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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TonySunshine

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I actually ordered and use this IEC coupler from AE
https://www.aliexpress.com/item/4000504988211.html?spm=a2g0s.9042311.0.0.79b04c4dmVxd6H

The seller actually sent it via DHL, which is awesome because it took like 3 days to arrive to me in the USA rather than the usual 1.5 months for anything else from AE


This looks good, but wow, it's a bit of a step up vs the TaoBao prices. Does AliExpress include shipping?

Also, I found this link on AliExpress for the barrel style (rather than base/platform style) connector: https://www.aliexpress.com/item/4000544425172.html - does anyone know if it's trustworthy / worth ordering?

What kind of buyer protection does AliExpress have if it's a dud? (I've never bought anything from there before).
 
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post-15499848
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earfonia

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does it come with a mic or just a coupler?
Option 1 comes with calibrated mic. And they will email the calibration file that we can use with app like REW
 
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TLDRonin

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So I have the 711 coupler + dynamic mic and Audio tools app but now I'm stumped on how everything works

What calibration file am I supposed to use? Do I need to ask the taobao seller for it?

I'm also kind of overwhelmed by all the settings in the FFT settings page. I want my measurements to be compareable to crinacles graph base, so I copied the information from his page:
  1. Microphone on "High Range" setting
  2. 32768 FFT points
  3. dB scale: 30dB to 85dB
Is everything else supposed to be as is?

I also downloaded the periodic pink noise he used for his tests but it stops playing in the background as soon as I go into the app
 
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post-15556892
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csglinux

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So I have the 711 coupler + dynamic mic and Audio tools app but now I'm stumped on how everything works

What calibration file am I supposed to use? Do I need to ask the taobao seller for it?

I'm also kind of overwhelmed by all the settings in the FFT settings page. I want my measurements to be compareable to crinacles graph base, so I copied the information from his page:
  1. Microphone on "High Range" setting
  2. 32768 FFT points
  3. dB scale: 30dB to 85dB
Is everything else supposed to be as is?

I also downloaded the periodic pink noise he used for his tests but it stops playing in the background as soon as I go into the app
It's been a while since I used AudioTools. (I ended up buying a $100 throw-away Windows 10 tablet. Super slow, but it works, it's just as portable as my iPad and it runs REW :wink:) Having said that, when I used AudioTools, it gave very good results, but I found the mic calibration settings temperamental. If I remember correctly, I had to force this to be flat/off (there are some preset mic calibrations that assume you'll be using the onboard mic, which obviously you won't be). I wouldn't worry about the calibration file from the tobao seller - most of these 711 couplers are close enough even without applying those corrections. I'll try and dig out my old iPad out tonight and run through the steps again to remind myself. I've never used my iPad as both an input soundcard and source driver simultaneously. But I believe that's what @crinacle is doing and I think @yuriv has also done the same. (Maybe he can comment? @yuriv - you still alive and covid-19 free?!?) To make that work, I believe you'll need an appropriate splitter cable for the 3.5 mm I/O and you might also need to use a particular app that's happy to play the periodic pink noise track in the background, while running AudioTools FFT in the foreground. As a backup plan - can you try playing the pink noise from something else? Do you have spare DAP? (Just try to find something with a low output impedance, otherwise this can mess up the FR of certain headphones.)
 
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csglinux

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Here's a walk-through of a little demo measurement I just took of the Final Audio A8000 IEM using iOS AudioTools... I first went into the app's settings menu, went to microphone setup and hit "Clear WAV" in the bottom right. (Do this before you plug in your external coupler mic!) I then went into the Acoustics->FFT sub-tool. You can use an FFT of 16384 or 32768 points (I really can't see any differences between the two). I used a full range FFT, flat plot, flat SPL, no peak track. I set some periodic pink noise playing into the IEM using an external DAP (because I don't own a 3.5 mm TRRS splitter). At the bottom right I had the FFT tool in "Average" mode. I waited a few seconds for the average to stabilize and then I exported the plot data to Dropbox. It comes out as 2-column ASCII data so that with the header and footer stripped off you can directly import it into REW or your favorite graphing tool. It agrees quite well with REW and a GRAS RA0045 coupler without the use of any mic calibration files for the Taobao coupler/mic:
audiotools.png


Here's the problem that I always have with AudioTools. If you go back to AudioTools (and/or start it) but forget to "Clear WAV" with the external mic unplugged first, it goes into some weird filtering mode where it gives results like this:
badday.png


I have no idea why it does this. I think it must be a bug, but it's been this way for years. So be sure to do the "Clear WAV" step first, because you won't always know whether the headphone you're measuring is capable of producing sub-bass or not :wink:
 
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post-15793068
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staticV3

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The Sounds Good Store on AliExpress seems to have the same product listed four different times, each with a different price. They all consist of an IEC711 ear simulator + dynamic/electret mic + 3.5mm adapter. Could someone tell me the difference between them?
https://www.aliexpress.com/item/4000224519631.html - looks like it comes with two extra adapters. Is that the only difference?
https://www.aliexpress.com/item/4000789796521.html - no extra adapters. Cheapest option
https://www.aliexpress.com/item/4000504988211.html - no extra adapters. The pics don't show it but the description says it comes with a 3.5mm cable
https://www.aliexpress.com/item/4000030253753.html (type 2) - the 1st pic shows a 3.5mm cable, but the description doesn't say anything about that

Links two and four mention an individual correction curve. Do links 1 and 3 not come with one?
 
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assassin10000

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Thanks for this post. Lots of information that helped me put together a budget measurement setup.

______________________


A windows laptop and this is what I'm currently using. The laptop soundcard had poor results, rolled off below 150-200hz and above 8khz. Fortunately I had a USB-C DAC I could use.

(USB C adapter -> TC35B -> IMM-6 -> DIY coupler)
IMG_20200818_150456.jpg

The DIY coupler is 2 layers of vinyl tubing (5/16" & 1/2" I.D.) and a short piece of latex tubing (1/4" I.D.). About $5 at the hardware store for a couple 1ft lengths of tubing to play with. A few iterations later and I got the length to where the resonant peak is about 8k.



I'm still figuring things out but I have ordered some large foam tips to try on future measurements. The medium foam tips I had on hand don't quite make the cut, as can be seen here:
Sony MH750 Foam vs Silicone.jpg


I may step up to a 711 clone one day, that won't have the sub-bass roll off the IMM-6 does.
 
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