Saturday 24 November 2018

NOS vs. Digital Filtering DACs: Exploring filtering turned off, implications, fidelity and subjective audibility. (Recent BorderPatrol DAC chatter...)

Hmmm... Non-OverSampled waveforms - "accurate", "high fidelity"?
The waveforms above were captured with my RME ADI-2 Pro FS ADC at 384kHz. As you can see, on the left side, we see the waveform from the TEAC UD-501 DAC with the digital filter turned off (Non-OverSampling - NOS mode). In the middle, we have the TEAC's "Sharp" oversampling filter engaged. And on the right, we see the same waveforms captured from an old 16-bit Philips TDA1543 x 4 DAC with chips in parallel (supposedly improves noise level), a multi-bit NOS chip, without any oversampling.
Here's the TDA1543 x 4 DAC board. Typically fed with a 12V DC power supply.

Furthermore, we see that these are supposed to be -6dBFS sine waves at 1kHz, 5kHz, 10kHz, and 16kHz. Clearly, the "Sharp" digital filtered tracing shows us that the reconstruction algorithm does a good job in recreating the intended waveform compared to the NOS tracings with visual inspection. While the NOS output from the TEAC and TDA1543 look similar, there are differences we can make out in terms of the output from the TEAC appearing to have more overshoot at the transitions.

Something else to notice is that as the frequency increases, with fewer samples to define the sinusoidal wave (since we only have 44.1kHz sample points), notice that many of the frequency peaks do not reach the full amplitude of the sine wave with the NOS output. This correlates with the dip in high frequency amplitude response which we can easily measure:

Notice in the graph above, I've included both the RME ADI-2 Pro FS output in NOS mode as well as the old TDA1543x4 DAC compared to the TEAC UD-501 with "Sharp" digital filtering turned on. This shows us that regardless of old (TDA1543) or modern (RME ADI-2 Pro FS with AKM DAC) device used, the moment you turn off the digital filter, one creates this dip in the treble response which in the measurements above are down to about -3dB by 20kHz.

For fun, I can use the "Extremus" filter setting with my Raspberry Pi 3 B+ Touch to oversample the 44.1kHz signal to 88.2kHz (this DAC can handle up to 96kHz) and create a smoother looking sine wave:

Notice that the upsampled waveform is still rather jagged looking. This is because the TDA1543 is only a 16-bit DAC, plus we're only upsampling to 88.2kHz here. What is obvious is that now all the sine wave peaks are at close to full amplitude at 10kHz at least. And this improvement of frequency response can be confirmed with measurements:

The SoX upsampled 16/44.1 test signal to 88.2kHz now has a flatter frequency response but it's still obviously not perfect. Less than -1dB dip into 20kHz compared to -3dB without filtering.

Finally, remember that those jaggy, squarish NOS waves imply that there are high frequency anomalies. Here's a look at the FFT analysis up to 192kHz (384kHz sampling rate using RME ADI-2 Pro FS) of what is simply the 10kHz sine wave through the TEAC UD-501 with filter engaged, turned off, the TDA1543 DAC in NOS and when sent a signal from the Raspberry Pi 3 with SoX upsampling to 88.2kHz.

Obviously, the old TDA1543 device (bottom row) is much noisier than the TEAC DAC (based on much newer TI/Burr-Brown PCM1795 chips). We see with the TEAC in NOS mode the ultrasonic imaging distortions, the result of ignoring the proper reconstruction based on sampling theorem, compared to the typical "Sharp" digital filter available to most modern DACs. As for the TDA1543, notice the improvement with less high frequency distortion when we use even a 2x oversampling from 44.1kHz to 88.2kHz for this 16-bit DAC.

