Article: Weiss Engineering DAC202 Review

[Lars]

I welcome the contributions from Gordon and Charles. The information is informative and their personal views interesting. One doesn't have to accept everything they say as the final word. <br />

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Chris could ban them, but the forum would be far less interesting.

[cfmsp]

"As far as I can tell both Gordon and Charles have shamelessly capitalized on their competitors review."<br />

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While having great respect for Daniel, I totally disagree. Gordon corrected a mis-perception about the operation of Firewire by the Weiss products that was reported incorrectly in this very review. Where else should that have been pointed out - in the fine print on page 25 the next day (a la standard practice of newspapers)?<br />

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Neither has Gordon discussed his products, just his understanding of how various products operate - one of which was reported erroneously(?) on the manufacturer's website, and was subsequently corrected here in this thread.<br />

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I do think it's unfortunate that discussion drifted to China manufacturing practices, but that's the way it is here on CA some times - threads drift a lot but the 'drifters' do tend to be the more interesting, IMHO. Who would be interested in a review thread that was simply filled with "me too" comments?<br />

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I think this thread has been fabulous for those interested in understanding how the best sounding DACs transmit data, and illuminating to know that the Weiss sounds great irrespective of it's Firewire implementation.<br />

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YMMV, and apparently does!<br />

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clay<br />

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[Audio_ELF]

Just for the record ... I had no problem with Gordon's questioning of how the Weiss DAC worked in respect of calling it asynchronous - though using asynchronous was to describe the transfer from computer to DAC was Chris's words not Weiss'. Possibly Chris as "the editor" should correct his article! I agree that Daniel has not discussed his own products.<br />

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On the other hand, Charles has made repeated comments about USB asynchronous technologies and how his new Blu-ray player has 24/192 capable transfer and how the board for the QB-9 should be available next month for upgrading those! He also disparaged the Arcam DAC for being made in China when it's unclear if that was fact or just propaganda - the product isn't even available yet!! This is pretty much the same as when jkeny started discussing modified M2Tech HiFace with a link to his own website - not that Charles Hansen even makes it clear that he owns / manages / designs product for (sorry not sure the exact relationship) Ayre when he makes these comments.<br />

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Contributions for manufacturers - especially those knowledgeable to question some claims, though we have to remember that different manufacturers have different philosophies which can lead to equally good product - are good, but not the subliminal advertising which has crept into this thread (IMO). It's not a case of 4 legs good, 2 legs bad anywhere in the Audio world!<br />

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Eloise

[4est]

This is exactly what I was talking about in respect to Gordon's posts. Whether one oscillator or two are used to establish a clock does not change the type of transmission as far as I can tell. An accurate low jitter clock at the DAC controlling the feed is the requirement. You or he may disagree, but I feel Gordon is creating a moving target. <br />

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Regardless, the manner in which Gordon posts smacks of inferiority complex and self promotion of his new product and his "expertise". Maybe it is my midwestern values, but in my experience the truly exceptional people do not need to expound about their qualifications. They let their work show it!

[weiss2496]

<cite>Whether one oscillator or two are used to establish a clock does not change the type of transmission as far as I can tell. An accurate low jitter clock at the DAC controlling the feed is the requirement.</cite> <br />

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Thanks for pointing that out, I wanted to do that as well. <br />

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I will do a post on the jitter topic. To state a single jitter figure for a clock is absolutely pointless. It depends what the (jittery) clock is used for and what frequency spectrum of jitter we are talking about. More later.<br />

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Daniel<br />

[cfmsp]

Again, I will totally disagree with your assessment here.<br />

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Gordon is NOT creating a 'moving target', he is clarifying his position as to what sounds best, and also the consensus definition of Async transmission as defined here on CA. That Gordon created the category means that his definition is the de facto standard. <br />

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Admittedly there is some confusion about CA's use of the term Async, and others, such as Bob Stern, have proposed alternate terminology. <br />

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For Gordon's part, he has argued for some time that we NOT use the word Async to describe the ideal scenario (but that cow is out of the barn), since that's not the defining characteristic - but rather - the use of a pair of fixed freq oscillators (one for each set of multiple sampling frequencies) as the master clock with no reliance on upstream clocks/PLLs/etc, to keep multiple clocks in sync, and or to do clock conersions (i.e. math). The reason Async terminology is in use is that this is the ONLY transmission mechanism that will allow such a design method to work (as near as we know).<br />

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Even if Daniel's DAC was Asynchronous in nature (and I disagree with your assertion that it appears to be), it would not operate in the manner that is ideal for keeping the potential for jitter as low as possible, which is to use the clock in the DAC (as close as possible to the circuitry relying on it), and use it as Master.<br />

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That it might still sound great even after having to employing jitter reducing techniques such as PLLs is not the issue here, it's the mechanism being used that is being questioned, and rightly so.<br />

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"Maybe it is my midwestern values, but in my experience the truly exceptional people do not need to expound about their qualifications. They let their work show it!" <br />

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That Gordon shares his knowledge here is a HUGE plus for this forum and the others that he frequents.<br />

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Besides, as Dorothy said, "we're not in Kansas anymore". <br />

