What qualities of a headphone cannot be equalized?

soundstage

 

resolution

 

control (e.g. you can add more or less bass via eq, but you cannot control if it sounds muffled, or boomy, etc.)

 

 

Ultimately, EQ can make adjustments to a headphones sound signature, but it really cannot fundamentally make it sound like a different headphone. Think of it as a minor error correction - you still need a good baseline performance to build on. 

Edited by liamstrain - 2/10/12 at 8:04am

In theory, you can, with an inverse FIR filter created from the impulse response. It would not fix any non-linear distortion, though.

 

To add on distortion products(which also affects resolution). Soundstage can be affected to a large extend using DSP techniques though your mileage will be a lot better with headphones with good base soundstage.

I wouldn't consider FIR filters a standard component of an EQ. But, technically, you are correct. 

 

It sort of becomes a question of what is easier and less expensive (or time consuming). Yes, you can swap parts and tune a Honda Civic up to where it performs like a luxury sports car. But by the time and expensive you've done so, you could have just bought the sports car - and you're still sitting in a civic, without the leather, wood trim, and comfort of what you were trying to emulate. *shrug*

Edited by liamstrain - 2/10/12 at 8:58am

Agreed, Eqing can be very time consuming/expensive, best is to upgrade the headphone first. The rule as was mentioned once by gregorio in room acoustics was solving 90%+ of it physically and the last <10% through EQ, that can be said to apply with headphones as well as EQ will inevitably introduce more distortion.

 

On another note, car analogies for the win! 

Good software parametric eq plugins (those that don't introduce phase problems, or other distortion) tend to run between $90 and $200 USD... and that's assuming you already have a listening system that allows for their use. Hardware eq is another big chunk, and he was talking about adding in custom FIR filtration which is a whole other ball of wax. 

 

Plus, depending on who you are and what you do, time = money. Setting up a well measured and distortion free eq takes time and know how. Sometimes, it just makes more sense to spend "more" money upfront, rather than incur it in effort and time. 

 

Everything is a balance and based on your own ability, needs, and preferences. 

Edited by liamstrain - 2/10/12 at 9:44am

I have to disagree. Spending more money does not guarantee an improvement, actually, the opposite can be the case since there is hardly any relationship between price and performance when it comes to headphones (if we ignore the cheap crap).

Got a headphone that you like and want to improve further? Give EQing a try. There are many free software EQs out there that are "good", no need / point to buy an expensive one if you don't have much experience.
Sure, tuning your EQ does cost some time but at this time is well invested since you'll learn a lot of things which you would not learn if you just bought other headphones. Actually I think that everyone should have some EQing experience before being allowed to take place in "how does headphone X sound" discussions.


With a stereo EQ you can reduce channel imbalances and therefore improve "soundstage".
Resolution often is just a matter of some boosted treble frequency ranges .. so yes, EQ can also influence this.
And you can also EQ a headphone to sound boomy, muffled etc. using a conventional EQ. Different Q factors do the trick.

There's even a paper on this that demonstrates that you can in fact make a good headphone sound like another headphone simply by EQing.

Absolutely not. Room acoustics/correction has not much to do with headphones. And no, EQ does not inevitably introduce more distortion. If you cut bloated bass you can actually reduce distortion.
Edited by xnor - 2/10/12 at 10:59am

 

Agreed, money does not automatically mean improvement. I mention the price only because I have had terrible modulation and other distortion problems with inexpensive eq plugins that took some research and trying many different ones to resolve. In the end, that meant spending some dosh. But my needs are not everyones.

 

 

 

 

Soundstage has more that channel balance involved. You can probably improve it some, but as far as I have seen, you cannot make a closed phone sound like an open one. EQ doesn't insert that air between instruments.

 

 

 

 

 

Boomy is often poor mechanical or electrical damping of the headphone. Also, the attack and decay characteristics (and square wave) have a huge affect on the apparent resolution, more than just boosted treble. I do not believe you can influence square wave performance via eq.

 

 

 

 

That is interesting. I'd be curious to see it. But I still maintain, it's probably better to consider eq a tool for tweaking, rather than drastic changes. 

I agree that it's better suited for tweaking. Indeed, you cannot, or lets say you can but should not, make extreme/drastic changes with an EQ.
Of course, but you can still influence it. I guess the problem with closed headphones are the reflections and resonances in the closed cups which you cannot magically EQ away. I've never tried EQing a closed headphone to make it sound similar to an open one though since I don't have a closed one atm.
It certainly can. A minimum phase can be used to fix both frequency response and phase response resulting in a better square wave performance.
I don't have the link handy but I'll post it as soon as I find it. I agree with your last sentence.
Edited by xnor - 2/10/12 at 12:56pm

 

Actually, that's not always true, for low frequencies corrections in a room+speaker system, the phase changes induced by a minimum phase EQ correct the room induced issues.

 

 

 

You can "magic" some resonances away for a subwoofer+room system since it's a a minimum phase system.

 

But coming back to headphones, and the size of the ear+cup cavity, it's probably minimum phase system from DC to the trebles, I wonder if we could treat the ear+cup cavity like a subwoofer in a room.
 

 

 

Edited by khaos974 - 2/10/12 at 7:31pm

we have these discussions repeatedly

 

clearly deep "holes" in the frequency response require lots of extra drive - if the amp can swing hard enough it may still cause bottoming of the driver against the magnet assy - gross nonlinear distortion

 

start with extended, smooth frequency response, low nonlinear distortion with adequate SPL headroom and you can manipulate most everything else - including "sound stage" - to the point you can't tell the (extensive customized DSP) "EQ'd" headphones from these speakers in front of you in this room

 

 

 

and no you can't do it with a graphic or parametric EQ, even crossfeed falls short - how restricted do you insist the def of "EQ"

 

some want to make distinctions about non-minimum phase - FIR Impulse correction - but I don't think it is necessary in a sufficiently general view of "EQ" to exclude the SVS Realizer DSP

 

 

Edited by jcx - 2/10/12 at 10:56pm

 

EQ to a large extent does cause distortion, loss in transparency unless you have a completely transparent hardware or software implementation. Its not just a matter of changing volume levels, its not as simple as you think it is. That is why most digital volume control implementations can be disastrous. 10% is still a good guideline for headphones.

 

 

 

Edited by firev1 - 2/10/12 at 11:30pm

 

Equalization only causes non-linear distortion to the digital signal if it is very poorly written, or is clipping (probably the most common problem for casual users), which can easily be avoided by pre-attenuating the signal. Of course, it does increase the dynamic range requirement for the DAC/amplifier/headphones, so quality degradation may occur in those stages (e.g. drivers distorting due to large amounts of bass boost).