Harman curve without ear canal? HD650, DT150_100P, DT770 Pro 250 Ohm, Bose QC25 measured

[Thomas_A]

If you're uncertain whether the acoustics of your room or speakers are up to this, then you could also try what Harman did in their reference room. And EQ the speakers to a flat in-room response at the listening position using a standard omni-directional mic. Then do some measurements at the same listening position with your in-ear or in-pinna mics. That will give you just the tonal response for each individual's pinnae, minus most of the room-related effects.

Combine the above pinnae responses with the in-room response curve of your choice using something like the stack feature in EAPO's Config Editor, and you should have a reasonably good reference curve for the in-pinnae response of your headphones.

If you want to save a couple steps, then you could simply try to EQ your speakers to match your preferred in-room response curve (rather than a flat response) at the listening position using the omni mic. And then just re-measure their response at the same position with your in-pinna mic, to get your in-pinna target for the headphones. Separating the pinna's response from the room effects, as in the first example, might make it a bit easier to experiment with some different kinds of in-room response curves though.

There is a wealth of in-room data from which to derive a reference in-room response curve in the spinorama data here btw...

A collection of loudspeakers measurements

Or you could just use a simple slope that's somewhere in the -1 dB per octave range for this. And then adjust the tilt a bit until it sounds right in your EQ tests.

I don't know yet how the experiments will be conducted in detail; so far I have only measured the LP response with Audyssey set on subwoofers (<100 Hz) using my OM1 microphone. I will need to re-measure using the ear-mics with and without body-head using 0 and 90° angles of the microphones.

 

[ADU]

There is a wealth of in-room data from which to derive a reference in-room response curve in the spinorama data here btw...

A collection of loudspeakers measurements

The in-room data shown in the above link (and in spinorama speaker graphs in general) is estimated from anechoic measurements, btw, rather than made from actual in situ measurements. But I'm sure you probably already knew that (especially if you've read Floyd Toole's book on Sound Reproduction, or watched his YouTube vids on this subject).

 

[DanielT]

Why exclude the ear canal where it obviously is part of differences between individuals.

Then closed headphones should make more difference in perceived quality of the music compared to open headphones. If you see it as if the ear and ear canal are a speaker. And speakers, we all know that the cavity and the design of them greatly affect the sound of the speaker element that is plop in to them. This should be reduced with open headphones, difference in sound between different people and headphones that is.
The same headphone can differ 10 dB in FR between two different people, if I remember correctly.

Now that is not a problem in itself. It's just to EQ to taste but still.

 

[solderdude]

open vs semi-open and closed vs semi-closed makes a difference. One can play with pad permeability as a tool as well.

It is easier to get more bass extension with closed headphones but is usually 'bumpier' in bass to mids response.
It is easier to get 'less bumpier' response below 1kHz with open headphones but often at the cost of bass extension
This has to do with how the rear 'energy' is handled in those headphones. In open designs it is easier to use that more targeted/wisely.
In closed designs you are 'stuck' with it and have to do something with it, often resulting in wonkier bass/mids.
For the bass extension a very good seal is often very important, more so than with most open models (big driver orthos also have different challenges from front vented designs in baffle design).

There are only so many tricks one can use and most of these tricks have benefits and downsides (also making changes you did not want).
@Dan Clark just added a new tool to the toolbox with the stealth. Not every manufacturer is equally inventive and most manufacturers just need to make something as cheap as possible and sell lots of them.

This is often why some TOTL models are quite expensive. Someone has to pay for the many hours of work going into this.

 

[DanielT]

open vs semi-open and closed vs semi-closed makes a difference. One can play with pad permeability as a tool as well.

It is easier to get more bass extension with closed headphones but is usually 'bumpier' in bass to mids response.
It is easier to get 'less bumpier' response below 1kHz with open headphones but often at the cost of bass extension
This has to do with how the rear 'energy' is handled in those headphones. In open designs it is easier to use that more targeted/wisely.
In closed designs you are 'stuck' with it and have to do something with it, often resulting in wonkier bass/mids.
For the bass extension a very good seal is often very important, more so than with most open models (big driver orthos also have different challenges from front vented designs in baffle design).

