Article: Weiss Engineering DAC202 Review

[gmgraves]

Perhaps you shouldn't be so quick to dismiss a little healthy skepticism. After all, listening tests without a stringent set of controls, aren't very useful. The poster who brought-up sighted and expectational bias has a valid point. Human beings are mighty susceptible to suggestive influences. It has been shown many times that people will imagine that something sounds better because they have been told that it's more expensive, or newer, or uses a "breakthrough" technology, or simply looks "cool", when in reality, a double-blind test shows that there is no real, detectable difference at all. I realize that a lot of audio enthusiasts want to believe their "golden ears" (As do I), but the fact is that many of these differences that we say we hear disappear under the stark reality of double-blind testing. DBT is the "gold standard" of science because it works. <br />

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So, instead of telling skeptics to go away, or suggesting that their skepticism represents " nothing constructive" to add to the conversation, why not welcome them and their views with open arms. After all, we can all use a healthy reality check every now and again.<br />

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Believe me, I'm not taking sides here, I just think that a little dissent is good for the soul.

[Audio_newb]

Clearly the headphone out on the 202 isn't its main feature, but it is still quite nice to have. And I know very little about running balanced headphones, but would there be impedance matching/ drive problems just going from the xlr outs without some sort of headphone amp in the chain? Anyone else running headphones straight from their dac outs?<br />

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As an aside and in answer to the above poster I think there is a difference between a healthy skepticism about audible differences (and I am certainly a believer in psychosomatic influences) and a general attitude towards commenting on these forums. What I mean by that is time and again I feel threads get hijacked by skepticism on price or general testing methodology. There may very well be importance to discussing these issues, but to have to hash them out for every new component gets frustrating. I think it is this aspect that Chris was replying to and in an effort to keep these threads interesting and useful I can't say I blame him.

[artk]

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I've attached a rather detailed scientific paper about how there's a real physical basis to perception bias. Tell me why the research is wrong? Tell me why it’s not reasonable to believe that auditory perception is subject to the same bias as taste and smell? <br />

[The Computer Audiophile]

Art - You keep beating this dead horse like you have a huge agenda. Everyone has already discussed this with you several times. <br />

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To answer your question it is totally reasonable to believe in auditory perception bias. <br />

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The problem is that you want to discuss everything unrelated to the component at hand. Name it and you've been there, indicting the audio industry, wine industry, price for components, expectation bias, etc... It's all in this thread. <br />

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I'll give you one more chance to answer the question I posed several weeks ago that you want to ignore like the plague. <br />

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Why do you post on this audio related website and what are you attempting to add to this conversation that isn't already known?<br />

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As I've said before you could indict virtually any other industry yet you keep hammering your agenda here. I don't mind skeptics but when debby downer strikes at every chance it gets very old.

[dvavc]

Quote: "Every Weiss owners bank account should hope that there's much more to their perception of its quality than the ESS chip. That’s a $20 part. That would mean that pretty much anyone could reproduce its performance for a fraction of the cost." <br />

Guys i don't really know why would anybody be wasting his time by engaging in this kind of arguments at all? At least in this forum. <br />

The "price v. value" of any hi-end component should not be even taken seriously. Are you kidding me? If it was mass production 202 was probably around $1500 or less. So what? This is completely irrelevant what is the production coast of the given component $5 or $5000. What is relevant however, whether any other component existing on the market TODAY can match or beat that sound quality for less than $6700? <br />

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[Lars]

I have to agree with our friend Barrows. By the way, it looks like you are doing a great job with your kit Barrows.<br />

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I am also using an ESS Sabre 32 module in my Wavelength DAC. The sound is just wonderful and much better than anything else I have heard. The execution of the design is not easy and simply using an ESS Sabre DAC chip doesn't guarantee success. <br />

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Skepticism without knowledge or experience is nothing more than ignorance.

