Article: Weiss Engineering DAC202 Review

[thotdoc]

Chris-<br />

It is amazing to me how f.u.so many commenters are. It's not pretty enough, it's too expensive, you aren't honest, on and on.<br />

<br />

I get it. You love CA and you want to educate us, as well, I'm sure to make a living at doing something you love.<br />

<br />

Have heart,<br />

<br />

[LesPaul]

Hi Chris, i think your review is very good. It is obvious to me that it has taken a great deal of effort to write it.<br />

<br />

Was there no negative aspects of the sound in your opinion?<br />

In my experience, a dac is usually a compromise, and is not normally best at everything.<br />

<br />

And how was this dac in comparison to the dcs gear?<br />

<br />

Thanks:)

[Andrew S.]

Dear fand1<br />

I am glad you liked Chris's review. I did not. I am sure the 202 is an excellent product. I have no axe to grind. I would be delighted to have a 202 in my system.<br />

Regards<br />

Andrew

[Audio_ELF]

<em>"I'm responding to the comment that for 1/4 the price you can get 3/4 the performance. I claim that you can get 99% of the performance for 1/4 the price. I have no idea how the poster intended to quantify 3/4, so I gave one possibility for my 99% claim: 99 out of 100 people can't hear the difference"</em><br />

<br />

I think I made that comment...<br />

<br />

The figures of 3/4 of the performance as pretty arbitrary figures. There is just no objective way to apply numbers to the performance of a piece of audio equipment so they can be compared in this way - however the 3/4:1/4 ratio is something thats often commented on. To (significantly) improve on a good £200 CD player - there's no point spending £500, you need to spend £800. Equally to improve on a £1,500 DAC that means spending £6,000 or so. Not that there aren't some products that are absolute bargains!<br />

<br />

As for if £6,000 is expensive - well you can buy a small car for that yes - but then you can equally spend £60,000 on a car which isn't much bigger and for day to day use won't get you "there" any quicker. <br />

<br />

Eloise

[Wavelength]

Chris,<br />

<br />

Sorry for being late to the party... Have been at NAMM showing my new guitar amps. Great show... utterly crazy music.<br />

<br />

Anyways... I did a lot of development with Oxford Semiconductor back in 2004 with their OXFW970 Firewire controller and then the 971 which is the basis for the DICE II as the Oxford stuff was sold to TC when Oxford wanted to work primarily on their USB/Firewire bridge products.<br />

<br />

In looking at the DICE data sheets I really cannot see how this can possibly accomplish an Asynchronous link. First how is feeding a word clock back to the computer going to accomplish this. This is only a reference the DICE chip locks the output I2S signal on the incoming stream which means... even if you do the word clock feedback that the resulting I2S clock going to the dac will not be exactly the same as the word clock output. Second as I can tell from the work I have done with sound groups for both MAC and PC that this is a generalized concept and not a finite one.<br />

<br />

Does the Weiss have fixed Master Clock oscillators?<br />

<br />

Really the only true way to accomplish an Asynchronous method for a dac is to have fixed oscillators at the dac chip and use these oscillators to derive the I2S feed going to the dac chip. Therefore the only real protocol between the Computer and the DAC would have to have some inherent feedback or flow control to make for an asynchronous link.<br />

<br />

Please explain???<br />

<br />

Thanks<br />

Gordon

[4est]

Gordon: I cannot help thinking that at best it is inappropriate to question a reviewer about the technical possibilities of a product. At worst it is disingenuous-verging on a shill for you or your products. If I were Chris, I'd have pulled that comment and strongly warned you...

[Lars]

Obviously 4est, you need to read Chris' review again. Chris mentioned that the Weiss 202 used an asynch interface with the computer. Gordon asked how this was accomplished.<br />

<br />

Why don't you answer this question for us?<br />

<br />

[Elprior]

Wow,<br />

<br />

I am more than interested in the issue this question has arisen.<br />

<br />

I am right now testing the weiss int202 on my dCS rig, and there is no benefit at all against my belcanto usb link.<br />

<br />

Could that be an explanation ? (I am desperate to find one).<br />

<br />

Elp

[4est]

You missed my point. I do not feel it is appropriate for Gordon to draw attention to himself and draw speculation towards his competitor. Chris is not an engineer, but a reviewer.<br />

<br />

It smells funny to me. I do not know the answer, but question the reason why it is asked in this fashion. It seems self promotional. He may have asked how this was accomplished, but only after touting his own expertise.

