O2 Op Amp Rolling

Discussion in 'Modifications and Tweaks' started by rtaylor76, May 18, 2016.

  1. rtaylor76

    rtaylor76 Can't wipe his tag

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    Exactly my point. He only tested the op amps for their low-noise performance, and then went on a long diatribe about A-B testing blah-blah. That is why he even called his amp the "Objective" as to not insinuate any subjectiveness that is I guess is "hogwash" to the designer. I think many have shied away from op amp rolling in the O2 due to these reasons- thus the reason for all my research. It seems to be a very popular amp, yet the op amps are just "meh" sounding.

    I also read something this week about dual channel op amps and most of them designed for differential purposes and I think singles are probably much better for audio, even if carrying the same signal, like in the O2 design.
     
  2. Madaboutaudio

    Madaboutaudio Friend

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    I still have this O2 amp(stock opamps) right next to me. Just for fun, I hooked up the Sony ZX2 to the O2 amp via the headphone out(ZX2 doesn't have any additional analog opamp, so I don't think it matter if I use the headphone out). I just can't believe how O2 amp makes everything sound so grainy and hollow and borderline harsh. There's not much sparkle left in music.

    Even the soundmagic A10(source: ZX2) sounded so much better than this O2 piece of shit.

    I think I will have to find a nice smooth opamp for this O2 so that I can pass it on to my nephew.

    Can any kind soul throw me a link to purchase the opamps that plugs into the O2 without using additional socket adaptors?
     
    Last edited: Aug 13, 2016
  3. rtaylor76

    rtaylor76 Can't wipe his tag

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    Here are the Digikey links since they are cheaper on shipping for small orders:
    Also, you could just go with three 2134's...it has a great sound as the 2228 can sound a bit more lean and clinical but has a touch more "realism". For the price, those are about the best two op amps you can get in a PDIP or DIP-8 package IMO. All other DIP-8's (OPA2111, OPA2107, Muse 01, Muse 02) cost way more. The 2111 and 2107 in DIP-8 run about $20 piece and the Muse op armps run about $40. Not sure it is worth it if you are going to give it away. I think the 2134 has the right touch of hi-fi to ge one hooked - it is also a pretty cheap and not so subtle upgrade.
     
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  4. rtaylor76

    rtaylor76 Can't wipe his tag

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    Sorry I haven't posted I awhile. I was messing with my O2 a couple of months ago and I accidentally put the batteries in with it still plugged in and it stopped working. It took me awhile to troubleshoot it down to the LED...yes, the LED is a part of the operation and not just an afterthought. Too bad it's an obsolete LED that's now a difficult one to find.

    So then I thought I purchased a suitable replacement, but it sat way too low. It was cool though...it was yellow. Anyway, in trying to get it to fit, I would up desoldering the pad on one of the legs. So it's kind of a mess.

    I just started a new job a month ago, and with two kids, I'm lucky to keep afloat. Maybe soon I'll get back on it. Still some more op amps I want to try.

    If anyone has any to add or has done their own op amp rolling, I'd love to hear your experiences.
     
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  5. tdockweiler

    tdockweiler Rando

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    I'm using the OPA2227 with mine and it almost make it seems too warm :confused:
    Warmer sounding than the OPA2134 which seems to be used in many of the amps I like.

    I use it as a bedroom amp and it seems to do a pretty good job.
    I almost accidentally killed it though. The other day it would not turn on and one of the op-amp legs were sticking out of it's socket and bent.
    I think I traded a Magni for it.

    I must be abnormal because I prefer the O2 to the Magni, but the Modi 1 to the ODAC.

    Modi 1 + O2 is a perfect budget setup and very underrated :)
     
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  6. Maxx134

    Maxx134 no one will touch his boy parts without $$$

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    I have went thru your excell file and it is just excellent.
    You have all your info well laid out.
    Because of your testing, I decided to get :
    U1 - OPA2228PA and
    U3/4 - two OPA2134

    Just received in mail today.

    The only issue is my O2 had one channel slowy fade away, so I think it also may be in need of repair.
    I will play with this over weekend..

    I feel the groundwork and foundation of getting a good performance amp , in specs, was half the work..
    And this thread actually finishes or completes the O2 amp with the type of testing they did not do.
    So they did the performance, and you did the
    Testing for musicality.
    :bow:
     
  7. thegunner100

    thegunner100 Hentai Master Chief

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    Wait... why are we seriously still playing around with O2s in 2016? @Maxx134 I'm disappointed.
     