[jhbpa]

Ayre: <br />

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Absolutely, a full blown Charlie (the master of the the analog output stage) assault on DAC/PRE would certainly challenge the industry, even Daniel, but Ayre has lots of preamps and CD players to sell. Totally adopting the computer audiophile mantra eliminates the need for 60-70 percent of traditional audiophile gear. I guarantee you that's bugging Charlie.<br />

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ArtK:<br />

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I wish everyone, including Chris, would just ignore him, he'll go away if we do.<br />

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John B.<br />

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[cfmsp]

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"Skepticism without knowledge or experience is nothing more than ignorance."<br />

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Lars, well said, I like it.<br />

can I quote you? <br />

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In my opinion, maintaining the status quo without basis (i.e. without knowledge or experience) is (also) nothing more than ignorance.<br />

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We see a good bit of that in audiophile-dom as well.<br />

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cheers,<br />

clay<br />

[cfmsp]

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"I wish everyone, including Chris, would just ignore him, he'll go away if we do."<br />

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agreed, but sadly, it only takes a single respondent to "feed the troll", including even requests that others NOT feed the troll.<br />

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Rarely does a good troll go to sleep un-fed.<br />

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just my two cents,<br />

clay<br />

[hojen]

Yes. As chris alluded to in his review, with a DAC202 in hand, almost any old PC or laptop with a firewire port, can now serve up high end, hifi music, assuming that you already spent the time acquiring and generating FLAC or other lossless files. <br />

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I have been doing this for nearly a decade, now. I already have a ready library stored on a couple of NAS units, on a gigabit network. This is the way of the future....<br />

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I find this very exciting. I has certainly made me to revive some old laptops decaying in the closet...

[hojen]

Hi Chris: I would like to tap into your experience with firewire links for an opinion of a few questions:<br />

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I recently sent you a note about how happy I am with the DAC202. My very first installation on the computer end is on my current working desktop, which is a fairly up to date, relatively high end machine:<br />

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ASUS P6T m/b, based on the X58 chipset;<br />

i7-930 Intel CPU<br />

12 gigs of ram<br />

Patriot 128g SSD for the OS; 600 gigs of HD space in RAID0 via 2 Western Digital 300g raptor drives.<br />

on board firewire 400 chip from VIA: VIA VT6315N PCIe<br />

2 PCIe DVI graphics cards, to drive 4 HD monitors, for a huge desktop space.<br />

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The machine is a monster! All of the superlatives I confirmed in my prior note were from using this desktop, to feed the DAC202.<br />

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I then tried to revive some older laptops and desktops with firewire ports, because I don't want to use my working desktop for music. As you know, there are lots of issue with getting firewire to work on other machines with different chipsets. The biggest one that plagues laptop users is the problem of prolongued DPC latencies, which produce "click and pop" artifacts in the analogue output from the DAC. You have to do much work to find, eliminate or update the culprit processes.<br />

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To summarize: After resolving all issues of DPC latencies, so that there are "click and pop" artifacts, no visible excessive DPC latencies reported by the DAC202's own monitering program, aftering passing the DAC202's bit transparency test, HD music fed via firewire STILL sounds better coming from my monster desktop, when compared to the same sources coming from a laptop (DELL latitude 820) or older desktop with an PCI firewire card.<br />

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I kept telling myself that this is NOT possible, but still I can hear the difference: more detail and clarity from the more power desktop! After listening with the laptop for a while, I began questioning my initial impressions of the DAC202: good but ??? great???? It was only after going back to the desktop that I realized the difference between the two computers. If the bitstream is confirmed to be bit perfect, and assuming that the firewire protocol has virtually eliminated siginficant jitter, I don't understand how there can possibly BE a difference.<br />

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Question:<br />

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Have others noticed differences in SOUND QUALITY (not noise or artifacts) when using firewire from different machines/chipsets ?? <br />

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If so, are some chipsets known to give better performance than others?<br />

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The practical reason for questioning is that I want to build a small, silent, PC such as your C.A.P.S., optimized for firewire and the DAC202. Oviously, I want to use a chipset and platform that is known to work well. So far, for me, that would comprise a machine built on the ASUS P6T m/b on a Win7 64x platform. I'm SURE this must be overkill, but I would do it, if that was my only option. (I would rather stay OFF the MAC platform, if possible.)<br />

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Thank you in advance for any suggestions you can provide. I apologize if this is the wrong forum for my questions.<br />

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[hojen]

Sorry for some of the typo errors:<br />

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To clarify, I am comparing relative sound qualitiy of laptop<->DAC202 vs ultra desktop<->DAC202, AFTER, I eliminated all the "pop and click" artifacts from DPC latencies on the laptop. Both have bit perfect stream, according to the DAC202's testing utility.<br />

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[Bob Stern]

Instead of Firewire, try a top-notch USB > S/PDIF converter between the computer and the DAC202, such as the Wavelength or the Halide Bridge.

