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The Opamp thread

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  1. raoultrifan
    No way, but what makes you think that?

    Packaging only, SOIC vs. PDIP; have a look to the bottom of http://www.ti.com/lit/ds/symlink/lme49720.pdf.
    Headmate likes this.
  2. CoiL
    Will take a look at OPA2227 specs and comments.

    I already got recommendation to try out OPA1692 + OPA2228 by You in that place and it is already ordered&paid for.
    I thought You already tried OPA1692 + OPA2228 ?
    Order is confirmed and shipped out via DHL :)
    Last edited: Jun 7, 2019
  3. Rroff
    Not in the combination you are using it for - I've used the OPA1692 (paralleled) for buffers (final stage in a stand alone headphone amplifier) as it can do 50ma output without breaking a sweat but not as a differential stage off a DAC.

    EDIT: I was assuming you were doing something like page 20 here http://www.ti.com/lit/ds/symlink/pcm1794.pdf with the OPA2228 in U1/2 and OPA2134 in U3 - I've mainly used the LM4562 in U3 position.
    Last edited: Jun 7, 2019
  4. CoiL
    This is insane-fast shipping! O_o
    3-4 days from Arrow US to Estonia (east EU border-country) and my LM4562MAXNOPB and OPA1692IDR are HERE! O_o
    Unfortunately I ran out of SOIC-8 to DIP-8 PCB converter boards, so it takes time for me to get those, solder chips and compare against eachother and with OPA2228.
    Ivan TT and LaughMoreDaily like this.
  5. HeyManslowdown97
    Sad News! Arrow.com no longer has free shipping under 50 dollars. :frowning2:

    Most likely has to do with “Tariffs”. Very simple solution a VAT at least that goes to the micro-economies!

    They are offering free overnight shipping for domestic over 50 bucks but will most likely pivoting to the very similar Digi-Key and Mouser type shipping and handling cost.

    “Free express shipping does not apply to purchases made on www.arrow.com/MyArrow nor purchases made on components.arrow.com. Orders under $50 USD will automatically have a handling fee of $12.99 USD applied to the order total. The $50 threshold is determined before taxes/fees and after any discounts are applied to the order. Arrow reserves the right to end this promotion at any time without notice.”
    Last edited: Jun 12, 2019
    LaughMoreDaily likes this.
  6. CoiL
    Well, that`s luck on my behalf and sorry for those who missed opportunity...
    HeyManslowdown97 likes this.
  7. Rroff
    Don't have the experience with the 827 to comment on soundstage but the AD8065 doesn't have a particularly wide soundstage but it does articulate the soundstage well if that makes sense - for want of a better technical explanation it seems to preserve directional cues down to lower frequencies than other opamps do which gives it some decent bass and a good sense of positioning/separation. One of my favourites as it has decent mid-range detail as well somewhat unremarkable for treble I'd say at best it is inoffensive when it comes to higher frequencies. In some applications you might find upper mid-range sounds veiled but that can usually be improved by bridging it's power supply pins with a small capacitor* and for some reason almost entirely goes away in circuits that use some kind of active ground setup.

    * Personally I use a 10uf Nichicon KZ electrolytic for this purpose but others swear by the use of a 0.1-0.22uf film cap there instead - I have no idea which is better from an engineering/accuracy standpoint but I know it sounds good to me.
    Headmate likes this.
  8. Headmate

    Thanks mate, which dual channel opamp, SOIC8 might have a wide airy soundstage to offer?

    I was unable to find LME series in SMD here. Have ordered AD8066 SOIC8.
  9. HeyManslowdown97
    Hey All- Gonna drop this Article I read from 2011 about Op Amps/Op Amps Rolling. I found it to be a highly practical guide on op amps.


    I have found often on audio threads many users using technical terms and highlighting specs and while hyping up an op amp because of this. It was extremely useful to know that not all op amp “benchmarks” apply to audio quality in order to make an informed decision on what sounds great or what works in a circuit board!

    The main thing I have learned about op amps in audio is to prevent them from oscillating and of course performance in areas that are important to audio only applications! Moreover, lots of circuit boards are specially designed as an evaluation board for a specific op amp therefore it isn’t as simple as dropping in an op amp you may like or has a great reputation.

