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O2 Build Complete: Let the objective, subjective listening tests commence!

Discussion in 'Sound Science' started by cheapskateaudio, Oct 27, 2011.
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  1. khaos974


    Quote:

    The issue at hand is a matter of burden of proof, electrical laws have been proven beyond the shadow of a doubt countless of times in all engineering domains, acoustic thresholds have been studied very seriously by various institutions (medical universities, the AES, hundreds of PhD theses...), the body of evidence is quite (very) large. Likewise, the evidence regarding placebo effects and bias is there (people getting high with sugar water in a cocaine DBT for example).
     
    Outright dismissing subjective evidence isn't very scientific, as isn't outright dismissing a circuits designer's 'new and non measurement based' approach to accuracy, but considering the existing body of evidence it's up to them to make a substantiated claim for their subjective experience or design. If you are making an extraordinary claim that goes against the body of evidence, prove it, in multiple ways if possible.
     
    The usual way people are asked to prove their subjective experience is blind testing. well documented measurements is possible too, it's then necessary to confront those measurements to the known acoustic thresholds. If the claim is that the current set of measurements is incomplete or not appropriate for auditory impressions, the designer making the claim should come up with a new measurement, after all what can be heard, can be measured, it's only a matter of finding the criterion.
     
     
     
  2. Br777
    my responses in blue.
     
    Quote:


    Whether this guy is truly right or not, he is not the first to think so, and he wont be the last.  There are many many companies out there claiming to have created the ultimate, or one of the best, or know more than anyone else who have strong fanbases, and equally strong nay sayers.    People will either remain open, to other possibilities, or they wont.
     
     
  3. tomb
    And to think you were the one I was trying to help ... sheesh, no good deed ... but that's fine - go have fun!
     
  4. Head Injury
    You're welcome to provide evidence that refutes anything Voldemort has said.
     
    Or, y'know, you can just keep calling us wrong and leave it. I hope anyone reading has enough sense to realize that shouldn't be enough to hold any water.
     
  5. Br777


    Quote:

    i'm lost.. what just happened?
     
     


    Quote:



    are you talking to me or TOMB.. if you're talking to me, I'm lost again..
     
  6. Head Injury
    Quote:

    tomb. You hadn't posted yet when I started to reply.
     
  7. wakibaki
    tomb
     
    The Harry Potter stories are fantasy.
     
    Your characterization of Head-Fi as 'Griffindor' is not complementary, although it's accurate to a degree. That the forum could not tolerate a simple exposition of fact does not reflect well on it. It certainly does not reflect ill on the nwavguy, who has only expressed views which accord with those expressed throughout all electronics with the exception of the narrow world of hobby audio, to say nothing of professional audio and science in general.
     
    The way he was treated was tantamount to a witch hunt, but in this case (ironically) he was victimised because he doesn't believe in magic.
     
    The Harry Potter stories are charming (!) to a degree (although in my opinion less so than many others, for example Peter Green's 'The Last Unicorn'), but the willing suspension of disbelief must end when the book is closed. You need to emerge from the spell that audiophilia has woven about you, and turn to more adult and productive pastimes, lest you remain locked in an unchanging state in perpetuity.
     
    Of course, like many others, your vested interest may make it impossible for you to change your position, which would make you more to be pitied than despised.
     
    w
     
  8. Shike


    Quote:


    Help?  With what exactly, the sellers that perpetuate shoddy audio equipment?  Those that make poor DIY designs?
     
    You're telling a member here that there's TONS of different audio he should try based on an opinion that isn't backed by evidence but rather superstition at this point.  Furthermore, saying one should avoid this design because the designer was banned from Head-Fi doesn't really provide a good argument.  There's a very popular amp recommended on here regularly that I purchased that people didn't know was dangerous for headphones - another one of their designs killed two headphones that were over $2K each (which they refused accountability for).  Anyone remember Single Power too, MOT iirc with tons of love?  Or heck, how about an improperly wired component which was a fire hazard from yet another company that another member here had to catch?
     
    All of these were MOT, and active participants at Head-Fi.  Some still are, but are not the point of discussion.  This doesn't even include stuff that just plain measures bad sound wise, but actually improperly designed and built goods in mine and many others opinion.
     
     
    Basically, one's relation with head-fi is irrelevant - it is not a guarantee of quality or competency in the least.
     
  9. shadow419


    Quote:


    Whoops, forgot to post my results.  I'm using  Ternergy Low Self Discharge 200mah, with primarily Sennheiser HD 25-1 II's. Love these cans for what I listen to mostly without having to fear waking up my girlfriend.  [​IMG]
     
    1st Discharge : Popped the batteries in without charging first and ran till discharged.  I got the turn on / turn off cycle that initiated the BOM revision for different resistors at R9 and R25.
    2nd Discharge: After charging over night, ran it again till discharge.  This time the amp just stopped playing like just as described in the build notes.  
    3rd Discharge:  Same as the second.
     
