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Theory: If I EQ headphones to Harman AE/OE curve, what other attributes should I look for?

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#1
Hi! Wanted to pose a little thought experiment:

Assume I can theoretically get a frequency response curve for a pair of headphones that matches the Harman 2018 target AE/OE curve (published at http://www.aes.org/e-lib/browse.cfm?elib=19436, and available at various places like RTINGS ratings and Oratory1990's EQs over on reddit). What other factors should I look at in a pair of headphones presuming I can EQ them to an ideal FR? For example, isolation would be one of the obvious ones.
 

JJB70

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#2
Try your own EQ adjustments, the Harman curve is just a reflection of the preferences of test subjects, it does not mean that it will be your ideal.
 

DonH56

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#3
I find the Harman curve a bit bass-heavy for me. I also do not think it applies directly to headphones so I'd be leery of using it blindly. As @JJB70 said, you can EQ to taste. I'd look for a set having flat frequency response (a known starting point to add seasoning always helps), comfortable to wear, and is fairly easy to drive unless I had a "strong" headphone amp. Isolation if needed; I have open- and closed-back headphones and prefer the open but if sitting in the family room while my wife is watching TV or whatever will use the closed. I also use the closed for monitoring during (amateur) mixing and mastering; for recording live it depends on how much of the live sound I want to hear.

FWIWFM - Don
 

flipflop

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#4
Rtings already covered most of them.

From the top of my head:
  • Impedance
  • Sensitivity
  • Distortion
  • Seal (and other causes for frequency response inconsistencies, such as headphone positioning)
  • Comfort
  • Isolation
  • Leakage
  • Detachable cable
  • Replaceable parts (especially pads)
  • Build quality
  • Quality control (driver matching, unit-to-unit consistency, failure rates, etc.)
  • Price
 

Fluffy

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#5
JJB70 is right. Herman (or any other target response) won't promise you the best sound. It's over all preferred, but you need to take your own preferences and listening habits into account as well.

Apart from frequency response, I believe low total harmonic distortion is an important attribute. Headphones that display a good frequency response and bad THD will not sound good and there is no way to correct this. On the other hand, headphones with good THD and less than ideal FR can be corrected to an extent.

And that’s the next point – the amount of EQ correction you can apply to a headphone is limited by its distortion. Bringing up missing frequencies will bring up the distortion as well. It's better to start with a headphone that has the RF you want than to take one that doesn't and force it to comply with aggressive EQ.

The next most important thing as far as I'm concerned is comfort. The best sound in the world can't make up for a headphone that is uncomfortable or even painful to put on.

You also should check that any amplifier you use is adequate in terms of impedance and sensitivity. As a general rule, impedance of the headphones should be at least 10X of the output impedance of the amp, and insensitive headphones will require more power to play loud.
 

DonH56

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#6
JJB70 is right. Herman (or any other target response) won't promise you the best sound. It's over all preferred, but you need to take your own preferences and listening habits into account as well. <elided>
Harman, unless you meant this guy:

1570560021871.png
 
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#8
the biggest factors for headphone preference other than frequency response imo is quality control and comfort. i would recommend the HD599.
 
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#9
Try your own EQ adjustments, the Harman curve is just a reflection of the preferences of test subjects, it does not mean that it will be your ideal.
Yes. I definitely have. I have an HD650, Sony MDR 7506, and Beyerdynamics DT 990 Pro EQ'd to their curve with EQ APO and I actually really like the target response curve!

That's why I mentioned in my OP that for the sake of this discussion, I wanted to presume that the curve is satisfactory and to focus on everything outside of frequency response that can influence the appeal and sound of a pair of headphones. For curiosity's sake as well as for further exploration.
 
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#11
I find the Harman curve a bit bass-heavy for me. I also do not think it applies directly to headphones so I'd be leery of using it blindly. As @JJB70 said, you can EQ to taste. I'd look for a set having flat frequency response (a known starting point to add seasoning always helps), comfortable to wear, and is fairly easy to drive unless I had a "strong" headphone amp. Isolation if needed; I have open- and closed-back headphones and prefer the open but if sitting in the family room while my wife is watching TV or whatever will use the closed. I also use the closed for monitoring during (amateur) mixing and mastering; for recording live it depends on how much of the live sound I want to hear.

