[Julez]

For those who are interessted in frequency curves.
I have three curves measured with "Monkey Forest"
and a "Head Acoustics" standard dummyhead.
It's just one position no average over 5 Positions
as it is usual. They are only useful to compare with
each other not measurements done by other people.
But you can get a rough idea of what requency
response these headphones have.
Unfortunatly screenprint does not cover the units of the
frequency axis! But frequency units should be obvious.
 
https://www.dropbox.com/s/0maze953skqg8y5/Stax%20Freq%20Curve.rar
 
(Why are pics not showing up in my post?????? How is this done????)

 

[MLudovic]

Yeah definitely interested in that kind of data, I wish I have my own dummyhead to measure my SR-3 and SR-404. Working by ear gives good results but fine tuning can't be done with blind adjustments. On your curves btw the difficulty of getting a good acoustic seal is visible, with the typical bump in the bass region.
 
To directly share picture you can upload them on the forum or on an external site and enter the link here (ex : http://imgur.com/)

 

[Julez]

Thanks for the hint about the pictures!
Yes that is from the bad sealing. It is not my dummyhead. It is the dummyhead of
my university. Therefore I'm not able anymore to measure them. But because I wear
glasses it matches what I'm hearing very well (that cool bassboost effect with glasses

)!

 

[MLudovic]

Julez do you still have the impulse files of your headphones measurements? Even if I've found a great tool to extract data from images, getting the source files is much more reliable.
 
By the way, did you made other measurements with your university gear?

 

[Julez]

Yes. What I really measured for my bachelor thesis where
HRTFs of 30 people to make a study about perception of
direction with full HRTFs and with lowpassed HRTFs (8kHz)
for a study on how to generalize HRTFs and what frequency
area is sufficient to represent spatial hearing with good results 
compared to hearing with the originals.

 

[MLudovic]

Very interesting! When trying to understand the whole HRTF concept I came across this document : http://hal.archives-ouvertes.fr/docs/00/55/11/45/PDF/000431.pdf. In short they tried to create personalized HRTFs from photo of ears... 

 

[Julez]

Interesting Paper! Unfortunately I don't speak French.
There's a paper from Møller et al 1995 on that HRTF
subject. I think it's a good start. I did start with this
paper and the book Auralization by Michael Vorländer 
to prepare my bachelor thesis.

 

[Jonathan66100]

Very interesting
This would be the ultimate solution to reproduce a 3D sound with the picture of our own ear.
Ludovic, for your curve 207 has a nice effect "out of the lead" ! 
I recommend to everyone who have a 207 to try.

 

[MLudovic]

Julez, here is a similar paper in english : http://hal.inria.fr/docs/00/60/68/14/PDF/PG08_Reconstructing_head.pdf
 
The whole HAL website is full of scientific publications and thesis, for example searching for "binaural" gives a lot of entries : =%40%2A&v[0]=binaural&orderby=DATEPROD&ascdesc=DESC&begin_at=0]http://hal.archives-ouvertes.fr/index.php?halsid=44aqi83mvih5bfm8ulipqmec12&action_todo=search&submit=1&s_type=simple&f[0]=%40%2A&v[0]=binaural&orderby=DATEPROD&ascdesc=DESC&begin_at=0
 
Wonderful amount of reading material!
 
Jonathan : Glad you like it, feel free to tweak it with rephase to make it match your own taste. I think I'm gonna go ahead and make EQ+DF curves for the other Stax models too.
 
Any requests ?

 

[Jonathan66100]

Hi Ludovic and Julez, it's me again : ) 
I would not be against a ".rephase" for the Stax SR-Sigma ( no Pro ) : ) .
The curve of 207 is very interesting : ) 
 
and have you seen this ?
 
http://www.ebay.co.uk/itm/HEAD-acoustics-HPS-I-Binaural-STAX-SD-Lambda-Pro-Electrostatic-Amplfier-/181216412772?pt=UK_AudioVisualElectronics_HomeAudioHiFi_Headphones&hash=item2a31570464
 
it's very strange !
 
 
http://www.head-acoustics.de/eng/index.htm

 

[DefQon]

Somebody please buy that reproduction system and report back on there findings.

