From the Spring 97 of Stereophile's Guide To Home Theater

By Thomas J. Norton

Digital Theater Systems (DTS) has long promised that we would soon see home-theater products and programs that incorporate the company's discrete digital surround system, but this promise has not been kept-until now. Software is now trickling, from producers, and as I sit at my word processor, at least three companies have introduced DTS-compatible decoders: Theta, Angstrom, and Audio Design Associates.

Audio Design Associates? Hardly an audiophile household name. But ADA has been around for years, sold almost exclusively through custom installers. The company made a splash at a couple of recent trade shows with a $50,000, tube-based, gold-plated Pro Logic decoder, but that was a show piece. Their bread-and-butter surround processors are technically sophisticated but far less eye-catching designs. For example, consider the SSD-66 (5.1); its model designation may he awkward and its appearance determinedly plain, but its performance is world class.

 

Features and Facilities

The SSD-66 (5.1)-which I will henceforth abbreviate to SSD-66 to keep my carpal tunnels happy-is available in either rack-mount or free-standing versions. (The latter, called the Select Series, appears in our photos.) This unit is, first and foremost, a Dolby Pro Logic and Dolby Digital (AC-3) decoder. The circuitry to perform both functions is onboard, with one exception. The RF demodulator needed for Dolby Digital playback from laserdisc is all optional outboard device, the RFD-1. While this is an added system complication and expense, the demodulator is not required if you plan to (eventually) source all your AC-3 from DVD. The most headline-grabbing feature of the, SSD-66 is DTS decoding. But to get this capability with the SSD-66 you must first purchase an outboard adapter, the DTS-1.

In its basic form, the SSD-66 lacks two significant features. First, there is no onscreen display. You can generate such a display only by purchasing another optional ADA device, the OSD- 1. Second, there is no provision for A/V recording loops; it is not possible to route audio recorders or VCRs through it for recording, only for playback. Yet another ADA box, the VS-3 video switcher, does provide eight audio/video inputs, three audio/video outputs (all composite video), and four S-video inputs, and it can be used in conjunction with the SSD-66.

Unlike the Meridian 565-which also has an optional A/V switcher-the SSD-66 does enough onboard A/V inputs for most applications. However, while the lack of S-video inputs and an onscreen display in the basic model is not a serious shortcoming in my judgment, the price of the optional VS-3 is likely to scare off buyers who would simply like a couple of A/V input,/output loops for convenient taping. (Neither the OSD-1 nor the VS-3 was included for this review.)

The SSD-66 performs all of its functions in the digital domain. Signals entering the analog inputs are converted to digital prior to processing, then reconverted back to analog at the outputs. I did all of my serious listening using its digital inputs, which not only bypasses an A/D conversion step, but eliminates the initial digital-to-analog conversion at the source component's output as well.

Unlike the Kenwood KC-Z1 (also reviewed in this issue), the SSD-66 has no "direct" mode to pass an analog, two-channel input directly to the outputs without any digital processing. As a result, any D/A converter you already own becomes a candidate, for SGHT's "VideoMart" classified section after you purchase a SSD-66.

 

Setup and Operation

Like the Meridian 565, setting up the SSD-66 is far from user-friendly, although the 60-page Operations and Installation Manual does a reasonably good job of leading you through the procedures step by step. I consider myself reasonably experienced at this sort of thing, but it still took me 4-1/2 hours to connect everything, configure the system, and perform the calibrations. (I should note that I was very deliberate with the step-by-step procedures.)

Given ADA:s background as a supplier to the custom-installation market, the complexity-and flexibility-of the SSD-66 is understandable. This device is clearly designed to be installed by a dealer, with the customer's participation limited to making his or her requirements and preferences known. It can be installed by a customer with only two thumbs, but I don't recommend it. As a result, treat the following discussion as an overview to acquaint you with the ADA's flexible setup options so you can discuss your needs intelligently with the installer; you probably won't want to do the Macarena with it yourself.

All major setup and operating functions can be performed from the front panel. A small, 12-character LED display is provided for setup and operation in the absence of a touchpanel or onscreen display, though it is really too small to see easily from across the room. This display and the other front panel LEDs are brighter than I would like and cannot be dimmed.

On the other hand, a unique and useful two-dimensional, six-quadrant "vector scope" (actually a rectangular array of LEDs) reveals how much information is present in each channel at a glance. This display's only drawback is that it has no sensitivity adjustment; at low average program levels, the "scope" readings are too low to be very informative.

The standard remote control is one of those general-purpose All-For-One (or is it One-For-All?) jobs. Although the remote is perfectly functional, its generic nature means that you must remember certain non-intuitive, non-labeled commands. For example, to mute the sound, you push the Mute button; no problem. But to unmute, you press the Power button. If you push Mute a second time-the intuitive thing to do-you put the processor 'in standby. Go figure.

Frankly, I consider this remote barely adequate for a product this sophisticated and expensive. But again, ADA's custom install mindset explains this. Most SSD-66s will find their way into systems that use elaborate multiroom keypad or touchscreen remote-control systems. [ADA is best known as a premier manufacturer of keypad-based multiroom control -systems.Ed.]

