Finding value in headphone measurements

[JohnYang1997]

Naturally so. I generally rarely see much utility from that sort of measurement for headphones, though - we can pull the phase and delay data directly from an impulse response, yaknow?

Well. For square wave and impulse response yes. They are basically measurements with little use. CSD though can be very misleading.
For phase, excess phase function in rew works really well. It's a must for multi-driver iems. Though many speakers do also have very weird phase response. Few correct this, like Presonus S6/S8.

 

[solderdude]

-1) Freq. response - it will tell me if it's bright or bass-head, also spikes around 5-6KHz will make me mad alot.
-2) Square and impulse response for bass (anything between 50...100Hz should do) - will give me a good idea how well it will reproduce the low-end freqs. (usually round corners means diaphragm will not be perfectly accurate for low-bass), also if bass is "fast" or "slow" (phase delay is high or not).
-3) Phase linearity and impedance across audible range - will tell me if it will pair well with "difficult" headamps (high impedance amps usually, but tubes amps too or badly designed amps that might oscillate if impedance is not constant).
-4) Fit and comfort - this is very important and without a good fit all other measurements will not matter, especially on IEMs.

if I may...

2: SBAF has been making attempts to capture tone bursts at various frequencies which give interesting results but may be hard to interpret correctly.
Maybe even more interesting than squarewaves ?
Measuring squarewaves through resonators (ear canal) may be hard to do as not only FR is affected but decay as well.
I assume mad economist will know if that would be easy to do.

3: The problem with showing the impedance plot is that the only way this is meaningful is knowing if it varies and how much. You would have to get out the old calculator to get an idea how much the tonal balance would be affected.
For this reason I measure the actual response between 2 output resistances to get a feel.
A suggestion for Amir would be to use the impedance plot and then use different color traces, overlayed in one plot for say output R's of 0, 5, 10, 20, 30, 60 and 120 Ohm (perhaps even higher) to show real world effects.

4: I agree these are, aside from sound, very important and underevaluated aspects.
Fit and comfort are really hard to determine. That what person A finds comfortable may be horrific or not fitting for others. Take the wing design of AT. Most folks love it. I can't get it to work on my head. There are people with big and small heads, big and small pinnae, protruding or flat pinnae. For some people pinnae touching the drivers is hell, others don't care. Some hate higher clamping force others need it. Clamping force differs with headsizes, Headshapes differ. Boney vs almost round. Some prefer velours, others find it prickly and annoying. Some prefer leather or pleather.
There is little to determine objectively and when you do this would be very time consuming and subjective as well.
I suspect in order to churn out a lot of headphone measurements the generation of data and reporting would have to be done quickly and automated. The comfort part will be hard to do.

 

[JohnYang1997]

if I may...

2: SBAF has been making attempts to capture tone bursts at various frequencies which give interesting results but may be hard to interpret correctly.
Maybe even more interesting than squarewaves ?
Measuring squarewaves through resonators (ear canal) may be hard to do as not only FR is affected but decay as well.
I assume mad economist will know if that would be easy to do.

3: The problem with showing the impedance plot is that the only way this is meaningful is knowing if it varies and how much. You would have to get out the old calculator to get an idea how much the tonal balance would be affected.
For this reason I measure the actual response between 2 output resistances to get a feel.
A suggestion for Amir would be to use the impedance plot and then use different color traces, overlayed in one plot for say output R's of 0, 5, 10, 20, 30, 60 and 120 Ohm (perhaps even higher) to show real world effects.

4: I agree these are, aside from sound, very important and underevaluated aspects.
Fit and comfort are really hard to determine. That what person A finds comfortable may be horrific or not fitting for others. Take the wing design of AT. Most folks love it. I can't get it to work on my head. There are people with big and small heads, big and small pinnae, protruding or flat pinnae. For some people pinnae touching the drivers is hell, others don't care. Some hate higher clamping force others need it. Clamping force differs with headsizes, Headshapes differ. Boney vs almost round. Some prefer velours, others find it prickly and annoying. Some prefer leather or pleather.
There is little to determine objectively and when you do this would be very time consuming and subjective as well.
I suspect in order to churn out a lot of headphone measurements the generation of data and reporting would have to be done quickly and automated. The comfort part will be hard to do.

Only thing I can think of is the linearity of pulse peaks with different input voltages VERSUS the steady state voltages with same input. I have seen their method of measuring pulses which is completely wrong. Not fund of the things they do really.

 

[Mad_Economist]

if I may...

2: SBAF has been making attempts to capture tone bursts at various frequencies which give interesting results but may be hard to interpret correctly.
Maybe even more interesting than squarewaves ?
Measuring squarewaves through resonators (ear canal) may be hard to do as not only FR is affected but decay as well.
I assume mad economist will know if that would be easy to do.

