TAS does it again...

[cfmsp]

TAS does it again...making erroneous, absolutist statements regarding computer audio, that is.

 

I posted some of the thoughts below in another thread, but thought I'd elevate it to it's own post. Apologies for duplication.

 

In an article on dCS [in the latest issue of TAS], Robert Harley states: "In most digital interfaces, including S/PDIF, AES/EBU (a variant of S/PDIF) and Firewire, the source component (the CD transport of PC music server, for examples) is the master clock to which the receiving device MUST LOCK."

 

and further says...

"Although the USB interface was never designed for transmitting high-quality audio, it inherently has the ability to allow the receiving device to control the data rate from the source device - a feature NOT POSSIBLE with S/PDIF, AES/EBU, OR EVEN FIREWIRE."

(capitalizations are mine in both instances).

 

What a clueless thing to say, when it can't be further from the truth with regards to Firewire. The main point being the absolutist nature of both comments - when neither condition is true - with use of words 'not possible', and 'must lock'.

 

Elsewhere in the thread, I said:

For those who believe TAS is engaged in a "freeze out" of Gordon Rankin/Charles Hansen via lack of discussion of their Async USB products, there is NO evidence I could find to challenge that view [in the Empirical review].

 

Indeed, it seems quite the contrary.

 

Despite opportunities in their Empirical article, the dCS article (and discussion of Async USB therein), and most importantly the RMAF review (and the specific focus on digital, including computer based audio, by Steven Stone), there was NO mention of Wavelength/Ayre's ground breaking Async USB devices anywhere to be seen.

 

Coupled with their consistent mis-reporting of Firewire's capabilities [as evidenced by the earlier Alan Taffel proclamation that NO Firewire DACs existed, coupled with the misrepresentation above] one has to wonder how long before their lack of credibility starts to become something more serious, i.e., intentional, as opposed to naivete'.

 

Frankly, I'm not sure it can be chalked up to naivete, or lack of knowledge, any longer.

 

clay

 

PS, FWIW, yes, dCS are an advertiser in TAS, and yes, they also pooh-pooh the capabilities of Firewire.

 

 

 

 

 

 

 

 

[cfmsp]

 

gratuitous bump to (hopefully) generate some comments.

 

clay

 

 

[Mike in MD]

I expect that I will keep reading TAS to see if I can figure it out.

 

Mike

 

 

[earflappin]

At least as regards Metric Halo, I was told by VRS that their firewire interface is NOT async. Clay, I know you have numerous posts on this and other forums where you state that the ULN-2 and ULN-8 uses an async fireware interface. You might want to check into this.

 

[Bob Stern]

On either this forum or AudioAsylum (can't recall which), Gordon Rankin said he withdrew the review sample of his Async USB DAC from TAS because he felt they were evaluating it without appropriate associated equipment. That certainly could explain why TAS might blackball his product.

 

It's inexplicable how TAS could be so clueless re Firewire.

 

I think TAS reviews in general have lost most of their credibility, and that's especially true for computer audio.

 

[icebreaker]

that if TAS keeps dropping the ball in regard to computer audio there are other publications that are willing to carry it. Those unwilling to adapt to changes in the market etc. etc.

 

[cfmsp]

I guess it might depend on what the definition of 'is' is.

 

If we define asynchronous as using the clock in the DAC as master, the Metric Halo devices are asynchronous when using the Firewire interface and the internal clock is selected as Master. (This setting can be selected via MIO software, or even Audio Midi Setup).

 

If people want to debate that, I'm okay with that, although surprised by the comment made by VRS. Did you talk with John or Vincent?

 

As we've discussed here ad nauseum, the actual issue is not whether the interface is asynchronous, but whether the clock in the DAC is used as the master clock, it's just that Asynchronous is the 'buzz word' that's been most prominently used to signify this.

