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Review: NwAvGuy's O2 DIY Amplifier

Discussion in 'Sound Science' started by shike, Aug 25, 2011.
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  1. zzffnn


    Quote:
    My comparison was not volume matched by ear. It was done by a sound pressure meter with headphones(LCD2s) cup fully enclosed around the meter. I actually gave O2 around 1-2db more than Beta22, because I wanted O2 to win my ears over and save my money. It did not.
     
    My comparison was sight by my wife, dogs and kids..... Seriously though, are you saying all audio impressions have to be done in your objective way? How many existing Headfi reviews were conducted that way (how many even bothered to use a db meter like I did)? So any review that was not done that way can not provide any useful information?
     
    Ok, I give up. People, if you believe these people who have not even heard both Beta22 and O2 side by side, go ahead.
     
    Search "beta 22" within this thread, and you will see that most if not all actual owners of Beta22 perceived a difference between Beta22 and O2. Feel free to not believe an actual owner's impression and believe those who SPECULATE based on specs and graphs. I hope you will enjoy your music more that way. And by the way, give your review in a subjective scientific manner or it is wrong.
     
  2. LizardKing1
    Of course your input is valuable, since you actually own both of the amps being discussed. And of course you taking the time to use an SPL meter helps. No, it's not absolutely required to make a double-blind test or volume matching in every review, but then you have to decide how much you want people to credit your experience. If you have nothing to prove, just do a sighted listening to both amps matched by ear. If you want to convince someone, certain precautions of objectivity should be taken.
     
    I didn't understand, so you yourself did not see which of the amps you were using? If you did this on a few trials and the B22 'won' with something like 75% or above, then it's obviously worth considering that there's some noticeable difference between the 2 that hasn't been measured. As for not owning the amp, no one's trying to argue that the input from someone who never heard them is as valuable as someone who owns both. But the Laws of Physics did not bend to either of these amps, so it's safe to make some assumptions, one of them being that there should be no distinguishable sound between these 2 if every variable has been accurately measured for both.
     
    That's what my earlier USB cable analogy meant: I have never heard the Audioquest Diamond USB cable. Someone who owns it claims it improves the mids, or whatever, and says that since I have not heard it I can't comment on that. Well unless somehow the USB protocol evolved on that particular cable, I can assume that it's impossible for the mids to be any different. On this case for example, you mentioned how the soundstage changed. As far as I know soundstage depends on the driver material, width, placement/angle, material the cups, air flow. Don't quote me on this, but I believe the only way for an amp to 'create' soundstage would be to have some sort of bleed from one channel into the other, along with some frequency change, and not only would this be very much measurable, the chances of this happening by chance are minimal.
     
  3. zzffnn
    Lizardking,

    I was not trying to convince anyone, except myself. Only my ear preference matters to myself.

    I disclosed that review condition because I was asked, so I provided that to be helpful.

    Like I said, you are assuming lots of things there. I see no reason to discuss further in this manner so feel free to assume further. Your cable analogy is not relevant.

    What you described in amp creating soundstage by bleeding is a crossfeed circuit, which will actually decrease soundstage width by reducing channel separation and blending.
     
  4. mikeaj
    Quote:
     
    If there's a nontrivial phase shift in the audible frequency range, then that should impact the soundstage.  I wouldn't necessarily count out any differences in frequency response, distortion, or something else as causing shifts in perception of anything, though.  With "good enough" amps, all the factors should be covered though.
     
     


     
     
     
    By changing the overall level you also could be changing the perception of the FR because of equal-loudness contours and so on, or something else.  Louder is usually perceived as better, but it's not an absolute truth.
     
    Most head-fi reviews done in the typical fashion, even about parts that aren't headphones, can have useful comments about build quality, aesthetics, functionality, features, ports, price, noise levels (if noticeable), and so on.  Most things relating to sound quality I would consider unreliable at best, given the circumstances.  For example, see differences in blind versus sighted listening here:
    http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html
     
    The idea that small differences in sound / color / force / whatever are not perceptible to humans, is not that controversial, I would think.  As mentioned earlier, reference the Carver challenge with regards to differences between amps, or maybe some formal studies.  In audio land as well as many others, results tend to shift greatly when there are bedsheets or paper bags involved.  Human ears and brains are amazing compared to current technology at a lot of tasks, but let's not get too ahead of ourselves.
     
     
     
  5. zzffnn
    Guys, see the reason why this review thread is in Sound Science?

    I found that electrical engineers here have amazing abilities to take the fun out of music listening with their objective methodology of comparison.

    If most of the sound description here at Headfi is not to be believed, then why do we gather here? Built features of a product can be easily seen on photo or spec. Without subjective sound description, do we come to Headfi to conduct scientific experiments to treat cancer or what?
     
