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In Reply to: RE: Do you have any specific examples to bolster your generalizations? posted by Chris from Lafayette on June 10, 2024 at 16:46:17
You mean the distortion from the lack of filtering from mass market DACs that makes them sound harsh? Rob Watts correctly points out that many digital DACs sound rough. The DACs that look like stepped square waves vice a smooth analog signal?Check out the review linked. There are other reviews with vey positive evaluations of the DirectStream DAC.
The major reason this DAC, along with Chord DACs, sound better than most DACs is the custom filtering, which the meter crowd totally miss. They simply can't figure how to adequately capture these characteristics.
Maybe some prefer the stepped sinewaves of the off the shelf DAC chips over the smooth outputs from the FPGA offerings? If they haven't auditioned the better FPGA DACs, how would they know any better? (They wouldn't).
" Don't look back. Something may be gaining on you"
Satchel Paige
Edits: 06/10/24Follow Ups:
Which products produce stepped sinewaves? Please provide specific names, if possible!
What's a stepped sine wave?
Ask, and ye shall receive.Watch this video, and you should get the gist of the issues.
DSD is just another method to work around the limitations of PCM being processed by off the shelf DAC chips.
ASR measurements to my thinking need to be taken with grains of salt, and their conclusions can be misleading. A prime example of this can be seen in this interview with Rob Watts and Passion For Sound.
https://www.youtube.com/watch?v=orXrRwP7xLE
" Don't look back. Something may be gaining on you"
Satchel Paige
Edits: 06/11/24
nt
He sure would have been perfect for that video!
View YouTube Video
You sure Mays is gone?
Wikipedia says he croaked in 2009. Of course, I don't always trust Wikipedia, but that's another discussion! ;-)
Well, I watched the short video about the operation of a Chord DAC, but I didn't see anything about a stepped sine wave. Can you just explain what you mean by a stepped sine wave. All the DACs I've ever owned produced ordinary analog sine waves. Of course, I've never owned a Chord DAC. Do they produce stepped sine waves?
Thanks!
John Elison
Dear John (heh heh) is this extended discussion referring to the output from the dac prior to the analog stage that provides the signal to the other system components or after? Not being snarky, my knowledge of digital signal production and processing is rather limited. Thanks.
As an aside, I agree with Abe C that the analog output stage of the dac probably influences the sound of the component more than anything else. Hence my first question-I really don't know enough to evaluate the output signal of a dac prior to analog conversion nor what effect differences at that stage of signal processing might have on final sound quality.
LowIQ
If you look at the video, one sees the stepped pulses connected via filtering. The stepped sine wave is a bit tongue in cheek, referring to sub optimal filtering. Some DAC measurements show a bit of a stepped looking sine wave vs. a smooth sine wave.
Here is a quick synopsis from AI regarding FPGA DACs:
FPGA DACs offer several advantages over traditional DACs, including:
Flexibility: FPGA DACs can be reprogrammed to perform a wide range of signal processing tasks, allowing for customization to meet specific audio system requirements.
Higher quality audio: FPGA DACs can provide improved signal-to-noise ratios and lower distortion, resulting in higher quality audio output.
Real-time processing: FPGA DACs can perform real-time signal processing, making them suitable for applications where low-latency is important, such as live sound reinforcement or gaming audio.
Cost-effectiveness: FPGA DACs can be more cost-effective than traditional DACs, especially for high-end audio systems.
Power efficiency: FPGA DACs consume less power than traditional DACs, making them suitable for portable audio devices.
Higher sample rates and bit depths: FPGA DACs can support higher sample rates and bit depths, allowing for more accurate audio reproduction.
Customization options: FPGA DACs can be programmed to support a wide range of audio formats and sample rates, making them versatile enough to be used in various applications.
" Don't look back. Something may be gaining on you"
Satchel Paige
Not saying the PS Audio Directstream sounds bad...never heard it actually; however, I have heard other FPGA based DACs, as well as countless Sigma/delta DACS and I will stand with my "old school" Burr Brown PCM1704 24 bit R2R DAC with tube output stage...sounds more like the real thing than other digital solutions I have heard.
Actually, the output from any DAC I've owned had no steps whatsoever. I've looked at the output on an oscilloscope and I've measured distortion using a spectrum analyzer. If there were even the slightest hint of steps in a DAC's sine wave output, it would produce gross distortion. However, sine wave distortion on all the DACs I've measured was below 0.01%. Many of my DACs had less than 0.005% distortion.
The output waveform from a DAC is filtered, which removes any steps. Even at 20-kHz, the sine waves from a test CD appear as perfect sine waves on an oscilloscope screen with distortion well below 0.01%, and there's only two samples per waveform at that frequency.
It's all about the filtering. The FPGA approach with upscaling provides much finer resolution of the resulting analog waveform over the small amount provided by off the shelf/NOS DACs.The stepped output was a tongue in cheek go at the folks who think custom filtering is useless, where by they use a small subset of measurements to justify flawed conclusion. Suddenly, they now know more that the real experts, based a on flawed evaluations.
