Active Device (op-amp/tube) coloring and distortion discussion

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by Hrodulf, Oct 30, 2018.

  1. maverickronin

    maverickronin Friend

    Pyrate
    Joined:
    Mar 17, 2018
    Likes Received:
    313
    Trophy Points:
    63
    Location:
    Midwest, USA
    I use PEQ too. I have presets for all of my (commonly used) headphones on my ADI-2 DAC. It's plenty useful.

    I've just never been able to fix those kinds of problems with it, and theoretically, I don't see how it would.
     
  2. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Pyrate MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,960
    Trophy Points:
    113
    Location:
    Irvine CA
    You mean you feel fixing the frequency response does not fix decay (CSD) stuffs?

    AFAIK, theoretically (and in the real world) that should work.

    Decay is not a non-linear problem.
     
    Last edited: Nov 1, 2018
  3. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Pyrate MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,960
    Trophy Points:
    113
    Location:
    Irvine CA
    @maverickronin, CSD are 100% dependent on impulse response and window selection, of which only the impulse response is driver dependent.

    When it comes to linear stuff there is not such thing as time domain only issues and frequency domain only issues. They are both different visualizations of the exact same data.
     
  4. purr1n

    purr1n Desire for betterer is endless.

    Staff Member Pyrate BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    89,778
    Trophy Points:
    113
    Location:
    Padre Island CC TX
    My listening faculties do not change, even while passed out. How do you think I can work a full-time job and listen to so much gear at the same time?
     
  5. purr1n

    purr1n Desire for betterer is endless.

    Staff Member Pyrate BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    89,778
    Trophy Points:
    113
    Location:
    Padre Island CC TX
    What's funny is how people think tubes or transformer boxes (from a few transformer selections in A-D converters) can "color" the sound, when transistors and opamps also color the sound. Heck, look at the opamp rolling threads on the various forums, including this one. Perhaps If more manufacturers made designs with swappable transistors, then people would understand that transistors are not exactly colorless.
     
  6. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Pyrate MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,960
    Trophy Points:
    113
    Location:
    Irvine CA
    I did some listening with different tubes on a Torpedo. And indeed things were not the same.

    Here is my personal take on it: I know folks call it coloring. But it's misleading IMO. Output power, distortion characteristics, and other things may change all of which can contribute to different results.

    Transistors should have a similar impact. But I don't know if there are the same level of varieties as with tubes. Same with Op-Amps. In many cases the circuit itself needs to change. Some Op-Amps may have a ton of current output, but quite a bit of DC offset and when used as a current buffer, a servo may be needed. All of which may have an effect in the final product. Some other Op-Amps may have other characteristics necessitating a different design.

    Only a subset of devices may be used for swapping in the same circuit. Or things may give their magical smoke.
     
  7. Azimuth

    Azimuth FKA rtaylor76, Friend

    Pyrate
    Joined:
    Nov 9, 2015
    Likes Received:
    6,838
    Trophy Points:
    113
    Location:
    Nashville, TN
    Home Page:
    I think tubes have wider sound variances than sifferent op amps. This can be attributed to several reasons that I will not speculate. And I have done my fair share of tube and op amp rolling on a few different devices.

    Op amps rely on a heavy amount of current feedback for operation and depending on,implementation can sound vastly different in different circuits. They also can operate on a wide range of input voltages and gains...to me, it is almost not worth discussing op amp rolling unless in a specific model, and for all the reasons @ultrabike said. Almost the same goes for tubes.

    And as long as it is not occilating or in melt down, the subjective impressions is about all one needs.

    And yes, everything is some kind of coloration.
     
  8. maverickronin

    maverickronin Friend

    Pyrate
    Joined:
    Mar 17, 2018
    Likes Received:
    313
    Trophy Points:
    63
    Location:
    Midwest, USA
    IME drivers and their interactions with their enclosures aren't linear enough for that to work 100%.

    Maybe someone's got a better way to tune a PEQ or maybe convolution will work better than I'm giving it credit for but I haven't seen any measurements on actual transducers to back that up.
     
  9. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Pyrate MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,960
    Trophy Points:
    113
    Location:
    Irvine CA
    I currently use PEQ on my bedroom speakers, and it worked well. I have measurements to back that up. It sounds much better after correction. What would you like to see?

    As far as interactions with enclosures, unless something is wrong, for the most part enclosure/driver interactions should be linear.
     
  10. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Pyrate MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,960
    Trophy Points:
    113
    Location:
    Irvine CA
    BTW @maverickronin, I don't really care that much to PEQ my HD600, but this little portable headphone Amp/DAC can do so nicely:

    https://www.minidsp.com/products/dsp-headphone-amp/ha-dsp

    I use their low end miniDSP for my Mackies and I'm happy. (Note: It should be pointed out that it has a Sabre DAC which some no-like.)

    As alluded to before, one thing that PEQ will have a hard time with is room correction. Besides differences in response depending on where one sits or passes out on the floor, position dependent multiple narrow nulls are also a problem. Those are linear, but pretty much impossible to address with equalization alone. Headphones have less of those issues, and more of others.
     
    Last edited: Nov 1, 2018
  11. maverickronin

    maverickronin Friend

    Pyrate
    Joined:
    Mar 17, 2018
    Likes Received:
    313
    Trophy Points:
    63
    Location:
    Midwest, USA
    I have next to zero experience doing that with speakers. Most of my experience is with "razors" in headphone CSDs to maybe we're just talking past each other.
     

Share This Page