As fate would have it, I had started writing this article when I was reminded this week that Stereophile reviewed and measured the BorderPatrol DAC SE back in August of this year. Imagine, in 2018, a 'new' DAC designed around the geriatric Philips TDA1543 DAC chip released back in 1991 with fancy copper case and supposedly great power supply going for somewhere around US$1000-2000. Evidently despite the power supply and fancy chassis, the device measures rather poorly to say the least - go figure... The owner of the company even claimed "I was aiming to make an affordable DAC that sounds refined, clean, relaxed, fluid, colorful and human and free from the artificial ‘hi-fi’ sound that characterizes so many budget designs"! Since when did jagged edged reproduction of digital become anything but "artificial"!? Since when is this "refined" as claimed by the Stereophile reviewer? And how in the world does that price tag represent a "budget design" or "a very reasonable price" when clearly that jagged simple sine wave output can be surpassed by almost any decent modern DAC at US$200 or less?

I see in the last few years that there are other "high end" DACs based on the TDA1543 around. For example, there's this 16-chip Computer Audio Design 1543 MKII DAC proclaimed to be the "world's finest" at a mere £7,250.

Stereophile's "As We See It" penned by Jon Iverson for this month's issue brought out the BorderPatrol DAC again (I noticed some similarities in the philosophy expressed with my previous post here). In the article, Iverson quotes Jon Atkinson as saying "If this is a 'great' DAC, I'll have to hang up my measurements." While I may not agree with some of Atkinson's opinions, obviously I do not want to see the loss of measurements in Stereophile; if anything there should be more emphasis on the importance of measurements especially for controversial stuff like cables, questionable DACs like this, and digital tweaks. Over the years, I have opined that it is the objective measurements in Stereophile that actually make the magazine worthwhile reading as an archive for information rather than just subjective opinion.

IMO, obviously Mr. Atkinson has no reason to worry about his findings regarding this not-great DAC. When measurements clearly show that there are all kinds of issues with a device - channel imbalance, linearity anomalies, high-frequency noise, clearly poor low-level performance, high jitter, and terrible ultrasonic characteristics inherent in NOS devices - how can anyone who desires "high fidelity" audio argue that these are "good" (forget "great") characteristics?

(BTW, notice Figure 8 on the measurements page and the similarity with my capture of the -90dB signal from back in 2013 of the TDA1543 x 4 DAC I have. Despite the expense and fancy power supply, it certainly doesn't look like the low-level waveform has improved any!)

Apparently the subjective reviewer was not able to hear these anomalies. The question is should the subjective reviewer have been able to? Should subjective reviewers have the hearing acuity to appreciate the channel imbalance found? Should the reviewer have been able to tell that this DAC inverted polarity (a "golden ear" claim of significance)? Or that the DAC allowed all kinds of nasty high frequency noise to hit the amp and speakers which could actually have added distortions in the audible frequencies?

I do not want to single out this subjective reviewer because the fact is that this applies to all subjective-only reviewers regardless of expectations of them having "golden ears". When faced with the objective realities of the device, the reviewer and we as the audience need to come to terms with obvious discrepancies especially in clear situations like with these NOS DACs. Let's remind ourselves that audiophile reviewers are indeed human with idiosyncrasies and biases (of course!).

Let's summarize... IMO...

1. NOS DACs are not "accurate" or "high fidelity" when asked to reproduce typical 44.1kHz samplerate material. Clearly they have reduced frequency response and create all kinds of ultrasonic distortions. Personally, the only time I ever listen to my DACs in NOS mode are if I'm upsampling to 192+kHz using good software that does the filtering for me or if I listen to native hi-res files 96+kHz (maybe with piCorePlayer with SoX upsampling, JRiver with upsampling, or HQPlayer).

2. Regarding the aphorism that gets trotted out by pure subjectivists frequently: "If it measures good and sounds bad—it's bad. If it measures bad and sounds good, you've measured the wrong thing." (D. R. von Recklinghausen) Supposedly this is the unofficial "motto" of Stereophile that originated from before the early 1990's. At least the rest of that article reads reasonably well.

While this might be true in some circumstances especially in the old days, who ever said this was universally applicable? After decades, with the maturity of sound technology, assuming the collection of measurements was done appropriately, an alternate explanation is just as likely: "If it measures bad and sounds good, maybe your hearing isn't as good as you think." I think it would be hard to argue against this perspective when a subjective writer waxes poetic about stair-stepped squarish waves coming out of an old NOS DAC as if there is some special, non "digital-sounding" quality. From my perspective, these squarish waves are as "digital-sounding" as it gets! Another example of this might be how forgiving our ears/mind are to the effects of jitter; objectively, it takes quite a lot of timing irregularity before most people would be able to put their finger on an audible problem. Yet think of all the times various reviewers have claimed that cables of all things affect jitter significantly or manufacturers seem to think femtoseconds are audible...