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all the best,<br />

clay<br />

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[Wavelength]

4est,<br />

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<cite>This is exactly what I was talking about in respect to Gordon's posts. Whether one oscillator or two are used to establish a clock does not change the type of transmission as far as I can tell. An accurate low jitter clock at the DAC controlling the feed is the requirement. You or he may disagree, but I feel Gordon is creating a moving target. <br />

<br />

It's a simple concept to understand... Jitter is the movement of the clock signal with reference to the data it is passing to the dac chip. A fixed oscillator will always preform better than one that is moving. Any oscillator or frequency synthesizer that is moving cannot preform as well because in a sense it is the root of what jitter is, in that it is moving.<br />

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A PLL created clock can never be nearly as good as a fixed oscillator. Some of the best ones claim 50ps of jitter. Heck off the shelf fixed oscillators claim less than 1ps of jitter. BUT!!!!!! remember the jitter numbers you read about in Stereophile are based on the word clock not the master clock. A 50ps Master Clock is going to give you a minimum range between 800ps and 1600ps which is not very good.<br />

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4est, I am not promoting my products, these are just facts.<br />

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Charlie...<br />

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Correction about Firewire, most of the interfaces ARE not bulk mode. Most of them are ISO mode. As BJ (Metric Halo designer) pointed out they use a combination of ISO transmission with a feed back pipe to control the flow of data. He also mentioned that with the DICE implementation that this was not possible. Which means it cannot be an async implementation.<br />

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Thanks<br />

Gordon

[Audio_ELF]

<em>[Gordon] is clarifying his position as to what sounds best</em><br />

Surely that is only "his position as to what <strong>he feels</strong> sounds best. Gordon, nor anyone, can dictate that one technology is the best way to connect a DAC to a computer. I'm sure if Daniel felt that the "Streamlength" USB technology of Wavelength sounded better he would be beating a path to develop his own version of it or license it from Gordon. A couple of times you've stated "Gordon created the category" but my understanding is that "async" USB is defined by the USB Standards Group and he just implemented it in his products before anyone else (though not sure how the timing compared to dCS).<br />

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<em>That it might still sound great even after having to employing jitter reducing techniques such as PLLs is not the issue here, it's the mechanism being used that is being questioned, and rightly do.</em><br />

Is it really correct to describe PLLs as jitter reducing techniques?<br />

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At the end of the day though, the "complaint" about DAC manufacturers and self promotion wasn't aimed at Gordon so much as Charles IMO<br />

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Eloise

[cfmsp]

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Thanks for the recommendations<br />

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I've just upgraded from a 96k Metric Halo ULN-2 to their latest product, the 192k capable LIO-8.<br />

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I admire your enthusiasm for the future of hi-res recordings, hopefully reality will be more nearer your projections than mine. <br />

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cheers,<br />

clay<br />

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[Lars]

"Regardless, the manner in which Gordon posts smacks of inferiority complex and self promotion of his new product and his "expertise". Maybe it is my midwestern values, but in my experience the truly exceptional people do not need to expound about their qualifications. They let their work show it!"<br />

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Your comments are ridiculous. Gordon has no inferiority complex. He can hold his own with any engineer. <br />

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The only thing that I do know is that you are not an exceptional person based on your technical arguments.<br />

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[Audio_ELF]

Chris - when you write reviews, do manufacturers get to read a copy prior to you posting it? Do you invite a "right to reply"?<br />

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I know it's not a usual policy, but it often sorts out any issues before the copy is posted.<br />

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Eloise

[weiss2496]

<cite>He also mentioned that with the DICE implementation that this was not possible. Which means it cannot be an async implementation.</cite><br />

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Gordon, then how do you explain that we can sync our DAC202 to an external sync, e.g. wordsync on BNC, and have the computer playing a file tied to that sync? And we do not have sampling rate conversion involved?<br />

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Daniel<br />

[4est]

"A PLL created clock can never be nearly as good as a fixed oscillator. Some of the best ones claim 50ps of jitter. Heck off the shelf fixed oscillators claim less than 1ps of jitter. BUT!!!!!! remember the jitter numbers you read about in Stereophile are based on the word clock not the master clock. A 50ps Master Clock is going to give you a minimum range between 800ps and 1600ps which is not very good."<br />

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All I can say is BS theroretical speculation. You may be a competent digital engineer, but that is analog and it is fool hardy to make that claim. Especially as complex as jitter is and how it may be measured. I still do not see how the clock is created as making a difference. There has always been more than one way to skin a cat. Maybe, just maybe his PLL deals with jitter in a way you do not understand. I'll leave that to Weiss. Then again, maybe it is you who is trying to learn something here...<br />

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I think it is time to put up or shut up Gordon. Send a Chris your offering and we will see. Funny though, that the DAC 202 is not even Weiss' top DAC.

[Forehaven]

I am enjoying this thread, and feel the contributions of the manufacturers are a positive influence overall. The way they implement async or not is something I want to know, and I appreciate their sharing of designing thoughts to us.<br />

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Chris<br />

[4est]

Grow up, I am not claiming to be an engineer. I am attacking his argument, and questioning the manner he is presenting his case. Weiss appears to agree with my question as well.