3: The problem with showing the impedance plot is that the only way this is meaningful is knowing if it varies and how much. You would have to get out the old calculator to get an idea how much the tonal balance would be affected.
For this reason I measure the actual response between 2 output resistances to get a feel.
A suggestion for Amir would be to use the impedance plot and then use different color traces, overlayed in one plot for say output R's of 0, 5, 10, 20, 30, 60 and 120 Ohm (perhaps even higher) to show real world effects.

4: I agree these are, aside from sound, very important and underevaluated aspects.
Fit and comfort are really hard to determine. That what person A finds comfortable may be horrific or not fitting for others. Take the wing design of AT. Most folks love it. I can't get it to work on my head. There are people with big and small heads, big and small pinnae, protruding or flat pinnae. For some people pinnae touching the drivers is hell, others don't care. Some hate higher clamping force others need it. Clamping force differs with headsizes, Headshapes differ. Boney vs almost round. Some prefer velours, others find it prickly and annoying. Some prefer leather or pleather.
There is little to determine objectively and when you do this would be very time consuming and subjective as well.
I suspect in order to churn out a lot of headphone measurements the generation of data and reporting would have to be done quickly and automated. The comfort part will be hard to do.

Tonebursts have largely the same issue with headphones that squarewaves do, and it's as @JohnYang1997 and I have been discussing - you can get all the same damn info from the impulse response if you're willing to look at a phase plot in addition to magnitude. Heck, for a single-driver headphone without a crossover, it's unlikely you even need to look at that...

Re: Zout and headphone impedance, I always liked Rinchoi's visualization of that:

Presenting both the delta and the compensated responses is IMO helpful for newer people/folks who ain't about eyeballing minutia.

 

[Mad_Economist]

Only thing I can think of is the linearity of pulse peaks with different input voltages VERSUS the steady state voltages with same input. I have seen their method of measuring pulses which is completely wrong. Not fund of the things they do really.

Anecdotally, in the cases where headphone linearity has been poor, it hasn't typically been for coil heating type reasons in my experience, so I'd be a bit surprised if continuous vs. burst testing showed much difference...but that sounds like a fun thing to examine if you have a headphone you don't mind making cry!

 

[solderdude]

Only thing I can think of is the linearity of pulse peaks with different input voltages VERSUS the steady state voltages with same input. I have seen their method of measuring pulses which is completely wrong. Not fund of the things they do really.

Agreed on the measuring of tone bursts and above all the(ir) interpretation of it. But at least they try 'simple things' and show results publicly.

Re: Zout and headphone impedance, I always liked Rinchoi's visualization of that:

You know what happened to Rin Choi ?

I meant plots more like this which are easier to read for non-nerds.

Of course the used 'compensation' of their HATS is completely wrong but the effect below 1kHz is of importance here.
What Rin did but with more output resistances as shown above. It is difficult for non technical people to estimate the effect other resistances have.
As most amps are below 33 Ohm to me it makes sense to also include 5, 10 and 20 Ohm that takes the guessing out for readers.

And yes, I am aware that tone bursts have similar issues as squarewaves and are problematic at the start and stop of the burst in particular.
What I meant with the remark is that at least they are trying to show 'different' measurements than the usual ones.

 

[Mad_Economist]

You know what happened to Rin Choi ?

I haven't seen the guy in quite a while, unfortunately. Do you know what he's up to?

I would suggest to create a plot that normalizes 0 Ohm and shows the delta at various impedances.
This way the absolute FR is taken out of the picture and only differences are shown.

I think both are handy - the delta (or "effective EQ" if you wanna keep things newbie friendly) and the absolute FR are useful for different purposes. That's why I like Rin's side-by-side of the pair!

What I meant with the remark is that at least they are trying to show 'different' measurements than the usual ones.

It's commendable to look for new ways to peer behind the veil of acoustics...but going straight to publication with them can degrade the SNR of headphone metrology on the internet. I always flash back to a Reddit post I once saw with a guy using Rew's "clarity" function to try to measure headphone clarity...

 

[solderdude]

Agreed on the Rin Choi plots but I would also include resistances below 30 Ohm, at least for low impedance MA IEMS.

I kind of agree with showing things one cannot really interpret and explain already from a science p.o.v..
On the other hand you can get others to chip in when you do.
I am not looking at this from a scientist nerd kind of thing waiting to publish things officially for peer review in some society but rather as a just above noob level 'exploring' kind of thing in the open community. Yes, not very scientific.

I love REW but yes, the clarity thing struck me as the strangest move as well. Perhaps he can explain, @JohnPM is active on this forum.
Oops I believe I just paged him by accident .

 

[solderdude]

I haven't seen the guy in quite a while, unfortunately. Do you know what he's up to?