[hojen]

Wouldn't that negate the precise clockrate control afforded by firewire? <br />

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Or do those USB->SPDIF units have the ability to receive an external clock rate like the Lynx? I was previously using coax SPDIF output with and M-audio audiophile 192 PCI card, which was pretty good. It, like the Lynx, can receive input from an external source such as the DAC202, for a more precise jitter control. But Chris felt that with the DAC202, this (externally clocked) SPDIF performance was SECOND to firewire.....

[barrows]

will achieve excellent performance by building your planned computer. As you note, some Firewire chips seem to work better than others. I know Weiss recommends Texas Instruments Firewire chips for perfect performance, you should have no trouble finding one of these on a PCIe card. Otherwise build a minimum machine, have plenty of RAM, and use a SSD (it does not need to be large) and store music files on an external drive which does not share the same bus as the Firewire.<br />

IMO, with the (very respected) Weiss 202 you should definitely be running it via Firewire.

[hojen]

Yes, thank you. Guess it's well known or well believed amongst the professional users of firewire audio interfaces that Texas Instrument-based firewire chipsets are preferred. I will certainly follow up on that lead.

[Dennis Graves]

Question One:<br />

I am storing my ripped CDs on a LaCie portable external drive, which has firewire, and plan on connecting the LaCie to my laptop, which I will use as a music server. (The laptop has a solid state drive which lacks capacity to store the music files.) <br />

The laptop has only one firewire connection. To get the best sound, should I have BOTH a firewire connection from the external drive to the laptop AND from the laptop to the DAC? Put another way, if I use a USB connection from the external drive to the laptop and firewire from the laptop to DAC, will the USB connection be a "weak link" that precludes getting the best quality sound?<br />

Question Two:<br />

I am not sure that I understand bit transparency. If I rip CDs to my external firewire LaCie drive, using J River Media as the ripper, and then use the firewire and USB connections as described above, will I eliminate the bit transparency issue? Or, do I still have to worry about whether the JRiver ripper gives me a perfect "bit transparent" rip?<br />

Thanks!

[hojen]

"bit transparency" simply means the ability to send the digital audio data, exactly as it is stored on the media (CD, audiofile,etc), untouched by the OS, to the DAC. This is typically a matter of taking care of the details of how you are sending the digital music to the DAC. In Windows, it is a matter of ensuring that the output wav file does NOT get intercepted by the windows music mixer on its way to the DAC after leaving the software player, by using mechanisms such as asio, wasapi, etc. I'm not familiar with the JRiver software, but it is well-regarded, and I'm sure that it has the appropriate measures to ensure bit-transparency.<br />

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Those familiar with JRiver please fill in???<br />

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As for the USB transfer of data from hard drive to laptop, that is a non-issue. It should be instrinsicaly bit-perfect, like any other piece of data. Otherwise, you have a serious problem, if you cannot ensure error-free data transfer from external hard drive to computer !<br />

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The audiophile preference for firewire vs USB is NOT a question of bit transparency. It is a matter of jitter control. Firewire allows uninterrupted data flow, as well as an intrinsic ability for an external device to control the rate of data flow, thus allowing superb jitter control. Whereas USB is NOT fundamentally designed for uninterrupted data flow. Better flow control is achieved only with 'asynchronous' mode usb data flow, which not all chipsets support.<br />

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Hope that clarifies the issue.<br />

[Dennis Graves]

Thanks for clarifying that USB v firewire is not a bit transparency but rather a jitter issue. From what you say, I would conclude that I would be better off with firewire connections BOTH from the external hardrive (which holds the music files) to the laptop and from the Laptop to the DAC. At present my laptop has only one firewire port so I would have to add a PC card with firewire for the output to the DAC. <br />

HOwever, I have a Berkeley Audio Design Alpha DAC and have been planning on getting their soon to be released device that will accept computer output via USB (but apparently not firewire)so as to allow connection from the device to the Berkeley DAC via an AES/EBU or SPDIF digital cable. If the Berkeley device indeed does not accept firewire, I am wondering if I will have audible jitter. <br />

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Thanks.