 

From the ULN-2 Manual:

 

"Clocking Considerations

There are five ways that you can clock Mobile I/O:

1. Internal, 2. Digital (AES/SPDIF), 3. Wordclock, 4. 256X

 

Each choice is appropriate for a particular situation. In general, you should use Internal clock if you can because you are likely to find that it makes your other digital gear sound better. However there are some devices that either must be the clock master or work better if they are the clock master. For these devices, choose the clock port which is most appropriate for the device."

 

MIO is the software controlling the ULN-2. NOTE: Both AES/EBU and S/PDIF are counted to reach the total of 'five' ways above.

 

clay

 

 

 

 

[salwani]

There is a post by Alan Taffel commenting on the outcry of his TAS article. It's an interesting read and in it he writes :

 

"My statement that “no FireWire DACs exist” was meant to say “no audiophile grade FireWire DACs exist”, and I owe readers an apology for not being clearer on this point. As many posters have rightly pointed out, there are a number of pro FireWire DACs available."

 

Bad salvage attempt considering Weiss' consumer firewire DAC.

 

I'd chalk it all up to just being ignorant. But i'm quite certain that we will see a direct correlation between the revenue generated from DACs/Music Server ads and the quality of the coverage of the same.

 

 

 

[cfmsp]

I think I discovered why VRS may have - erroneously, IMO - stated that Metric Halo devices are NOT asynchronous.

 

From the ULN-8 manual:

"ULN-8 audio transport takes advantage of FireWire’s support for isochronous transmission, in which the ULN-8 can reserve a dedicated amount of bandwidth on the bus for moving audio samples. Since the audio must be transmitted on a regular basis to ensure continuous playback and recording , the isochronous model is perfect."

 

If they believed that isochronous and asynchronous modes are mutually exclusive, that might explain their comment.

 

[WIKIPEDIA says: Unlike other serial buses, such as PCI, FireWire fully supports both isochronous and asynchronous applications]

 

The manual further states:

"Control changes and meter data are transmitted using asynchronous transactions on the FireWire bus. This transmission approach makes use of the unreserved bandwidth on the bus and competes with things like FireWire hard disk accesses for time."

 

This reference to 'asynchronous' describes the type of communication from DAC to source (needed) to control the flow of data from the source. That this information exchange IS asynchronous is NOT the same as saying the data communications is asynchronous. Asynchronous communications (whether USB or Firewire) is most often used to describe when data is transmitted asynchronous to the source clock, which is the case when using the ULN-2/8's Internal clock as master.

 

So, Firewire interface on the Metric Halo devices offers the advantage of 'guaranteed bandwidth' (aka isochronous mode), and provides communications asynchronous to the source clock - instead relying on the high quality Internal clock as master (for data communications).

 

hope this explains any possible confusion,

 

clay

 

 

 

 

 

 

[earflappin]

Very helpful indeed Clay. Thanks. From an interface design perspective this is clearly superior to AES/EBU.

 

[beetlemania]

I used to buy an occasional copy but it didn't often appeal to me. The last time I seriously looked at a copy was about three years ago - took me about 15 minutes to go thru it, then I regretted that I had wasted that time.

 

Regarding their freeze out of asynch USBs, it seems clear to me that Wavelength is collateral damage in TAS' revenge for Charles Hansen publicly airing the Valin cable debacle (search the AA archives for the history). It's pretty clear that TAS will not even mention Ayre other than to bash their products.

 

http://www.avguide.com/comparative-review/high-end-loudspeakers?page=4

(Note that Valin loves the sound of the system ("astonishing") - driven by Ayre amps - but when he changes sources and doesn't like the sound as much, it's the Ayre's fault. LOL!)

 

In addition to the cable incident, Valin has lost any credibility with his series of "best ever" products (i.e., the one he's reviewing that month). Meanwhile, we've got the Taffel article, the Stone article, and, now, the Harley article (I haven't actually read any of these other than thru the discussions on this forum). If TAS has any credibility whatsoever - and I'm only hedging 'cus I think Sue Kraft is still with them - it sure ain't in the computer audio department. Hopefully, folks that really want to learn about computer audio can find CA and AA (maybe Stereophile, too) 'cus TAS appears to be intentionally skewing the story . . .