Is there any theoretical reason why open-back over-ear headphones should be able to outperform IEMs after EQ'ing?

[pwjazz]

I know it's a pretty open ended question, but it seems that the general consensus on a lot of discussion boards is along the lines of "open back over-ears deliver the best possible sound, although some expensive IEMs can get close". What confuses me is this ...

I use three primary headphones:

- Sennheiser HD58X
- Audeze LCD2C
- Revonext RN-QT2 (Chifi IEM)

I've invested a fair amount of time in EQ'ing the QT2 to my tastes and at this point I enjoy listening to it more than my more expensive over-ear headphones. As I see it, the big headphones have two primary theoretical advantages:

1. They don't bypass the outer ear and so have an easier time delivering a natural sounding frequency response to a variety of people
2. Using larger drivers, they can produce more bass SPL with less excursion

The first point seems like it can be mitigated through careful EQ (though speaking from personal experience this can get pretty involved). The second point seems a little moot since well-isolating IEMs need considerably lower SPLs than open-backed over-ears.

Things that would seem to be to the advantage of IEMs:

1. Using much smaller drivers it might(?) be easier to achieve a fast and well damped transient response
2. Not having to deal with the outer head and ear eliminates problems from resonances/reflections caused by specific people's physiology (excepting the ear canal)

What am I missing?

 

[watchnerd]

It's all about implementation.

Saying that open backed headphones are inherently superior is just bad thinking.

Like anything in engineering, it's about compromise.

Companies like AKG make phones of all types. If one was inherently superior, they'd only build that.

It makes about as much sense as claiming that sealed speaker boxes are superior to ported, or vice versa.

 

[pwjazz]

It's all about implementation.

Yes. I suppose a different way to look at it is that different form factors create different engineering challenges, for example it's generally harder to achieve high bass SPLs with smaller speakers. So perhaps a better way to phrase my question is, does the IEM form factor create worse challenges for implementers than the open-back over-ear form factor?

 

[watchnerd]

Yes. I suppose a different way to look at it is that different form factors create different engineering challenges, for example it's generally harder to achieve high bass SPLs with smaller speakers. So perhaps a better way to phrase my question is, does the IEM form factor create worse challenges for implementers than the open-back over-ear form factor?

These days, with modern materials and rare earth magnets, no, not really.

The fact that you can get IEMs in a wide range of prices shows that it's solved problem.

For the common designs, it's all about designing to a price point, as opposed to fundamental R&D challenge.

Now if you wanted to make plasma gas charged headphones, that would be a different matter....

 

[watchnerd]

Yes. I suppose a different way to look at it is that different form factors create different engineering challenges, for example it's generally harder to achieve high bass SPLs with smaller speakers. So perhaps a better way to phrase my question is, does the IEM form factor create worse challenges for implementers than the open-back over-ear form factor?

Cases in point:

https://www.innerfidelity.com/images/BowersandWilkinsC5.pdf

https://www.innerfidelity.com/images/EtymoticER4XR.pdf

 

[andreasmaaan]

Things that would seem to be to the advantage of IEMs:

1. Using much smaller drivers it might(?) be easier to achieve a fast and well damped transient response

The BA drivers used in IEMs tend not to be able to cover as wide a frequency range as the dynamic drivers used in headphones, so generally 2 or more BAs are used in IEMs to achieve as good distortion levels and frequency bandwidth as a single-driver headphone.

In these cases a crossover must be used, which necessarily harms the transient response by introducing excess group delay.

I'm not suggesting this will be audible necessarily, but that at least on paper the transient response will be inferior than for a single-driver headphone.

 

[andreasmaaan]

Companies like AKG make phones of all types. If one was inherently superior, they'd only build that.

This is the only point I disagree with Manufacturers prove over and over again that inherent inferiority is no obstacle to choosing a particular design approach.

 

[Pavano]

This is the only point I disagree with Manufacturers prove over and over again that inherent inferiority is no obstacle to choosing a particular design approach.

