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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. palmfish
    Well, I am about to come full circle with my audio setup.
    I started with a pair of HD600's for quiet-time listening, and found they didn't pair well with my 80's vintage Carver receiver. This led me on a search for a more headphone friendly solution. I ended up with a Peachtree Nova, which I love thanks to it's built-in DAC and great analog and digital switching capabilities.
    I lived with this nice setup for a few months but I was never quite happy with the HD600's - they were so balanced I never found anything I liked better, but I was always bothered that they were a little on the bass light side of things for my preference. Then a month ago, I discovered the Denon AH-D7000 and everything changed. They sounded fantastic to me, but I started worrying that with their low impedance, they weren't a good match for the Nova (30 ohm output impedance). This is about the time I discovered the O2, so out of curiosity, I bought one and a Violectric V90 to see if a low output impedance amp would be a better match for the Denons (even though I couldn't detect any problems with the Nova, which sounded great).
    What I found is that all three amps sounded extremely similar to each other. I came to the conclusion that, because the Denons have very stable impedance across the audible frequency range, they are not picky about amplifier output impedance. With this conclusion on my mind, I decided to see how my Carver receiver sounds with the Denons. I hauled the Carver home from work today (I have been using it in my office system) and hooked it up. Well, what do you know? It sounds terrific with the Denons - I really can't tell it apart from the Nova or the O2. Maybe with extreme eye squinting and A/B switching I could spot some tiny differences, but my primary conclusion is that the Denons are just really amp friendly and I really don't need any special gear for them.
    The bonus for me with the Carver receiver is that it has Tone Controls. With all the other setups I've sampled and owned, there were always some albums that weren't mixed "neutrally" and sounded poor to me. Some old rock albums that sound thick and muddy or 80's CD's that sound too "U" shaped. For 80% of my collection, everything was great, but with that other 20%, there was nothing I could do so I just avoided listening to them.
    So I've come full circle - back to my beloved Carver. I'm going to keep the O2 because it's just really cool and I like it - I'm sure I'll find a use for it. I've already sold the Violectric because I don't need it, and now I think I'm going to sell the Peachtree Nova too - I'm going to Europe this summer so the extra money will be helpful. I will be in the market for an inexpensive DAC to replace the Nova's DAC, but even if I spend $300 or $400, I'll still come out ahead.
    Sorry if this wasn't interesting to you, but I had to let it out somewhere. I thought this was a good place because it was NwAvGuy's blog that educated me about output impedance and the O2 which got me to experimenting. Thanks for reading!
  2. zzffnn
    @ thehadi,
    You may want to fully charge O2 first. My JDS O2 revealed distortion upon arrival, which went away completely after charging overnight.

  3. thehadi


    I will try it, thank you zzffnn. I will try it with DX100 after i get it and with ODAC when it's on the market.
  4. Maxvla Contributor

    It had to do with his posting saying to the effect of 'Hey I have this information you just have to see, click the link and see it on my blog' which uses Head-fi to generate traffic for him and make him money from said traffic. That's just not something you do. If he had simply posted his information here he probably wouldn't have been banned at all. A lot of his negative comments about various products spread around Head-fi are still here unedited, so it wasn't that.

    The rule about not talking about banned members is common courtesy. He can't defend himself against comments posted, so we don't allow those comments to be posted. It's not about censoring, it's about giving respect to someone who didn't give us respect.

    And in that spirit, lets let it die and continue on.
  5. frenchbat
    As much as I understand the no-linking-to-increase-oneself's-blog-traffic part, AFAIK there's not a single ad on his blog. So I fail to see how one can make money without ads. Go see for yourself, not even google ads.
    Why this need of making him a vile and interested person ? I just can't, for the life of me, understand that. The same thing is popping out every now and then, when talking about the design he simply gave everyone. The funniest part of all is that while he has been banned, Head-fi sponsors are now making money though head-fi with his design.
    tmars78, maverickronin and madtone11 like this.
  6. mikeaj
    As always, there's (at least) two sides to every story...but saying that he makes money from generating traffic is a complete falsehood, unless you believe something like he has some shady under-the-tables profit from Epiphany or JDSLabs or maybe whichever companies he (the bench equipment really) gives good product reviews for.  Some say he's after profit in some non-monetary sense.  Choose the conspiracy theory of your liking.  The linking seems to be a website policy though, but arguably it seems to be "selectively" enforced.
    Some people don't have time to repost lengthy (and with him it's generally going to be lengthy) explanations all the time, so the convenient thing would be to link the information directly.  Is it considered respect to knowingly leave people in the dark?  Of course, depending on your perspective and beliefs--which may or may not be founded in reality--you could call it proselytizing.

