Can anyone here explain headphone speed and why it wouldn't be affected by digital equalization?

[pwjazz]

This is one of those audiophile terms that's hard to unpack but used pretty frequently. I've gone wild with digital EQ lately and run across people who maintain that headphone speed is somehow inherent to the hardware and unaffected by EQ. The closest thing I can think of for an objective measurement of speed would be the rise time on a square wave response, but I'm really just guessing here. Since I don't have an oscilloscope, I don't have a way of measuring the effect of EQ on square wave response. Does anyone here like @solderdude have any insights into this?

 

[maverickronin]

IME "Sseed", as a subjective description, and doesn't correlate well to any single measurement.

It's an evaluation of a lot of things beyond frequency response like energy storage/decay and even harmonic distortion profile. Those thing can't be changed by simple EQ.

 

[amirm]

"Speed" is not a proper term for anything in audio. Most of the time they use it to talk about bass but bass frequencies are very low and last thing they can have is speed.

Where it is sort of valid is in ringing in low frequencies. There, notes can elongate. Fortunately DSP absolutely fixes that. You just pull down the offending frequency or frequencies.

 

[pwjazz]

energy storage/decay and even harmonic distortion profile

Thanks for your response. That makes sense, an underdamped headphone with lots of lingering energy is going to sound "slow", likewise one with lots of distortion from lower frequencies that masks high frequency details could lead to this perception as well. I personally think of this more as clarity, especially the decay-related phenomenon, but I agree that it's not really fixable with EQ. Regarding harmonic distortion though, in my experience it's often worst in the bass, which of course allows it to wreak havoc across the frequency spectrum, but if you're willing to live with less bass you can always EQ the bass down and reduce masking that way.

 

[Vincent Kars]

You can measure impulse response e.q. https://www.innerfidelity.com/images/SennheiserHD800S.pdf
This is something not affected by EQ as far as I know.

 

[pwjazz]

Where it is sort of valid is in ringing in low frequencies

Yeah, bass is a really tricky area to get right. I think a lot of times when people talk about things like "speed" they might be conflating multiple concepts and really just equating a transducer's speed with how good fast bass playing sounds from it. I love listening to fast acoustic bass work like that of Phronesis and GoGo Penguin's. A realistic and "fast" sounding bass requires fast decay as well as low distortion in the lower frequencies to avoid muddying things up, but interestingly it also requires a frequency response that includes adequate higher frequency detail to properly render things like the attack of a plucked string, the strings slapping the fretboard, the player knocking on the tonebody, or the sound of a bow rubbing the strings. Because of this, bright headphones could actually be heard as having "fast" bass because they emphasize some of those details that make acoustic double-bass sound "alive". I remember being wowed when listening to Phronesis for the first time with the DT 1990 Pro because it has relatively low distortion bass and more than adequate high frequencies that really made things come alive. Of course it was so bright that it messed up timbre on a lot of acoustic instruments and gave me headaches and tinnitus unless I EQ'd it, but that's another subject!

 

[pwjazz]

You can measure impulse response e.q. https://www.innerfidelity.com/images/SennheiserHD800S.pdf
This is something not affected by EQ as far as I know.

When I measure impulse response in Room EQ Wizard using a sine sweep, the impulse response is definitely affected by EQ. In fact, the frequency response can be derived from the impulse response without any additional information.

 

[pwjazz]

When I measure impulse response in Room EQ Wizard using a sine sweep, the impulse response is definitely affected by EQ. In fact, the frequency response can be derived from the impulse response without any additional information.

Just to drill down into this, as you see on that link:

This means that any linear system can be completely described by how it changes the amplitude and phase of cosine waves passing through it.

My understanding is that nonlinearities in a headphone's behavior primarily show up as distortion.

Distortion can't be "fixed" with EQ, but frequency response can, so it seems to me that for headphones with mostly linear behavior (i.e. very low distortion) their sonic performance is almost completely tunable with EQ. Does that make sense?

 

[solderdude]

Perceived 'speed' of sound (I would call it 'attack' or 'clarity' is in the 2-5kHz range.
'speed' of bass is a bit lower I reckon. A peak in the overtone range of a bass can improve the 'perceived' attack.

