[Tyll Hertsens]

@ Jamey  Thanks bud, cool tool, feel free to talk about it here, no worries.
 
@Udauda  I haven't gotten to start working on the IEMs yet, but there's merit to your comment.  However, if you're talking about information up above 8 kHz it may be difficult to get really accurate measures on the HeadAcoustics with IEMs.  A Zwisloki coupler does seem to be the best way to get accuracy up high, and also there may be a need to use a different compensation curve for IEMs than regular headphones. Not exactly sure where all the features on the current graphs are coming from given those two possibilities for error. Keep your eye out here and we'll look into it when I get back to work.

 

[udauda]

Dear Tyll, that's just ecstatic to know.  Since HEAD Acoustics HATS system is already equipped with IEC-711 ear simulators by default, its absolute accuracy should be more or less same to that of the Zwislocki couplers. Also, your current compensation DF curve is ISO 11904-compliant, and should be good enough for IEM measurements as well.
 
Below is Zwislocki coupler vs PCMAG's HEAD Acoustics HATS(IEC711): 

The high frequency deviation here should be mostly due to the insertion depth issue. (thus it's little too shallow for PCMAG, little too deep for Headroom)
 
BTW have fun while traveling!

 

[Tyll Hertsens]

Quote:

Dear Tyll, that's just ecstatic to know.  Since HEAD Acoustics HATS system is already equipped with IEC-711 ear simulators by default, its absolute accuracy should be more or less same to that of the Zwislocki couplers. Also, your current compensation DF curve is ISO 11904-compliant, and should be good enough for IEM measurements as well.
 
Below is Zwislocki coupler vs PCMAG's HEAD Acoustics HATS(IEC711): 

The high frequency deviation here should be mostly due to the insertion depth issue. (thus it's little too shallow for PCMAG, little too deep for Headroom)
 
BTW have fun while traveling!

Thanks!  Once I get this Hobby Lab thing going and know that I can survive, I'm VERY tempted to get one of the couplers specifically for the IEMs.  It's just very hard to know that your insertion depth is correct on the head with the ear in the way and all.
 
ANd Mead Killion at Etymotic said that though the Head Acoustics ear canal claims to be up to spec, nothing really is except a Zwisloky.  You'd have to ask him why he said that though, or wait til I learn more.
 

 

 

[udauda]

Quote:

It's just very hard to know that your insertion depth is correct on the head with the ear in the way and all.

It's absolutely true! Now if there's a way to take the ear out.. (so that you can use the coupler directly) You may get a new simulator; However, technically you're going to end up with 3 couplers in your possession. (2 from HATS + 1 from the simulator)
 
 
Quote:

ANd Mead Killion at Etymotic said that though the Head Acoustics ear canal claims to be up to spec, nothing really is except a Zwisloky.

HEAD Acoustics ear canal should be good enough. Dr.Killion should already know that, although the Zwislocki coupler is accurate as well, the current international standard in effect for an ear simulator is IEC 60318-4(formerly known as IEC 711) only.
 
From Impedance of Real and Artificial Ears, Per W. Brüel, 1976:

This is an average acoustic impedance curve measured from real ears, and ear simulators must simulate the response within the standard-specified tolerance up to 10kHz.
 
In his application note above, W. Brüel from B&K commented on the Zwislocki coupler: "By comparing the curves, it can be seen that there are rather large differences between the specimens[Zwislocki couplers], and none of them fits the design goal...the Zwislocki design seems unnecessarily complicated."
 
And Gunnar Rasmussen of G.R.A.S in Denmark came up with a simple coupler that meets the goal, and it was eventually selected as an international standard. Consequently, the Zwislocki coupler got discontinued when Knowles, the manufacturer of the Zwislocki coupler, sold its HATS system KEMAR to G.R.A.S. (I had a chance to contact Dr.Zwislocki, the inventor of the coupler some time ago, and he was not even aware his coupler was discontinued decades ago! I blame Knowles for this..

)
 
I recommend you to check out this page(German). You should be able to gather all the basic information regarding ear simulators.

 

[Tyll Hertsens]

Hi folks!!!  Packing the system into the van today for the trip to CanJam, and I just wanted to post some sample graphs of the test as it sits.
 
Here's the pdf of three headphones measured; and then an image of one page.
 

 
 
See you in Chicago!!!!  

 

[SP Wild]

Hi Tyll,
 
I have found that when I tap a headphone when on my ears and with no music playing I get a resonating tone.  This tone seems to correspond to the sound signature of the headphone.
 
http://www.head-fi.org/forum/thread/495039/resonant-frequency-of-four-phones-reviewed#post_6685680
 
I believe this explains how it is impossible to EQ a K701 to sound like a HD650 or vise verse, because one cannot EQ the inherent resonance of the phone chassis which contributes to attributes such as phasing staging and imaging.  Is this something you can look into some more?  I have no other phones available for me to test, or any measuring equipment.
 
Cheers.

 

[Shahrose]

Hey Tyll, when can we expect more of these measurements (for other headphones)? Great stuff.

 

[xnor]

Quote:

I believe this explains how it is impossible to EQ a K701 to sound like a HD650 or vise verse, because one cannot EQ the inherent resonance of the phone chassis which contributes to attributes such as phasing staging and imaging.  Is this something you can look into some more?  I have no other phones available for me to test, or any measuring equipment.
 
Cheers.

Heard of impulse response? K701 -> HD650 would be impossible, yes, but the other way around should be doable.

 

[SP Wild]

What is this impulse response you speak of?

 

[xnor]

"the impulse response describes the reaction of the system as a function of time", says Wikipedia. Want to find out more? Google it! 

 
 
Btw Tyll, that "Impulse Response" in your measurements should read "Step Response", shouldn't it?
 
edit: (step response)
 
k702

 
dt880-32:

 
 
edit 2: (impulse response)
 
k701:

 
 
hd650:

 
 
px100:

 

[SP Wild]

I have both these phones and tried eq'ing them to sound like each other.  Here's the problem - I can't replicate the large soundstage and fast transient response (rise time?) of the K701 through EQ, trying the other way around poses the same problem.

 

[xnor]

Eq will only give you the same tonal balance, that's why I mentioned impulse responses. The only problem is that you need reasonably decent equipment to capture them.

 

[odigg]

Tyll,
 
At CanJam your computer monitor was sitting on this big box that all your wires were going into.  I assume this was your digitizer?  Could you tell me the model number of it?  You have probably mentioned it in this thread but I have scanned through and did not find it.
 
Thanks.

 

[Pyriel0]

Any idea of when the pdf of all headphones measurements will be available for download? Also is there a link to how the compensation was done or is it in a post here and I just missed it?

 

[jcx]

Quote:

I have both these phones and tried eq'ing them to sound like each other.  Here's the problem - I can't replicate the large soundstage and fast transient response (rise time?) of the K701 through EQ, trying the other way around poses the same problem.

it should be possible to eq any reasonable LTI response with today's DSP horsepower - but not necessarily with a simple "graphic equalizer"
 
right up to the limits of the Linear and Time Invarient assumptions
 
Smyth SVS Realizer does it with in ear microphones
 
of course even the same headphone can be audibly different depending positioning on your head