When the technology is advanced enough to exceed perceptual thresholds, this is exactly what one would expect. The human perceptual system has been surpassed in many domains already. When this happens and there is a desire to differentiate devices, creative imagination becomes a greater factor and the mind projects descriptions of the devices fed by psychological expectations and biases than objective reality.

3. As I've said in the past, it's okay to be a "euphonophile". Some distortions could be subjectively perceived as "better". Examples might be the "BBC dip" or the "Harman Listener Target Curve" where non-flat frequency responses are psychoacoustically preferred. Likewise, higher even harmonic distortion with certain tube amps might sound better to some than an ultra-clean solid state sound. Our job as audiophiles is to recognize this. In my opinion, there is such a thing as an "objective euphonophile". A person who is honest enough with him/herself to say that he/she likes certain types of distortions in the sound, can objectively point to that which they desire, because it "sounds good" to them. This also means that the person accepts that he is not aiming for "high fidelity" sound. Rather, his pursuit is of a certain "coloration" to the sound that is possibly idiosyncratic rather than universal or ideal - by definition, this pursuit is not faithful to what was on the recording.

As such, a NOS DAC connoisseur could still say "I love the sound of old NOS DACs because I think the higher noise floor and ultrasonic frequencies through my amplifier and speakers result in a subjective 'lusciousness' that I desire even though it wasn't on the original recording". If a reviewer said something like that, I think many would applaud the honesty and congratulate the person for the level of insight and implied understanding of the technology. No need to waffle on right/left brain ambivalence, claim authority based on some kind of "experience", or flowery language to suggest some questionable redeeming quality (as we see in the Stereophile review of the BorderPatrol).

This same principle applies to those who love vinyl and turntables. One can appreciate the limitations to the technology. Absolutely, acknowledge benefits like album art and the physicality of vinyl. At times I like the sound from my LPs as well. But please don't keep insisting that LPs are "high resolution" media that surpasses true hi-res digital though! Let's be honest about the "fake news" in the audiophile world...

Audiophiles. Know thyself?!


Just want to let everyone know of a cool new tool by Yamamoto2002, our man in Japan :-) - WWShowUsbDeviceTree.

With this program, you can inspect a bunch of USB parameters of devices hooked up to your computer which of course includes USB DACs. Things like USB Audio Class compatibility, compatible bit-depth, power requirements... Here's what my ASUS Xonar Essence One looks like:

Yeah, totally geeky. Have fun if you're into this kind of thing. :-)

I was over at an audiophile friend's place the other evening. He put on the DSD128 version of Jacintha's Fire & Rain. Sounds good with nice dynamic range (~DR13) if you're into the audiophile female vocals genre and James Taylor cover songs :-|. When examining the DSD128 files, I noticed the noise floor was higher than expected for a high resolution production.

The Bohemian Rhapsody (DR8) soundtrack with its mix of remastered tracks and live recordings was certainly fun listening to that evening! And if you're interested in some older-sounding new pop music, be sure to check out Steve Perry's Traces (2018, DR6) - especially if you're a Journey fan back in the day :-).

Enjoy the music folks. Happy Thanksgiving weekend to the American friends.


  1. Great article, as good as ever on this site. This blog is a constant source of nice audio and related information. And well written, too.
    It seems - no need to strive for NOS DACs especially at 44.1/48 kHz playback.
    Extremus filter is nice, but I'm staying at the moment with 95.4 passband for SoX upsampling.

