Delta Sigma: An Inconvenient Truth

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by k4rstar, Jun 21, 2020.

  1. Jay

    Jay Facebook Friend

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    That's good to know. I've read good things about iFi, and it sounds like I might like their sound.

    That makes sense. The AKM4399 in the old Bifrost is far less offensive in the treble than the AKM4493 in the Modius, but things are a bit drier in 4399 overall than the 4493, which has a bit more humidity.
     
    Last edited by a moderator: Apr 12, 2021
  2. famish99

    famish99 Friend

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    I'm finishing up my time with @k4rstar's Abbas 0.1 loaner and in short, I quite like it. It sounds like a grown up Gungnir Multibit A1, a lot of the same tonality and technical flaws, but I find the congestion issue on the 0.1 less offensive than I did on the A1.

    The key defining strength of the Abbas would definitely have to be its punchiness; to the point that with certain transports, like the Pi2AES SPDIF output, it can be too aggressive. With the Theta Miles it took away the fatiguing quality and turned it from overly aggressive to extremely fun sounding in that pentode amp sort of way. The stage is ok, a quite upfront and not super deep, but not flat either, works out to my preference because I tend to prefer that upfront presentation. Imaging is also typical NOS in that they're thick, voluminous images packed in tight into the stage, but as I alluded to earlier, takes a bit more complexity in the mix to get bogged down than other DACs of the price point.

    I would definitely be interested in the higher end models for the sake of seeing which technicalities to be gained while keeping that thick and lush tone and great dynamics it has to offer.
     
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  3. YMO

    YMO Scatologically ribald obsessive

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    Funny you said Musical Fidelity, this guy been selling this on my local CL for a month. He still has it. Not too sure if I wanna bite.
     
  4. Jay

    Jay Facebook Friend

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    Looks like a nice DAC, although the descriptions are confusing. MF's page says it's a DS DAC, but they don't list the actual chip. Other sites claim it uses multiple DSD1796s, which are hybrids.
     
    Last edited: Apr 14, 2021
  5. Jay

    Jay Facebook Friend

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    Ok, slap me and my mama. Hell, slap my larger extended family as well for what I'm about to claim.

    I've been doing some critical listening of the V-DAC II for a few days now, and I've really gotten a handle on the sound on how it compares to other DACs in my collection.

    I'm using S/PDIF, so USB is a moot point. I'm sure any USB gen from Schiit over the years will beat the USB of the V-DAC II because it's such an old design, but it is asynchronous, which was relatively novel for that price point at the time.

    First, it takes about 2 hours to warm up. At that point, the treble settles down a bit and the bass has some more slam.

    Also, oddly enough, I prefer the sound when powering it from the wall-wart vs. the upgraded V-PSU II that I fell for the marketing tricks years ago that convinced me it would "take the sound to another level." The wall-wart is linear, so it's not a piece of crap. But it doesn't have all that fancy magic dirty power filtration of the V-PSU. In comparison, the wall-wart sounds a little warmer and the V-PSU sounds leaner. I'm not a big believer in major differences between power sources (if they don't have something wrong with them, that is), so maybe this is just placebo. I went back and forth and the differences were detectable. Maybe my ears prefer dirty power.

    Ok, the V-DAC II is better to my ears than the Modius. The bass is more layered and textured, and the treble is sweeter. Overall, the V-DAC II has a more smooth presentation while avoiding warmpoo. In comparison, the V-DAC II is more crowded and when using headphones the sound is more in your head. One of Modius' strengths is air and width of headstage. However, I hated using the Sennheiser HD650 with the Modius. It never sounded quite right, and we're not talking just about the treble, but that alone was on the spitty side. Bass tended to be one-note and had more midbass hump than I would have preferred. The V-DAC II also lets me use my cheap impulse buy Philips Fidelio X2HR for longer periods of time, when the treble was basically a murder box when using Modius for certain tracks.

    Detail retrieval between the Modius and the V-DAC II is about the same, but I feel that imaging is more precise on the V-DAC II.

    I need to do more listening, but the V-DAC II doesn't embarrass itself at all compared to the Gungnir MB A1. On shitty recordings I would probably fail a double-blind test between the two. It's the good tracks that puts some distance between them.

    All in all, this is a nice little DAC that some of you might have some fun toying with. It can probably be found for a few bucks and is probably cheaper than the price of tubes some roll into their Vali 2s.
     
  6. Armaegis

    Armaegis Friend

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    There might be something to be said for those old hybrid multibit/DS dac chips.
    PCM1794 (Forssell)
    CS4398 (Prism)
    AD1955 (Dangerous Music, Lavry)
     
  7. k4rstar

    k4rstar Britney fan club president

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    I updated the first post of this thread with an index of loaner impressions for the abbas DAC
    I'll crawl through the rest later and link to any other worthwhile posts

    the point of this thread and the subsequent loaner was to advise and then demonstrate to people that digital can sound different. I consider it a success as several people who heard the abbas DAC went on to buy other non-oversampling R2R DACs, despite previously having no interest in NOS or writing it off.

    from speaking with various loaner participants in private, it became clear to me that the potential of the DAC was probably not heard by everyone due to transport differences. the popular pi2aes for instance does not seem to be a good match in terms of sonic aesthetics.

    regardless, a thank you to everyone who participated in the experiment. personally, I cannot listen to 'high-end' D/S or OS DACs anymore. cheap stuff and dongles are fine and where this technology belongs. In fact the $99 HELM bolt dongle I just picked up sounds better to me than any schiit DAC I've heard. that is all.
     