Most people tend to think it is in the 10-20kHz range and is related to the actual speed a driver has.
I have not found a clear correlation between 'snappy attack' and squarewave response.
Squarewave response changes dramatically with EQ (of course) as that has a linear scale so you see differences already that may just be bareky audible.
I have found some correlation between 'realism' and 'separation' (pinpointing) instruments with treble quality when looking at squarewaves and impulse/step response.

Have done plenty of squarewave plots and the faster sounding headphones mostly have a peak in the 2-5kHz range.
It is affected by EQ in that range but when a headphone has a serious 'dip' in that area I find you can only get it to improve somewhat but not get is as good as headphones that already have a good 'attack'.

Impulse response plots can only say something when one knows how high the actual stimulus is.

You can't polish a turd is my opinion. I have found that good headphones react well to EQ as long as it isn't too much.
Poor performing headphones may improve somewhat but will never become good headphones.

 

[RayDunzl]

Since I don't have an oscilloscope, I don't have a way of measuring the effect of EQ on square wave response. Does anyone here like @solderdude have any insights into this?

 

[Blumlein 88]

My experience EQ'ing microphones is some can have brightness or zing in the upper midrange EQ'd out and others not so much. The general consensus is some have ringing in the diaphragm at those frequencies. With a microphone you can't EQ prior to the input only afterwards. So you can tone it down, but sometimes can't really get rid of coarseness over some of the frequency range.

Ribbons have a rep for taking upper midrange EQ well. I don't think a ribbon will be ringing up there. And they usually need boosts not cuts. Some condensers can be bright, but EQ right down fine. Other's sound wrong even with EQ. In my limited experience if you see the frequency plot of a condenser mike and the 3-8 khz range is very uneven it won't EQ well. It can be very inaccurate, but with a smooth rise and it will EQ well. Now it is also possible those with uneven response just mean you need extremely precise EQ to fix it. I can imagine a similar situation in headphones that might have resonances or highly even upper mid response making precise EQ difficult to accomplish.

 

[Blumlein 88]

View attachment 17097

Square waves as you know are the fundamental and odd harmonics. If you boost the bass or near the fundamental lower frequency enough it will get more like a sine wave. The middle of the square rounds up like in your graph. If you boost treble the higher harmonics will show up near the leading and trailing edges like you are seeing above. You might even be inducing ringing with the treble boost.

http://sound.whsites.net/articles/squarewave.htm

 

[pwjazz]

Have done plenty of squarewave plots and the faster sounding headphones mostly have a peak in the 2-5kHz range.

You're a treasure to the community! I've learned a ton from reading your reviews and love being able to interact with you on forums such as this.

when a headphone has a serious 'dip' in that area I find you can only get it to improve somewhat but not get is as good as headphones that already have a good 'attack'

Can you please elaborate on that a little? Are you saying that some headphones simply refuse to accept a boost in that region or that they distort? My LCD2C has a dip in that region, but the headphone responds well to EQ in that area (at least at my normal listening levels). EQ'd, I end up with a raw frequency response like this on my MiniDSP E.A.R.S. (which includes an artificial ear).

In addition to sounding definitively clearer than stock, I also don't notice any weird distortion. The distortion measurements back this up, showing what is still impressively low distortion in that region:

You can't polish a turd is my opinion.

I've never actually run into problems EQ'ing in the high midrange and low treble. Where I do sometimes find difficulties is in increasing bass on open-backed dynamics with high bass distortion, and with trying to add high treble to balanced armatures that just physically can't reproduce the highest frequencies.

 

[SIY]

My experience EQ'ing microphones is some can have brightness or zing in the upper midrange EQ'd out and others not so much. The general consensus is some have ringing in the diaphragm at those frequencies. With a microphone you can't EQ prior to the input only afterwards. So you can tone it down, but sometimes can't really get rid of coarseness over some of the frequency range.
... Some condensers can be bright, but EQ right down fine. Other's sound wrong even with EQ.

This correlates with polar pattern- you can't EQ that out.

 

[pwjazz]

I can imagine a similar situation in headphones that might have resonances or highly even upper mid response making precise EQ difficult to accomplish.

