to avoid nasty artefacts in treble area.
(http://t3.gstatic.com/images?q=tbn:ANd9GcRX5vy7DqBrd1orNF9Dwt3HIUGeWGHe1e7w7VoHEISNBYPO-AK-BtljP94L7g)
Biscuit should give good results too.
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Nice for positioning the headphones right.
purr1n looking at the headphone on your rig, isnt it too stretched and too much pressure?
It's the same width of my head. I think it looks a little stretched once headphones are put on it and the angle of the photo.
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Nice Purrin! I appreciate you sharing the info about your rig.
Just wanted to add that I've been using the Dayton UMM-6 with some good results as well with a jig that Tyll loaned me.
Felt ears work well but I'm also considering ordering some artificial ears. Seen some cheap ones on eBay but also some nice ones from 3Dio:
http://3diosound.com/index.php?main_page=product_info&products_id=44
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You could check these out:
http://www.amazon.com/Thumbs-Up-UK-Headphone-Cable/dp/B0082C4GOE/ref=sr_1_7?ie=UTF8&qid=1429284843&sr=8-7&keywords=earphones+tidy
May need to make a hole in the middle of where the canal should be. I've done it and FWIW it fits my mic.
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You can use earpiece from GRAS, if you're rich. 300USD per piece, 600USD for pair. :)
It is for Kemar HATS.
http://www.gras.dk/catalogsearch/result/?q=kb
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https://translate.googleusercontent.com/translate_c?depth=1&nv=1&rurl=translate.google.com&sl=auto&tl=en&u=http://goldenears.net/board/26718&usg=ALkJrhh1Ohffy_EylDWrdMR6V5-nDwp5Og
DIY Dummy head of goldenears.net. They used custom dummy head before they purchase the 4128C HATS.
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This is kind of a cool discussion. I am so glad that a lot of you guys are going about and experimenting. One of the reasons I didn't want to reveal my rig is that I had to deal with too many armchair quarterbacks who read more than they did. There are a lot of nuances learned when you start doing measurements.
For the purposes of my V2 rig, I elected not to use an ear. Why do you ask? Because the use of an ear may require compensation. I wanted to get fast results that did not need compensation. Also, think about this: when we measure speakers, we measure with a bare microphone wand. If we measure speakers with an artificial head, we will need to compensate or every element (pinna, canal, head, etc.) to arrive at the equivalent microphone measurement.
What I wanted was a measurement that was equivalent to a standard speaker measurement at the listening position.
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In addition to the flat coupler I used a silicone ear, with the mic placed where the eardrum was supposed to be. As expected measurements showed - among other things - quite an excursion from 2-4kHz. So, compensation would have been inevitable. Like Marv I did not want to bother with this, so I went back to the flat coupler. Whatever method you use, you have to stick to a method to make measurements that are reliable in your own measurement system.
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One good read might be this:
http://www.stereophile.com/content/grado-hp-1-headphones-measurements
The goal was to measure the cans free space for the upper mids and treble since not a lot of acousitc impedance is needed at those frequencies. For these ranges, measurement performance may be similar to speakers. For the lower frequencies, the baffle was used to approximate required driving volume for bass reproduction.
The goal of some rigs which provide added absobtion material in the baffle is to try to get both measurements in one rig instead of having to merge the two separate measurements.
The added benefit of the different baffle approaches is that measurements are much less positionally sensitive. This may be indeed one reason of why speaker measurements themselves don't get measured with an ear simulator either. Another problem is the fact that different shapes of ears affect sound differently, and compensation is therefore not universal. Yet, the baseline for audio reproduction is external to the head: live sound, which is universal. By this I mean that if two different people were seated in the exact same location in a concert at the same time, the audio signal sources will be the same. The equipment is responsible to reproduce the single source of the signal, not model the different receivers of it.
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^ That was the V1 approach which I (and OJ) feel might yield slightly better quality measurements than V2. V2 workflow is faster.
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(http://i.imgur.com/hjJjsTH.jpg)
Here's mine. Using Panasonic WM61a and DIY preamp circuit with shoddy wiring. There's a bigger block of foam that accompanies it. Build for uber-cheapness and versatility (it measures speakers too!). It's still evolving because I'm looking to up the performance of the whole system.
(http://i.imgur.com/WulXuar.jpg)
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So here I am, 2:25am, staring at Purrin's C.U.N.T. and trying to figure out how one might fit a 6" microphone inside it.
Sometimes i question my life choices.