Nope, that's why I asked. It looks like he pulled an 'NwAvGuy' kind of thing.
It's strange to me why passionate folks suddenly drop what they are doing and disappear without any hints/explanations.
Did they loose interest ? Were they threatened ? Did they die ? Were they locked up in jail or madhouse ?

Was sad to see Golden Ears stop as well. I really liked their informative 'sliders'
have been thinking of re-introducing something like that.
It is simple things like those sliders that are easy to understand for everyone that I meant with 'additional' info for the general public.

 

[Mad_Economist]

Agreed on the Rin Choi plots but I would also include resistances below 30 Ohm, at least for low impedance MA IEMS.

Indeed - although that does make for a tad more work. Perhaps just 10/100?

I love REW but yes, the clarity thing struck me as the strangest move as well. Perhaps he can explain,

I'm unsure what John would explain? Clarity and other decay time measures make quite good sense for Room EQ Wizard - it's not his fault we're all using it for headphones

 

[solderdude]

Indeed - although that does make for a tad more work. Perhaps just 10/100?[/QUOTE]

I would assume it is very easy to generate automatically from a measured impedance plot. I measure at 0.2 and 120 myself which is more work indeed as it requires 2 sweeps and manually overlay 2 traces and report on the level differences that have to be taken into account.
HD650 on 0.2 Ohm and 120 Ohm (yes, I know... I know.. no HATS used and the slight difference the acoustic impedance this has on the electric impedance is not accounted for)

I'm unsure what John would explain? Clarity and other decay time measures make quite good sense for Room EQ Wizard - it's not his fault we're all using it for headphones

LOL, I have a narrow look at REW only from a headphone pov. I don't use it for rooms so could make sense.

B.t.w. as a side note... why doesn't it say 'technical expert' below your avatar ?

 

[trl]

I like Tyll's square plots because in his graphs the headphones that were able to better reproduce those squares are mostly planars, like Audeze/Fostex/Hifiman and the bass coming out from these is different, in a better way, than dynamic cans.

Accurate square response of the diaphragm do tells me how fast and precise the bass will sound.

Designing a diaphram able to quickly rise and quickly fall is very difficult and I tend to appreciate the folks who design headphones that measure better with square signals, although I'm aware that only this kind of measurement doesn't tells much about the sound profile or audible THD.

 

[Jimbob54]

B.t.w. as a side note... why doesn't it say 'technical expert' below your avatar ?

Wanna badge, you pay the Watchman.

 

[LearningToSmile]

I meant plots more like this which are easier to read for non-nerds.
View attachment 78993

I agree, I find that clear and useful, and it was one of the things I looked for before buying my current set of headphones, and had trouble finding.

 

[solderdude]

Wanna badge, you pay the Watchman.

I don't want the badge, really I don't because I am not an actual expert, just an enthusiastic hobbyist, like others in here but just wondered why mad economist didn't have one given his experience in this specific field.

 

[JohnYang1997]

I like Tyll's square plots because in his graphs the headphones that were able to better reproduce those squares are mostly planars, like Audeze/Fostex/Hifiman and the bass coming out from these is different, in a better way, than dynamic cans.

Accurate square response of the diaphragm do tells me how fast and precise the bass will sound.

Designing a diaphram able to quickly rise and quickly fall is very difficult and I tend to appreciate the folks who design headphones that measure better with square signals, although I'm aware that only this kind of measurement doesn't tells much about the sound profile or audible THD.

Not really.

 

[Chocomel]

I like Tyll's square plots because in his graphs the headphones that were able to better reproduce those squares are mostly planars, like Audeze/Fostex/Hifiman and the bass coming out from these is different, in a better way, than dynamic cans.

Accurate square response of the diaphragm do tells me how fast and precise the bass will sound.

Designing a diaphram able to quickly rise and quickly fall is very difficult and I tend to appreciate the folks who design headphones that measure better with square signals, although I'm aware that only this kind of measurement doesn't tells much about the sound profile or audible THD.

For headphones the square wave basically just reflects the FR, them being generally minimum phase systems and all. For the perfect square wave you just need a flat FR

 

[JohnYang1997]

For headphones the square wave basically just reflects the FR, them being generally minimum phase systems and all. For the perfect square wave you just need a flat FR

And if one follows the target the square wave will look fked. And one can also eq to get perfect square wave.

 

[Jimbob54]

I don't want the badge, really I don't because I am not an actual expert, just an enthusiastic hobbyist, like others in here but just wondered why mad economist didn't have one given his experience in this specific field.

I meant @Mad_Economist needs to pay the Watchman if he wants a badge. You can get an "Aquatic Avian" badge if you ask nicely , Im sure. Or a herring.

 

[solderdude]

You can get an "Aquatic Avian" badge if you ask nicely

Like this one... ?