    I'd say roughly 6.5-7 hours of play time before it just stops working.  Plenty for me in the few situations I'd use it away from home.
     
    Btw put together my second one, and she's a beauty.
     
    dcfn00022.jpg dcfn00073.jpg
     
  10. PelPix
    Is that an O2 with RCA ins and 1/4 outs?
     
  11. shadow419


    Quote:


    Yarr matey!  The 3.5mm in/out also work, although I wouldn't connect two headphones or sources at the same time.  Just have to wire the in/out to the pads on the board, and cut 2 small traces that mute the input if the 3.5mm jack isn't plugged in.  The only pia was the volume pot since it's still a through hole pot with tiny pins vs lugs.  Not really that hard but I'm not a soldering virtuoso by any means.
     
  12. Anaxilus


    Quote:

    Dynamics and inner resolution.  Also it's treble is a just a touch harsh or tizzy for one thing even w/o the HD800.  Yes it measures flat, many things do that don't sound the same, there is a tonal quality or presentation beyond that single metric.  Warmer phones that might not be as uber-critically resolving seemed a better match for it by my listening.  It's a solid piece of kit don't get me wrong.  YMMV.
     
  13. mikeaj
    I hate to say this, since this is a very uncharitable statement for this season...but sometimes I think that all the people who have all the opportunity to learn and choose to spit in the face of science and engineering findings and principles, have forfeited their right to use the results of modern medicine and technology, including computers and headphones, and all that.  To me, one of the great characteristics about modern technological advances is that you don't need to understand them to be able to use them.  Therefore, they can improve the lives of everybody.  We don't all have to be hunter-gatherers anymore, where nobody has any significant specialization.  Ignorance is fine; we're all here to help each other out and discuss and teach new things.  I just don't appreciate willful stupidity (and this comment is not directed at tomb or any particular recent poster here).
     
    Anybody have a list of papers disproving currently-established thresholds of audibility, or in the very least, their own tests with the very minimum of experimental controls applied?  Models can be wrong, even for fitting existing data points.  But there's a long way to go, to accept some arguments as more than hot air.
     
     
    Anyway, it's not like we've come to the end of a road.  I'm still waiting to see more amps--DIY or not--at lower costs and with legitimate published specifications, with smaller size, longer battery life, less EMI susceptibility, more output for HE-6 / vintage K240 / whatever, tone controls, and so on.  Of course, I'm not expecting all those features in the same amp, since that would have to be magic.  How many low-priced amps have a knob for adding warmth (increasing the second order harmonic distortion and whatever else you think is appropriate here)?
     
  14. Br777


    Quote:



    This is what I'm really interested in learning more about.  Are there measurements that can make these distinctions?
    If not, how is this established as more than just someone's imagination.
     
    I'm not saying this b/c i dont believe it, I really am curious.
     
     
  15. Willakan
     
    Regarding tonality, there is slightly more to it that just FR, but nothing hugely complicated - and frequency response tells most of the story. Distortion can make a contribution, not to mention output impedance (as it is often not documented and has a huge and measurable effect on FR). Indeed, the lack of documentation for many specs means that it can be difficult to make a call about something's performance without hearing it (Blind, of course!).
    In the wonderful cases where performance is fully detailed into a variety of loads, it saves me the bother. If I don't like the sound, I can always EQ it: but I know I have a perfectly accurate starting point, as far as my ears are concerned.
     
    As for the calls to realise what "real DIYing" is about...
     
    Be afraid, Br777, for we lead you astray into the dark realms of science, logic and verifiable claims! Abandon hope for expensive cable improvements all thee who enter here!
     
    Okay, I'm taking the pee; the audio DIY community at large, is, however, much less science orientated, for much the same reasons the audiophile community is. There are people agonising over 50ps of jitter, there are people pulling out coupling caps out of gear with perfectly good FR and phase response and claiming miraculous changes to the soundstage, there are people earnestly discussing the sound signatures of capacitors (I know badly-chosen coupling caps can have an audible effect, but this effect is big, measurable and not too difficult to mitigate with different caps - the crap about airiness and PRAT is, well, crap) and people shoving their favourite opamps into circuits that they weren't designed for, with no way of verifying whether the opamp is even happy, and claiming all kinds of ridiculous improvements.
     
    If you want to buy into that, fine. Most do: after all, surely all these people must be right?
     
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