Classé Omega Super Audio CD player:
Page 3
And back to analog
The analog circuitry comprises three sections: the analog filter, the current-to-voltage conversion, and the output driver. All are unusual in the Omega SACD. The analog filter is a second-order passive type. Because of its 12dB/octave rolloff, it doesn't offer the same out-of-band rejection of a more complex, steep-slope filter, Classé's white paper explains. "However, with a corner frequency at 35kHz and 96dB of attenuation at 2MHz, this filter provides more than sufficient noise suppression to prevent both audible artifacts and intermodulation distortion."

The catchily named Current Conveyor is described as a "feedback-free circuit on the second stage of analog filtering to convert the current output from the first stage of analog filtering to a voltage signal...It provides a nearly zero-impedance input for the current signal. The Conveyor converts the low impedance (non-ideal) current signal into a robust high-impedance current output. This signal could be converted to a voltage with a shunt resistor. However, here the second stage of the passive analog filter is used as a resistor to generate the output voltage."

The voltage produced by the second stage of analog filtering, explains Classé, is actually sufficient to drive the output, but they feel that current buffering (gain) is required to drive the preamp inputs. This is seen to by a zero-feedback output driver, "where the lack of feedback has similar advantages as the Current Conveyor circuit. However, using an output driver with no feedback has an additional advantage: The output driver prevents external noise, such as RF picked up by the cables, from entering the unit. An output driver with feedback feeds the output signal back to the input, thus offering an opportunity for such noise to enter the circuitry.

"Notice," Classé finally can't help but crow, "that the entire output circuit requires no voltage gain and no feedback. This elegant simplicity is representative of the approach taken with every aspect of the Omega SACD design."

Well, he who has the last laugh laughs best, they say! On to the listening...

Listening
Here's how to start your J-10-sanctioned listening session. If there's one SACD disc that all Stereophile reviewers should have, it's Duke Ellington's out-of-print but not-too-hard-to-find Blues in Orbit (Mobile Fidelity Sound Lab UDCD 757).

First, enjoy some instant sex by playing the SACD layer of track 4, "Sweet and Pungent." I gay-ron-tee the midrange will leave you ravaged in your listening chair. Right from the opening bars, it sounded positively lascivious—just like a film noir blond putting her arms around you (you wish!) and giving you one of those looks. Big boy.

In audiophile terms, that meant a big, very transparent soundstage and a delightful cushion of...not so much of air (although there's plenty of that), but of defining movements of air—the volume of space from which the horn laments and wails far forward in the center of the soundstage. The drums were fabulously resonant, farther back left, the bass rather indistinct in that it's-all-in-the-room sound, rather than something more tightly miked, as we find on recordings today. And there's a lot of body and thus dimensionality, a hallmark of the Omega player's style.

But the whole of the music was so much more than its many parts. The midrange lusciousness, especially in SACD, had me on my audiophile knees [crick] begging for more. "This is what it's allll about," I babbled in my notes.

When I listen carefully to track 7, "Blues in Blueprint," I can hear a ground loop in the studio, along with the most restrained, lovely horn intro I've ever experienced. The Classé laid it all out like I've never been privileged to hear before. "Blueprint" is more evocative than the other, bigger numbers on this disc: the acoustic space seems bigger, more full of instrumentation, all nicely limned by the Classé in SACD. The tunefulness, speed, ease, purity—the plain loveliness of the plaintive horn—the interplay of sonorities, the effortlessness in settling down deep in the music...were all a great pleasure.

Then I did myself a favor and let the Omega go on to track 8, "The Swingers Get the Blues Too." Ah, that somewhat distant horn, the fullness of tone, and then, almost a minute in, the fuse lights and ka-bam. The air, the space, the sonority were fabulous. So were the drive, the urgency of the music, the joy in the playing.

I couldn't stop. Next was track 9, the sublime "The Swinger's Jump." Notes: "Truly amazing sound, so real and present, the Classé just like the Nagra PL-P in perspective—I'm right up on the outer edge of the recording stage, the sound all around and behind me and the speakers, but not so deep." In any case, the sound was big, full, dramatic, colorful, detailed, and airy. All hallmarks of this great player in SACD and, surprisingly, CD mode too.