    When only discussing equipment for me it’s important that:

    a. the source material is using genuine parts and knowing in some countries that they aren’t available as a point of reference. Nothing against op amps sourced in China it’s just when discussing a particular op amp one that comes from China vs it’s genuine counterpart in a DAP is like comparing Apples to Oranges.

    b. Getting to the Point. Many threads have technical jargon that may appear to be intelligent and knowledgeable but upon there conclusions often lack reference to how it relates to sound quality. (These tend to be most wasteful time consuming “noise” reads).

    My objectives are simple. Arm yourself with informed facts to make an informed decision and to have a constructive criticism made up in your mind of the useless jargon on the internet ‘hyped’ by marketing and regurgitated by threads as a form of “garbage in, garbage out.”
    raoultrifan likes this.
  10. Rroff
    It is an age old contention when it comes to this subject. From many 100s of hours of messing about with this stuff (I have no professional background/training) there are subjective sides to this that defy any amount of on paper engineer testing.

    Nwavguy's work is well known around these parts - some history involved.

    I know the O2 amp design so well I can build it on prototype board practically in my sleep without referencing a schematic.
    Last edited: Jun 14, 2019
    HeyManslowdown97 likes this.
  11. HeyManslowdown97
    Yea not to mention $20,000 worth of testing materials to test the op amps.

    Majority of DIYERS are very practical and are primarily hobbyists with the occasional snob or two. I find myself humbled by trial and error tweaking around but it can get expensive so it’s worth reading as much about something you want to accomplish beforehand.

    Relatively new to modding but would love to actually hear The OPA627 perform in it highest form for audio in a DAP specifically designed for it with a “high octane” DAP that’s got an Formula 1 esque control center to Monitor it’s performance in real time that I cannot design! I feel that way Audio chips as well made by AKM and ESS. :wink:

    How are the O2 designs? Are they cool sounding??
    Last edited: Jun 14, 2019
  12. CoiL
    Got roll-able socket and chips soldered. Put things together and tried LM4562 first, I was shocked that left channel was making weird noises like EMI from PSU or something...
    so I thought I fu''ed up something with soldering... but LOL, I forgot to attach headamp board and main PCB ground screws!
    Huh... everything seems OK now and first impressions say that LM4562+OPA2228 is more detailed and tight compared to OPA2134. Will have to buy new OPA2134 chip to compared cuz I destroyed it because it was easier to remove by snapping off pins from chip.
    Now will go and test OPA1692IDR+OPA2228 too.

    Edit: One thing though, LM4562 seems to get pretty hot. Is it ok for such opamp or does it need to be cooled down? Or better not to use it?
    OPA1692 seems to work @ about room temp. Latter seems to sound tad more "airy & open" by initial impressions.
    Will let them "burn" and report sometime soon about sound.
    Last edited: Jun 14, 2019
  13. HeyManslowdown97
    I’ve done crap like that especially when your über focused in one area. Yea let us know how the combo works out for you with the Opa1692 + Opa2228!

    Heard nothing but great things about the LM4562 in the output stage! I’m gonna pick up the NJR version cuz it’s cheaper in bulk. Nifty little Op Amp that one!
    Last edited: Jun 14, 2019
  14. Rroff
    The O2 is an engineering masterclass and measures very well but the "musicality" is a mixed story - personally I find it performs very well with actual current thirsty headphones (which are kind of rare these days) but find it lacking a certain something with headphones that like voltage i.e. Sennheiser HD600. Throwing about the price of the amp again (which goes against everything the amp stands for) on uprating certain parts to "boutique" components IMO makes a much more satisfying listening experience even though it is only of an order of "5%" differences. I also think nwavguy sabotaged himself in some ways it was designed to very strict tolerances and performs very well within those tolerances but can be improved on if you are operating outside of those tolerances - in some cases just spending a tiny little bit more on certain components gives it a much wider range of performance or compatibility capibility.

    This is why I say annoyingly as the LM4562 produces very detailed, tight output but IMO often comes at the expense of sounding a bit clinical which can be fatiguing.
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