[4est]

Is the sync in on your DAC2 similar to the DAC202?

[Lars]

4est,<br />

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I'll try to grow up before my next post. Thanks for you suggestion .

[The Computer Audiophile]

<i>"when you write reviews, do manufacturers get to read a copy prior to you posting it? Do you invite a "right to reply"?<br />

I know it's not a usual policy, but it often sorts out any issues before the copy is posted."</i><br />

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Hi Eloise - For this review I specifically asked Daniel if the DAC202 operated in Async mode as well as other questions before publishing the review. I frequently send snippets of the review that pertain to technical issues to make sure I have my facts straight (and did so for this review). I also encourage all manufacturers to read the review thoroughly and point out any technical inaccuracies.

[cfmsp]

"I am attacking"<br />

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well, at least you got that going for you!<br />

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the rest of us are trying to have a civil conversation.<br />

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clay<br />

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[cfmsp]

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"Is it really correct to describe PLLs as jitter reducing techniques?"<br />

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you're right, poor choice of words while trying to update a post before it was replied to. I probably should have said clock management techniques (for purposes of reducing potential for jitter)?. <br />

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OTOH, perhaps we can describe it as jitter increasing technique? ;0<br />

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"At the end of the day though, the "complaint" about DAC manufacturers and self promotion wasn't aimed at Gordon so much as Charles IMO"<br />

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Agreed that this is where it should have been aimed, but 4est mentioned Gordon by name in each 'complaint'.<br />

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Gordon created the category of Async USB DACs, just as he created the category of USB DACs prior to that. <br />

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As we now know, the definition of Asynchronous USB DACs is not entirely consistent with the definition of asynchronous modes in either the Firewire or USB protocols, so I don't take the publication of a protocol spec for a category creator. <br />

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cheers,<br />

clay<br />

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[manisandher]

I'm as interested in the technology that Weiss, Ayre, Wavelength, MH, etc use in their products as anybody. BUT... I think it's important to remember what many people have already said (and I've been guilty of this myself): it's not just the technology that's important, but the way it's implemented within a product as a 'whole'.<br />

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You know, having an engine hanging out beyond the back axle of a car is just crazy - physics says it should sit in the middle. Yet a Porsche 911 will beat most other cars in its class when actually put on the road against them (see 'Top Gear' review of 911 vs. Aston vs. BMW). Why? Well because the guys at Porsche have spent decades tuning and perfecting their implementation of this particular technology.<br />

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As an example, Gordon believes that the AES3 connection is terrible. And yet it's an AES3 connection that Keith Johnson uses to create the RR HRx recordings, which sound pretty good to me (actually the best hirez I've heard). But from personal experience, I know that it takes ages (not decades thankfully!) to 'tune' the AES3 connection so that it works well. But work well it certainly can.<br />

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I own a Weiss firewire product and know that it works well, irresptive of what technology it actually uses.<br />

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Mani.<br />

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PS. I <em>totally</em> support manufacturers chiming in on these discussions - the rest of us get to learn so much from the advocacy of their respective corners. Long may it continue.

[weiss2496]

<cite>Is the sync in on your DAC2 similar to the DAC202?</cite><br />

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Yes, they use the same technology.<br />

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BTW, a PLL certainly can be designed to reduce jitter. A PLL is like a flywheel. A flywheel reduces jitter as well.<br />

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Daniel

[4est]

I have kept my mouth shut about Charles because I feel his arguments are not even relevant to this thread. What I find disconcerting is that two or three times Daniel has refuted Gordon's claims, and yet he persists in his claims. This isn't about USB at all, but Async transmission. I still do not see how you can substantiate your claim that PLL has more jitter. Do you even understand the electronic physics of this? Are you even aware of some of the very accurate General Radio mechanical clocks based on tuning forks for instance? They operate a lot like the flywheel in Weiss' PLL. <br />

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But really though, you and others are taking Gordon's argument on faith that it requires two oscillators to get the clocking right. Even if that were to be correct, it doesn't negate the Async nature. At best, Gordon can only say that in his opinion, two oscillators are more accurate than one -or is there a jitter spec also associated in defining Async that I am not aware of?<br />

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As for true expertise, I'd take D. Weiss or BJ of Metric Halo over Gordon anyday! IME, the people that feel the need to honk their own horn the way Gordon has are usually compensating for something (which is what set me of in the first place).

[4est]

Clay,<br />

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I'd say you are being his lap dog. He is the one who keeps falsely refuting a claim by the manufacturer this thread is really about. I am just calling him on his logic and the premise. Frankly, I do not know if any of this make a difference, I just do not like false information disseminated. From what I have seen in the past, neither do you. Therefore, as you have questioned me in this thread, why is it you feel the need to defend a false statement? What I do not get is why people are trusting Gordon over Daniel about Daniel's product? Does he even have a schematic? If not, it is all conjecture that I called BS. I am done with this, you can put your head in the sand if you care to...<br />

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And whose using ad hominem now?

[The Computer Audiophile]

You guys have both made your points. Let's move on.