One Day Ticket for Stax Galaxy - The STAX Compendium

Discussion in 'Headphone Measurements' started by sorrodje, Apr 27, 2016.

  1. ultrabike

    ultrabike Measurbator - Admin

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    Yes. I would leave the measurements w their flaws and make sure readers understand couplers used are not perfect.

    I hope at some point research in headphone measurement will attempt to tackle coupler-driver interactions.

    Anyhow. Great discussion and good point about SNR.
     
    Last edited: Apr 27, 2016
  2. Serious

    Serious Inquisitive Frequency Response Plot

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    @sorrodje
    lol, I simply wanted to mention that the distortion is so low that the S/N ratio of the mics we use (typically self noise is around 30dbA) will dominate it, at least for D3 and D4. What you wrote mainly concerned the ringing in the CSDs which is caused by the coupler - as you have mentioned. Basically what you said
    is 1000% true.


    @ultrabike
    The dips in FR are indeed a coupler issue (as you said - this can be confirmed by listening to sweeps). The resulting "distortion" however is simply the noise floor of the measurement system. When a headphone has a falling treble response, the S/N ratio of the measurements also decreases as frequency increases. This makes the "distortion" higher at higher frequencies (lower S/N ratio) - compare the SR009 measurements to the Lamdba measurements. The graphs with distortion and FR let us easily seperate the noise from actual distortion, unlike those distortion in % graphs (I think the distortion in % make more sense and are easier to compare but you should keep in mind that it could very well be noise).
    Basically, a higher S/N ratio of the measurement equipment could get rid of both the distortion spikes and the rising distortion at higher frequencies. Measuring in free air could get rid of the dips, but as long as the rest of the FR stays the same (it won't, it will be much flatter - see @OJneg's L700 graphs), it will not get rid of the slope at higher frequencies.

    Look at this graph for the SR-Omega:
    omegfa8.jpg
    Measured at 100db at 1kHz - the 2nd order distortion is at less than 40db throughout most of the audio range. This was measured with a B&K 4134 mic (in a 4153 ear simulator), which is rated at 18dbA thermal noise or a 5db 1/3rd octave noise level at 1kHz (http://www.bksv.com/doc/Bp0100.pdf). A 66db signal to D2 ratio would equal 0.05% of distortion.

    I think someone at Sennheiser once mentioned that they measured the SR009 and the HE90 still has lower distortion - I would be very interested in seeing those plots.

    All this talk about distortion doesn't really make sense - what really matters are @sorrodje's subjective impressions.

    EDIT: Updating this post as I don't want to derail the thread:
    Actually, the fact that the distortion significantly decreases as the signal level at the microphone decreases tells me that this (mic+preamp distortion) may vey well be the case (Almot all of the measurements show a decrease in D2 from 1kHz on, corresponding to the FR).
    I get the same problem with my WM61-A mic and my preamp. There are ways to minimize this (look at this: http://www.johncon.com/john/wm61a/). I doubt that the cheap measurement mics (I also have a DBX RTA-M, which had slightly lower distortion at higher levels than the WM61-A + preamp config I am using now, but similar self noise - both are 1/4th inch capsules after all) are much better than the WM61-A. A good 1/2 inch micophone capsule would be preferred but the capsules alone cost hundreds of dollars. From a price/performance perspective I'm quite happy with the 2$ WM61-A.
    Also, amp distortion also plays a role in stat measurements. This obviously depends on the amp. Ideally measurements should be compensated for this, or atleast amp distortion at the measurement level should be given. This is also very hard at the level we're measuring at. One thing we can tell for sure is that all of these STAX headphones are super low in distortion.
    Look at Tyll's measurements. Even his measurements benefitted from the use of the KGSS, either due to lower amp distortion, or lower amp noise (hard to tell, as even his stat measurements seem mostly limited by noise).

    I would actually argue that flat coupler measurements are by definition more accurate at capturing certain things. I like to refer to the beginning of this video ( T.H.E SHOW 2012 Headphone Panel Part 2 of 2 ) by @purrin. I really like the flat coupler measurements and they are a great help for the community.

    300-400$ for an entry level stax system is nuts.
     
    Last edited: Apr 29, 2016
  3. purr1n

    purr1n Finding his inner redneck

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    This is THE definitive STAX compendium, with the measurements and commentary.
     
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  4. sorrodje

    sorrodje Carla Bruni's other lover - Friend

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    Thks for all positive comments. it helps to keep motivation and propose new contents. And I have some ideas for you guys. ;)

    Next Steps :

    - Will add Links to UB's measurements in the first post
    - I'll add my comments and impressions in addition to Ali-Pacha's
    - I'll add old SR-507 measurements I have somewhere. I know I have neighbours with Lambda pro and SR-507. So maybe I'll ask them if I can visit them with my computer and my mic.
    - I hope to be able to measure and hear more Stax headphones and I'll add them in this thread.

    @purrin , @ultrabike and others definitely had a stellar idea when they opted for the flat coupler for measurements. With little money and some experiments, it's quite easy to build a rig and propose some reliable measurements that could be compared to other measurements from similar rigs ( for example UB's and mine in the present case) . it allows us to bring a measurement rig everywhere in a simple bag. Compared to classic measurements system for sure , we're maybe not as accurate and precise but at least , it somewhat democratizes measurements so it helps to bring more light into this hobby and fight against obscurantism. The fact we all have similar results allow us to act as a community. In my book, those are stellar achievements from CS and now SBAF community.

