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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. Magedark
    Well, I'm sure I could put it in 30 minutes...If I took three hours to sort all the parts first :tongue_smile:.

    But yeah, that really is all there is too it. But still, putting in parts in, reading the correct polarity, bending leads, cutting leads, cleaning the board, tinning the iron, it all adds up. Maybe I'm just horrendously slow.
  2. Fred_fred2004 Contributor
    Take your time and enjoy building it, it's not a race :)
    micmacmo and LizardKing1 like this.
  3. firev1
    It took me about 4 hours, cus I have clumsy hands and I don't use the solder(thank god for school) too often. Other then those issues, the O2 is really easy since there is a checklist on you-know-who's site on what to do(testing and mosfet handling) already. 
  4. Questhate
    Yeah, it took me about 3 to 4 hours as well, but I wasn't rushing at all. Most of the time was spent taking the parts out of their little zip lock bags, and then just double-checking before moving on to the next set of parts. And bending/cutting the resistor leads were a bit annoying as well. 
    I'm sure someone could take much less time if they sped through everything, but that wouldn't be any fun. Like Fred2004 said, pour yourself a glass of wine, and enjoy! 
    I found it easiest to put the R-parts first, then the D-parts, then C-parts, then everything else (S, J, BT), with the U-parts and Q-parts last. The "O2 Details" post on the blog is about as thorough as a walkthru as you'd need.
    Good luck on your builds! 
  5. WhDemon
    There we go :)
    IMG056.jpg IMG057.jpg
  6. Magedark
    Very nice build! I was thinking of wiring off board inputs if I make another O2. I'm pretty content with mine, just minor stuff like I don't enjoy how all of the connections are in the front, but it works.

    I don't know if this thread has talked about it yet, but anyone having problem with the suggested knob with the suggested pot?
  7. Fred_fred2004 Contributor


    What sort of problem? mine works fine
  8. WhDemon


    I bought the black/red knob. Wasnt fitting.
  9. Magedark
    The wasn't fitting part. Mine doesn't fit and took forever to get one. Also, it falls off. Well I was just going to get a screw-on one, but I'm checking if it other people had that problem or just me.
  10. cheapskateaudio
    Over on DIYaudio one mod that was posted is implementing a CRC filter on the bottom of the board under the power supply caps. I implemented an RC filter and this resulted in significant increases in the performance of the amp. Previously the amp had that harsh top end and was distinctly thin and bright with the HD650's, the filter has greatly reduced the horrific glare that was previously present. It also totally and completely eliminated the heat issue with the v-regs, which now barely get above room temperature. I can't feel warmth at all when I touch them.
    I highly recommend this mod if you're not satisfied with the sound or if you think v-regs shouldn't burn when you touch them. 
    To do it as posted on DIYaudio, you have to cut the traces connecting C2 & C4, as well as C3 & C5. There is a trace top and bottom for C2 & C4 that both need to be cut. After that, bridge the now cut rails with a 10R 1 watt resistor (don't bridge the top trace between C2 & C4), and solder 1uf caps across the bottom pins of C2,C4,C3 & C5. I only implemented an RC filter with caps under C4 and C5.
    I can actually live with the amp now and to my ear it is much more honest about the music coming through it, but that is probably because it's no longer deafeningly harsh.
  11. mikeaj
    To guys with potentiometer cap fitting issues...which one?  There's multiple options on the BOM including Alps and Bourne models, 20mm and 15mm shafts, and so on.  I have the default black/red plastic cap, and that fits very snugly on the 20mm Alps (RK097122008T).
    On a side note, I'm pretty sure my build issue wasn't the diode either...it was PCB damage around the power supply filter caps, so traces were no longer connecting parts that were supposed to be connected.  Most likely this is from me not having anything worthwhile to cut leads with, so I "cut" them by bending them back and forth until they snapped (yes I realize that sounds like a terrible idea).  I added a wire on the bottom of the PCB to manually connect the negative side of the filter caps to the input of the negative regulator and it works!
  12. cheapskateaudio
    If anyone has a uDac, the knob fits perfectly.
  13. cheapskateaudio
    Looks like I spoke too soon. While the RC filter definitely reduces the temps the v-regs reach, after leaving the amp plugged in for a full 24 hours the sound regressed towards the oomphless smeary sound I've become so familiar with.. The v-regs are still reaching close to 50C, and at those temps I do hear a difference in the sound quality. 
    Heat is a nasty thing and this amp encourages it blatantly.
  14. wakibaki


    What? How can you expect us to take this seriously? Haven't you ever heard of burn-in? Get back to us after a decent amount of time has elapsed. Say, 4~5 years...
  15. Shike


    I've left my amp on for a week straight and don't get nasty temp issues.  Sounds like you pooched your amp, you're really going to need to fix it before many of us will take you seriously.
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