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  8. Maxx134

    Maxx134 no one will touch his boy parts without $$$

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    Lol!
    Its for those that are starting (budget)

    I started with this amp.

    Its a nice power for budget and is better than *most* any Cmoy (in power) because I had Cmoys.

    Maybey there is a cheapo amp that is better, like the Vali, but I think the O2 is the cheapest and has potential or I wouldn't bother.
     
    Last edited: Oct 21, 2016
  9. Maxx134

    Maxx134 no one will touch his boy parts without $$$

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    For me, I need a cheapo unit for burning in my headphones and rather not use up my expensive tubes for burn in headphones, plus its nice to tinker what is obviously needing badly.
     
  10. thegunner100

    thegunner100 Hentai Master Chief

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    Sorry man... the one time you brought your O2 to my house, I thought it sounded like garbage :(. There are much better amps nowadays that you can get over the O2, at a low price.
     
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  11. Maxx134

    Maxx134 no one will touch his boy parts without $$$

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    Sonically of course I would have to agree..
    I don't know how much is the O2..

    I am hoping I can boost the musicality with the op-amp roll,
    because it does have alot of power...
    That is its only strength for me.
     
  12. tdockweiler

    tdockweiler Rando

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    Not that anyone asked me, but I think the E9 sounds better than the O2 :eek:
    LOL Don't shoot me! At least it's a bit more musical or whatever.

    There was a lot of hate for that amp, but I never understood this.
    It has a hint of warmth and might not be a great match with the HD-650.
    I believe the E9 uses an OP2134 like the Matrix M-Stage did. Doesn't mean much but I believe it can be swapped out.

    PS there's measurements of the E9 on Golden whatever site.
     
  13. Maxx134

    Maxx134 no one will touch his boy parts without $$$

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    Yep.
    In my situation I want some power to push a planar.
    Most those nice small portable amps have one third to one half the power of an O2.
     
  14. jexby

    jexby Posole Prince

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    buy a Jotunheim without the DAC and throw your O2 amp in the trash.
    hell, even a Vali2 would warrant throwing an O2 amp in the trash.
     
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  15. Jh4db536

    Jh4db536 Friend

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    All I hear are mids (n shaped fr). The top and bottom end are rolled off. For staging, I think all the cymbals and bells are placed way behind my head or halfway our of phase. All the details are lost... But who needs all that extra noise anyway right
     
    Last edited: Oct 21, 2016
  16. thegunner100

    thegunner100 Hentai Master Chief

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    Or as Marv usually likes to say, it should be floated down the LA river.
     
  17. jexby

    jexby Posole Prince

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    truth. except El Lay doesn't have a river if they don't buy or steal the water from Colorado in the first place.
    so F the river.
    and throw the O2 in the trash.
    (not recycle, please.)
     
  18. purr1n

    purr1n Finding his inner redneck

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    TBH, @jexby's advice is sound.

    You can't really roll the output opamps, as the JRC4556 are unique in that they can put out a good amount of current, much much more than other opamps. So basically you are stuck with those craptastic sounding opamps, which do BTW happen to synergize well with Grados. I guess you can replace them, but you will likely lower the current capacity of the O2 design significantly.

    With the voltage gain opamp, you need to be super careful of how close it can swing to the power rails. nwavguy chose an opamp that did well in this aspect, but even then a lot of folks were still clipping with their gain settings and the output levels of their sources. Any other opamp will likely exacerbate this situation.

    You really have to understand and read the datasheets before rolling opamps in the O2.

    The best option really is to throw in the trash and get something else. If you want to power a Sennheiser headphone, a CMOY with higher gain and with highish voltage rails, +/- 12V 24VPP or +/- 15V 30VPP (not just a + 9V), sounds much better than an O2.
     
    Last edited: Oct 21, 2016
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  19. Armaegis

    Armaegis Friend

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    You guys remember when opamp rolling with the iBasso portable amps was all the rage? Yeah...
     
  20. T.Rainman

    T.Rainman Acquaintance

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    I thought the O2 has +/- 8.2V voltage rails (16.5Vpp) when operating on batteries and +/- 11.6V (23Vpp) when operated on mains not a single 9V ?
     
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