I think a common example of this is the infamous 6 KHz spike on Sennheiser's HD800 which is caused by some ringing. I've never used the headphones myself, but from what I understand you can improve the spike somewhat with EQ, but many people opt to add a helmholtz resonator to the headphones in order to counteract the ringing. IIUC the issue with EQ is that with ringing behavior, you'll still get some ringing at 6 KHz even if your input signal doesn't have any 6 KHz content, so EQ'ing down the input signal at that frequency only helps a little.

 

[pwjazz]

I think a common example of this is the infamous 6 KHz spike on Sennheiser's HD800 which is caused by some ringing. I've never used the headphones myself, but from what I understand you can improve the spike somewhat with EQ, but many people opt to add a helmholtz resonator to the headphones in order to counteract the ringing. IIUC the issue with EQ is that with ringing behavior, you'll still get some ringing at 6 KHz even if your input signal doesn't have any 6 KHz content, so EQ'ing down the input signal at that frequency only helps a little.

I did once own the DT 1990 Pro, which IIRC also has some high frequency ringing. I found the treble supremely uncomfortable and applied pretty heavy EQ to bring it down. This helped, but I still found them a little tinnitus inducing. To get them to the point where they were completely comfortable, I had to EQ the treble down so far that they lost their alluring sparkle and just sounded dull. Perhaps that was only dull in comparison to their natural sound though, I'm not sure.

 

[pwjazz]

View attachment 17097

Well, now I'm going to have to play with this! I have a MiniDSP E.A.R.S. and it looks like there's a straightforward way to apply its calibration as EQ in Audacity.

 

[solderdude]

Can you please elaborate on that a little? Are you saying that some headphones simply refuse to accept a boost in that region or that they distort? My LCD2C has a dip in that region, but the headphone responds well to EQ in that area


In addition to sounding definitively clearer than stock, I also don't notice any weird distortion. The distortion measurements back this up, showing what is still impressively low distortion in that region:


I've never actually run into problems EQ'ing in the high midrange and low treble. Where I do sometimes find difficulties is in increasing bass on open-backed dynamics with high bass distortion, and with trying to add high treble to balanced armatures that just physically can't reproduce the highest frequencies.

Ah but the LCD2 (with its huge linear dynamic range) isn't a turd.
It reacts well to EQ.

With some headphones that have issues in the area to be EQ'ed the results are always disappointing. High amounts of distortion. You can get it tonally more balanced in that case but won't sound great.

As you mentioned... when too much EQ is needed or a headphone simply isn't up to it the results are disappointing.

The EARS is fine.. the 'standard' correction that comes with it is wrong IMO.
I know Marv is trying to improve on it. For the range above 500Hz he is doing a much better job, below 500Hz mini DSP is much more accurate.

Edit: Noticed he recently made some adjustments in the lower FR part and think his compensation is MUCH better than that of mini DSP itself.

 

[solderdude]

I did once own the DT 1990 Pro, which IIRC also has some high frequency ringing. I found the treble supremely uncomfortable and applied pretty heavy EQ to bring it down. This helped, but I still found them a little tinnitus inducing. To get them to the point where they were completely comfortable, I had to EQ the treble down so far that they lost their alluring sparkle and just sounded dull. Perhaps that was only dull in comparison to their natural sound though, I'm not sure.

Yes, one headphone that works well with my Tinnitus is the HP50.
When I EQ the treble of the HD800 down to neutral levels it maintains it's detailing. Most other headphones need a little boost in that area in order to not sound 'dull'.

 

[pwjazz]

The EARS is fine.. the 'standard' correction that comes with it is wrong IMO. I know Marv is trying to improve on it. For the range above 500Hz he is doing a much better job, below 500Hz mini DSP is much more accurate.

Oh very interesting! You're talking about the HEQ profile that targets a harman-like response? Do you know where I could find Marv's work product (presumably somewhere on SBAF?)

Ah but the LCD2 (with its huge linear dynamic range) isn't a turd.

Most certainly true! I guess I've been lucky to only try EQ'ing headphones that are relatively decent on distortion (at least outside of the bass region).