    The most important thing I'm proud of in this thread is to show how a lot of Stax headphones , including old ones deserve much more praise than they actually receive. An old Lambda Normal Bias + a SRD7 is around 300/400$, maybe less. It trounces shitloads of multibuck headphone rig. Hands down. Stax are not only luxury headphones for rich people. @Ali-Pacha is there to prove it. He's not rich by any means but Stax is a part of his life since he was kid. He was babied with HD600 and Stax.. should make sense for a bunch of us.
     
    Last edited: Apr 28, 2016
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  5. aufmerksam

    aufmerksam Friend

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    As someone who is still approx. 5 years from plunging into staxland, this thread is amazing and helpful. Thank you for putting this all in one place, and not being arrogant pricks mafiosos arrogant pricks about it.
     
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  6. DrForBin

    DrForBin Friend

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    hello,

    kudos to @sorrodje and @Ali-Pacha, this is a marvelous thread, thoughtful, informative and user friendly.

    makes me want STAX more than ever! :bow:
     
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  7. Ali-Pacha

    Ali-Pacha Friend

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  8. Arnaud

    Arnaud Almost "Made"

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    I am ruining the value of the liking system, I think I nearly applauded every posts lol :). Awesome job sorrodje, you just got talent to find interesting things to do and post ! Ali, you're a precious item in the stax community, I hope you get your well deserved bhse soon ;-).
    Speaking of which, mine died again yesterday, and it's not looking good this time around (keep blowing fuses after the delayed relay kicks in...). Trying to work it out with Justin but I think I am back to that unsold 727 amp through the summer :-(((. Actually, that will get me motivated to do the feedback mod, did you do it by yourself ali?
    Cheers, arnaud
     
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  9. Ali-Pacha

    Ali-Pacha Friend

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    BHSE and soon...mmmh, doesn't compute, Arnaud :p
    Anyway, three times the BHSE, one time the TotalDac, looks like something is definitely rotten in your house's power grid :drunk:
    Speaking of the mod, I had it done by a guy in Germany who has some knowledge in Stax amps...whenever you have soldering skills, it should be easy. Don't forget to adjust balance / offset with TVR1/TVR2 pots (the small white ones on the boards : http://www.head-fi.org/a/adjusting-bias-on-stax-tube-amplifiers ), it's the same procedure as the one shown by Justin in his BHSE video.

    Ali
     
  10. evanft

    evanft Acquaintance

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    This reminds me that I really need to hear a well done Stax set up.
     
  11. ultrabike

    ultrabike Measurbator - Admin

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    It seems peaks in distortion levels in % plots may indeed be artifacts of reference levels. Here are distortion measurements in absolute dBs.

    I should have done more averaging to make sure that distortion measurements are not limited by noise in the measurement equipment. However I think @sorrodje distortion measurements may provide some leads to this if displayed in absolute levels.

    SR-009 Distortion (Absolute Levels)

    Right

    SR009_dist_abs_right.png

    Left

    SR307_dist_abs_left.png

    SR-307 Distortion (Absolute Levels)

    Right

    SR307_dist_abs_right.png

    Left

    SR307_dist_abs_left.png
     

    Attached Files:

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  12. sorrodje

    sorrodje Carla Bruni's other lover - Friend

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    @ulltrabike:

    SR009

    SR009_Disto_DB_SPL_L.jpg

    SR009_Disto_DB_SPL_R.jpg


    SR507
    SR507_Disto_DBSPL.jpg
     
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  13. Arnaud

    Arnaud Almost "Made"

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    BHSE is back in business. :D. Turns out the issue was with the fast blow fuses in there. I am pretty sure Justin sent me slow blow fuses when he shipped the replacement IEC block, I am not sure why they lasted so long. It's singing again, hopefully it will last... Also, quick comparison to HD800S (driven from headphone out of my D1-six): amazing soundstage but treble bit too hot for me still. Works on some music but piano still sounds too bright to me, kind of like having the head stuck between the board and the strings. Regardless, that's a pretty amazing sound out of dynamic driver.
    arnaud
     
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  14. Ali-Pacha

    Ali-Pacha Friend

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    Glad to hear it Arnaud |\/|
    But hey, the rule here is : no BS-endless comparison HD800/Stax à-la-head-fi :p

    Ali
     
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  15. sorrodje

    sorrodje Carla Bruni's other lover - Friend

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  16. Serious

    Serious Inquisitive Frequency Response Plot

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    @sorrodje
    Distortion does indeed look limited by the measurement rig. Moved that discussion to this thread, to clear the noise from this thread.
     
  17. Arnaud

    Arnaud Almost "Made"

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    I am just an acquaintance over here ali, don't suite know the rules, my bad ... ;-)
     
  18. uncola

    uncola Friend

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    Fifty lashes with a nordost valhalla cable for Arnaud
     
  19. JK47

    JK47 The Beer Houdini

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    I picked up my Lambda Pro Bias headphones and SRD-7 mk2 adapter this morning from the post office. I had a new set of 507 leather pads waiting in the wings. The Pros's ebay pics showed the foam rotted away and the old pads in poor shape. I'm pleasantly surprised by the sound, even with the old pads. The headphones and adapter performance wise are a fantastic value,

    Old pads
    Lamda Pro Moldy.jpg

    New pads
    New pads.jpg
    DSC_0227.JPG
    I'm also using the the CA 640A speaker taps to run my other balanced headphones (HD800SD, HD650 modded, LCD2 2016 drivers), with great results, and yes, Gungnir Multibit's canon is fully functional. Loaded with black powder and a standard BB, it will shatter beer bottles ;)
     
    Last edited: Dec 7, 2016
  20. cocolinho

    cocolinho Acquaintance

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    I sent my L700 to Sorro for measurements. A nice set to add to this compendium I guess :D
     
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