    1. I agree. Keep up the awesome work, Arch. If I may call you Arch. ;)

    2. Cool Honza. NOS at 44/48 is really silly IMO!

      No worries Doug. "Arch" is fine :-)

  2. I just can't fathom why anyone would use the TDA1543 in a new design. The chip was designed around 1990 as a low-cost DAC for cheap CD players. No corner was left uncut. It was a poor performer at the time, and today it is nothing short of terrible. Moreover, it was intended to be used with 4x upsampling. Designs running it at 44.1 kHz aren't even using it right. It all goes to show that the so-called high end in audio is a scam, a delusion, or both.

    1. Hey Mans...

      No kidding. It's really just bizarre. Imagine if any other engineering-based industry did this kind of thing!? Eschewing actual progress and insisting that low-quality devices and technologies from past decades be embraced. So-called "leaders", "champions", and "respected" members of the hobby unable to recognize the difference!

      BTW: For those who didn't click on the TDA1543 datasheet. Clearly on the front page, the device is described as an "Economy Version" DAC! And to think in 2018 some companies want to charge thousands of dollars for machines with this as the heart of the device? Wow.

  3. As a veteran of the impoverishing DAC wars of the '90s, I have been amused by the NOS fad (which I thought had faded away - apparently not enough). Such DACs (and tube DACs, for that matter) are simply expensive tone controls for people who don't believe in tone controls. They believe in many other silly things, but not tone controls, which remain blasphemy to their sect.

    I expect (hope) that this will die out as time marches, but as the hipsters have taught us, while science advances, voodoo remains entrenched. When CDs first took over, many made money off of the understandable misconception that the problems of turntables would also be found with CD transport mechanisms, leading to "green dye" pens and massively overstabilized players and transports. Those of us who grew up with analog playback were particularly susceptible to these sorts of appeals. On the surface, they made sense, if you didn't understand how digital worked.

    Similarly, the "preemphasis" assumptions and other recording techniques of the Vinyl Age caused some really lousy, screeching CDs to be produced. I asked a recording engineer whether he was still boosting the high end when he recorded digitally, and he said yes. (It was obvious from the recordings, but I was being diplomatic.) He is a pro, and yet he was still conditioned to compensate for the high end loss of analog tape despite recording now entirely in the digital domain.

    I have to question whether old-timer buffs like me actually hurt matters, given that the two methods (analog v. digital) do not work the same way and require not only different equipment but different understanding. I don't doubt that many of the "problems" former analog listeners discerned with digital media caused the development of some of the most useless shit ever for digital playback. And I think many of them were sincere, at the beginning. (I am not so generous with the antics of those who knew better, or learned better but still scammed consumers without conscience.) Literally, a new technology with its own new language has taken over, and did so quite a while ago, and like WWI biplane aces confronted with Saturn rockets, older music lovers were caught flatfooted. The average 12-year-old has a firmer grasp on digital systems than anyone my age (with a few exceptions), even the audio "experts."

    The late Tom Nousaine once said that, in the future, audio equipment will be considered appliances, like refrigerators and hot water heaters. And no one subscribes to Frigidaire Monthly. As the difference between components and playback machines approaches zero, there are people who will be out of work.

    And to be honest, I find your work fascinating, even though I am more than happy with 16/44 media and a house full of CDs.

    1. Hey Jeff... Sounds like you've been through the trenches in the audiophile wars over the decades with the wisdom at the end of the day to stick with what works :-).

      Actually, I think many of us here are completely happy with 16/44 CD quality - so long as the recording was done properly as you alluded to.

      Yeah, the NOS brethren have been with us for awhile haven't they? I remember reading about this whole NOS thing in the 1990's as well and I believe Audio Note and 47Labs remain ardent supporters. Regardless of how the devices sound, I suppose there's always the sense of "belonging" in whatever tribe we hang with :-).

    2. As long as 16.44 is well upsampled ..... I live with it very well.
      It would be nice to do testing, whether upsampling to 24/176.4 or 24/352.8 provides better results (filtering, ringing, sound quality) than to 24/88.2.

    3. Once again:
      1. we, as audiophiles, should push to redefine the "CD Quality" as being 16/48: it's completely (mathematically, at least) stupid to down-sample 24/96 material to 16/44.1
      2. we should abandon PCM (at least for listening): after the conversion to DSD128 the difference cannot be simply said to be "more pleasant".