FWIWFM - Don
Yeah, I do think it's a little bass heavy. I've pondered a bit about whether there is a difference between a FR that sounds the best for a short duration (say 1-3 songs) vs a FR that sounds good hours of listening. In other words, the "fatiguing" quality that is often associated with certain headphones. I don't think I've seen an AES paper yet that addresses the concept of listening fatigue and preferences.

Regarding the target curve for headphones vs loudspeakers, their recent studies have focused on establishing a different target preference curve for headphones. They have found that it is similar to the loudspeaker target curve (neutral speaker + plus room gain), but with some different "room gain" applied when measured at the ear drum. That paper from 2018 references the most recent headphone target curve based on preferences, and I understand it is the same curve used at RTINGS and that reddit link I posted above if you want to take a gander.
 
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#13
Rtings already covered most of them.

From the top of my head:
  • Impedance
  • Sensitivity
  • Distortion
  • Seal (and other causes for frequency response inconsistencies, such as headphone positioning)
  • Comfort
  • Isolation
  • Leakage
  • Detachable cable
  • Replaceable parts (especially pads)
  • Build quality
  • Quality control (driver matching, unit-to-unit consistency, failure rates, etc.)
  • Price
Yeah, good shout. Here is their opinionated weighting of different factors that contribute to their "Sound" score, fwiw:

Score components:
I wonder if Sean Olive has done any research on soundstage. I know nothing about it. But that weighting surprises me given the research into the strong correlation between FR and user preference, which as I understand it has a 95% correlation with user preference based on their latest study.
 

Fluffy

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#14
Ok, testing time. Just for amusement, I applied the curves from that list to the Audeze LCD2C and Focal Clear, which I own. And OMG NO. What the hell is this? I don't know if the measurements are wrong or this Harman curve is even less ideal than I suspected, but those curves sound awful. They are light years apart from the curves I made on my own for this headphones, even completely the opposite in some cases.

In the LCD2C they decided to put a whopping 10 DB increase at 4060hz! Of course, this is unlistenable and sounds insanely harsh at any volume other than very very low. I actually bought the lcd2c because of their very relaxed and warm sound, and at most I put a general +0.5db upward tilt to bring back some presence. This intense boost in mid treble is totally unjustifiable. The Bass rise is actually similar to what I use (they put +5 db low shelf at 110hz, I use +4 db at 130hz), and the overall curve lowers the very irritating mids that I find to be too boxy, so I also apply a reduction there. But the overall sound signature with their curve is hollow and extremely harsh.

As for the Clear, it's tamer, but still wrong for my ears. They for some reason put a -4db reduction at 200hz, a region I usually boost up because those headphones just lack in the bass guitar region. It gives a really anemic presentation. They also seem to think this headphone doesn't have enough treble energy because they put some boosts there, which makes it even more piercing than usual. I do agree on the general reduction in energy around 3500hz that I also apply myself, but they boost it back up at 4300hz which defeats the purpose. Again, this sounds to me a bit hollow and quite harsh.

Finally, I tried putting on pink noise and listening through the suggested curve of each headphone, to see if it actually results in a similar tonal balance. It's not, and I could even dare to say they sound more dissimilar with the curves then without them.

So my conclusion is that based on this very rough experiment, the Harman curve is just probably not for me. I could see how it would be appealing for short term listening because of its emphasis on presence and impactful lower bass, but for long term it seems to me extremely fatiguing and lacking in warmth.

