Theta Digital Casablanca surround preamp

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When Theta Digital's Neil Sinclair told me more than a year ago that he was thinking about introducing a home theater surround processor, I wondered which category the new Theta would wind up in. Would it be like processors from Proceed and Meridian, which took home theater seriously from the outset and de signed innovative, high-performance surround sound preamplifiers that hit all the right notes for music and movie soundtrack processing? Or would the new Theta be another of the oddball processors that eschew even basic Dolby Pro Logic processing in favor of nothing more than active versions of the 30+ year-old Hafler passive sum / difference matrix circuit, meant to subtly enhance stereo music rather than properly decode movie soundtracks?

Coming out with a multi-thousand-dollar surround processor these days that doesn't have Dolby Pro Logic, much less Dolby Digital (AC-3) or DTS, is just plain frightening. And most high-end surround processors that do decode Dolby Sur round are flawed in other ways, such as having overly wide steps in the channel level-calibration scheme, skimping on the number of inputs because the designer's got no idea how many sources can pile up in a home theater, failing to include proper bass management and subwoofer crossovers, or adding on-screen menus only for the composite video output, not the S-video. Or or or.

At first glance, the Theta Casablanca looks like the biggest, beefiest surround preamp you've ever seen. This thing's huge! At 19 inches wide x 16 inches deep x 7½ inches high, and weighing in at a healthy 43 pounds, it's even bigger than Theta's Data III laserdisc/CD transport, which was the biggest slab in my equipment rack before the Casablanca arrived. Why's it so big? Because aside from its multiple over sized power supplies, its design is more akin to that of a personal computer than a hi-fi component. In stead of everything mounted on the same circuit board, the Casablanca is basically a mainframe and power sup ply on a chassis, with a series of slots that accept Theta's various circuit cards, each handling a different task. Just as a PC has slots for internal modem cards, video cards, sound cards, and so forth, the Casablanca has card slots for digital input, analog audio, video, Dolby Digital/Pro Logic, DTS, and anything else that develops down the road. I think this is a great idea (as does Meridian, which adopted the same kind of PC-like de sign for its new 800-series electronics). State-of-the-art home theater is such a moving target these days, and a PC-type design makes customization and upgrading as easy as installing an internal modem.

You start with the base model Casablanca, which runs $4,500 [1997]. This includes the digital input card, which has six coaxial S/PDIF inputs and two Toslink optical inputs, and the analog input card, which has provision for six analog stereo audio sources. The analog card can be thought of as a signal router and high-quality analog preamp, with a gain stage and a stepped attenuator for each of the Casablanca's six audio out puts. The attenuator-which consists of a digitally controlled, precision, metal-film resistor ladder with an active buffer stage on its output-is the last stage before the output jacks.

Unlike other DSP-based surround pre amps, such as the Meridian 565 and Lexicon DC-i, the Casablanca has an "Analog Direct" mode that bypasses the A/D and D/A conversion stages entirely to get the best sound from stereo-only analog sources, such as LPs. I say "stereo-only," because the Casablanca doesn't perform any kind of analog surround decoding. If you want to hear Pro Logic surround from an analog source, such as a VCR, the Casablanca converts the analog audio to digital through its high-quality, 18-bit A/D converter and then sends it on to the DSP engine that enables the various surround modes. The Casablanca does have what Theta terms an "Analog Matrix" surround mode, however, which pass left and right signals like bran flakes through a goose, simultaneously tapping them to the A/D converter to derive a DSP-generated L + R center channel and L - R surround channel-essentially a Robo-Hafler circuit. I've never found myself in any listening/viewing scenario where this particular mode was the most appropriate, but at least brawny owners of Audio Research and Naim surround preamps won't be able to kick sand in your face at the beach.

However, you can't run home and plug this thing in right away. You still need to add some D/A conversion cards, which is where the customizing comes in. The Casablanca has three D/A card slots, and Theta offers two grades of DIA cards, Standard and Superior. The 18-bit Standard card is said by Theta to be somewhat better than its $695 Chroma D/A converter, while the 20-bit Superior card is said to fall between its DS Pro Basic 111-a ($2,100) and its flagship DS Pro Generation V-a Balanced ($5,600). I happened to have a Generation V-a on hand, so I compared the sound of the Superior card to the V-a plugged into an analog input with the Casablanca in "Analog Direct" mode. Yes, the V-a sounded better, but we're really splitting ant hairs here. I didn't hear much tonal difference, but there was a bit more sense of depth with the V-a than with the Superior card. If I were a rich man, yada dada deeda dada dee da deeda deeda dee, I would plug a V-a into the Casablanca for the very best sound from my CDs. But back on planet Earth, I'd be more than happy with Theta's Chroma-grade Standard card for the front-channel audio, much less the 20-bit Superior card.