[Bob Stern]

I believe "hojen" overstates the benefits of Firewire.<br />

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As discussed earlier in this thread, both Firewire and USB can minimize jitter if the DAC has a fixed master clock and the DAC sends flow control messages back to the music server computer so that the data from the computer never over- or under-flows the input buffer in the DAC.<br />

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This is the method used by the so-called async USB DAC's and by some Firewire DAC's such as Metric Halo.<br />

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Apologies to Daniel Weiss if I misunderstood him, but I believe he stated earlier in this thread (6/30/2010) that the DAC-202 does NOT perform flow control. Instead, the Weiss DAC uses a phase-locked loop (JET-PLL) to track the word clock of the audio data, regardless of whether the data is received via the S/PDIF or Firewire input of the DAC. This is the same method used by Berkeley and other DAC's with S/PDIF input. (Although the DAC-202 generates a fixed frequency master clock for the Firewire bus, I believe this does not sync the audio data word clock to the Firewire bus clock.)<br />

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http://www.computeraudiophile.com/content/Weiss-Engineering-DAC202-Review#comment-48008

[hojen]

Yes, thanks for the correction. Upon review of the documentation for the Weiss DAC202, turns out that it uses a two-stage PLL circuitry, which corrects for both high and low frequency jitters, rather than controlling the source input rate per se. Might explain why I could consistently hear a difference between different brands of firewire cards, on different machines. I thought I was just plain crazy.<br />

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But as Bob Stern points out, the DAC202 CAN be used as an external master clock, with good audio cards such as the lynx, which will accept an external clock input. Funny, then, how music through firewire sounded better than music through an externally synced lynx audio card via SPDIF, on the same setup, in Chris' thorough assessment of the DAC202. I haven't tried this yet, but you sure can't beat the super convenience of a single digital wire such as firewire, versus needing a PAIR of cables.<br />

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BTW, Dennis, I don't think you needed firewire for the ext HD to Computer link. USB has a higher peak bandwidth than firewire, and the magnitude of data transfer from ext HD to computer is much higher than intrinsic audio data flow rates from computer to DAC. I have seen issues with temporary frame freezes when watching video from usb-external HD, but I doubt this would affect even HD audio.<br />

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[Dennis Graves]

Thanks for your comments. I guess I take away three points from this discussion:<br />

1) There are few absolutes -- a properly implemented USB DAC may be better than many firewire DACs <br />

2) Regardless of the technical theories, the bottom line is how things sound. That is why I have rarely bought any audio component without hearing it in my system. Unfortunately, you can't do that with computer audio.<br />

3) It is nearly impossible for us non-tech types to sort through these issues with any certainty.<br />

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[roscoeiii]

Elsewhere on this site I have seen folks recommend that the DAC and hard drive not run off the same connection interface. So if you have a USB DAC, use a Firewire hard drive. If you have a Firewire DAC, go with a USB hard drive.

[hojen]

Yes, avoiding the DAC and external HD on the same set of cables makes intuitive sense. <br />

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However, for all true COMPUTER audiophiles, I highly recommend a NAS unit on a gigabit ethernet, for convenience and robust, ultra-huge capacity music storage. This potentially noisy box does NOT even have to be in the same room as the rest of your audio equipment.<br />

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Then, you don't have to worry about interference with traffic from PC to DAC.<br />

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The total gear in my cramped little office (the NAS unit is in another room) is DEAD SILENT, except for the headphones !!<br />

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[XP9433]

Hojen<br />

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I see you have listed the Rudistor RP101B Headphone quad mono headphone amp in your office system. Does this impy that the headphone amp on the DAC 202 isn't up to the same quality?<br />

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Thanks<br />

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Frank<br />