Rega DAC D/A processor Page 2

Here's another great disc (of course, you'll want the CD, not MP3 downloads): Black Coffee, by Ann Savoy & Her Sleepless Knights, with violinist Kevil Wimmer and guitarist Tom Mitchell (CD, Memphis DOT 0225)—inspired, I'm sure, by Joe Venuti and Django Reinhardt. Known for Cajun music, Savoy sings in English and French; try "Cette Chanson est pour Vous." Both DACs did splendidly with this album, which should be far better known. When it comes to popular taste, I must be totally asynchronous, which the Rega DAC isn't.

Asynchronous means that the clock on your computer (or server) and the clock in your DAC are out of sync—ie, they work independently of each other. I asked Terry Bateman about this stuff, since any USB DAC that isn't asynchronous is a nonstarter, at least for some hi-fi scribes. "I feel the subject of asynchronous vs synchronous USB is getting tiresome, and I personally don't see USB as a high-tier audio interface anyway," he said.

But "completely synchronous" is "old-school," Bateman also wrote. That's "where the DAC is completely controlled by the computer." If the computer speeds up, the DAC follows and the reverse happens if it slows. Instead, the Rega DAC reclocks the incoming datastream "on the fly," in order to avoid data loss and reduce jitter—exactly what Bateman said you would achieve with independent asynchronous DACs.

In the case of direct USB connection, the data go to that Burr-Brown PCM2707 receiver mentioned above. With S/PDIF inputs, the data go to a Wolfson Microelectronics WM8805 receiver chip. "There are no sample-rate converters driving the Wolfson DACs, so the sample rate that goes in gets sent to the DACs." Bateman refers to the parallel-connected Wolfson WM8742 DAC chips, not the Rega DAC as the entity itself. In other words, when I connect my Sony player to the Rega DAC, the receiver chip sends the 16/44.1 data to the Wolfson DAC chipsets unchanged. However, the Wolfson WM8742 DACs oversamples the "native" datastream to 192kHz.

You can upsample with the Rega DAC, using a software program like Foobar to convert your 16/44.1 CDs (stored on your hard drive) to 24/192. Alex Ross, classical-music critic of The New Yorker, calls such measures "bitty manipulations." Terry Bateman seems to suggest that they're better avoided. If you have a program like Foobar, you can fuss with the data rates all you want.

The fact that the Rega DAC itself doesn't upsample may provide a clue, or even the key, to its unforced, organic sound quality. I wish I had better words, but I think you'll hear what I mean. There are other factors, too, such as close attention to power supply design. Like other great DACs, the Rega DAC represents more than the sum of its parts.

So that the user has something to play with, Rega included 10 digital filters: five for data rates of 48kHz and under, five more for data rates up to 192kHz. The filters, in effect, come with the Wolfson WM8752 DACs; all Rega had to do was supply the buttons and LEDs. They did so. This fits with Rega's philosophy, as Bateman expressed it: "Keep things simple and straightforward."

But there are complications. While Rega recommends using Filter Setting 1 as the default, you might find that Filters 4 and 5 have their charms. (I could not and so did not try the filters for higher data rates.)

Filters 4 and 5 are apodizing filters. Apodizing is another buzzword: it means a minimum-phase digital filter that avoids introducing pre-echo, or pre-ringing, to the signal. The result should be quicker, cleaner, clearer transients—exactly what I heard. But don't make life complicated; Terry Bateman is right to say that the effects of the different digital filters are subtle. When I told him of my fondness for Filter 4, I could see him nod, even though I don't have Skype. I found Filter 4 most apodizing.

So which should it be—the Musical Fidelity M1 DAC or the Rega DAC? At $995, the Rega DAC costs about 30% more than the M1 DAC, at $695. One could buy both, as I ended up doing, and still not be an audio spendthrift. But it's mere reviewer's artifice to pretend that the M1 DAC and the Rega DAC are the only two choices. There's also BJR's Marantz CD5004 player, which I haven't heard yet.

I'll be danged if I know which DAC, since each wrests such great sound from those much-despised (though not by me) CDs. Your choice, if it is between these two, might come down to brand preference. If you want Musical Fidelity's matching M1 HPA headphone amp, then you'll probably want the M1 DAC. Keep in mind, too, that the M1 DAC has balanced XLR analog outputs; the Rega DAC does not.

If you're a Rega person, you'll gravitate toward the Rega DAC for its distinctively Rega sound quality: rich, full-bodied, almost tube-like. I can't think of any better way to upgrade while keeping, say, a Rega CD player as a transport.