  6. upstateguy
    @zzffnn
     
    Since you have both amps, are able to match the volumes and hear differences, would it be so hard for you to do a null test?
     
    Everyone is afraid to use the Audio DiffMaker.  All you need is a cable from the output of the amp to the input of your computer.
     
    It is not absolutely conclusive but it would help a lot if someone who had both amps did it.
     
    Even if you don't want to use the DiffMaker, make some Audacity files and post them.  There are a lot of people here who can use them to eyeball a null test.
     
    I also wanted to ask you what the volume and gain level you had the O2 set to for your comparison? 
     
     
  7. zzffnn
    Volume matched to 80 db. 2.5x on O2 and 2x on beta22.

    I do not have time for another test, as I have done one to convince myself. I do not care to convince anyone else. And yes, I am afraid of doing that computer test. I guess by saying that I can get a break from these "objective test"? If so, then yes.
     
  8. upstateguy


    Quote:


    it is unclear what position the O2 volume was set at?  Is 2.5 the low gain setting?
     
     
     
  9. mikeaj
    Quote:

    Music is an art.  I've played in many musical groups like orchestras for years (not professionally), and I know plenty of professional musicians.  IMHO audio reproduction has a lot more to do with science and engineering, though I would say there's a bit of craftsmanship and sometimes more finesse rather than hard numbers, with regards to headphone/loudspeaker design, maybe room treatment and loudspeaker placement, and some other aspects.  This is about understanding amplifiers, so we can compare them and hopefully get to enjoy the music, rather than think about the gear (non-transducers gear), which tends to make less difference than most probably expect.  I'm not sure why that would have anything to do with taking fun away, unless maybe you're talking about the fun of reading gear reviews or playing around with new gear?
     
    I'd say you're downplaying the value in some other aspects of gear reviews on head-fi, for revealing things like trends of manufacturing defects, headphone jacks that are too loose or tight, how hot some stuff gets, turn on/off transients and other irregularities, and so on, that you wouldn't see from pictures.  Manufacturer descriptions of features are often incomplete as to how they work exactly.  Also, a lot of manufacturers offer little in the way of specs.  That's again, not to mention the headphone / IEMs reviews, which I think is the primary resource of interest.
     
     
     



    Does this really matter that much?  It's not like O2 performance is much different on different gain settings or volume levels.  80 dB is kind of low too, for comparison purposes, assuming it was taken with a 0 dBFS tone for normalization purposes.  If it was some kind of eyeball-the-meter with music playing, as an average, then that's better than nothing but probably not very accurate.  Anyhow, an "I don't care" or "don't bother me" kind of response seems perfectly fine and reasonable to me, so I (we?) can let this go since you're not interested, and whoever wants can have the last word.
     
  10. bellsprout


    Quote:

    heavens forbid there being electrical engineers. the headamp world would be so much better without them.
     
    in the meantime ill buy a car without a speedo. as long as it has a bodykit and a loud engine i'll think its fast and nobody can tell me otherwise
     
    maverickronin likes this.
  11. Shike


    Quote:

    You shouldn't be trying to convince anyone, including yourself.  Using such a mindset, and purposely setting either amp hotter than the other makes your "findings" questionable at best.
     
    I don't understand your shock and indignation for someone calling you on this.  Your test was no better than any other sighted test, and should be seen as such.
     
  12. zzffnn
    ^ Please go and buy said car and post some impression With photos here. I have no doubt that car would be super fast.

    Note I said engineers HERE in this thread. Not all engineers. Some are good at explaining science better than others, and some are good at designing real audio products. Some can only offer assumptions based on theory and confuse people.
     
  13. zzffnn

    Please do not tell me what I should do or should not do with my gears and ears. I gave O2 advantage in volume because I wanted to favor O2 such that I can get rid of beta22 and save some money. I could be wrong in doing that, but I still could not favor O2 in view of the volume advantage it had.

    I did not say that my test is better than any other test. I do not care if you see it better or not.
     
  14. bellsprout


     
    Quote:
    like your test? 
     
    edit: sorry didn't see the "based on theory" part
     
  15. zzffnn
    @ shike,

    Why should I feel bad? Because my test is poor in your eyes? I find it amusing that you think it that way.

    My test is not bad. Please be respectful and don't be personal.

    My test was aimed at telling which amp is subjectively better, blindly, even when amp x is a little louder. I did not even pay attendtion to tell which amp is louder or which is beta22. I said a little louder because 3db is perceived as significantly louder, while the 1-2 db more i gave to O2 in average may not even be audible. Variation can easily be 1-2 db.

    I challenge you to do a better test between beta22 and O2 and offer some objectively better results. Otherwise you are not provide any useful information here, other than personal attack and BS. You have to build a beta22 though. No, I will not loan you mine.
     
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