With these two grades come further options. You can get a two-channel Superior D/A card if you want the Casablanca to be just a stereo digital preamp. For surround sound, you can stick a single six-channel Standard card in the first slot or a three- channel Superior card in the first slot for the front channels and a three-channel Standard card in the second slot for the subwoofer and surround outputs. Or you can go whole hog and stick Superior cards in both slots for 20-bit processing all around the room. The six-channel Standard card has unbalanced RCA outputs, while the three-channel Superior and Standard cards have balanced XLR as well as unbalanced RCA outputs. And the third slot? Well, that's for when your wife finally leaves your scary ass because you wanted a third three-channel card for right front sub, left front sub, and surround sub (figuring if you can go there, you're capable of God-knows-what).

The base model Casablanca includes Theta's proprietary DSP surround engine. But if you want to add Dolby Digital, you'll need to get the $500 Dolby Digital board and, if you want to play AC-3 laserdisc soundtracks, the $500 RF demodulator board (DVDs won't need the RF demodulator stage, as they deliver the Dolby Digital bitstream directly via a standard S/P DIF output). The RF demodulator board has two RF inputs plus an AESIEBU digital in put, a BNC digital input, and a Toslink optical input; an ST or Theta Single-Mode optical input is optional. DTS decoding requires another $500 board. All three boards were in my review sample.

Although the video card wasn't ready for me to review, it should be available by the time you read this. Forgoing this card means having to plug all of your video sources directly into your video monitor and doing the video switching there while the Theta preamp switches the audio! As I understand it, hard-core video goons do this as a matter of course and look down on anyone who routes video through a surround processor. But, criminy, who wants to punch two remotes every time he switches sources? Theta's video card will handle even the most comprehensive home theater rig, it will have six composite video inputs, four S-video inputs, and full on- screen menus for both types of connection.

Ml the best surround processors have enough bass management options to cover most systems, but the Casablanca really goes to the mat with its DSP bass crossovers. Not only can you send each individual speaker a full-range signal (or one that's high-pass-filtered to remove the bass-in systems where a separate subwoofer handles the low end), but you can adjust the cross over frequency in 20-Hz steps from 40 to 120 Hz. You can also decide how steep a slope you want the high-pass filter to have: 6, 12, 18, or 24 dB per octave (first through fourth order, respectively). And when you decide to bass-manage any of your speakers, the Casablanca is smart enough to send the bass to the front left and right speakers if they're full-range or to a separate sub- woofer if one is connected.

Okay, on to the audio modes. In its basic form, the Casablanca has seven modes: "Analog Direct," an all-analog, no-processing, purist stereo pass-through; "Analog Matrix," the Robo-Hafler mode that passes the left and right analog signals and digitally derives an L + R center channel and an L - R surround signal; "Simple Matrix," a full DSP iteration of the Robo-Hafler mode for digital inputs; "Special Matrix," a DSP mode similar to Dolby Pro Logic but with more extended high-frequency response in the surround channel and what sounds like a subtle stereo-izing there as well; "Dolby Pro Logic" itself, tweaked and polished in the DSP realm by Theta; "Stereo," which is straightforward, two-channel D/A conversion for listening to CDs via a digital trans port; and "Mono," which for some strange reason combines the left and right channels into one and sends it to both the left and right speakers. Why it does this, I have no idea, because it would sound much better and more coherent if the mono signal were sent to just the center speaker; off-center listeners won't hear the apparent image jump over to whichever main speaker they are sitting closer to, for one thing. And then, of course, there are the optional surround modes, Dolby Digital and DTS. (I'd love to see other manufacturers offer their own plug-in cards for the Casablanca, like an Audible Illusions phono stage or a Pioneer karaoke board. Karaoke in digital surround would be a turning point for mankind! Why are they keeping this from us?) Here's another great thing about the Casablanca: This thing is a breeze to set up. Two buttons, "Mode" and "Setup," and an up/down/left/right quartet of cursor controls are on the front panel and duplicated on the remote. "Mode" and "Setup" get you into option menus, and the cursor controls get you where you want to go. As Theta puts it, "The same button that gets you into a menu gets you back out of it." Sounds simple, but believe me, this one thing makes all the difference in the world. Without on-screen menus or even reading the manual, I had the Casablanca dialed in and ready to rumble in no time flat. Theta really scores here for designing a surround preamp that's so comprehensive and yet re mains so easy to set up and operate.

So how's it sound? Given my strong liking for Theta's two-channel D/A converters over the years, I expected the Casablanca to rock. And looking at the circuit flow chart and feature set, I immediately could tell that Theta had paid full attention to those little areas in which some competitors come up short. Theta must have taken notes about the weaknesses of earlier processors, be cause it has avoided every one of them. But more important, Theta imported its legendary DSP and D/A conversion and then hung a simple, audiophile-grade analog preamp on the output, avoiding the volt age-controlled amplifiers, digital-domain volume controls, and other sonically com promised approaches to multichannel level control found in other processors. The result is surround sound like I've never heard it before, even from such standard-bearers as the Meridian 565 and the Citation 7.0. The Theta Digital Casablanca is the cleanest, meatiest, and best-sounding surround processor I have heard.