On the other hand, this is the same sound signature I heard in numerous high-end headphones (maybe with tamer bass though), that I generally despise. So maybe there is a large percentage of the population that do appreciate this sound. Well good for them, I say. But I still don't think every manufacturer should aim for the same response. Otherwise where is the diversity and opportunity for surprise?
 

flipflop

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#15
I wonder if Sean Olive has done any research on soundstage.
AFAIK the only non-FR study he has published was the one you linked to in your previous post.
But that weighting surprises me given the research into the strong correlation between FR and user preference, which as I understand it has a 95% correlation with user preference based on their latest study.
They didn't do their homework properly.
When Harman's model for predicting preferences is compared to Rtings' data, the correlation between their scores and the predicted preferences is also quite low:
6T5A3001.jpg
 
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#18
AFAIK the only non-FR study he has published was the one you linked to in your previous post.

They didn't do their homework properly.
When Harman's model for predicting preferences is compared to Rtings' data, the correlation between their scores and the predicted preferences is also quite low:
View attachment 35490
This is cool, do you have a link to the source?
 

Cosmik

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#19
Let me try to explain why a target curve, as opposed to flat, makes no sense, and why this myth has come about. Understanding one concept is crucial: we 'hear past the room'. Quoting Dr. Toole:
Humans evolved while listening in reflective spaces, and are comfortable listening in them. In fact, it is now widely recognized that we perceptually "stream" the sound of the room as separate from the sound of the sources - that is what happens in live performances. A Steinway is a Steinway; only the hall changes. ...a good loudspeaker is a good loudspeaker, and its virtues are appreciated in a wide variety of rooms
The only question is whether you believe it or not. If you believe it, then it follows that the 'target curve' makes no sense. Not only is the concept of a 'target curve' an inversion of what is in reality a passive correlation, but it also has no relevance to headphones - it is a double absurdity for headphones.

Where this myth comes from is this: you, the listener, are able to separate the sound of the room from the source (including the speaker as source) as described above. This is an evolved ability, crucial for recognising and locating the sources of sounds in arbitrary environments. You hear the source as though there is no room; you hear the room as separate 'ambience'.

A measurement mic and laptop has no such ability: it simply measures the amount of 'frequency response matter' that passes through a time window during the measurement, including the direct sound from the speaker and the reflections. The natural effect of reflections in a real room is to attenuate higher frequencies more than lower, so the measurement of a perfectly flat 'ideal' speaker in a room shows a droop at high frequencies. But this is not what you are hearing. You are hearing the speaker as though there is no room, and "streaming" the room separately.

So why do people seem to prefer a target frequency response? The answer is: they don't. What they prefer is a flat speaker. Putting it in a real room changes the in-room frequency response measurement, but not their perception of the speaker. Most good speakers in average rooms will tend to produce similar in-room frequency response curves, hence what appears to be a 'preference' for a particular frequency response. But this is the wrong way of thinking about it. And it does not follow that reproducing that in-room curve using EQ in a different room will sound the same to the listener. It won't. You will have modified the speaker's sound by changing its EQ. The listener will then hear the speaker as arbitrarily modified regardless of the room.

And it certainly won't sound the same in headphones. With headphones there is no room, so they should be adjusted to flat. There is, however, the possibility that if some recording studios are making the same mistake (believing the target curve myth), then their recordings become skewed for listening with the 'target curve' - what Dr. Toole calls 'the circle of confusion'. There is no answer to that conundrum.

Sadly, even if all engineers used headphones adjusted to the same target curve, and you did the same, it still wouldn't produce a perfect result. If they mixed the recording followed by a perfect EQ inversion of the mistaken 'target curve', the result would be perfect. But in reality they will probably assume they are hearing perfection (the target curve is 'official' after all) and simply adjust faders and adjust EQ of individual channels ad hoc, meaning that they get it 'about right', but you, and they, will still be hearing the 'target curve' smeared over the top of those flat and arbitrarily EQ'ed sources. It's a mess.

Ideally, all headphones should be adjusted to flat.
 
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solderdude

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#20
A target curve is also loudness (amplitude/SPL/volume) dependent.
When you listen at low volume(SPL) it differs from when playing at loud volume(SPL) .

Some headphones with a specific curve thus sound 'better' on low listening volume(SPL) and others sound good at realistic or loud volume(SPL) .
 

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