" Don't look back. Something may be gaining on you"
Satchel Paige
Edits: 06/11/24
In any case, you're free to like any DAC you want, no matter how flawed your own evaluations are and how star struck you are over a promo video. And I'll defend your right to like whatever you want too! ;-)
Or do you listen with your eyes? Isn't that what you accuse Amir of doing? ;-)
View YouTube Video
Seems like the Chord people may have been able to exploit your predispositions. ;-)
I believe that I will stick with using my ears as the final listening device. Not some useless measurement device that is ultimately meaningless.
It's just like with religion: I will defend to the death your right to believe in whatever astrology cult you might prefer! ;-)
It seems that all too often you follow a high minded phrase with a snide and scornful conclusion. How come?
LowIQ
I'm all too susceptible to the rhetoric and tone of the general discussion. But you're right, I should be above all that.
Single tones are not the same as music.There are lies, damn lies, and statistics.
For a more detailed set of explanations about DACs:
" Don't look back. Something may be gaining on you"
Satchel Paige
Edits: 06/11/24
.
Yes, that is correct. So what? You didn't answer any of my questions. Do you feel that you hear the stair-steps when you listen on non-Chord equipment? Can you hear the stair-steps better with music than you can with single tones?
BTW, I found your link somewhat mystical and poorly reasoned (a la Darko). For something more grounded in reality, check this out:
View YouTube Video
Not bloody likely. Rather arrogant approach to take.
I'll trust Rob Watts/Ted Smith over you and ASR any day of the week. They have put in the blood, sweat, and tears to make some excellent gear. Yes, its very obvious to hear the difference between the Chord DAC and a off the shelf DAC chip. There is tons of digital ink spilled over on Head-Fi.org about this. Headphone listening is much more revealing of DAC performance over standard loudspeaker playback.
Taking a small subset of incomplete measurements and declaring absolute results is not scientific. The ASR review is a bit misleading, which is why I posted the response to it.
Lies, damn lies, and statistics. We are done here.
" Don't look back. Something may be gaining on you"
Satchel Paige
Your latest post seems to be a variety of the "argumentum ad verecundiam" fallacy.
And you STILL haven't clarified whether you believe you can hear the supposed "digital stair-steps" on non-Chord equipment. Why did you even bring up the subject then? I suspect it was because you were star-struck by their promo videos, which attempted to show that stair-steps were part of all digital playback, but that Chord had "refined" their approach SO much that their stair-steps were MUCH tinier and less audible. LOL!
And talk about declaring "absolute results":Headphone listening is much more revealing of DAC performance over standard loudspeaker playback."
Sez you - LOL! BTW, many years ago, I believed that myself - but I've now come to see the error of my old ways! (Well, for one thing, it depends on which headphones and which speakers, doesn't it?)
Guess you are having trouble grasping the engineering behind the advancement in DACs.
Try actually listening sometime. You might be surprised.
" Don't look back. Something may be gaining on you"
Satchel Paige
. . . and I wish you the VERY BEST - no matter how divorced from reality your understanding is.
The engineers at Chord and PS Audio know FAR more about DAC design than most people, including the so called audio critics/reviewers. Arrogance is no substitute for actual knowledge. Reading a flawed review from ASR does not suddenly make you smarter than the design engineers.Believe whatever you wish, but there is a body of evidence that suggests the DACs with advanced filtering DO sound better. For example, Stereophile DOES a creditable job with evaluations on audio hardware, and conduct a good set of measurements. Their rankings strongly suggest that FPGA filtering DOES offer sonic advantages.
" Don't look back. Something may be gaining on you"
Satchel Paige
Edits: 06/12/24
"The engineers at Chord and PS Audio know FAR more about DAC design than most people, including the so called audio critics/reviewers. Arrogance is no substitute for actual knowledge. Reading a flawed review from ASR does not suddenly make you smarter than the design engineers."
Sure they know how to cheat your ears and make their stuff more "musical". Some people simply like distortion and soft sound.
I never think of ASR as a subjective review site though Amir will give his impressions. And those might be clouded by expectation bias if a device does not measure well but, then, compare that to all the subjective reviewers who give stuff great reviews based on their expectation bias driven by company marketing material like the Chord video linked earlier in the thread.The ASR DAC measurements are completely valid, they tell you very specific things about what a DAC does. It is ironic that DAVE does not measure so well as some low priced DACS that use the cheap DAC chips treated with disdain in Chord's video. Rob Watts does talk a lot about atributes, like noise floor modulation, that could be a big thing but cannot be measured. And he claims to be able hear an artifact that is -300dB (this is, of course, ludicrous). These things may be the most important aspects of a DAC but after all Chord's talk about the objective performance I'd expect them to get the obvious, measurable, things right and at least be at the top of the ASR SNR table.
As to 'advanced filtering' I am in the filter-schmilter camp. Most DACs have a digital filter to remove aliases (these are related to a stair stepped waveform, remove the aliases and you remove the stair steps. That is why you still see stair-steps in NOS DACs). Different manufacturers adopt different approaches e.g. Meridian and Ayre promoted minimum phase filters that have no pre-ringing for an impulse response. Rob Watts uses a straight forward filter but his twist is make it as close to a brick wall as possible hence his pursuit of many, many taps. His filter will pre-ring for a long time. And pre-ringing is a red herring anyway as any music signal should be band limited before sampling so it does not have any edges sharp enough to make the filters ring.
