Measuring HRTF for headphone use

[solderdude]

Just to be clear, what I posted (and compared to your measurements) is with no DSP or EQ of any kind. There was no room curve, I just placed the Harman line on the same chart to illustrate that the in-ear response of HD650 closely resembles the recommended Harman room curve of -10dB.

Yes I got that part.. What I mean is that I lowered the response below 200Hz a few dB in my measurement on purpose (as to mimic how I perceive it) .
You measured it 'RAW' and justified it by drawing in an 'in room preference curve' which basically is the exact same thing.


Most 'loopbacks' are done using the line input or input set to line levels.
In mic position the frequency response might not be flat any more.
Could also be that the mic is not optimized for the mic input.
I don't know... just summing up possibilities that may be relevant, or may not be.
In any case I know this isn't the case with my dedicated pre-amp with 100% certainty.

 

[pkane]

My point of view here is the following. Basing 'exact' EQ on measurements is flawed simply because of variances in measurement rigs.The HD650 is the most measured headphone in the world and 'exact' compensations aren't recommended when you look at the analysis above.
And remember most are from calibrated and compensated expensive HATS with prof equipment.

What I do see however is a clear correlation between all measurements. In my opinion one should thus not compensate 'exactly' acc. to measurements (as one compensates to the flaws of the rig which are compensated rather than the actual response) BUT must look at the great picture and apply some 'gentle' and average EQ in the area's which need improvement.
Remember, when actively 'compensating' narrow peaks and dips we also get ringing in the audible band.

That's the conclusion I've come to, as well. Compensating FR based on someone else's measurements is not going to work well. The measurement rigs differ, as does compensation applied, as do the measurement devices. For this reason, I wanted to do my own measurements, and the in-ear mics seem to be a better approach than some artificially constructed ear.

 

[Shikamon]

That's the conclusion I've come to, as well. Compensating FR based on someone else's measurements is not going to work well. The measurement rigs differ, as does compensation applied, as do the measurement devices. For this reason, I wanted to do my own measurements, and the in-ear mics seem to be a better approach than some artificially constructed ear.

Which is one of the reasons why I like doing Greisinger's way of finding a decent compensation curve using noise bands. Though just like @solderdude mentioned earlier, hearing loss, speaker sound quality, and even the room you do it in add too many variables that can cause some error if done incorrectly. Jeez... I get into the most challenging hobbies ever....

 

[pkane]

Which is one of the reasons why I like doing Greisinger's way of finding a decent compensation curve using noise bands. Though just like @solderdude mentioned earlier, hearing loss, speaker sound quality, and even the room you do it in add too many variables that can cause some error if done incorrectly. Jeez... I get into the most challenging hobbies ever....

If you think audio is hard, you should try my other hobby: astrophotography

 

[Shikamon]

If you think audio is hard, you should try my other hobby: astrophotography

Yeah. I went through 4 years of engineering school. This is pretty much like my engineering homework but I actually enjoy it this time. lol

 

[solderdude]

You could check the mic amp part using a loopback.
In that case you would have to apply 40dB attenuation (or about that level) by using a resistor divider.
40dB = 100x so using a 10 Ohm resistor in parallel to the mic input of the Behringer (as close as possible to the input plug) and put a 1k resistor between the output of the DAC and hot part of the input (on the 10 Ohm resistor)
This will attenuate about 40dB (almost 40.1dB) and you can check for linearity.

As my mic pre-amp (gain = 35dB) is line level I never had to do this, just looping the line part was enough for me.

 

[pkane]

Here's a comparison between the in-ear and out-of-the ear measurements with HD650. Same amp, different mics, no EQ, green is the out of the ear measurement:

For outside the ear I used a jig I made using a half of a plastic bottle, filled with foam to hold the mic in a fixed position relative to the headphone can.

 

[andreasmaaan]

Here's a comparison between the in-ear and out-of-the ear measurements with HD650. Same amp, different mics, no EQ, green is the out of the ear measurement:

For outside the ear I used a jig I made using a half of a plastic bottle, filled with foam to hold the mic in a fixed position relative to the headphone can.

Nice, do you have a pic of the jig? Curious to see exactly how you did it.

 

[pkane]

Nice, do you have a pic of the jig? Curious to see exactly how you did it.

Sure: https://www.audiosciencereview.com/...headphone-software-correction.3453/post-85252

Not a high-tech solution, but also didn't cost me anything to make since I already had all the parts.

 

[Shikamon]

Hmm interesting.... What do you prefer as the better accuracy in measurement @pkane? :0

 

[pkane]

Hmm interesting.... What do you prefer as the better accuracy in measurement @pkane? :0

The in-ear mics, as that is a better representation of what I'll hear when playing music through the headphones.

 

[Shikamon]

The in-ear mics, as that is a better representation of what I'll hear when playing music through the headphones.

I see. What type of in ear mics do you have to do these measurements? I'm might try them myself someday.

 

[pkane]

I see. What type of in ear mics do you have to do these measurements? I'm might try them myself someday.

We've come full circle Here's my first post with the details:

https://www.audiosciencereview.com/...suring-hrtf-for-headphone-use.3962/post-93816

 

[Shikamon]

Awesome! I'll probably order them in a couple of weeks. Wished I seen these sooner. xD

 

[RayDunzl]

he in-ear mics, as that is a better representation of what I'll hear when playing music through the headphones.

I plead ignorance in this area.

What do in-ear measurement microphones look like?

 

[Blumlein 88]

I plead ignorance in this area.

What do in-ear measurement microphones look like?

Here is one version.

https://www.amazon.com/LOW-NOISE-EAR-BINAURAL-MICS/dp/B002N6PAMM

 

[RayDunzl]

Here is one version.

Oh. Not so "in ear" as I might have imagined.

https://www.soundprofessionals.com/cgi-bin/gold/item/MS-TFB-2

 

[Blumlein 88]

If you need some new ears, there is this:

https://www.amazon.com/MS-BINAURAL-...words=sound+professionals+binaural+microphone

 

[RayDunzl]

If you need some new ears

I do, but not the outside part.

 

[solderdude]

These mics may still be useful when you want to do modifications to a headphones and like to see the differences.

From what I can see they aren't accurate for checking headphones, as in being a true reference and accurately showing FR of a headphone.
The differences are too big compared to other measurements.

Will bet you can make quite decent binaural recordings with it, that's what they are designed for.

I have experimented with the same mics I use in my test rig (not the same mics shown above) but could not get decent results.
Below a picca with that small mic inserted in my ear flush with the ear canal entrance.