 

[Jonathan66100]

Prices of new products of head-acoustics are expensive but they work on a large public product, and it is possible to have your customized morphology impulse file in . Wav to be able add this one eg at convolution plugin of Foobar and thus totally eliminate their equipment, the person I got on the phone (very professional and very friendly) even proposed me an appointment to see what it is, and may be offering me reasonable price for take my HRTF I could then theoretically used this one with Foobar. if I take an appointment I'll let you know.

 

[Julez]

Hi Jonathan thanks for the interesting link to the Head Acoustics HPSI!
 
I know this company since I used their equipment during my bachelor thesis.
I used the HPS IV power amp (three models later) with the PEQV preamp/
digital eq. Here's a picture of the setup with Monkey Forrest in the background:
http://www.head-fi.org/g/i/932632/a/805627/head-acoustics-stax-sr-303-reference-system/sort/display_order/
As far as I have understood from the manuals the HPS IV is just an poweramp
without volume control. You need the PEQ V for volume control. The HPS IV 
is calibrated with/for a one specific Stax headphone by the company itselve.
The calibration is about exact volume match (I saw the certificate) up to a
100th of a dB between the channels. In this case as you can see for a SR-303.
Now they told me that they use 307 and 407 when I was asking what phones
they use now. The price for a PEQ V + HPS IV + 307 combination is about
6500 Euro.

 1) PEQ V 3.193,00 € 2) PVA IV.3 2.730,00 € 3) HA III 659,00 €

The PEQ V is for manipulating the frequency response. There are several
eqs: for diffusefield(ISO), freefield (ISO), for ID (identity curve) flat and user.
There is also a button called filter. That is for a better perception of sound
(I don't know how to better describe). It does this and is called subjective filter:
http://www.head-fi.org/g/i/932648/a/805627/head-acoustics-stax-sr-303-reference-system/sort/display_order/
 
Each PEQ V is again calibrated for a specific headphone as you can see
on the photo. If you zoom in you can see the matching serialnumbers on
the PEQ V and HPS IV.
 
Now to the important part: Yes I took my own Stax headphones (007MKI
and Sigma) with me to test it with the Head Acoustics setup.
I must say it's a good amp but all the features are overkill (like calibrated
volume for audibility tests etc.). A SRM-717/727 is better to use I think. First in
usability and second soundwise not really worse and a LOT cheaper. I would
not recommend that amp without a proper preamp due to lack of volume control.
But the most interesting thing about this system is that ability if you need it
for scientific research (like in sound desing of cars etc).
 
 
 
I hope I could help.

 

[Jonathan66100]

Hi Juelz.
Yes head-acoustic is mainly for the scientific and commercial research.
thank for your detail about their products.
 
You think that taking a HRTF come back at equalize the volumes with equalizer or is it more complicated than that ?
if it's just a equalization of volumes by reports our ears and our body, I could try to get a capture with http://www.head-acoustics.de/eng/nvh_bhs_II.htm and http://www.head-acoustics.de/eng/nvh_squadriga_II.htm and then equalizes the volume level with Windows by coping my equalization of my HRTF, and thus enjoy with my games, my musics and my movies.

 

[arnaud]

AFAIK, head-acoustics specializes in binaural recording and reproduction at actual levels for people doing sound quality evaluation of products.

E.g., it's more about playback of a recording at the passenger seat of a vehicle under driving conditions at the correct loudness level and with reasonably accurate binaural cues than trying to create the most realistic auralization like what the smyth brothers are after with the realiser and personalized hrtfs.

As such, I am actually surprised HA are proposing their services for acquiring hrtfs.