There are only so many tricks one can use and most of these tricks have benefits and downsides (also making changes you did not want).
@Dan Clark just added a new tool to the toolbox with the stealth. Not every manufacturer is equally inventive and most manufacturers just need to make something as cheap as possible and sell lots of them.

This is often why some TOTL models are quite expensive. Someone has to pay for the many hours of work going into this.

Sounds quite reasonable what you say about bass considering the design principle of headphones.

Here's a DIY that builds AMT headphones. There are some pictures in the thread so you can look at them. He ordered this for his project:

faktiskt.io • Visa tråd - Solhaga tar sig åt huvudet

It was ambitious that he built these for his project:

3d binaural microphone by GilbertPot

I have been experimenting with binaural microphones so my first effort was to make a binaural dummyhead of a 3d scan of my own head..It's heavily decimated to make it more 'generic'. Still working on this one..It's also quite large to print so i had to split the model in 4 pieces... I have also...

www.thingiverse.com

I enclose the pictures from that thread.

Edit:
Or wait now "ears" were included in the pact, in the video what I understand. Why then 3 d print your own? If hm mr DIY might designed according to the shape of his own ears? That's way too advanced DIY for me, but the video was interesting.

 

[Thomas_A]

So I made some initial experiments with the OKM2 in-ear microphones (studio version). These seem to be a bit elevated in the treble compared to my reference OM1 microphones (+/- 1 dB, 20-20000 Hz), and I have yet to check the 10-100 Hz region as well.

A simple measurement of my DT150 with the DT100 velour pads on my head (large ears...), L and R (non-calibrated):

And the the BOSE QC25:

 

[MayaTlab]

So I made some initial experiments with the OKM2 in-ear microphones (studio version).

It's these, isn't it ?

Soundman OKM II Classic/Studio Solo

Selected Pair Omnidirectional electret microphones, Enables spatial recordings in live, voice recording, and video recording appliances, Operatable with line inputs, To be used like ear plugs when recording (artificial head stereophony)

www.thomann.de

How far are they inserted in the concha / ear canal ? I'm having a little difficulty figuring out how they sit in someone's ears given their design.

Have you had the opportunity to measure the HD650 on your head during the same session ?

 

[Thomas_A]

It's these, isn't it ?

Soundman OKM II Classic/Studio Solo

Selected Pair Omnidirectional electret microphones, Enables spatial recordings in live, voice recording, and video recording appliances, Operatable with line inputs, To be used like ear plugs when recording (artificial head stereophony)

www.thomann.de

How far are they inserted in the concha / ear canal ? I'm having a little difficulty figuring out how they sit in someone's ears given their design.

These variants do not sit far in, more of filling up the "concha". These were what I had, but I am looking for some other mics as well. At least it appears quite repetitive.

 

[Thomas_A]

It's these, isn't it ?

Soundman OKM II Classic/Studio Solo

Selected Pair Omnidirectional electret microphones, Enables spatial recordings in live, voice recording, and video recording appliances, Operatable with line inputs, To be used like ear plugs when recording (artificial head stereophony)

www.thomann.de

How far are they inserted in the concha / ear canal ? I'm having a little difficulty figuring out how they sit in someone's ears given their design.

Have you had the opportunity to measure the HD650 on your head during the same session ?

The HD650 will be measured as well along with three heads including my own. Just not today.

 

[ADU]

Very nice! Thanks for sharing these, Thomas_A.

 

[Thomas_A]

While waiting for the test folks and more HPs in the weekend to measure I made a loudspeaker measurement in-room with OKM ear mics, LP, both speakers running sweep. There are some wobbles, ear-dependent, above 5-6 kHz.

 

[Thomas_A]

I used my room response (speakers) and OKM microphones to make a very approximate "calibration", dotted points below. (It is both speakers - both ears average, not left as indicated in figure).

Using that as reference I get the following curves for DT150/100P and QC25:

In the weekend I will add the HD650 and DT770 Pro using 5 individuals.

 

[ADU]

So you are using the same in-concha mics to measure both the speakers and headphones on your own head?

 

[Thomas_A]

So you are using the same in-concha mics to measure both the speakers and headphones on your own head?

Yes.

 

[ADU]

Yes.

This looks very good, Thomas.

Were the speakers EQ-ed at all before the in-concha measurements? Or were those done with them essentially "as is".

 

[Thomas_A]

This looks very good, Thomas.

Were the speakers EQ-ed at all before the in-concha measurements? Or were those done with them essentially "as is".

The speakers were "as is". Since they are my own DIY I have measured them quite a lot. Basically within +/- 2 dB anechoic; room adds variations as we all know. Largest difference with the in-ears vs. normal mic measurements at LP is the sharp drop at 4-6 kHz, and loss of energy below 50 Hz.

 

[ADU]

The speakers were "as is". Since they are my own DIY I have measured them quite a lot. Basically within +/- 2 dB anechoic; room adds variations as we all know. Largest difference with the in-ears vs. normal mic measurements at LP is the sharp drop at 4-6 kHz.

So then you have designed them to a flat anechoic response? How would you determine something like that from in-room measurements with a standard omni mic?

To get some smoother headphone targets from the speakers, you might consider taking several different in-concha measurements, maybe with your head in slightly different orientations to the speakers each time (e.g. titled/angled +/-5 degrees in each axis, XYZ). And then computing an average response curve for each ear from those different samples.

 

[Thomas_A]

So then you have designed them to a flat anechoic response? How would you determine something like that from in-room measurements with a standard omni mic?

To get a smoother target from the speakers, you might consider taking several different measurements, maybe with your head in slightly different orientations to the speakers each (e.g. titled or angled ~5 degrees in all three axes, XYZ). And then computing averages for each ear from that.

I have done both gated measurements and near-field measurements and my speakers are quite flat on axis (and wide dispersion) . I could do more extensive tests with the in-ears, but I think that the relative differences between headphones and individuals will be the main interest. I am however quite surprised that the measurements are not too far from what I have seen published(e.g. the QC25/QC35).

 

[ADU]

I have done both gated measurements and near-field measurements and my speakers are quite flat on axis (and wide dispersion) . I could do more extensive tests with the in-ears, but I think that the relative differences between headphones and individuals will be the main interest.

Understood. Doing multiple samples for each ear, like I described above, and then computing an average curve from those might help to improve the precision of your target though, I think.

If you're not sure how to compute an average from multiple curves, I can explain a couple fairly simple workarounds I use for this in EAPO.

I am however quite surprised that the measurements are not that too far from what I have seen published(e.g. the QC25/QC35).

Yes! Your compensated graphs do look similar to compensated graphs of the same headphones made by other sites... which is a good thing. These are some compensated plots of the Bose QC25 by Rtings and Ora for comparison...

Headphones v1.5 - Graph Tool

www.rtings.com

The Rtings graph was compensated with their proprietary target response curve. And Ora's plot is compensated with the 2018 Harman over-ear target.

And you should expect to see some differences between them and your curves in the higher frequencies.

 

[Thomas_A]

Understood. Doing multiple samples for each ear, like I described above, and then computing an average curve from those might help to improve the accuracy of your target though, I think.

If you're not sure how to compute an average from multiple curves, I can explain a couple fairly simple work-arounds I use for this in EAPO.



Yes! Your compensated graphs do look similar to compensated graphs of the same headphones made by other sites... which is a good thing. These are some compensated plots of the Bose QC25 by Rtings and Ora for comparison...

Headphones v1.5 - Graph Tool

www.rtings.com

View attachment 201502

The Rtings graph was compensated with their proprietary target response curve. And Ora's plot is compensated with the 2018 Harman over-ear target.

Thanks,

yes I'll guess I'll look at the curve again when I've measured the HD650 and the DT770 Pro. Based on the many measurements made on these I could better estimate how off my humble target curve is. Right now it based only on my speakers, my room and my body&ears. I also guess that most individual variations will be seen above 4-5 kHz, where peaks and dips will vary.