If I just used Oratory's Anniversary Edition EQ then he boosts that quite dip at 3kHz, therefore that would be super magnified on the K702 that doesn't have that dip - that's extremely noticeable, I remember playing around with different dB's that controlled that spot in his EQ and 1 dB change was noticeable....so yes, definitely couldn't have used his Anniversary Edition EQ without modifying it.
Looks like a bit of a dip at 3.5k on the 702 to me.K702:
HD600:
HP50:
K702:
HD600:
HP50:
All these curves look really quite different to the ones I'm used to seeing on Oratory's pdf e.g. HD600 (https://www.dropbox.com/s/dm0m6u3s3b4zqzl/Sennheiser HD600.pdf?dl=0 ) and also Innerfidelity K702 (https://github.com/jaakkopasanen/AutoEq/tree/master/results/innerfidelity/innerfidelity_harman_over-ear_2018/AKG K702 )? I'm thinking part of that is down to the fact that you're using different scales, and also your measurement gear doesn't have have an artificial ear? Personally I find the scale of the Oratory graphs and Innerfidelity ones I linked more easy & useful to read (but I have used them since Day 1).Part of the dip will be filled in by Pinna gain.
https://www.rtings.com/headphones/reviews/akg/k702
View attachment 73873
This would leave one to believe that there is no dip at all at 3kHz but instead there is a +5dB peak at 2.5kHz where as I measure the peak at +3dB
This peak is what makes the K701/K702 sound 'forward'.
Its the 7kHz peak that needs to be addressed. A small dip isn't as bad as a peak in equal dB's.
Also the sub-bass (below 60Hz) needs a small boost. About +6dB at 20Hz (this including some bass boost somewhat similar to O-W)
Personally, I would'nt trust both. The only technique I would rely on is an insitu measurement.
Part of the dip will be filled in by Pinna gain.
https://www.rtings.com/headphones/reviews/akg/k702
View attachment 73873
This would leave one to believe that there is no dip at all at 3kHz but instead there is a +5dB peak at 2.5kHz where as I measure the peak at +3dB
This peak is what makes the K701/K702 sound 'forward'.
Its the 7kHz peak that needs to be addressed. A small dip isn't as bad as a peak in equal dB's.
Also the sub-bass (below 60Hz) needs a small boost. About +6dB at 20Hz (this including some bass boost somewhat similar to O-W)
Thanks for the detailed & thought out response, I appreciate it. That's a lot to take in, and I think I got the majority of it, but I'll need to look at it again with fresh eyes, digest it a bit, then I might ask you some questions.Diffuse field is incorrect compensation for headphones. This is why O-W started developing their own compensation curve and added the bass enhancement. That extra bass is needed for several reasons. Not everyone, however, needs the same amount of extra bass. This is for several reasons such as age, gender, people listening at lower SPL (here is where equal loudness contours comes in) and preference or people have gotten used to an incorrect reference (speakers with a substantial room-induced) bass boost. O-W compensation lows compensation is based on this.
Pinna effects with DF correction are incorrect for headphones. Also corrections for speakers from in front of you are incorrect.
Also measuring at ones own eardrum is incorrect.
What one needs to know is what the actual driver produces. Not what a 'standard' Pinna and earcanal CHANGE and then subsequently use an incorrect 'correction' based on measurements that differ substantially from an actual headphone situation and then claim it should be done this or that way because a 'standard' tells them to.
A standard is fine if one want to peer review and come to a similar 'result' when measuring acc. to a standard.
But what if the standard is 'off' because the used standard has is not obtained using a standard 'headphone' but based on multiple speakers with certain angles and distances that do not resemble anything like a headphone situation ?
If that were the correct method all headphones measured and EQ'ed would sound exactly the same and I guess we all know they don't.
Yeah, I know the HRTF is blamed because all Pinnae differ. Here is the thing though. When we hear a music (live or otherwise) we never hear it from the side of us. We always here it from in front of us and that's where the Pinna (HRTF in total actually) makes the most difference.
The FR is modified differently when coming from the sides.
Sound from the side is going directly into the ear canal, partially blocked by the Tragus. Look at ears from the side and some Tragus are totally blocking the ear canal and some only partially. This is driver size and diameter dependent as well.
This is where our friend Griesinger comes along and hands us a method where that actually is taken into account. Measurements won't.
With measurements you can (at least the way I measure) actually measure what comes from the driver.
One can argue what kind of 'correction' that needs. Measuring a driver through a bunch of narrow bandfilters (acc to a standard) and 'correcting' them partially with other 'standards' that have no relevance to mimic a headphone isn't exactly the way to go about it. When you want to know what the driver does, measure it's output at the same distance as an ear canal and use the same kind of damping around the microphone as the skin dies.
You are aware that Tyll, from day one because he got incorrect advise, had a completely wrong 'correction' in place. Headroom later made better 'corrections' available. The raw measurements can be used IF you know exactly how these should be compensated. His HATS requires different compensation from what O-W uses so you need to get an exact (and correct for headphones) compensation, which AFAIK, has never been made.
A year before he retired he played with his HATS at Harman to find out what compensation he actually needed.
However, he really didn't want to revisit all of his measurements and as so many 'old (and incorrect) ínfo was already out there he couldn't come up with very different, but correct, FR plots.