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You need to understand the technology and then you shall get all the insight you need. (:blu winky smiley:)
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Actually, that quip got me thinking --- if we re-purpose the silicone materials of sex toys to create an artificial ear and ear canal lining, the high-grade silicone might actually do a good job of simulating the absorbance and reflectance properties of human skin... p:/
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I don't think I could bring myself to remove what little pleasure OJ has left in this life. :'(
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Silicone? Sounds like my jerry-rigged echo measurement rig.
Not fully suited for headphone measurement, because the pinna is just sculpted, not real, and the silicone has not been treated with "skinner" additive, so is a bit too dense.
I'll post the fancy pic of that half-head for echo thingy later - it also had to shape air through mouth.
(Insert silicone sex joke here :)p12 )
How does it work? You placed it on a speaker, calibrated via REW to flatter frequency response if needed (it boosted lows like a real mouth and face), put a cellphone on a proper stand or mount, put measurement microphone at Reference Point and you got your echoey recording. Generally got -35 dB echo from that, much more than free air.
I'm very slowly making one based on my own actual pinna and ear canals. Partly done - ear canals exist and work, pinnae negatives exist (positives do not yet), cheek simulator does not either.
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Actually, that quip got me thinking --- if we re-purpose the silicone materials of sex toys to create an artificial ear and ear canal lining, the high-grade silicone might actually do a good job of simulating the absorbance and reflectance properties of human skin... p:/
Now I'm imagining putting measurement mics inside a ReallDoll's head and writing it off on your taxes as an expense for your headphone measuring website/business.
After all, it's very important to simulate the acoustic effects of hair, shoulders, and of course breasts, on open headphones...
p;)
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Now I'm imagining putting measurement mics inside a ReallDoll's head and writing it off on your taxes as an expense for your headphone measuring website/business.
After all, it's very important to simulate the acoustic effects of hair, shoulders, and of course breasts, on open headphones...
p;)
Maverick Kronin, the professional measurer of acoustic effects and open headphones.
How would you measure the simulated acoustic effects when filing your taxes?
"This paper file has acoustic properties and effects when hit by sound waves produced by my open headphones. Dear IRS, please explain how this furthers your ability to perform checks and collections? I hereby offer my services to measure the acoustic effects in ..."
Almost like testing what yelling at a screen has for effect while listening to Sepultura through your open headphones. Then recommend headphones and Amp-DACs for therapeutic purposes...
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it's very important to simulate the acoustic effects of hair, shoulders, and of course breasts,
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Oh yes!
And here was I thinking that I wasn't that much inclined to wards science. I guess I just never found my niche.
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http://www.innerfidelity.com/content/innerfidelibits-vibro-labs-veritas-alex-rosson-audeze-resignation-telos-acoustics-sennheiser
Vibro Labs Veritas is on pre-order, and they insists that it is IEC 60318-4 compatible coupler. But it's only 79$, so I'm not sure it is real.
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http://www.innerfidelity.com/content/innerfidelibits-vibro-labs-veritas-alex-rosson-audeze-resignation-telos-acoustics-sennheiser
Vibro Labs Veritas is on pre-order, and they insists that it is IEC 60318-4 compatible coupler. But it's only 79$, so I'm not sure it is real.
I just buy one to see if it worth it. I own Spiral Ears SE5 ref, we will see the result against the measurement from Marvey!
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Hey guys, I had to change the way I was wording things, it wasn't really clear. Vibro Veritas is not IEC 60318-4 compliant, I just used the documentation for the IEC spec when designing this low-cost coupler... and speakerphone, this is the coupler I was emailing you about a few months ago! Hope that clears things up!
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Seriously. Don't waste your money. Use a rubber tube from Home Depot. Buy a panny capsule mic. You'll need to come up with a good compensation curve either way. IEC-XYZ compliance doesn't mean shit. You'll still need to come up with a good compensation curve.
(http://slingshotforum.com/uploads/monthly_11_2010/post-715-0-49905500-1290627711.jpg)
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Hey guys, I had to change the way I was wording things, it wasn't really clear. Vibro Veritas is not IEC 60318-4 compliant, I just used the documentation for the IEC spec when designing this low-cost coupler... and speakerphone, this is the coupler I was emailing you about a few months ago! Hope that clears things up!
omg That was you? I never knew that...
why did you sold your coupler as if it's IEC compliant? You shouldn't have advertised like that.
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Sorry for the flippant attitude, but it helps if you introduce yourself. Especially if you sell something. Really does go a long way here. Unlike Currawong, I don't have ESP or Professor X powahs.