Hello Everyone,
I am curious to learn the dummies-simple- beginners-crash-course concerning sound measurement.
I would like to know the least theoretical and most practical way of getting my feet wet measuring headphones and iems.
Second, is how to interpret measurements and use EQ to compensate for irregular frequency responses.
I know this is a very complex and naive requst but we all have to start somewhere.
What inexpensive hardware and software would I need to get started?
Thanks,
John
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I would start by reading the previous posts in this thread. There are details, links, and discussions that answer most of what you want here already.
Beyond that âŚ
You pretty much have to decide if youâre willing to do a certain amount of DIY to build a measurement rig, or if you want to buy something âready-to-goâ. And buying something really means the miniDSP EARS. Which, unless youâre willing to solder stuff together, is only about $80 more than youâll spend to use a calibrated microphone and the bits youâll need to tinker together to use it measure cans.
A source/amp will also be required to drive the headphones/IEMs being measured. Schiitâs Fulla 2 is one inexpensive option. A better one is the Topping DX3 Pro. Do NOT buy an âAudio Interfaceâ (e.g. Focusrite 2i2) for this, as most of them have relatively high output impedance which will screw up the FR with low-impedance (most) headphones).
Software wise, REW is free (though donations are recommended) is easy to learn, very capable and multi-platform.
The EARS unit comes with an excellent step-by-step guide to getting it working, specifically with REW, and you should be able to make measurements within half an hour of opening the EARS box.
From there itâs practice, research and experience.
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Tyll Heartson (previously) from Inner Fidelity wrote a wonderful a set of articles for an introductory purpose. Definitely a good read.
I also think Keith Howardâs Between the Ears very worthy, too.
https://www.stereophile.com/features/808head/index.html#WYb761pco4zYioG4.99
You may easily find both articles were written with a bit different nuance. Indeed acoustics â particularly headphone acoustics â is far from being âwell studiedâ. This led people to various perspectives and beliefs. I recommend to read as many articles as possible to shape your own view.
That said, one of the most effective ways is actually DOING it. Fortunately in 2019, it is no longer only available via super expensive Audio-precision or GRAS measurement devices (I respect both companies, by the way). Check out this:
https://www.minidsp.com/products/acoustic-measurement/ears-headphone-jig
Finally I should mention REW: https://www.roomeqwizard.com/index.html
Itâs a software originally intended to work on room equalization based on in-room measurements. It is now widely used to measure headphones, speakers, and even more â very noticeable for its FREE availability.
It also has a hyper great web-based help file. It concisely explains relevant concepts assigned to each feature. Nearly a MUST read.
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No apologies necessary.
But have a read, and then come back with appropriate questions.
@VimStory, @pwjazz and @antdroid, @Resolve and I all do measurements here (not deliberately excluding anyone else that may, but those on that list do employ some rigor, consistency and attention to detail in what they do and how they do it, using largely common equipment, if different overall setups.
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And Iâd like to mention that the quote above could be VERY PUZZLING than you might think. Bottom line, it needs to deeply understand at leastâŚ
- What is IRREGULAR ⌠and natually WHAT is REGULAR?
- How do we IDENTIFY it, even if defined well (indeed not)?
- What can be compensated, what can be done more difficultly, and what can NOT be.
Each question remains a good amount of ambiguity and imperfectness â if you can answer well, you can publish a paper. No joke.
So, be patient, donât rush, and honestly ⌠DON"T EXPECT MUCHâŚ
As youâll spend more hours days years in this area, youâd think itâs rather a very specific and customized solution to your individual need, rather than something that is largely agreeable. Unfortunate. But such is the status of this hobby (science-wise).
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As mentioned with @torq in a completely non-relevant thread the other day, I brought the SMSL SU-8 home to measure the differences between the different sound options.
Now, I am not sure what I have done wrong here but all the options give me the exact same measurements. I measured these both on RCA outputs and on XLR outputs, repeated the measurements various times, and apart from the XLRs giving a higher output, there are absolutely no differences in the graphs.
In the image below, it looks like there might be a slight difference in the low readings, and also over 9kHz but that is just because there are so many overlapped lines and it is zoomed out to catch the whole frequency. Zooming in (in REW) there are absolutely no differences.
My signal is REW (Win 7) > SU-8 > UMC204HD > REW
In both cases (XLR and RCA) the cables used have been made by me and use Belden cable with Neutrik connectors.
So⌠any ideas what I am doing wrong or was I imagining the differences (I thought?) I heard between the different sound options??
(top line is all the overlapped sound options on XLR outs and bottom is the same on RCA outs)
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The âSound Colorâ settings are (from what SMSL claim) supposed to change the distortion products rather than the frequency response, so youâll need to measure for that.
If you want to see if your setup is actually capturing the right thing, then measure the frequency response for the different reconstruction filters. There ⌠if switching between the filter settings on an ESS 9038-based DAC doesnât show frequency response differences, then thereâs something wrong with the implementation or the DAC itself.
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This tilted me for a few days. FYI for who trying to measure stuff but is using Linux. The driver could make some funky stuff which creates a bump in a bass region.
Strangly, this doesnât happen when I do my measurement on my Windows Virtual machine
My Windows WM is using ALSA output as Host and Intel HD Graphic as guest
I might have to dual boot Windows just for measurement then -_-. Still, this tilted me.
For more information, this is my measurement with a steel coupler through Apple USB-C to 3.5mm converter combining with a TRRS splitter.
The measurement above are my BL03 left channel
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Another rig out of Denmark from from a company called Loudsoft
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This is very interesting. Do we have a sense of how accurate this is?
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Per that website, this thing seems to be intended for production QC, so I would assume the focus is more on precision than on accuracy relative to a real human ear.
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@Resolve I looked deeper into the doc the Danish team is using a rig from Cry Sound out of China. Originally I found this via the Precision Measurement ( Primasound) website. I am thinking about getting an M1 also to help me with some other work I do.
Ear Simulators and Coupler are here
http://www.crysound.com/en/product/lists/27.html
They work with the CRY801 Testing Jig.
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One thing if you have Qubuz Here is a nice set of test signals
Album is called âAudio Line-Up Test Tones (Calibration Reference Check)â
https://open.qobuz.com/album/dcon58qby5yxc
Try the frequency tests from 10 Hz to 20 kHz at -30dB when do you stop hearing the sweep in 15k to 20k range. Also 10 Hz -30 dB do you headphone reproduce any signal.
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I like this disc in general. Has a similar sweep as well along with some other tones and âtestsâ.
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Audio Tone Test Utility (Soundsystem and Soundbar Calibration)
Here is a second Audio Utility Album with few more tests.
https://open.qobuz.com/album/7630037916338
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Here are set great article on measuring headphones in AudioXpress April 2018 issue
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I love this quote in the article
âFor headphone engineers benchmarking against these flagship headphones, the response above 10 kHz is often measured with the headphone driver removed and mounted on a baffle with a precision wideband microphone in the near field. When testing, all you can do is keep the test setup the same and check the relative extended range response between products. But, what is linear to the earâs perception is anyoneâs guessâalthough there have been a number of white papers recently on what sort of response curve is preferred by headphone listeners.â
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SneakyâŚ