KOSS ESP-950 Thread

[jude]

  You can't expect to derive anything out of comparing FR of two headphones from two separate measurement archives (different equipment/compensations)...

Purrin and Tyll use totally different measurement techniques and apply totally different compensation curves. It is absolutely pointless to cross-compare them...

 
This is an oft-overlooked discussion, the comparison of headphone measurements made by different people with different setups. As catscratch said, it can make measurements made with different systems rather challenging to compare.
 
For example, Tyll Hertsens (Editor-In-Chief of Innerfidelity), as he describes here, uses a measurement head (the Head Acoustics HMS II.3). It is one of the industry standard tools for measurement. From that link above, you can read about Tyll's complete measurement system, including the acoustic isolation chamber he custom-built, the Audio Precision System 2 Cascade audio tester, and other components of his setup (and his methodology). Here are photos of his setup that he posted in that article (click the images below to see them in full size):
 
 
 
In one of the more recent headphone studies presented at AES by Sean Olive (Director Acoustic Research at Harman International and President-Elect at AES) and Todd Welti (Research Acoustician at Harman International), measurements were made using a G.R.A.S. 43AG Ear and Cheek simulator equipped with an ITU-T type 3.3 pinna. (More specific details can be found in the full paper--Convention Paper 8744--on the AES website.) Again, the G.R.A.S. piece and pinna is another industry standard measurement setup. Here are photos of the G.R.A.S., both without and with a ear/cheek affixed (click the images below to see them in full size):
 
 
 
Keith Howard in Stereophile also mentions that he uses a G.R.A.S. ear and cheek simulator; Brent Butterworth of Sound And Vision also uses a G.R.A.S. device.
 
I've been to several headphone manufacturer facilities, and have seen gear similar to the above-mentioned equipment in them (heads, head-and-torsos, and devices like the G.R.A.S. devices).
 
On the more homegrown fronts, purrin and Rin Choi have created their own setups.
 
purrin has elected not to use a dummy head or, to the best of my knowledge, a pinna. I'm not sure that his measurement system was ever discussed in great detail. When asked about his measurement system on Head-Fi, purrin called his coupler "semi-secret." (link)  During a discussion at the Newport Beach audio show last year, when asked (on video) which coupler he uses (link), purrin (Marvin Chen on the video) responded: "I'm actually not using a dummy head. The reason is I actually did try a dummy head and there's some issues with that. With dummy heads you've got the ears, and the really good ones have got the tubes in them, and those create some specific resonances, that...don't necessarily represent what we hear. If I were to do a CSD measurement with one of those couplers, there would be resonances that are inherent to the human auditory system which I feel that the brain filters out. So what I actually did was I built a custom coupler. Essentially, what it does...it tries to minimize the effects of the ear, the ear canal, while at the same time try to be realistic of what we actually hear."
 
Here are photos of purrin's custom coupler setup (click the images below to see them in full size):
 
   

 
Rin Choi (who goes by udauda on Head-Fi) created his own dummy head that he named EURI (photos below). It is covered in a latex skin to "effectively simulate the damping effect of a human skin & insulate any acoustic leakage between the pinna simulators & the head itself." Inside of EURI can be found IEC 60318-4 occluded ear simulators. On his website, it seems to me that Rin is shooting for using industry standards (in terms of methods and gear), and, with his own measurements, compares his EURI head to commercial alternatives.
 
Here are photos of Rin's EURI head and the 60318-4 occluded ear simulator (click the images below to see them in full size):
 
 
 
Again, the measurement setups and methodologies can differ substantially from measurer to measurer. Some use more industry standard equipment and methodologies; still others claim to sidestep industry standards for individual reasons and/or claims of more accurate measurement results. So, as was stated earlier, it can be tough to make meaningful comparisons of measurements between the results of the different providers of them.


 

...The ESP 950 is definitely one of the headphones to beat, though probably not the only one...

 
I absolutely agree with you, catscratch. I've spent more and more time with the Koss ESP-950 recently, and it is absolutely one of my top headphone recommendations even at its retail price of $999.99. Of course, if you find a better price than that, its value only increases.
 
FlySweep seems to also like the ESP-950, but, like you, catscratch, I'm certainly more enamored of the ESP-950 (than FlySweep)--however, I certainly agree with FlySweep's statement that the ESP-950's midrange is "liquid."

