DAC Amp Measurement Methodlogy and Equipment Discussion

Discussion in 'Headphone Amplifier Measurements' started by schiit, Nov 5, 2015.

  1. atomicbob

    atomicbob dScope Yoda

    Friend BWC MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    10,240
    Dislikes Received:
    3
    Trophy Points:
    113
    Location:
    On planet
    1) stunningly easy to get bad measurements - why it takes me so long to do a set of measurements as repeats to observe consistent results are necessary
    5) Bad settings - including OS interference at times causing more grief (MS K-mixer comes to mind)

    According to the measurements I shouldn't be bothered with the Bifrost Multibit when I have both the Gungnir Multibit and Yggdrasil. Yet my ears are drawn to this design marvel, not to mention the experimentation possibilities afforded by 176 and 192 KS/S modes.
     
  2. m8o

    m8o Rando

    Joined:
    Nov 2, 2015
    Likes Received:
    15
    Dislikes Received:
    0
    Trophy Points:
    3
    In regard to the USB2/3 question...

    I think i did find driving the FiiO Alpen E17 via USB3 to be inadvisable. Will be interesting to see the case with the soon to arrive M9XX. But as far as my non portable device is concerned...

    Driving my McIntosh MHA100 from my HP 8740w via the USB2 interface gives me a lifeless & flat 2D presentation of the music when compared to every other input type of the amp.

    Switching to the USB3 port (same cable) brings the streamed computer audio, be that HD flacs or Redbook sourced flacs or mp3s, on par with the coax or optical spdif in of Redbook CDs, or the analog in of SACD or DVD-A discs. (I have no idea why the font got big in this paragraph ... isn't so in the editor)
     
    Last edited: Nov 14, 2015
  3. Hekeli

    Hekeli Almost "Made"

    Contributor
    Joined:
    Sep 28, 2015
    Likes Received:
    144
    Dislikes Received:
    9
    Trophy Points:
    43
    Location:
    Finland
  4. The Alchemist

    The Alchemist MOT: Schiit - Here to help!

    Friend
    Joined:
    Sep 24, 2015
    Likes Received:
    1,371
    Dislikes Received:
    1
    Trophy Points:
    113
    Location:
    The SchiitR
    Home Page:
    @schiit - are there any RCA interconnects that you recommend? A few members mentioned Blue Jean Cables http://www.bluejeanscable.com/store/audio/index.htm

    But I am not sure which ones to get. They have a few different options. Their favorite is the BJC LC-1 Stereo Audio Cables. But I was also curious about the Belden 1694A Stereo Audio Cables because they claim to be a good choice if RFI is a problem. With the buzzing issues with my Valhalla 2 in high gain mode, even with AC line restoration and RFI and EMI blockers I still get the buzzing/humming on the Valhalla 2 in High-gain mode, which I pretty much need to use with the HD800's.

    Are there any RCA interconnects your recommend? I know it is best to have the shortest RCA interconnect cables as possible, but the way my setup is I need at least 5 or 6 feet in length.
     
    Last edited by a moderator: Mar 25, 2016
  5. logscool

    logscool Friend

    Friend
    Joined:
    Sep 28, 2015
    Likes Received:
    72
    Dislikes Received:
    0
    Trophy Points:
    28
  6. firev1

    firev1 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    37
    Dislikes Received:
    0
    Trophy Points:
    18
    Location:
    Singapore
  7. Earfonia

    Earfonia Rando

    Joined:
    Dec 7, 2015
    Likes Received:
    5
    Dislikes Received:
    0
    Trophy Points:
    3
  8. purr1n

    purr1n Finding his inner redneck

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    50,679
    Dislikes Received:
    82
    Trophy Points:
    113
    Location:
    Antarctica
    The QA stuff cannot be used for audio playback or recording.
     
  9. Earfonia

    Earfonia Rando

    Joined:
    Dec 7, 2015
    Likes Received:
    5
    Dislikes Received:
    0
    Trophy Points:
    3
    I see. Thanks!
     