    4. Hi Teodoro,

      Well, not sure about the DSD conversion bit since I'm happy with my PCM and remember, DSD is not amendable to DSP. Furthermore, not all DACs handle DSD. So while each of us can choose to do transcoding from PCM --> DSD as the final step to our playback chain, leaving it as PCM for ReplayGain, DSP room correction, EQ, etc. would practically be the "right" thing to do and serve more music lovers.

      Alas, "CD" is 16/44.1 and obviously there is no way to now expect the RedBook media specs or player specs to change.

      I of course routinely convert stuff to 16/48 or rarely 24/48 simply because few records "deserve" to stay as 24-bits IMO :-). The beauty of our digital streamers, DACs, and playback systems is that we can be very flexible these days and mix/match bitrates and even PCM/DSD.

      As stated years ago:

      If they could "standardize" on 16/44 and actually release reliable recordings that deserve hi-res as 24/96, that would be good for consumers. So much of the "hi-res" out there is just upsampled or poor recordings that there's nothing worth buying or will simply turn consumers off because there is practically no difference in the sound.

      Instead of diddling with specs like 24/192, DSD-this-and-that, or MQA, the industry needs to just get things done that the consumer sees as being of value rather than potentially "scammish". Not sure if they have the capacity to appreciate the difference or even care...

    5. I do have a sample rate converter, though, frankly, I have little doubt I'd fail to distinguish 48 from 88 from 96 from 192. I thought 96 sounded better, but then I thought 88.2 sounded better, but then I thought maybe 44.1 sounded just as good. I've got it set to 48 now, though god knows why. Then again, I am at the age where an equalizer makes sense, so I can recapture those sizzling highs. But as usual, speakers (and the room, of course) make the difference.

      Archimago, I'd hate to tell you the various DACs I bought before I wised up (and even after). Some years ago I picked up a Theta DS Pro Gen Va, considered the ne plus ultra of DACs, for a song. I listened closely for hours, but I'll be damned if I could hear veils dropping. I plugged in an old PS Audio DL3 (20-bit BB PCM1702J DAC chips) and, of course, it sounded exactly the same. And the DL3 was the PS bottom of the line at the time. Good times.

      TDA chips are simply tone controls for the Vinyl Resistance. Technology has passed this nonsense by. Today you can buy offerings from Topping and SMSL, in the $75-$500 range, that have better specs by far than anything available in the '90s and '00s for the price of a small Swiss chalet (airfare not included). And people under 25 frankly don't give a shit about the "true fidelity" of LPs.

      I firmly believe that future strides will be made in transducers. What more, audibly, can we do with DACs? Or amplifiers, for that matter? Sure we can make them smaller and cheaper, but the actual improvements must come from speakers.

      BTW, how do I do italics on these comments? And will you damned kids turn that music DOWN???

    6. There's nothing wrong with pre-emphasis if the proper de-emphasis is applied on playback. However, I don't know of any recording label that used this after 1995 or so. Unfortunately, some later CD players (like my Cambridge Audio 840C) opted not to support this, so any pre-emphasized CD would sound screechy when played back.

    7. Maybe there's nothing wrong with pre-emphasis, but I struggle to see anything right with it either. What problem is it supposed to solve?

  4. Thank you for introducing WWShowUsbDeviceTree!

    About NOSDAC, there are two drawbacks caused by missing component (low-pass filter):
    ①Aliasing noise is not filtered out and leaking (it is ultrasonic range noise but it may led to IMD noise on hearing range on later stage).
    ②Slight frequency roll-off in highest edge of hearing range.
    Cascading low-pass filter to cut aliasing noise on NOSDAC output resolve these issues :)

    1. Hey Yamamoto. As usual, great work on the programming!

      Alas... Presumably the folks who like NOS seem to have no problems with those anomalies.

      Have a look at the comments on "As We See It":

      LOL. Quite some disagreement with dragging in of the Benchmark DAC into what amounts to unsubstantiated subjective opinion-making...