You can still use IF plots as comparisons between his measured headphones where you can compare to known (to the listener) headphones.
I believe Jaako uses Tyll's raw plots and applies a different correction. But as I already mentioned, a HATS is not really suited to measure headphones. They are fine for other applications for which the actual 'compensations' are designed.
About scales of plots:
I know there are standards for plots. However, these have too small dB scales which make them seem 'flatter' than they sound to me.
So, again against conventions and standards, made my own 'standard'. Just because I measure headphones for myself and to get correct EQ not so one can overlay with 'standards'.
I mean the bottom plot seems to be a lot 'better' than the one above it, doesn't it ?
But if I wanted to EQ to it the upper one tells me more about how it actually sounds and what compensation is needed. This, to me, is far more important than meeting a standard (which I don't consider a real standard)
For electronics and speakers things are different. Certainly for electronics the standards are holy for numerous reasons. Measuring headphones is still in its infancy so I feel it is only fair to make my own 'thing' which is no standard by lack of a real standard.
I mean, overlay ALL measurements of the same headphone made by different folks... they all differ and sometimes well over 10dB.
There is no REAL standard, there are some folks that bombarded something to a (their) standard. Its not the same as an actual standard.
Full agreement!
I think it comes down to whether we measured the response at our ear drum or using a mic in middle of air. Another thing regarding flat response might be because we are adapted to our ear shapes, we would found that flat response at our ear drum is not flat from our experience. I am also curious how much the pycho effect can affect us, and if we listen to the real flat response for a long time we might adapt to our new experience.
There's definitely some good points and logic in there, and some insightful explanations including some of the shortcomings of an averaged HRTF. I'm yet to be convinced on Equal Loudness EQ, but don't try to convince me, it's something I might look into more myself. It's a pity that headphone listening is so much more complicated than speaker listening I suppose ultimately by virtue and at the most basic level that it is a more unnatural setup with the sounds being strapped directly to your ears just centimetres away! These Sennheiser HD600 that arrived with me yesterday are great at stock, I might try chilling with the EQ and enjoy them at stock for a while before revisiting EQ'ing them. But I am a proponent for EQ'ing headphones, my EQ experience with AKG K702 and NAD HP50 has been very positive based around Harman Curve EQ, but the HD600 sounds so good to me stock that EQ'ing it seems like it's gonna be a bit more tricky so as not to remove some of it's finer qualities.Yes, Flatplate also isn't perfect for several reasons as well.
But if you want to EQ above 5kHz (where most of the nasties are) it is the better method.
Anything below 1kHz is similar to HATS. The method is questionable between 1khz and 5kHz where Pinna gain (frequency alterations)is happening.
But look at the pictures on the bottom of this post. These will differ from person to person.
Admittedly 'a standard' is prefferred in this frequency range but not above 5kHz, yet many people rely on EQ made with an expensive GRAS rig assuming (are convinced) it is accurate because it is 'a standard' and very expensive.
You would have to use a pretty good in-ear that is flush with the ear entrance which rules out a lot of commercial in ears which stick out a bit.
I also experimented with this (of course), this is my attempt (my ear with a WM6A capsule in it.
As can be seen (photo taken at an angle from the front) is that my Tragus is not (partially) covering the mic.
I found that the results did not correlate at all with what I heard, I picked up some more hum, it was very difficult to get the insert angle correct as well.
It probably is a decent way to map some of the HRTF but that's about it.
measuring the eardrum itself is nigh on impossible because when you stick something in your ear it will change the ear canal diameter and requires very expensive equipment and access to perfectly flat speakers in various positions around you in anechoic conditions to map out the HRTF in a spherical plane. This takes a lot of time.
Simply photographing the Pinna probably isn't enough to do it properly.
For this reason alone Griesinger's method to ascertain the HRTF is quite do-able. It EQ's the headphone itself as well as your HRTF and possible hearing losses in one go.
Of course, Rob is correct that when you use it to EQ only (which you cannot separate) it will be level dependent so you would have to do this with noise bands around 80dB SPL or so (measured around 1kHz band).
It also requires quite a lot of experience. It looks simple how he does this on the video but it isn't when you do this without experience/knowledge.
Of course Griesinger himself has a LOT of experience and knowledge, he is not some rando acting as a know-it-all.
As said, measuring headphones properly is in its infancy despite O-W giving it a proper effort as well as Rtings. Tyll may have started it all.
Too bad he got poor advise from the guys who installed it back then.
some random ear shapes:
What can be seen is a substantial variance of ear shapes and thus HRTF taken from the side only. Taken from the front they will also differ.
This means there can never be a 'match' with an artificial Pinna and ear canal (these also differ in length, diameter and shape) and a 'standard'.
Regardless of how much money it costs.
This of course is just my take on this. I am not a professional in this field, Analog electronics is.
Yeah, defintely, a flat frequency response at the ear drum, as in a graph showing dB SPL on the y-axis and frequency on the x-axis....if that were to be a straight line across that whole graph from 20Hz to 20kHz, then that would sound totally shrill and awful to you....so that graph is/should not be flat when measured at the ear drum.....that's due to HRTF effects of your head/body/ear/ear canal as well as the actual perceptual sensitivity of the eardrum itself that influence the strength of the frequencies that arrive at the eardrum and also how the eardrum perceives those frequencies.