[cfmsp]

"If I were Chris, I'd have pulled that comment and strongly warned you..."<br />

<br />

<br />

<br />

Gordon made not one but two very cogent, and appropriate comments about specifics in Chris's review, although admittedly Chris might not have the answer at hand (to Gordon's questions), nor should he be expected to.<br />

<br />

1) He pointed out that Weiss' Firewire DAC might not be operating asynchronously (per the definition normally used by posters here on CA). This is important due to the fact that Firewire is not always Asynchronous, and, in fact, requires effort by the manufacturer to implement it thusly.<br />

<br />

2) He also pointed out (or rather, reminded all of us) that Asynchronous transmission is not the best manner in which to describe the design characteristic that is normally attributed to Async - i.e. use of fixed oscillators by/in the DAC (as the master clock).<br />

<br />

In other words, a DAC might be using an Async interface, but NOT be using fixed oscillators as the master clock, and thereby not be benefiting from the gains many here associate (incorrectly) with Async interfaces.<br />

<br />

Clay<br />

[4est]

Jeez- Come on, Weiss doesn't need me to promote his products, nor defend them. It just seems a bit bush league to have done it in this fashion. Rightly or wrongly, there was a less self promotional way to ask this question.<br />

<br />

If I am the only one whom feels this is a bit "off", then please forgive me.

[manisandher]

I'm not sure how relevant this is, but my Weiss AFI1 uses the 'DICE' chip, and not the 'DICE II' chip. I suspect the DAC202 uses the former.<br />

<br />

Gordan, do your comments apply to the 'DICE' chip also?<br />

<br />

Mani.

[barrows]

has brought up some relevant points here, and I for one would like to know the exact answer. Does the Weiss 202 use fixed frequency oscillators for the firewire input, or is the clock derived from the PLL circuit? In other words, is the Firewire interface used in a truly asyncronous fashion (as understood by those here to mean fixed frequency oscillators, controlling both the flow rate of data from the computer and the DAC chips)?<br />

On the other hand, Gordon's post does seem a little self serving (even more so if he is incorrect) and it would probably have been better for him to contact Chris, and/or Daniel Weiss through private e-mail to discuss whether there is an error in the review, and then allow Chris to make revisions if necessary.<br />

Ultimately a Stereophile review of the DAC 202, with a measured jitter spectrum would likely be the best answer, as then the measured jitter performance could be compared directly with that of the Ayre QB-9 (as also measured by John Atkinson, Stereophile).

[cfmsp]

<br />

This from the DAC202 manual, explaining how the DAC202 suppresses jitter.<br />

<br />

<br />

"... the D/A converter has to run synchronous to the incoming digital audio signal and thus the frequency of the internal sampling clock generator has to be controlled so that it runs at the same sampling speed as the source (e.g. CD transport). This controlling is done by a Phase Locked Loop (PLL), which is a control system with error feedback. Of course the PLL has to be able to follow the long term fluctuations of the source, e.g. the sampling rate of the source will alter slightly over time or over temperature, it will not be a constant 44.1kHz in the case of a CD. But the PLL should not follow the short-term fluctuations (jitter). Think of the PLL as being like a very slow-reacting flywheel.<br />

<br />

In the DAC202 we employ a two-stage PLL circuitry, which very effectively suppresses jitter."<br />

<br />

Doesn't seem like either Asynchronous transmission OR fixed rate oscillators are in use to me.<br />

<br />

Further in the section of the manual referring to Sync Sources are details on using the DAC's Clock as Sync SOurce (i.e. Master)<br />

<br />

"- Internal: The DAC202 generates the sampling rate clock internally. Note that in this mode the source has to be synchronized to the internally generated sync. With Firewire as input source this is done automatically via Firewire. With the other inputs the source, e.g. a CD transport has to by synchronized via e.g. the sync out<br />

BNC connector at the back of the DAC202."<br />

<br />

Kudos to Daniel Weiss for putting together a great manual, complete with details on the theory (as seen by Weiss).<br />

<br />

clay<br />

<br />

[The Computer Audiophile]

Hi guys - I don't want to hinder any discussion but I do want readers to carefully think about posting armchair engineer "answers" to this developing async question. This statement is not directed at anyone in particular.<br />

<br />

I asked this exact async question before publishing the review to exercise due diligence. I am now working hard to find a definitive answer for the CA readers.<br />

<br />

Please be patient.