And usage scenario
Open headphones in crowded environments don’t work

Watchnerd’s argument therefore is not exhaustive

 

[watchnerd]

And usage scenario
Open headphones in crowded environments don’t work

Watchnerd’s argument therefore is not exhaustive

Sure...I assumed the use case of sonic isolation not working for open cans was a given.

Hence, a non starter in some studio scenarios.

 

[watchnerd]

The BA drivers used in IEMs tend not to be able to cover as wide a frequency range as the dynamic drivers used in headphones, so generally 2 or more BAs are used in IEMs to achieve as good distortion levels and frequency bandwidth as a single-driver headphone.

In these cases a crossover must be used, which necessarily harms the transient response by introducing excess group delay.

I'm not suggesting this will be audible necessarily, but that at least on paper the transient response will be inferior than for a single-driver headphone.

This is the same theoretical argument used for planar speakers vs dynamics.

That hasn't stopped dynamic driver based speakers from becoming world class designs and dominating the industry.

Again...it's all in the implementation.

 

[andreasmaaan]

This is the same theoretical argument used for planar speakers vs dynamics.

That hasn't stopped dynamic driver based speakers from becoming world class designs and dominating the industry.

Again...it's all in the implementation.

I agree And it's not an argument, just an observation (I'm in the camp that says there's no evidence that excess phase caused by typical dynamic driver crossovers is audible).

 

[watchnerd]

I agree And it's not an argument, just an observation (I'm in the camp that says there's no evidence that excess phase caused by typical dynamic driver crossovers is audible).

And group delay over the micro-distances of an IEM would be amazingly minute, I would think.

 

[andreasmaaan]

And group delay over the micro-distances of an IEM would be amazingly minute, I would think.

No, it’s not a result of the physical distances between drivers but rather the filters used in the crossover. A given low-pass or high-pass filter will introduce the same group delay regardless of the size or position of the drivers.

 

[watchnerd]

No, it’s not a result of the physical distances between drivers but rather the filters used in the crossover. A given low-pass or high-pass filter will introduce the same group delay regardless of the size or position of the drivers.

Electrically, yes.

Acoustically, not necessarily.

Comb filtering can have all sorts of effects that make this moot...or aggravate it.

 

[andreasmaaan]

Electrically, yes.

Acoustically, not necessarily.

Comb filtering can have all sorts of effects that make this moot...or aggravate it.

Sorry but I disagree here.

Once a passive crossover filter has introduced group delay, it will necessarily be present in the acoustical output.

That’s absolutely not to say it will be audible, of course.

 

[maverickronin]

1. They don't bypass the outer ear and so have an easier time delivering a natural sounding frequency response to a variety of people

This is one of the primary issues. In theory it's possible to correct for, but requires absolutely massive amounts of trial and error since I'm not aware of any way to place mic directly on the eardrum for proper measurement and convolution.

2. Using larger drivers, they can produce more bass SPL with less excursion

This isn't an issue since the drivers have to move so much less air.

Acoustically, not necessarily.

Once a passive crossover filter has introduced group delay, it will necessarily be present in the acoustical output.

Many designs claim to time align the drivers. There are also plenty that divide up the drivers into groups with separate chambers and bores all the way to the end of the nozzle.

 

[andreasmaaan]

Many designs claim to time align the drivers. There are also plenty that divide up the drivers into groups with separate chambers and bores all the way to the end of the nozzle.

I appreciate this, but time alignment can't alter the fact that passive electrical filters introduce group delay (unless they are 1st order filters of course).

 

[watchnerd]

I appreciate this, but time alignment can't alter the fact that passive electrical filters introduce group delay (unless they are 1st order filters of course).

And this is exactly the case that proves that group delay can be offset acoustically...

 

[andreasmaaan]

And this is exactly the case that proves that group delay can be offset acoustically...

Yes obviously But what does comb filtering have to do with this?

 

[watchnerd]

Yes obviously But what does comb filtering have to do with this?

Nothing.

But when combined with the comb filtering that does happen in the ear, which varies by person, the whole goal of trying to create a time aligned, phase coherent set of drivers at millimetric distances is just a hot mess of 'why bother'.