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So, the Objective2 headphone amp - designed entirely around the measurements? (PLEASE READ RULES BEFORE POSTING)

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  1. Willakan
    Jude has kindly agreed to lift the ban on discussion of the works of banned members to allow discussion of the O2 headphone amp. However, please pay attention to the following before posting, otherwise this thread is likely to get locked:
    1.This thread is about the amplifier, not NwAvGuy.
    2. No links to NwAvGuy's website, or resources maintained directly by him.
    3. No links to sites where NwAvGuy is in direct and regular communication with people on such a site.
    4. No discussion of the above rules or indeed moderation, as usual.
    (The schematics and bill of materials I am mirroring (in compliance with CC license) in order that they may be linked to)
    So, down to business. The O2 is a headphone amp designed purely around objective measurements and released under a non-commercial license (Creative Commons). It is cheap to build (PCB+parts run to 30 dollars) and also generally goes against much of what can be considered audiophile design philosophies; there are capacitors in the signal path, plenty of  50-cent ICs and it uses an AC wall transformer as part of the power supply.
    It also has an incredibly low noise floor and vanishingly low distortion, as well as easily enough power to drive popular dynamic headphones (K701, HD650, DT880) - even enough for high-end orthos if you don't listen excessively loud. Other notable features include current limiting and the ability to run off two 9V (8.4 volt in reality) batteries (power management kicking in to shut down the amp when the batteries are getting too low). Finally, it also fits perfectly into a cheap ($10) enclosure and has no SMD parts.
    Amp schematics and BoM (mirrored on my Google Docs): https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=1WGBCwFbHXt-q82Ujih8IVu2vXsgMtlNpe6oHLLg_Klrf2LFxv5e9F1zloEZK&hl=en_US (WARNING: OUTDATED. See designer's site for latest)
    So, are you planning to build one? Any other thoughts?
    EDIT: Added Measurements Summary
  2. Head Injury
    I definitely want to build one. If I succeed (or if prebuilt ones are available this month [​IMG]) I'll grab an Asus card or something for a DAC and return my DAC1.
    That parts list is very intimidating for someone who's never touched an opamp or soldering iron.
    Also: Finally, an official thread which isn't going to be closed (I hope).
  3. b0ck3n
    This will be my first, and likely last as it neatly covers all bases, foray into the DIY world. I'm still hoping for a pre-assembled PCB to hit the market early on though.
  4. Citan
    Version with a dac and pre amp please!
    stevenswall likes this.
  5. Steve Eddy
    Well, let's put it this way. The B22 was also an objective, simulation/measurement based design. I don't recall anyone complaining about that. So I don't see why the O2 should be impugned for taking the same approach.
  6. rroseperry
    I'm interested, but having never soldered together anything, I'd have to wait for a kit or something to get one.
  7. Satya
    If it's any good, and that cheap, I'm hoping that populated PCB boards will be sold, and all one has to do is put it in a case and hook up some power, which is about the extent of my technical skills.  I'm sure there will be quite a few DIYers building them in the coming weeks, so I guess we'll see how well it performs and whether it it deemed worthy of partially assembled versions.
  8. Head Injury

    A DAC with the same design goals would be great. Quality DACs are more affordable than quality amps in this market, it seems. Maybe because audiophiles respect neutral DACs but like colored amps.


    There's very respectable measurements of the prototype online, but we can't post a link to them. It would be nice to see third-party measurements once some are built.
  9. Currawong Contributor
    The litmus test, IMO, will be its performance with complex music with a variety of headphones. That is something measurements don't show.  I might build one, for fun. I need a good transportable amp for testing headphones in-store that has consistent performance.
  10. Steve Eddy


    Only if no one makes the measurements.
  11. SpaceTimeMorph
    Are you going to sell some of these Steve Eddy?
  12. deadlylover
    Who's going to be the first? Or is everyone waiting for the boards?
    I'll probably have it done by next weekend, so long as Fedex doesn't balls it up (or I fall asleep and miss the delivery).
    I don't have any dynamics to use though, all I can borrow is the AD900 and LCD-2, and those are both very easy to drive.
  13. SpaceTimeMorph


    I put two orders into mouser for the parts, and am working on gathering some of the other stuff... but should be pretty quick once the boards are done.  I just want to error check as much as possible... it is a pretty solid design by the looks of it.  And all I have are Pro 900's, e3c's, ... yep nothing hard in this camp either.
  14. Anaxilus
    Somebody build one for Tyll.  Go!  Till someone with his pedigree hears it I'll remain skeptical. [​IMG]
  15. Steve Eddy


    No. Why?
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