[Charles Hansen]

>> $500 and Async USB. I just know someone can produce this stuff for this dollar amount. <<<br />

<br />

Yup.<br />

<br />

Just make it in China and use only op-amps instead of discrete circuitry.<br />

<br />

Those things aren't good or bad except to an individual user. But that's how you make things for $500. Heck, Gordon's Proton is Async USB and it's only $900. It's made in the USA and uses only op-amps. Starting to see a pattern? It's called "there's no such thing as a free lunch".<br />

<br />

Clearly there is a demand for less expensive DAC's. I don't think the DAC Magic is what most people are looking for. For many people the Arcam will fill the bill quite nicely. But don't pretend that you are getting a $2500 DAC for $500.

[cfmsp]

Chris,<br />

I was in the middle of editing my post, and was unable to update it due to your reply. At risk of not heeding your comments, I am posting my updated comments below<br />

<br />

<br />

"- Internal: The DAC202 generates the sampling rate clock internally. Note that in this mode the source has to be synchronized to the internally generated sync. With Firewire as input source this is done automatically via Firewire. With the other inputs the source, e.g. a CD transport has to by synchronized via e.g. the sync out BNC connector at the back of the DAC202."<br />

<br />

There is definitely room for interpretation here.<br />

<br />

The question becomes - what is meant by "done automatically by Firewire"?<br />

<br />

Does this mean that Firewire (in Internal mode) obviates the need for synchronization (as described above), or does it mean that Firewire drivers provided by Weiss synchronize the clocks in a manner similar to use of an external clock? <br />

<br />

Presumably it doesn't even matter so long as the DAC's clock is being used as Master, and is a fixed oscillator.<br />

<br />

As Chris says, probably only Daniel can provide the answer.<br />

<br />

clay<br />

[Lowlands]

Just a thought r.e. your question on feeding your DCS stack... <br />

Do you convert PCM to DSD before DA or use other (a-sync) SRC? If so... you might be pretty much fixed (and async) .. :-)<br />

<br />

The INT202 will allow the higher samplerates over the Belcanto..<br />

Just my 2 cts<br />

<br />

Hans<br />

[rlodad]

Just a couple of comments from the eye surgeon who knows just enough about electrical engineering to frustrate the whole list with his questions.<br />

1. I enjoy manufacturer's comments, and enjoyed reading those by Gordon Rankin and Charlie Hansen. We know who they are, let them talk.<br />

2. I do not want their comments "suppressed" by direct e-mails to Chris. I want to know what they think, at least as much as I do any for the other so called "experts" on the list. If they are wrong, tell them so. If we can't do that what the heck is the net worth anyway?<br />

3. Charlie, I know there is no free lunch, but I'll say it since you can't- the QB-9 is one fancy Ritz dinner for the price of a diner sandwich compared to the Weiss or Berkeley (that I bought). Yes, the Berkeley is better, but no where near twice as good, for twice the price, plus cost of a lynx card. You two both take some credit for that.<br />

4. Gordon, any news on the Wavelink 24/192? I can't wait to compare the Berkeley with the Wavelink to the 202 or DCS stuff. Is the Apple software glitch fixed yet? <br />

<br />

I gave you the introduction- feel free to comment on your product as a response to my question, hopefully without the fear of an accusation of manufacturer bias....<br />

<br />

:^)<br />

<br />

<br />

[The Computer Audiophile]

Hi rlodad - If you want to discuss products unrelated to the subject of this review I encourage you to start another forum thread. That way others will certainly find it when browsing the forum for such information. The answers to your questions should see the light of day and not be buried 100 comments down in a review about the Weiss DAC202.<br />

<br />

Thanks for your understanding :~)

[Audio_ELF]

@Charles Hansen...<br />

<br />

At the risk of sounding like I'm biting the head of another manufacturer commenting on a competitors products, do you know for a fact that the Arcam R-DAC is made in China (or other Far East country) as generally Arcams products are made in the UK. They did go through a period where their AVR line was made in China but the recent (AVR600 and 500) have returned to UK manufacture. This includes (afaik) the Solo range which superficially the R-DAC is part of. <br />

<br />

Eloise

[cfmsp]