  8. Dzerh

    Dzerh Friend

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    I don't think non-hybrid, pure one-bit, PCM DAC chips for audio are still produced, all PCM chips on market are hybrids. Which brings its own can of worms.
    I think what @Jay likes is Burr-Brown implementation. I liked PCM1794 even in Aliexpress products.
     
  9. 7seven

    7seven Acquaintance

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    There may be a distinction between 'multi-level' delta sigma DACs , which as you say includes pretty much every delta sigma chip made in recent years, and Burr brown's segmented PCM1794 architecture.
    Segmented PCM1794 is described as having 'true' multibit DAC for the most significant bits, while a multi-level delta sigma modulator for lower bits. AKM/Sabre/etc DACs seem to be described as using multi-level delta sigma modulator for entire conversion.
    Not really sure but it's something I've been wondering myself, It's hard to find clear answer on it.
    Even though the newer AKM and Sabre DACs win on measurements the old PCM1794 might actually be using a superior architecture with potential to sound better, like the even older true multi-bit DACs
     
  10. Jay

    Jay Facebook Friend

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    This is my understanding as well. From what I've read, the hybrid approach tries to unite the strengths of both DS and R2R while minimizing their weaknesses. For example, R2R is better with high-level signals (weaker at low-level) and DS is better with low-level ones (weaker at high). I also read something about how the lower bits being converted by DS avoid the problems in 0 crossing in PCM. I have no idea what that means, so maybe someone more knowledgeable can explain that.
     
  11. Cooper32

    Cooper32 Facebook Friend

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    I remember @Torq reviewing a Ross Martin DAC that uses one of the Burr Brown / TI "Advanced Segment" hybrid DS/R-2R chips.

    https://www.superbestaudiofriends.o...sil-watering-the-ash.4036/page-21#post-137380

    My first DAC was a Ross Martin DAC that I got used from a friend for $60. Back then, I had no idea what a bargain I got. I know I'm nowhere near as a trained listener as @Torq so I can't really say I can hear all the differences he wrote about between the Ross Martin and the Modi Multibit.

    Even today, I still prefer the Ross Martin DAC to my Modi 3. I haven't done an in-depth comparison but from years of listening to both, I like the less square presentation of the Ross Martin.

    Like @crenca and @Jay mentioned, sounds like iFi might make a modern implementation of the hybrid DAC chips.
     
  12. dllmsch

    dllmsch Friend

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    I saw PCM1794 mentioned and dug out my first DAC---Music Streamer Pro from HRT, which I believe is using PCM1794 for DA conversion. Years ago I just upgraded it to a modi multibit without any proper comparsion.

    With my BF2, both being fed by USB to make it fair. Music Streamer Pro is less smooth, has less low end sustain, worse imaging, smaller stage and more grain(I consider Pi2AES-->BF2 to be grain free, unison has some). Note that this DAC is almost 10years old and only have USB input, which probably is holding the performance back.
     
  13. rlow

    rlow A happy woofer

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    Chips ain’t everything. It’s in the implementation. Ifi has been using mostly the same BB chips for many years and they just keep eeeking more out of them with each DAC revision. Power supply, input stage and output stage have a huge impact on ultimate SQ even with DS DACs. Still not going to sound like a Schiit DAC or an R2R (NOS or OS) DAC though, which generally have custom digital filters (or none).
     
    Last edited: Apr 14, 2021
  14. Ruined

    Ruined HD700 ruined my ear holes

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    I still have a PCM1795-based dac (Musical Fidelity MX-DAC) and to me when comparing PCM and DSD files derived from the same master (of which there are many commercial releases available) decoding each in native format, the sound is identical

    The main advantage of having DSD capability is that there are a handful of top-tier masters that are available ONLY in DSD, and the software-based routines to decode DSD > PCM that programs like jriver have sound slightly worse than playing back the DSD in the PCM1795 hardware.

    Overall I am very happy with the sound from this dac (MF MX-DAC). Detailed but not harsh, organic, fantastic soundstage, tight bass. Very nice overall.
     
    Last edited: Apr 23, 2021
  15. EternalFury

    EternalFury Rando

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    A waveform comes into the ADC.

    A waveform comes out of the DAC.

    I would like to compare the distance between these 2 waveforms for any particular DAC.

    Otherwise, I feel we can only express our preferences and attribute them to decoding performance superiority, while these 2 things might not be related.
     

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