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

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  1. kwkarth


    Quote:

    Please, let us not quibble over farkles 'n' fairy dust.
     
     
  2. The Monkey Contributor
    Everyone relax and just build the gotdam thing.  Children.
     
  3. c61746961
    You know what?, I question your motives and attacks more than his*, and you should wonder why, since you have a social responsibility here, and he doesn't.

    * You keep openly judging people and locking threads whenever someone questions the forum's policies, you also pass your opinions as facts as much as anyone else, I know this is a big place, it's free, and there's lots of work to do, but power comes with responsibility, and a forum is nothing without its audience.

    Back on topic, I don't know how can some people still be weary about this, there is already a product, there's absolutely no point in speculating anymore.
     
  4. BobSaysHi
    subscribed. I'll wait for others to get this amp and give it a once over before I buy anything though.
     
  5. qusp Contributor


    Quote:

     
    you didnt seriously just open up a can of wisdom on his ass did you? it really isnt the time or place for portable audiophile hiaku 
     
  6. nikongod
    Serious thoughts:
     
    In the schematics posted on the first page:
    u2b (one of the op amps used as a voltage source in the PS) does not have a 270Kohm resistor on it like U2a. These resistors and the0.22uf caps block anything but DC from reaching the mosfets. 
     
    Why arent the mosfets Q1/Q2 in the feedback loops of the opamps? It would reduce the output impedance of the power supply which would probably drop the crosstalk of the amp. 60db is "good" not "excellent" if we are talking about measurements without reference of audibility. 
     
    R25 could be exchanged for a JFET CCS or a CRD. CCS's are pimp. 
     
    The bandwidth limiting resistors and caps before the opamps is a nice addition. I hope this catches on in other amps. 
     
    Im 50/50 on the idea of the "opamp before the volume control" thing. Its not conventional, but has been done before. It solves the problem of noise from the opamp elegantly, BUT the gain stage is prone to overloading with excessive input voltage. This is noted on the schematic - its worth noting if you hook up to pro-level outputs. The fist kid who figures out how to set the gain to 10 (because 10 is more and more is better :facepalm: ) is going to have a wild ride. 
     
    The selected gains of 3 and 7 are pretty tasteful. Id lean towards just one. 3 or 4 covers you for 99% of all headphones, people just like switches.
     
    I think the 0.8db channel matching quoted in the test data may be misleading. Channel matching is primarily a function of the channel matching of the volume control, which is not generally great in those little pots. Maybe they all line up nicely at maximum volume, but at real levels Id bet on worse. Not really a fault of the designer just saying...
     
    Coupling caps, UGGGGGGH. UGGGh, uggggh. Thats the kind of stuff you'd expect to see in the kind of tube amp a guy like nikongod would design. Why not DC couple it? Ugggggh. At the very least put them in front of the pot where the signal is larger. Uggh, really? And just no. I guess they will save the headphones (sort of, but no) if the gain opamp goes all funky with excessive input signal. 
     
    I like the option of an output resistor outside of the feedback loop for the output op amps even though nobody will use it. I wonder if this admits the importance of subjective quality in spite of "knowing" how to do it right. heh. Id put a switch across this one so the user can switch on the fly like on the XIN amps. Its a good spot for ferrites or hand wound inductors should the need arise in actual use. 
     
  7. c61746961
    That's interesting. You should question those design decisions in one of the places he can get into, though. The diy audio thread would be a great place.
     
  8. nikongod


    Quote:

    you called?
     
    wow this amp is great
    it fits nicely in my hand
    but it sounds like trash
     
    Not directed at any amp in specific.
     
     
  9. maverickronin
    Quote:

    Well a few headphones here and there are supposedly designed for non-zero output impedance.
     
  10. nikongod


    Quote:

    I know, Im all about it (listening to HD800 from an amp with 450ohm Zo and loving it) jsut that its a monor thing that I like. Im mostly bummed so few people try it. 
     
     
  11. ujamerstand


    Quote:
     
    09.png  
     
    now that's signature worthy material.
     
     
     
  12. maverickronin
    Quote:


    Did Senn specifically design them for that or did you just play around with different resistors until you found something you liked?
     
  13. digger945


    Quote:

    I'm gonna try it.
     


    Quote:
    heh, or a cold or forgot-to-solder feedback resistor. Rail slam + parallel buffer = magic smoke.
     
     
     
     
  14. nikongod
     
    Quote:

    There is an optional standard for 120 ohms that it "feels" like they follow. 
     
    The amp has this output impedance by chance. I got the HD800, plugged them in, and was like whoa! 
     
    I know a few people who own 800s and B22's who dont like the amp. Maybe its what Im used to, but I like how it calms down the highs just a touch. 
     
  15. DingoSmuggler
     
     
    Quote:
     
    Ha ha - but with $0.70 opamps, the magic smoke has a less pleasing aroma than most magic smoke.
     
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