  10. Earfonia

    Earfonia Rando

    Joined:
    Dec 7, 2015
    Likes Received:
    5
    Dislikes Received:
    0
    Trophy Points:
    3
    I'm looking for something reasonably priced (under $1k) to measure both USB DACs and headphone amps. After some readings, QA401 seems only useful for amplifier measurement, but I don't see how to use QA401 for USB DACs measurement, to run automated measurement like RMAA to measure USB DACs output S/N, THD, frequency response, etc. Probably we can analyze USB DAC output manually, like generating a tone and analyze it on QA401. Or probably I just don't understand QA401 measurement features.

    Is it possible to use QA401 or QA400 to run standard automated measurement (such as RMAA) for USB DAC?
    Thanks!
     
  11. Priidik

    Priidik Friend

    Friend BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    1,441
    Dislikes Received:
    2
    Trophy Points:
    93
    Location:
    Estonia
    Where did the Studio measurements all go ?
    I had an argument with a guy who went all HydrogenAudio with me spewing crap like 2-nd harmonic 'creates' artificial depth of soundfield heard on tube amps.
    I wanna show him some measurements, but can't find em.
     
  12. chakku

    chakku Friend

    Friend
    Joined:
    Oct 13, 2015
    Likes Received:
    663
    Dislikes Received:
    2
    Trophy Points:
    93
    Location:
    New Zealand
    Home Page:
    Seems a bit of a moot point to argue when nobody really understands yet how amplifier measurements relate to things like soundfield.
     
    OJneg likes this.
  13. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    4,950
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    They are on changstar

    Also Ken Rockwell has some measurements on tube amps as well as Pete Millett
     
  14. ultrabike

    ultrabike Measurbator - Admin

    Staff Member Friend MZR
    Joined:
    Sep 25, 2015
    Likes Received:
    8,562
    Dislikes Received:
    16
    Trophy Points:
    113
    Location:
    Irvine CA
    IMO or IME or whatever, 2nd harmonic creates straight forward and simple crap, as opposed to artificial quantum depth of relativistic soundfield.

    Showing measurements is probably going to make no difference. Reason being that...

    1) If the measurements are good (whatever good subjectively means to said person), then person may argue that it all is below the audibility thresholds and subjectively no better than (insert said person's favorite amp), so extra effort is all for not.

    2) If they are not as good (whatever not as good subjectively means to said person), then person may argue that it's all shit and worse that (insert said person's favorite amp), and so extra effort is all for not.

    Of course, if said person finds out that (insert said person's favorite amp brand) came up with an update of his/her (insert said person's favorite amp), then the next generation is awesome and fixes all or the problems of the previous version.
     
    OJneg and landroni like this.
  15. Priidik

    Priidik Friend

    Friend BWC
    Joined:
    Sep 27, 2015
    Likes Received:
    1,441
    Dislikes Received:
    2
    Trophy Points:
    93
    Location:
    Estonia
    No need to convince me, I'm religiously confident that the totl tubes I've experienced are closer to the original signal than any transistor based device.
    I simply wanted to turn a minion.

    The kind that does so has been sometimes deliberately implemented, like is the case with some Decwares and I'm pretty sure Apex Pinnacle had something like that in it that works sort of like cross-feed.

    Thanks.
     
  16. Dotard

    Dotard Acquaintance

    Joined:
    Nov 6, 2017
    Likes Received:
    95
    Dislikes Received:
    0
    Trophy Points:
    18
    Location:
    Red Deer
    I had a question in general regarding tube amplifier measurements in particular. How does one tease apart the thd which is from the tubes versus thd which is from the circuitry? Obstinately some people use tubes exactly to introduce thd at certain points, so a relatively high % of thd is not necessarily a bad thing as long as it happens at moments where one wants them to happen.

    Are tube amplifiers measured using something like LISST tubes, to isolate between the circuitry and the tubes?

    Note: I am interested in measurements mainly as a curiosity, they would never drive my own purchase decisions, probably because I am a tube amp enthusiast and am fundamentally not exactly looking for cold hard 100% accuracy anyway.
     
  17. Cspirou

    Cspirou They call me Sparky

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    4,950
    Dislikes Received:
    5
    Trophy Points:
    113
    Location:
    Northwest France
    With tube amps the biggest sources of distortion is likely to be the transformer. Tubes don't really have more distortion then transistors, they are just usually used in a way that allows a lot of distortion to pass through. Just look at measurements for the Schiit Saga which has better measurements then a lot of SS preamps.
     
    Dotard likes this.

Share This Page