No doubt Ted Smith and Rob Watts are earnest and insightful but only the listener can determine if their products are worth the asking prices. One way to persuade the punters is to have a good back story and the whole 'FPGA' thing is part of that. I am pretty amazed there have been so many revisions of the direct-stream DAC firm ware, it kind of seems like they didn't get it right the first time, or the second time, or the third time - or is it Ted Smith's way to keep getting paid :). As an aside, Rob Watts is not an employee of Chord and lives off royalties from Chord products. Maybe Ted smith is the same. I suspect that PS Audio and Chord do not own those technologies but license them from the inventors.
Edits: 06/12/24
"The ASR DAC measurements are completely valid, they tell you very specific things about what a DAC does. It is ironic that DAVE does not measure so well as some low priced DACS that use the cheap DAC chips treated with disdain in Chord's video. Rob Watts does talk a lot about attributes, like noise floor modulation, that could be a big thing but cannot be measured. And he claims to be able hear an artifact that is -300dB (this is, of course, ludicrous). These things may be the most important aspects of a DAC but after all Chord's talk about the objective performance I'd expect them to get the obvious, measurable, things right and at least be at the top of the ASR SNR table."
I would proffer that the (ASR) measurements of the DAC do not tell one as much as it is inferred. For example, Chord maintains that jitter does not matter in their designs, due to the FPGA implementation. I think this subtlety is missed. Given the fact that the DAVE is considered among the very finest DACs in the world, the fact that ASR does not like the measurements tells me that something fundamental is being overlooked in the measurements. I will never forget the first time I heard a Chord Hugo 2 DAC. I was floored how much better it sounded compared to my Benchmark and RME DACs. I'm not knocking those DACs, they have excellent measured responses, and get great reviews. The Chord Hugo 2 just sounded way more like music. BTW, Rob Watts must have some method to measure noise floor modulation. That was a big tool in his filter designs. This goes back to my point about DAC measurements, some of the key factors with DAC performance are likely not being adequately captured.I get folks are cynical when engineers go on about their designs. Having said that, the information Rob Watts puts out is largely verifiable. It is complex, but most people can grasp the concepts behind the explanations. It made me understand why the Cord DACs sounded as good as they do.
"No doubt Ted Smith and Rob Watts are earnest and insightful but only the listener can determine if their products are worth the asking prices. One way to persuade the punters is to have a good back story and the whole 'FPGA' thing is part of that. I am pretty amazed there have been so many revisions of the direct-stream DAC firm ware, it kind of seems like they didn't get it right the first time, or the second time, or the third time - or is it Ted Smith's way to keep getting paid :). As an aside, Rob Watts is not an employee of Chord and lives off royalties from Chord products. Maybe Ted smith is the same. I suspect that PS Audio and Chord do not own those technologies but license them from the inventors. "
I wondered about the constant firmware with the Direct Stream DAC as well. I held off getting one until the firmware stopped updating and the price dropped to the point it was worth trying. Having been a Devialet owner since 2016, numerous firmware updates are not a big deal to me. It is definitely a great sounding DAC. I use it primarily as the processor for a high end headphone setup, which it really shines.
" Don't look back. Something may be gaining on you"
Satchel Paige
Edits: 06/12/24 06/12/24
An advantage of an FPGA based design is that you can control clock jitter everywhere whereas you cannot with DAC chips because you have no control of clock distribution inside the chip. That said, chip DAC designers know what they are doing and they won't allow the on-chip clock to limit resolution. And, further, I think the whole jitter thing is a red herring (see link) and it is only a thing for manufacturers to try to differentiate their products (except that everyone does it these days).I do not believe Rob Watts has a method to measure noise floor modulation (I watched his latest seminar video recently, I will look again to be sure) just he has he cannot measure the diode effects in contacts that he claims are audible. These effects may be important but my point remains why aren't the obvious common-or-garden measurements also first class? If there is a reason where SINAD is compromised to optimize for something not measurable why not say that and make that a feature? And don't forget about the -300dB artifact claim he makes - he sort of shrugs it off saying 'I know it's a big number but I can hear the effect'. That is not good enough, 300dB isn't just a big number it is a very hugely massively enormous number and Rob knows that. At best he is hearing correlation not causation, at worst it is hubris that he thinks his hearing is special.
That all said I've never heard a Chord DAC and if people like them that is great. But one of my mantras is that if you like something then enjoy and don't worry about it being the best objectively because you will be disappointed to find out it is not. Like supporting a football a team, if you insist they win every match then you won't have much fun. And I'm primarily a vinyl listener, a medium that is very compromised objectively but it makes me happy.
Edits: 06/13/24
. . . don't know a thing about DAC design?
And on one hand, you disparage audio critics and reviewers. And then you turn right around and say "Stereophile DOES a creditable job with evaluations on audio hardware".
LOL! Excuse me, Freo - I've got to get back to the real world now! ;-)
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