Bob Katz talks about mastering audio, digital filters, dsd and Schiit

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by Madaboutaudio, Dec 26, 2015.

  1. Madaboutaudio

    Madaboutaudio Friend

    Pyrate
    Joined:
    Sep 28, 2015
    Likes Received:
    545
    Trophy Points:
    93
    Location:
    Singapore


    A lengthy video, quite technical and informative
     
  2. Madaboutaudio

    Madaboutaudio Friend

    Pyrate
    Joined:
    Sep 28, 2015
    Likes Received:
    545
    Trophy Points:
    93
    Location:
    Singapore
    Jump to 54min:55sec to listen to the part where Bob Katz is asked about what he thinks about Ladder/Multibit DACs from Schiit.
     
  3. sphinxvc

    sphinxvc Gear Master (retired)

    Staff Member Pyrate BWC
    Joined:
    Sep 28, 2015
    Likes Received:
    3,320
    Trophy Points:
    113
    "Half of it is that...if you have a really good design and you do one thing wrong, like use the ladder [multi-bit], but everything else is good, you could beat a poorly designed delta-sigma." - seems to sum up his view.
     
  4. Chris F

    Chris F Boyz 4 Now Fanatic - Friend

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    805
    Trophy Points:
    93
    Location:
    Ottawa, Canada
    I don't see much of a scandal. Bob is a guy who trusts his ears and his ears told him that the Yggdrasil was the equal of top end delta sigma.

    It seemed to me that that his bias against R2R comes from hearing lots of bad implementations.
     
  5. Madaboutaudio

    Madaboutaudio Friend

    Pyrate
    Joined:
    Sep 28, 2015
    Likes Received:
    545
    Trophy Points:
    93
    Location:
    Singapore
    Maybe Bob feels that the more expensive laser trimmed resistors cost way too much more and doesn't justify itself for the extra cost. Maybe he feels that Schiit could have implemented a sigma delta dac with the same closed form filter.

    I.e. The same internals of the Yggdrasil without the expensive 4 x AD5791 instead with 8 x AKM4490 or any of the better regarded sigma delta designs.

    Maybe if the Yggdrasil had a sigma delta option(while retaining it's closed form filter), it could have been 60-70% of it's price?

    In any case, maybe Mike Moffat could have already done a prototype sigma delta dac with the same closed form filter and didn't like the sound coming out of it.
     
    Last edited: Dec 27, 2015
  6. Chris F

    Chris F Boyz 4 Now Fanatic - Friend

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    805
    Trophy Points:
    93
    Location:
    Ottawa, Canada
    Correct me if I am wrong but I think the mega burrito filter only works in a multibit design.
     
  7. Andre Y

    Andre Y Friend

    Pyrate
    Joined:
    Oct 4, 2015
    Likes Received:
    220
    Trophy Points:
    43
    Location:
    Southern California
    You can in theory use the mega burrito filter on a delta-sigma DAC. The Theta Pro Prime used their proprietary 4x oversampling filter on a Philips 1-bit delta sigma DAC chip.

    Why didn't Schiit use a DS chip? I can only speculate:

    1. Market differentiation: being one of the few companies to use a multi-bit DAC. I think Jason's said as much.

    2. Technical reason: the DS DACs currently available (unlike the Philips 7350 used in the Theta) may not accept an 8x/4x whatever oversampled signal, and may implement their own internal OS filter which may cancel out any good an external OS filter may have.
     
  8. lm4der

    lm4der A very good sport - Friend

    Pyrate
    Joined:
    Sep 26, 2015
    Likes Received:
    1,461
    Trophy Points:
    113
    Location:
    Seattle, WA
    Maybe design philosophy - Moffet always talks about delivering the samples unadulterated. D/S approximates voltages, whereas ladder DACs have a resistor for each bit. Still, I would love to hear @schiit comment on this. In a sense I think one could argue that the ladder is more "pure" with respect to bits.
     
  9. beemerphile

    beemerphile Friend

    Pyrate Contributor
    Joined:
    Dec 19, 2015
    Likes Received:
    755
    Trophy Points:
    93
    Location:
    Danielsville, GA USA
    Has not every DS DAC that they have redone in multibit form gotten much better?
     
  10. lm4der

    lm4der A very good sport - Friend

    Pyrate
    Joined:
    Sep 26, 2015
    Likes Received:
    1,461
    Trophy Points:
    113
    Location:
    Seattle, WA
    Right, but we don't know how much of this to attribute to the megacomboburrito filter or the multi bit dac. Hence the question about combining that filter with D/S.
     
  11. mtoc

    mtoc SBAF's Resident Shit-Stirrer

    Banned
    Joined:
    Oct 22, 2015
    Likes Received:
    85
    Trophy Points:
    28
    yap, we should put the megacomboburrito filter with other D/Ss.
     
  12. dark_energy

    dark_energy Friend

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    1,040
    Trophy Points:
    93
    Location:
    Forest
    DS has time domain and voltage approximation. There's a reconstruction of the voltage value in each sample. It seems it has something to do with that and why one might choose R2R instead. With R2R the voltage values are already there, there is no reconstruction, therefore more accurate time domain.

    Two R2R DACs i have heard are in an other league compared to 10 or more DS DACs... Not sure why.
     
    Last edited: Dec 28, 2015
  13. meloman

    meloman Acquaintance

    Joined:
    Sep 29, 2015
    Likes Received:
    56
    Trophy Points:
    18
    Location:
    Bay Area
    There is already a software implementation of a closed form filter that can be tried with any DAC, d/s or multibit. Maybe someone with MB Bifrost in NOS mode can experiment with HQPlayer and compare with megacomboburrito.
     
  14. lm4der

    lm4der A very good sport - Friend

    Pyrate
    Joined:
    Sep 26, 2015
    Likes Received:
    1,461
    Trophy Points:
    113
    Location:
    Seattle, WA
    Honestly, I am not super impressed by Bob Katz. It's hard to put my finger on why, just lots of little things.

    EDIT: I should also add that I'm not necessarily qualified to hold this opinion.
     
    Last edited: Dec 27, 2015
  15. Andre Y

    Andre Y Friend

    Pyrate
    Joined:
    Oct 4, 2015
    Likes Received:
    220
    Trophy Points:
    43
    Location:
    Southern California
    I checked out a couple of datasheets for modern DACs including the AD1955 and the AKM4399 (that's used in the base Gungnir), and both allow for external digital filters, with the AD part even having an internal bypass for one, so it appears possible to use the megaburrito filter (or whatever other oversampling filter) on currently available audio DACs. That might make for an interesting Gungnir update ... megaburrito filter + AKM4399.
     
  16. Madaboutaudio

    Madaboutaudio Friend

    Pyrate
    Joined:
    Sep 28, 2015
    Likes Received:
    545
    Trophy Points:
    93
    Location:
    Singapore
  17. Judeus

    Judeus Facebook Friend

    Banned
    Joined:
    Sep 28, 2015
    Likes Received:
    202
    Trophy Points:
    43
    Location:
    summit-fi purgatory
    The lack of taps are disturbing. Must consult chord.
     

Share This Page