 

[ultrabike]

Well. If one reads Stereophile, their review on the Grado HP 1 features the following disclosure about their measurements:
 
"Measuring headphones is fraught with practical problems, mainly due to the fact that the target response for a drive-unit that fires straight into the ear canal is anything but flat, given the frequency-response–modifying natures of the pinnae and inner ear canal which are unique for each person. Fig.1, extracted from an excellent 1980 AES paper (footnote 1) from Audio Contributing Editor Jon Sank, shows the envelope of responses he found desirable for conventional headphones to sound flat. For this review, I measured the responses of the headphones both in free space, with a B&K/DPA 4006 ½" microphone approximately 1" away, and pushed against a flat wooden baffle by a G-clamp with the same mike set flush. Neither situation duplicates the environment faced by a headphone forced against the head and firing into the ear canal. In addition, the ½" microphone capsule is not that much smaller than the headphone drive-units, and would thus be expected to influence the local acoustic. Nevertheless, as I regard review measurements as primarily providing support for the listening comments, I felt it sufficient to use a setup that would produce relative, rather than absolute, data. The following curves should be viewed in this light."

"Fig.2 Grado HP 1, anechoic frequency response in free space (blue) and against baffle (red)."
 
"Fig.2 shows how the Grado HP 1's free-space response (blue trace) is modified by the baffle (red trace). The exact degree of upper-bass boost and LF extension will be affected by the pressure with which the headphone is held against the baffle. Nevertheless, the HP 1 offers a generous bass response, with usable extension to a low 30Hz, with a bright treble presentation. Note also the generally exaggerated lower midrange, which correlates with the HP 1's warm tonal balance and which will also contribute to the subjectively rather depressed top octaves."
 

"Fig.5 Grado HP 1, cumulative spectral decay plot in free space."
 
"The associated cumulative spectral-decay or "waterfall" plot (fig.5) shows three residual resonances at 3kHz, 10kHz, and 24kHz, though these are mild in degree. No wonder the Grados sounded smooth—this is one well-behaved diaphragm!"
 
There was no associated dummy head or fake ear to extract the associated CSD plots in the Stereophile publication. Instead, a free space measurement was used, which might have correlated better to what JA heard.
 
I believe, perhaps erroneously, that just as with speakers, headphones should be measured either by compensating using as reference a "flat" speaker, or by using an "anechoic" plate which might approximately offer the necessary acoustic impedance of a flat wooden baffle, and the properties of a free space response.
 
I also highly respect the efforts or Tyll and GoldenEar, and do use their measurements relative to their own measurements, and relative to my own perception.
 
---
 
EDIT: Some of these issues have been discussed here:
 
http://www.head-fi.org/t/641860/hrtf-and-binaural-measurements-of-sennheiser-hd650-hd700-akg-k550
 
and it seems a related AES paper about this is in the works:
 
http://www.head-fi.org/t/632286/aes-2012-paper-relationship-between-perception-and-measurement-of-headphone-sound-quality/60#post_9381888
 
http://www.aes.org/events/134/papers/?ID=3474
 
---
 
BTW, IMO of course, I also like the ESP-950 quite a bit though it's a little rolled at the edges and might benefit from a brighter amplifier than the one supplied.

 

[anetode]

Bass extension is a tricky thing to measure as it can be notoriously fit-dependent, so couplers which mimic normal ear anatomy and use a skin analog often have the edge in accurately portraying response. Even then you have to account for the type of pad (material/porosity) and its relative wear, as well as the clamping force. Unfortunately the plastic construction of the ESP-950 doesn't lend too well to fit adjustment, nor are its pads of particularly high quality. Here stax has the edge.

 

[ultrabike]

Quote:

Bass extension is a tricky thing to measure as it can be notoriously fit-dependent, so couplers which mimic normal ear anatomy and use a skin analog often have the edge in accurately portraying response. Even then you have to account for the type of pad (material/porosity) and its relative wear, as well as the clamping force. Unfortunately the plastic construction of the ESP-950 doesn't lend too well to fit adjustment, nor are its pads of particularly high quality. Here stax has the edge.

 
Possible. The ESP-950 is an open back headphone. Not saying fit doesn't affect open back headphones, but I believe fit/seal might be more of a problem with sealed cans (perception and measurement wise.) For measurements, I think one can modify the "anechoic" baffle to provide better seal, maybe by adding a silicon liner or the likes where the hp pads makes contact with the baffle. Not saying that is the "best" way, but it seems to give "decent" results...

 

[anetode]

Quote:

 
This is an oft-overlooked discussion, the comparison of headphone measurements made by different people with different setups. As catscratch said, it can make measurements made with different systems rather challenging to compare.
 
For example,
 
...
 
Again, the measurement setups and methodologies can differ substantially from measurer to measurer. Some use more industry standard equipment and methodologies; still others claim to sidestep industry standards for individual reasons and/or claims of more accurate measurement results. So, as was stated earlier, it can be tough to make meaningful comparisons of measurements between the results of the different providers of them.