      "The Border Patrol DAC reproduced the church walls, the reverb, the positions on the floor where the musicians were standing; plus all the subtle breathiness of Macy Gray’s voice. With the Benchmark, the majority of that information (which is definitely on the master file and appears via David’s $100K MSB DAC and via my $2K Holo Spring DAC) disappeared !!! Your so-called "accurate" DAC removed this important information that is unquestionably on the master file..."

      Says a certain reviewer...

    2. "The Border Patrol DAC reproduced the church walls, the reverb, the positions on the floor where the musicians were standing; plus all the subtle breathiness of Macy Gray’s voice. With the Benchmark, the majority of that information (which is definitely on the master file and appears via David’s $100K MSB DAC and via my $2K Holo Spring DAC) disappeared !!! Your so-called "accurate" DAC removed this important information that is unquestionably on the master file..."

      This is pathological nonsense. To say nothing of impossible.

  5. There is a foobar resampler plugin with zero order hold support, would be handy for some illustration purposes.

    Related discussion, ended in a rather sad way, poor user nhash...,112883.0.html

    1. Thanks Bennett for the link to the plug-in.

      A convenient way to listen to some NOS/ZOH! Now everyone can have a NOS DAC :-). Indeed, looks like things did not end well for nhash. Better luck next time.


    "Give every track the sound of vinyl with Vinyl Processor"

    "Get lost again in the richness of the melodies and dynamics of your favorite albums by giving back the character of vinyl to your digital tracks. Subtle reproduction of the low-frequency resonance, tone-arm resistance, and surface noise deliver an authentic listening experience."

    In other words, for over $8k we will add the euphonic vinyl distortion to digital.

    1. This vinyl simulator is free:

      Sony claims DSEE HX is able to improve lossy files with AI. IMO it is not entirely impossible, what matters is how it actually sounds. If Sony is really confident about their algorithm, they can make an online trial version of DSEE HX, let users upload some short lossy audio clips and evaluate the algorithm. Of course, users should avoid uploading published music so that Sony cannot cheat by identifying and replacing the clip with a lossless one in their database.

      It also seems that Sony is quite confident with the sound quality of their "audiophile" SD card as well :P

      Sony is also very clever by inventing and monetizing the "Hi-Res Audio" logo.

    2. Several companies have software based microphone and open reel simulator plugins for home studio work. Cheaper than a Studer A800 or AKG C12. I'm surprised there are not digitized simulations of classic gear aimed at the so-called audiophile. Sort of like the stuff you used to find on classic Carver gear...sonic holograms and t-mods, etc. Maybe a Koetsu filter, or SP3a phono equalizer. LOL

    3. @Dtmer Hk: That tool is not giving you the real Vinyl sound as it lacks any kind of distortion emulation. Recommenced tools for really real Vinyl sound are Vinyl Strip, and even better Abbey Road Vinyl. A detailed review can be found here:

      Use Google translate to read it in English. Here is the summary of izotope:

      The free iZotope Vinyl Plugin is all about typical noise associated with vinyl and (historical) analog technology, such as mechanical and electrical hum, chirping, rumble, dust, scratches, and pitch modulation by corrugated plates. Factors that engineers worked hard to get rid of in the heyday of the analogue age. Conclusion: the tool is not suitable for creating the sound that today's vinyl lovers are looking for. The use is limited to creating effects, be it in intros, outros or at special moments within a track - or for movie sound.

    4. Of course no one should expect too much from a freeware. I was involved in the audio restoration field for a few years, while have no love or passion to study vinyl in depth, I still know the sound of real vinyls.,111421.msg918698.html#msg918698

      The problem is how good is Sony's algorithm to simulate vinyl, especially when asking for a price like that.

    5. Well, Sony's advertisement fairy tales on this unit are so full of crap that I don't expect anything useful or realistic from that vinyl emulation. Just some harmless EQ nonsense. Exactly what you can read out of its description...

    6. @Techland: Well, ya gotta admit that the copper, brass, gold plated knob looks very beautiful and screams "bada$$ audiophile" gear targeted at the discerning listener!