Setting up the SSD-66 begins with configuring and naming the various inputs. This can be a little intimidating, which is another reason that the unit should be installed by a dealer. I will not go into the procedures in detail here. Suffice it to say that almost any type of system can be accommodated (except tape loops), even without the optional VS-3 A/V switcher. And while most of the programmable settings are global-i.e., they apply to all inputs simultaneously-it is possible to make certain input-specific settings. For example, the subwoofer level can he adjusted separately for each input, compensating for the fact that not all sources have the same bass balance.

After setting up the inputs, the user tells the processor about the configuration of the loudspeakers in the system. In general, this process is not significantly different from that employed by other surround processors. You specify parameters such a full-range or small loudspeakers, rear channel delays, etc. In addition, SSD-66 lets you delay the center channel to compensate for the position off the center speaker, which is typically a little closer to the seating position than the left and right speakers. This is an increasingly common feature with all-digital surround processors.

The actual level-calibration procedure is also conventional. However, I have one minor complaint: the level adjustments can be made from the seating position via the remote, storing the settings in memory must be done from the front panel.

The SSD-66 provides a single subwoofer output, which is an increasingly common design decision (and a limitation, in my opinion). This output can be configured in one of three ways: the sum of all the bass from all channels plus the LFE (low-frequency effects) bass, the LFE bass alone, or the sum with the LFE bass reduced by 10 dB. In addition, there is a bass-redirect function that re-routes the bass from certain channels to other channels (e.g., center channel bass to left and right) or the subwoofer.

There are several user-selectable parameters that operate only during Dolby Digital playback. One of these is a peak limit filter. While ADA recommends that you leave it on, I turned it off for most of my listening with no adverse effects. After a quick audition, I also turned off the dialog normalization (a form of dialog dynamic-range compression); the unit sounds better without it.

The SSD-66 also provides other forms of dynamic-range compression in the Dolby Digital mode. In addition to full (uncompressed) and "night" (maximum compression) modes, you can select a wide range of intermediate settings. I found these settings to be of limited use. Most people will probably be perfectly happy with either the full, uncompressed mode (which I used for all my serious listening) and "Night" mode.

The volume-control buttons operate at variable speeds. When you push and release Volume Up or Down quickly, the volume increments in 0.5 dB steps. (This is nice; of the processors I have tested, only the Proceed PAV and the SSD-66 have digital level controls that increment in less than 1 dB steps.) If you hold down a volume button, however, the level soon starts to jump in 3 dB steps. I found this irritating until I got the hang of it. Also, the volume level changes immediately with the first push of the volume buttons, before the volume display illuminates . This design is now so common that I guess I'll have to treat it as a lost cause and stop complaining about it. Am I the only one who would like a readout of the existing setting before anything changes?

In addition to Pro Logic, Dolby Digital, and DTS, the SSD-66 provides conventional stereo and three "music surround" modes. In my judgment, these music surround modes are best avoided. The so-called "Music Mode" is Pro Logic with full-range surrounds, which is a bad idea. While Pro Logic sometimes works for music, the logic steering after which this mode is named can do peculiar things to music not specifically encoded for Dolby Surround. In my opinion, the other two music Surround modes-"Quad Bypass" and "5 Ch Bypass"-are also poorly conceived. In these modes, the left and right surrounds receive the same information as the left and right front channels. Can you say "bloated soundstage," boys and girls.

 

The Sound

The systems used to review the SSD-66 were essentially the same as those used with the Aragon 8008x3 amplifier reviewed elsewhere in this issue. (The Aragon was used for the LCR channels here.) The main changes where in the two channel stereo system; the speakers were Sony SS-M9s instead of Energy Veritas v2.8s, and the CD transport was a Mark Levinson No.31.5.

I began my listening with Pro Logic playback. On Gcronimo: An American Legend, the sound was extremely dynamic with powerful, room-shaking bass and an open and detailed but honest and unhyped midrange and top end. Dialog and sound effects were first-rate, and Ry Cooder's exceptional score never sounded better. (His music for this film is a real challenge, encompassing everything from synthesizer to full symphonic orchestra, with stops along the way for guitar and military brass band.) I also found little to complain about on the musical selections from The Commitments, thanks to the ADA:s sweet yet detailed top, driving bass, and overall high resolution.

Jumanji is a genuine sonic spectacular that enjoyed another stellar performance from the SSD-66. Despite the convincingly real and properly positioned sound effects and clear, natural dialog, it was the recording of the musical score that stood out. Recording engineer Shawn Murphy (arguably the best in the business) is a master not only at rendering space and depth, but gut-wrenching bass as well. Nothing about the performance of the SSD-66 suggested that Murphy's work had been shortchanged.

If I could find fault with anything about the sound of the SSD-66 in Pro Logic mode, it might be the quality of the bass. There is no lack of extension and power, but it is less well controlled than the best I have heard through the same system. I didn't really find it objectionable, but I felt that the bass from the Kenwood KC-Z1, for example, is tighter and a little better defined, though less powerful and pulsepounding.