<br />

eloise, <br />

your question is certainly a fair one, but I didn't get the impression Charles was referring specifically to the Arcam. I took his response as general in nature. I do agree with his point (perhaps mostly implicit) that just becuase a DAC might be Async doesn't mean it will sound as good as better engineered DACs, whether Async or not. Cheaper DACs have to cut corners somewhere. Providing a low-quality Async DAC becuase it's a hot market for such will disappoint many and drag down the appeal of Async USB - neither of which is good for anyone. Mind you, I do NOT think anything Arcam does will be low quality.<br />

<br />

I AM interested in Arcam's products generally, esp. use of trickle down from dCS, as my last CD player was the Arcam CD23 with dCS RingDAC.<br />

<br />

Do you know if in fact they are licensing dCS Async USB?<br />

<br />

cheers,<br />

clay<br />

<br />

<br />

[barrows]

"2. I do not want their comments "suppressed" by direct e-mails to Chris. I want to know what they think, at least as much as I do any for the other so called "experts" on the list. If they are wrong, tell them so. If we can't do that what the heck is the net worth anyway?"<br />

<br />

Suppressed, really?? This is quite a cynical comment. My point in suggesting that Gordon contact Chris directly was made in the view that Gordon was not certain exactly what is happening inside the Weiss 202, he was just raising a suspicion. In any case, I would never expect Chris to be one to "suppress" information as long as that information was confirmed to be correct. A manufacturer needs to be held to a high standard when commenting on public forums, especially if commenting about a competitors product, and speculative comments seem a little over the line to me.<br />

<br />

Clay: re the sections of the manual that you have refferred to, I find it unclear as to whether the PLL circuit is the clock generator only for the SPDIF inputs, or also for the Firewire input. For the SPDIF inputs a PLL is necessary, so it is understandable that there is one in the 202. In any case, I think we can relax and wait for Chris to get confirmation from Daniel Weiss as to how the clock is generated for the Firewire input.

[labjr]

Does quality really have anything to do with the cost of parts? or whether or not opamps are used? How much more can discrete circuits cost? When I see the inside of any of the top rated DACs or high end products I can't help but think the cost to make the boards appears to be minimal compared to the MSRP of any of these products. I'm thinking they spend more per unit on marketing than building the product.<br />

<br />

The sound probably has more to do with brilliant engineering. Some designers are more talented than others. And some of the best are more generous than others and their products are more reasonably priced. ie; Metric Halo seems to be a good example of brilliant engineering combined with generosity. You get a lot for the money. And people are raving about the sound of those opamps!

[Bob Stern]

The TC Electronic DICE II PLL chip used by the DAC2 and DAC202 is described in US patent 7,495,516 and in the following AES technical paper (which is easier to understand than the patent):<br />

http://www.tcelectronic.com/Media/frandsen_travis_2006_clean_clocks_tc(1).pdf<br />

<br />

The paper clarifies that the DICE II chip is a PLL that performs the same function as any other PLL. It is a specific PLL design, not a scheme for avoiding the PLL.<br />

<br />

Any use of a PLL to extract a clock from an incoming Firewire or AES audio stream is completely different from the flow control and fixed master clock used by asynchronous USB DAC’s from Wavelength, Ayre and dCS.<br />

<br />

Specifically, the paper states the purpose of the DICE II chip is to synchronize a local clock to the clock of an input stream, such as a Firewire 1394 isosynchronous input stream (see Abstract; sec. 1.1, last paragraph; sec. 2.3). The DICE II chip uses two cascaded PLL’s: (1) a digital PLL with a fixed master clock and numerically-controlled digital frequency divider, followed by (2) an analog PLL with a voltage-controlled oscillator. One of the stated advantages of the DICE II chip is to avoid the need for multiple fixed frequency clock chips (sec. 2.7).<br />

<br />

This supports Gordon Rankin’s interpretation that, in Internal Clock mode, the Weiss DAC202 acts like an external master clock that sends a clock to the computer to regulate the timing of the Firewire audio signal, but the DAC202 then treats the incoming Firewire audio no differently than an AES signal. That is, the DAC202 uses the DICE II PLL to extract the clock from the Firewire audio signal the same way it extracts the clock from an AES audio signal.<br />

<br />

(This interpretation is further supported by the existence of the Operation Mode / Stability setting in the DAC202 control panel software. This appears to control the parameters of the PLL. It would not be needed if the DAC202 were using a fixed master clock instead of a PLL.)