      As for the description of the free iZotope Vinyl plugin:

      The free iZotope Vinyl Plugin is all about typical noise associated with vinyl and (historical) analog technology, such as mechanical and electrical hum, chirping, rumble, dust, scratches, and pitch modulation by corrugated plates. Factors that engineers worked hard to get rid of in the heyday of the analogue age. Conclusion: the tool is not suitable for creating the sound that today's vinyl lovers are looking for...

      Actually, at maybe 5 or 10% intensity, this could be exactly what the modern "vinyl lover" could be after! I'll have to check this one out :-).

  7. This comment has been removed by the author.

    1. I bought the Abbey Road Vinyl plugin just for fun. It was on sale at for $50. Not cheap, but whatever.
      It actually does work. And if you turn the dials of some of the distortions up over the default settings, it makes the playback sound like an old not well cared for LP - real crap.
      Sort of funny.
      I will probably apply it to some of my most harsh/hard digital sounding recordings. It does, among other things, "soften" the sound.

  8. Hello Archimago,

    For couple years I use a NOS DAC based on AD1865 chip which I DIYed using this project . Measurments of the DAC module in this implementation are decent (THD:0031% and THD + N: 0,011% at -6db dBFS).
    With tube output/ solid state amp it sounds very natural to my ears. I have had couple of mid-priced SABRE based DACs to compare this one with and this one and it left them in the dust. I think it is implementation that matters.

    And reviewers... I read most of them just to see what's new on the market, however I have no trust in their opinions. Belive it or not one of the respected Polish hi-end reviewers, in summary of his various file types comparison, wrote that if there will be "japan master HD" copies of files available he will be first to buy them :)))

    1. Hi Przemek,
      Glad to hear the AD1865 worked out for you and that the DAC can handle to 24/192 as well... Yes, decent numbers and I'm sure the sound could be great!

      LOL. "Japan Master HD"!? I guess the bits and bytes coming from the Japanese Archipelago must be superior to Polish bits and God forbid any North American bits end up on the digital stream!!!

      The real mystery is why, how, and with whom did this hi-end reviewer become "respected"?

  9. Is the DAC's digital filter same thing as some player's "Upsampling"'s feature?

    1. Hi Ka Yue.

      Depends on how they're wording it or doing it. For some DACs like my ASUS Xonar Essence One from 2013:

      The "upsampling" feature is an extra step done with the device's microcontroller (or FPGA as the case may be depending on the unit) rather than using the TI DAC chip's default digital filter setting.

      Often this extra upsampling step will be resampling the input to something like 192kHz before handling the data off to the DA converter. Other upsampling algorithms like the Sony "remastering engine" will up/resample to DSD rather than PCM...

    2. What's your opinion on Upsampling? --

    3. "What's your opinion on Upsampling? --"

      Great for improving filtering! Most DACs upsample and it does the job. ;-)

  10. Nice measurements. Perhaps if you also measure phase and impulse response, you will find some objective evidence that NOS has some advantages counterbalancing the flaws you rightly point out.

    1. Hi Unknown,
      Phase is fine with a linear filter. And impulse response as discussed elsewhere is using an "illegal" signal that doesn't conform to Nyquist bandwidth limits so even if it looks nice as a "square" waveform, does not represent actual music in any way. Audio manufacturers and magazines tend to make too much of the "ringing" which is not an issue:

  11. Using foobar (sox 88.1Khz) with a DAC Lite NOS (8x1543).
    I tried all that high priced high sampling rate stuff and it sounds bad to my ears NOS sounds a lot better to me. I made the mistake of overlooking NOS type DACS until I hit a brick wall with delta sigma and had to do a U turn. Some comment here about dac 1543 being a budget type DAC, well the entire reason of bit-stream was to further cheapen the DAC making process so no precision resistors (R/2R) were required and the new bitstream dacs could work from batteries, if anyone remembers that (1990ish) was about the time portable CD players arrived on the scene. CD never recovered from the overblown budget technology that is bitstream/delta-sigma. Multi bit tried to recreate analogue by using a quasi- natural process (r2r) bitstream achieved the same thing by crazy over sampling rates and noise shaping etc and by 1990 CD had so no one really cared about records by then. As the budget DAC chips became cheap and more common many manufacturers simply played the old trick of putting it in fancy case with a fancy power supply along with a favourable review..or three and that's that. I can fully appreciate why certain manufacturers avoided using bitstream. Bitstream look good in the frequency domain (as seen by the oscilloscope) and it trades this for precision in the time domain (not seen by the oscilloscope unless you do an impulse test)and this is what I believe is being heard by people who prefer NOS.