    By the way, charging the batteries will only help if it's clipping the gain stage (which it might be), and only if you're actually running it off the batteries.  Clipping happens if the battery voltage is too low and the source and gain are too high; however, it's a somewhat narrow range of values where the combination of source and gain will clip the amp when on low batteries, but the combination will not clip the amp on high batteries.
    maverickronin and madtone11 like this.
  7. frenchbat
    Of course there are 2 sides, and Voldemort himself isn't without his own quirks. I had a few words with him and he's a very opinionated guy which might fail to see the point you're trying to make. But saying he has a big mouth is one thing, and saying he's fooling everyone is another. 
    Oh well, the success of the O2 will bring whomever wants to read the blog straight there by a simple google search I guess. At least it seems like using his name is now tolerated, and that's already a sufficient indication. 
  8. Maxvla Contributor
    Since you can't help but discuss it...

    Whether he gained money from it or not isn't the point, really. You show up on a popular site and blatantly try to pull their traffic, you will be removed. It's really plain to see. It has nothing to do with Head-fi or NwAvGuy. If this happened on some other forum with someone else they would respond the same way.

    The 'don't have time to post twice' excuse doesn't work either. How long does it take to copy/paste something of any length? A few seconds? Someone acting in this manner is already making the post to link to his/her site. They've already copied and pasted their link. Instead of the link it could be the message.

    If I had a message that was for the public good and nobody would be harmed in any way by saying it I still couldn't just drive up to my local TV station and expect air time on their hard earned network. On a public forum, though this is allowed. Take it a step further and instead of your message being played on the TV station, you demand that their TV station say 'This is channel 5, there is an excellent message on channel 6, watch their channel, not ours'. This is what people who spam links to blogs are demanding the right to do.

    The whole 'staff thinks he's a vile person' I don't believe is true. There was a policy breach, I'm sure he was warned a few times, then banned as a matter of course. Because he didn't want to play by the rules here, and with his message of returning to real fidelity and not taking any benefit, I believe many members misunderstood and became angry scapegoating the staff to console themselves. It has continued to fester all this time.

    Now please drop it or take it to pms. I've already talked about it more than I should, but I'm tired of this attitude tainting this design, the designer, and our staff. I fully support the designer and intend to buy an ODA or ODAC when they are available. It think it's refreshing, but the way it was done could have been better.
    Eric_C likes this.
  9. frenchbat
    It's not that I can't help but discuss it, but you can't just say the guy is actually making money out of something, thus creating the image of a biased person, and say "now let's stop talking about it". If you had left it at the no-external link policy, I probably wouldn't have posted anything.
    Now I'll quietly go back to the shadow, where I'm usually staying.
  10. Maxvla Contributor
    I actually haven't looked at his blog much and assumed there were ads or some form of monetary compensation for the traffic, but that being false doesn't make it right. I apologize that I didn't look into it clearly enough and stated incorrect information.
  11. Shike
    His banning had nothing to do with blog spam, and that was out of Jude's mouth http://www.head-fi.org/t/562736/what-causes-this-amp-related/120#post_7619633
    This also doesn't include his side of the events though.
    Now that that's out of the way, let's drop it alright?  Next time don't speculate on subjects you don't know, and more importantly don't derail the topic at hand.
    Maxvla likes this.
  12. jude Administrator
  13. zzffnn
    Guys, let us calm down and just talk about the amplifier and its sound. Discussing more about those sensitive "political" topics will only get this thread locked.
  14. wje


    Agreed.  I received a nicely-build O2 amplifier from JDS Labs on Saturday.  Prior to that time, I had been using an O2 amp build by another individual that, essentially, had problems all along.  These various issues added up to the point where I contacted the builder and was able to return the amp and get the JDS offering.  Just a short bit ago, I picked up a HifiMAN EF-2A tube amp.  While I love how the O2 provides a clean signal, I'm also interested in testing some amps that might potentially color the sound slightly.  In the case of the HifiMAN amp, it also has a built-in DAC where Burr-Brown chips were used.  This hobby gets bigger as the days go by.
  15. mikeaj

    Just out of curiosity, what were the issues with the build?  (unless you earlier mentioned who the builder is and don't want to slander his/her name with more details)  I know it's a fairly easy build, but several things can go wrong, and JDSLabs even said they had issues figuring out all the tricks to get the yield rates high.  
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