As you might expect from any box sporting the winged Theta logo, the Casablanca has amazing bass. Not just tight and powerful bass but fast, detailed, multidimensional bass, the likes of which I don't hear from the Citation or the Meridian. Bass sounds of all sorts were unraveled by the Casablanca, revealing more complexity and texture than I'd previously noticed. Even some thing as simple as the opening bass riff at the start of Apocalypse Now, when the chopper flies across the screen and The Doors kick off "The End," suddenly sounded like a real electric bass being played by a real guy's finger. (This passage wasn't that clear on the original record and sure didn't gain fidelity when Francis Ford Coppola's technician dubbed it onto the soundtrack, reversing the right and left channels.) It had all the added upper-bass character and color of an old Ampeg tube bass amp.

The Casablanca also beat the other processors in sheer dynamic impact. The Citation is very, very good in this respect, while the Meridian's smoother, gentler character seems to rein in its ultimate fury. But the Theta is the champ here, by a long shot. It's no wonder that an all-out, no- compromise $8,500 processor (the price of the configuration I reviewed) can sound more gutsy and unrestrained than one less than half its price, but the Meridian 565 AC-3/562V combo is right in the Theta's ballpark price-wise, and it doesn't convey anything like the sense of dynamic scale that the Casablanca hurls at the rest of the system. Hearing this difference reminded me of the first time I compared a purely passive preamp to one with a good active buffer on its output. Both sounded pristinely clean and detailed, but the buffered preamp seemed to hurl dynamics at the amp and speakers. Music sounded like it was being played at a faster tempo, and transients leapt into the room like they do in real life. That's precisely the effect that installing the Theta Casablanca had on my reference system. It has never sounded as good as it does with the Theta at the wheel.

The Casablanca sets a new high-water mark for spatial coherence, too. On first listen, it sounded as if its surround channels were lower in level than those of the Citation or Meridian, even though my SPL meter showed perfect channel calibration for all three processors. But after a while, the Theta's subtler, more natural presentation won me over. The Citation's "6-Axis" surround mod throws so much front left and right info back to the surrounds that the sheer quantity of information coming from them can be distracting (even though most of the time it sounds so cool). The Casablanca, on the other hand, carves an ac curate sound field that presents the original mix, nothing more and nothing less. It took some getting used to after living with the Citation for so long, but now I'm hooked.

Even in Pro Logic mode, the Casablanca presented surround mixes that sounded precisely anchored, as if I were hearing a good discrete Dolby Digital mix. It's the same kind of improvement I heard when I first compared the sound of a good Philips CD player to the sound of that player's dig ital output driving a Theta DS Pro Basic D/A converter. In the first seconds of my initial session with the Casablanca, I could tell that its image solidity was markedly better than that of the Citation and Meridian processors. I did most of my auditioning with the Casablanca set for Pro Logic (the "Special Matrix" mode doesn't sound that different, and I found I preferred straight Pro Logic on most movies), but my comments about image solidity apply to Dolby Digital soundtracks as well. The few DTS demo discs I had on hand to audition the

Theta's DTS board sounded fine, although I heard nothing in the DTS-encoded laserdiscs or music CDs that suggested any kind of sonic advantage over Dolby Digital. (DTS CDs may someday be filed next to dbx LPs in the Dumb-Ass Audiophile Ideas warehouse. But if you want the option to play whatever titles come out in the format, Theta again has got you covered.) Is the Casablanca perfect in every way? Yes and no. In terms of sound quality and movie surround processing, it's far and away the best I've heard. But I did not find the music surround modes very interesting or usable. It's not that they're whacked out, like so many of the cheap 'n' cheesy DSP surround modes in typical A/V receivers, but just the opposite. Being nothing more than Robo-Hafler sum/difference circuits, the Theta's analog and digital matrix music surround modes sound relatively dull and just aren't as sophisticated and awe-inspiring as the Citation 7.0's "6-Axis" mode or the Meridian 565's "Tri-Field" mode. Both of these modes take a stereo music signal and generate an intensely vibrant, always appropriate, very natural surround presentation. Yes, the Theta has an L + R center channel and an L - R surround channel, but to my ears they sounded dated and weird on most of my CDs. Maybe these modes would sound better with classical music than with Hendrix, Coltrane, and Sebadoh. As it was, I ignored the matrix modes and used just Dolby Pro Logic for movies and straight stereo for music. The Casablanca's startling sound quality in these modes made it pretty easy to forgive its lack of cool music surround capabilities.

That aside, the Theta Casablanca is an undeniable success. Its combination of simple, intuitive setup and operation; stunning Theta-grade digital sound quality in stereo, Dolby Pro Logic, Dolby Digital, and DTS; and an obsolescence-free design push it to the front of the race for best surround preamp on the market. If your main goal is synthesized music surround from stereo CDs, you will be happier with the Meridian 565 or the Citation 7.0. But you won't get better sound quality in stereo and Dolby Digital/Pro Logic. And if the best is what you're lusting after, the Theta Digital Casablanca should be the beginning of a beautiful relationship.

[ Orig. publ. in Audio magazine/APRIL 1997]

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Updated: Friday, 2015-06-05 6:01 PST