    1. Greetings 405line,
      Been awhile since I looked at the comments here so apologies for not commenting earlier.

      Yeah, the bitstream process of reducing bits eventually down to 1-bit SDM was a cost-cutting way to achieve 16-bit dynamic range. However, we should not see this as a "bad" thing given how things have evolved. These days multibit SDM is pretty well the norm with modern DACs (like ESS, AKM) and the performance overtakes those older Philips 1543, etc.

      I know people will have different preferences. That's OK.

  12. I would define myself as a skeptical audiophile... In any case, I have the Boarder Patrol DAC mentioned. I have tested several Delta sigma dacs from McIntosh, musical fidelity and auralic. I reached the same conclusion as most reviewers who tell readers that this DAC simply sounds better than most dacs regardless of price. I suspect, as one comment noted, it excels in some other (not measured) spec like time domain,etc. Or there is something happening on the psychoacoustic level because the specs tell us this thing should be a hot mess vs newer chips. I assure you, as far as the end result, it is not. BTW, I don't think LP's think sound better.

    1. Hi Unknown,
      I don't think NOS sounds bad and as I noted above, I believe that many people will like the sound. Nonetheless, a DAC like the Border Patrol when playing NOS(-like) 16/44.1kHz, there will be those jagged, squarish waves in the signal which some audiophiles like to point out as emblematic of "digital" sound.

      Just like this old 1543 DAC I measured years ago:

      I certainly don't think NOS sounds bad but those DACs do have their limitations technically. And yeah, some might like that sound.

      BTW, I had a listen to the Border Patrol SE a few months ago at a dealership. Sounded fine. Not the best noise level when matched with some excellent Boulder amps and B&W speakers.

  13. What is nagging me since I've read this and some other blogs about NOS, when you play a common 44,1 khz file with a heavily oversampled rate like 384 Khz, shouldn't you be able to have the advantage of perfect impulse and little to no aliasing since the mirror frequencies start at extremely high frequencies? And even a 20khz sine wave should look pretty fine oversampled at 384 Khz.

    1. Hi anphex,
      Yes, if we upsample 44.1 --> 384kHz, we do have the ability to push the mirror imaging artifacts to something like 200kHz. We can see this for example with HQPlayer, even if upsampled just to 192kHz it's great:

      So long as the resampling algorithm (eg. high precision sinc filter) does the job cleanly, we can achieve excellent filtering.

      As for impulse response, if we define "perfect" as looking like a little square wave without "ringing" then, no, a good FIR upsampler will always have ringing. The amount of ringing depends on how steep that filter is. In fact, the more "brick walled" the filter around Nyquist 22.05kHz is, the more ringing.

      As discussed here:

      Do not worry about the impulse response ringing with DACs because this does NOT translate to poor sound. There are times where we can use minimum phase settings such as with DSP effects to shift to post-ringing only which masks the ringing, but when we're looking at simply reproduction of music on CD which to begin with should have been properly filtered already from the studio to take out >22.05kHz content, there will be no "ringing" in the reconstructed signal.

      As for digital content that contains "illegal" frequencies outside 22.05kHz (like an impulse response, or severely loud and clipped content), then you can try something like the intermediate phase filter:

      Which balances between "ringing" because the CD was poorly produced while maintaining reasonably linear time-domain performance without going completely minimum phase during playback (which would shift relative frequency phase relationships). I believe some music servers like the 432 EVO have specific processing for this and it would not be difficult to add this kind of upsampling in Roon if they wanted...

  14. I'm a bit perturbed about all this talk of 'preferring' a DAC and its 'sound', without *any* checks for the usual errors/delusions that flow from sighted, non-levelmatched listening and comparison.