 
& then there's Paul Barton & Mike Stinson's measurement system teased at that RMAF panel you might be familiar with

 

[anetode]

Quote:

 
Possible. I believe that is more of a problem with sealed cans though. I think one can modify the "anechoic" baffle to provide better seal, maybe by using a silicon liner or the likes of it. Not saying that is the "best" way, but it seems to give "decent" results...

Decent results - definitely, provided proper baffle material/setup. However given the range of variability (including my own meager couple of attempts from a couple years back) I wouldn't say that it's ideal.
 
 
BTW, ultrabike & vid also deserve recognition for their recent contributions to the wealth of hobbyist measurements

 

[ultrabike]

Quote:

Decent results - definitely, provided proper baffle material/setup. However given the range of variability (including my own meager couple of attempts from a couple years back) I wouldn't say that it's ideal.
 
 
BTW, ultrabike & vid also deserve recognition for their recent contributions to the wealth of hobbyist measurements

 
Thanks mang!

 

[aj-kun]

Can you do a head-fi TV esp-950 segment jude?

 

[Operakid]

Quote:

I'll jump in about a few posts on the last page.
 
I think the 950s sound like stats in that they are quick, clear, delicate, and airy.  While they don't have the treble energy of the 407s being talked about, the treble is light, airy, delicate, like stats seem to do.  In some ways I think the stat sound can be on the lightish, airy side compared to real music, so "stat sound" to me can mean both good things but also a type of deviation from real music.  On both scores the 950 show their stat design to my ears.  I own many headphones of all types, including HD800, and I would never confuse the Koss with a dynamic headphone.  
 
As far as confusing the 950 with orthos / magnetic planar, I still think the 950 sound like stats, not orthos.
 
Comparing the Stax 407 to the 950, the 950 are "brighter"  and that can mean a good or not so good thing, depending on your tastes and ear sensitivity.  In some ways I like the 407 better, some ways I like the 950 better, but the 950 are easier on my ears, which are sensitive to harshness.  Not saying the 407 are harsh, but can be harsher than 950 or Stax -009.  
 
I still like my LCD-3 better than all of them when considering musicality, detail, dynamics, ease of listening, bass response all wrapped together.

SORRY!  Huge mistake! in my above post.  I meant "the 407 are brighter"!  I hope when I later said "the 950 are easier on my ears" it became clear that I mixed up the prior sentence when I said the 950 are brighter.  No way, the 950 are not bright at all IMO.  

 

[Mad Lust Envy]

Lol, true that. My point exactly, the 950 is a very well behaved, smooth, well balanced headphone. A little more polite and soft hitting, but it's simply elegant. Classy sound, even.

 

[Gary in MD]

Quote:

 
I'd place the blame with the E.90 here.  It can swing a lot of voltage but nobody ever said it did that well or had enough current to back it up under real conditions. 

Yes, but the E-90 has the major advantage of coming with the headphones, and it sounds good enough if not pushed too hard. 
 
On the other hand, I'd love to hear what the ESPs sound like with a Stax amp or any better amp... care to loan me one for a demo?  I promise to send it back after a few weeks with no dings or dents... Please?  I'll even write a nice review if I like it...  Pretty please?

 

[Operakid]

Elegant and classy is a nice way to put it, true.  And folks should be aware it's not like they don't have hit.  Lighter than some, but they have some punch.
 
I've bought a lot of headphones, way more expensive than the 950, and I love my LCD-3, but will not part with the Koss 950.    

 

[Mad Lust Envy]

To me, the only real problem I have with them is that they just fit too loosely. If they had some standard clamp, I think I would've fallen deeper in love with them.

 

[spritzer]

Quote:

Yes, but the E-90 has the major advantage of coming with the headphones, and it sounds good enough if not pushed too hard. 
 
On the other hand, I'd love to hear what the ESPs sound like with a Stax amp or any better amp... care to loan me one for a demo?  I promise to send it back after a few weeks with no dings or dents... Please?  I'll even write a nice review if I like it...  Pretty please?

 
That would cost 300$ is shipping alone so not really worth the effort. 

 

[Gary in MD]

Quote:

 
That would cost 300$ is shipping alone so not really worth the effort. 

Yeah, I figured it would be pricey, but hey, it never hurts to ask!  I guess I'll just have to suffer with the stock amp.  Not really suffering though. 
 
At some point I might try finding a used Stax amp around here, but that'll have to wait a while, since I'm still working on an amp for the LCD-3s, and I'm not gonna go crazy with headphone equipment this year like I did last year.  One nice toy per calendar year, and that's it.  At least for now.  I think.  Well, maybe if the right deal came along.  Arrgh!!! Must... Not... Give... In.. To... Desire... For... More... Toys...