Then, too, your choice might come down to your speakers and the rest of your system. If your amplifier and speakers lean toward leanness, the Rega is your obvious choice. If your speakers have a different, darker tonal balance, then perhaps you'll prefer the lightness, openness, and airiness of the M1 DAC. With the Triangle Comète Anniversaire speakers, I prefer the Rega; when I switch back to my Harbeth Compact 7 ES3 speakers, I might fancy the Musical Fidelity.

Ideally, you'd find a dealer who carries both and audition both. Even more ideally, you could borrow both and take them home. Even more ideally—and why not, if Bernie hasn't made off with your money—you could buy both. One good DAC deserves another.

Here's what I love about the Musical Fidelity M1 DAC and the Rega DAC: Each enables a bloke to wrest from Compact Discs the best sound possible. You can be stuck in the past without forestalling the future. My blessings on both—my imprimatur, as it were. And may you enjoy a long life to go along with them, before you die!—Sam Tellig

Jon Iverson auditioned the Rega DAC in October 2011 (Vol.34 No.10):

My pal Bruce Rowley e-mailed to say he'd just picked up the new Rega DAC ($995) that Sam Tellig wrote about in May, and would I mind if he came down so we could check it out on my system. You see, Bruce has all tubes and Quad ESL-988 electrostatic speakers in a smallish room, and I'm all solid-stated and subwoofered and bigger than life, with 11' ceilings and lots of space. Bruce was looking for a very different point of reference—but he and I used to work in the same audio store: his listening credentials are solid. "Absolutely," I said. A few days later, we were set up.

We sat down in the sweet spot (actually, Bruce sat there; I stood behind him, in Son of Sweet Spot) and started in with various tunes and various settings of the Rega, popping its apodizing filter in and out. We heard nothing too dramatic with these choices, so I decided to get down to business, drop my obsession with peachy song titles, and put on the trusty Roxy Music track I've used with most DACs here: "For Your Pleasure," from their second album.

First the Rega, then the Benchmark DAC1 ($1295), then the Rega, then the Benchmark. After a dozen plays, Bruce said, "I know what the difference is now. The Benchmark feels precise and in control, the Rega warmer but a bit fuzzy." Bingo.

Now we pitted the Peachtree iDac ($999) against the Rega. Again the Rega had the warm and fuzzy feeling, but the Peachtree's presentation felt more real—maybe a tad short of the Benchmark, but the difference in that sense of realness was unmistakable. We'd seen the door ding on the Rega and now could pick it out every time. I then played some higher-rez recordings downloaded from HDtracks.com, but nothing we heard changed our initial impressions.

Where the Rega had a slightly heavier feel in the bottom end and added girth to voices (I was surprised at how noticeable this bass boost was), the Peachtree laid back to simply reveal what we both felt were more accurate portrayals of what had been recorded. Bruce said, "The Peachtree allows me to see deeper into the music, but the Rega adds body to vocals." You might prefer the Rega if your system needs fattening up a tad, and/or you have smaller speakers.—Jon Iverson

COMPANY INFO
Rega Research, Ltd.
US distributor: Sound Organisation
159 Leslie Street
Dallas, TX 75238
(972) 234-0182
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COMMENTS
Mark Bolech's picture

In both Sam Tellig's as well as John Atkinson's contributions some confusion on apodizing filters shows. Apodization is nothing more than windowing. Possibly the confusion originates from Peter Craven's proposal to use a very steep filter that completely stops frequencies of half the sample frequency (Nyquist frequency) or higher. For CD this requires a very steep filter, that introduces lots of pre-ringing or pre-echo if the filter is realised in the usual, linear way. To overcome this, Peter Craven proposed to have the steep filter, but in a minimum phase version, that only has post ringing or echo, which is psycho-acoustically to be preferred over pre-echo (which does not occur naturally). Now such filter is often named "apodizing" in short. "Apodizing and minimum phase" would be more exact and exclude confusion.

Products like Meridian 808i.2, Linn Klimax and Ayre C-5xeMP make good use of filters as proposed by Peter Craven, and in Stereophile reviews, these products were praised for their sonics. Now the amazement: in the Rega DAC there appears to be a preference for using an apodizing, but linear filter, whereas the minimum phase filters -apodizing or with a more gentle slope (like Ayre uses)- are not preferred. I really wonder why the minimum phase filters in some cases really make  a difference, but apparently fail to do so in the case of the Rega DAC.

greetings,  Mark

Erranti's picture

 

 

treb74's picture

John,

Thank you for the measurements. Would the 120Hz power supply related anomalies you measured present themselves differently in Europe where the voltage/frequency are 220v/50Hz?

Thank you,

Stephen

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