Pulse-pounding also describes the performance of the SSD-66 in Dolby Digital. Like the Meridian 565, the SSD-66 is particularly successful at minimizing the slight brittleness that can sometimes compromise Dolby Digital playback. I noted an unusual smoothness in the soundtracks of Outbreak and Congo with the ADA. Even Crimson Tide-whose soundtrack can turn edgy on some processors but is otherwise so exceptional that I readily forgive it that single flaw-was smoother-sounding than usual without losing any of its impact. The other qualities of Dolby Digital-surround envelopment and (where present) discrete surround placement-are also as effective and convincing as I have as ever heard them.

The Meridian 565 was not on hand for a direct comparison with the SSD-66, but the Kenwood KC-Z1 was. Auditioned side-by-side, the ADA is definitely richer and more full-bodied than the Kenwood, with less of an edge on top during challenging program material. The ADA never loses its cool.

However, it was during the direct comparison between the Kenwood and the ADA that I discovered a possible anomaly in the SSD-66's design. The bass of the SSD-66 in Dolby Digital mode is more potent than I can recall ever hearing from other surround processors. My measurements indicate that the LFE channel, which is supposed to be 10 dB above the level of the main channels, is actually 17 to 18 dB higher. This does sound sort of exciting, but it will certainly be a challenge for your subwoofer and isn't technically correct. Fortunately, you can select the "SUM-10" setting for the subwoofer during setup, which reduces the bass output of the LFE channel to something resembling normal earthquake mode.

 

DTS Comes Home

The program material currently available for DTS playback is still very limited. It consists of a new DTS sampler CD with several music selections and a number of test tracks, two other test CDs (not commercial releases) of music and sound effects, and early samples of the DTS mastered laserdiscs of Jurassic Park, Apollo 13, and Casper.

I started with the music selections on DTS's newest test CD. I wish I could be more positive, but, frankly, the results were highly variable. A choral selection from Tchaikovsky's 1812 Overture (Delos) was pleasingly spacious and open. It was a little bright (brighter than the standard Delos release, which is recorded in Dolby Surround), but effective nonetheless. However, two rock selections-Seal's "Prayer for the Dying" (Warners) and Alan Parsons' "So Far Awav" (HDS)proved only that an overly bright rock recording in 5.1 channels is still an overly bright rock recording. A Touch of Surround Madness from Telarc is a compilation of short excerpts from a number of Telarc recordings,so-so to respectable. It's never exceptional, though, and nothing I'd care to hear more than once.

I've had enough experience with DTS to put the blame for these results on something other than the format-or the SSD-66. Despite the truly discrete nature of DTS, much of what I heard on these DTS-encoded music CDs reminded me of the bloated quad (four-channel) sound of the early'70s. Admittedly, my surround setup is optimized for film surround and not music surround. The wall-mounted Aerial Acoustics surrounds are configurable for either dipole or bipole radiation; I tried both and found the bipole setting a little better for true discrete playback. But as with any new creative technology, there will inevitably be a learning curve while engineers nail down what works and what doesn't.

There is one group of recording engineers with plenty of experience with discrete surround: film sound engineers. And the three DTS laserdiscs available to me are all superb. Of the three, only Casper makes frequent, dramatic use of surround effects. But that seems entirely appropriate, given the sheer fantasy nature of the film. Jurassic Park is more science fiction than fantasy, a story that could happen (though it's, ah, more than a little unlikely). And, of course, Apollo 13 did happen.

The important consideration here is the quality of the DTS discrete surround on the ADA SSD-66. In a word, it is superb. I have noted before in SGHT that DTS on laserdisc sounds better to me than Dolby Digital, which was confirmed with the SSD-66.

This conclusion must be tempered by the fact that the same program material is not available in both formats. Nevertheless, there is a smoothness and lack of grain in DTS playback that I never quite sense with Dolby Digital. This quality varies with the material, but even fairly bright soundtracks such as Jurassic Park and Apollo 13 benefit from it. In fact, I have never heard JP sound better than it did here, only rarely displaying the edge it had in its DTS theatrical run. (The home DTS algorithm is superior to the more primitive theater implementation.)

Only one aspect of the SSD-66's DTS performance is less than stunning. As with other material, the bass is less tight and defined than I would like, and perhaps less powerful than what I hear from Dolby Digital through the same unit. (Again, these conclusions must be hedged due to the lack of identical program material.) In any event, the difference is very subtle, and I doubt that many listeners will feel bass deprived when listening to these DTS laserdiscs. I used the "SUM-10" subwoofer setting for DTS playback, which ADA recommends (and so do I).

For my setup, I used both digital outputs from my Pioneer CLD-D704 laserdisc player. I connected the player's TosLink output to a digital input on the SSD-66 (for CDs and normal, nondiscrete surround laserdisc playback), and the coaxial output to the DTS-1 for DTS decoding. However, if you accidentally feed the undecoded digital datastream a DTS laserdisc to a normal digital input, you hear nothing but very loud hash that sounds much like pink noise. It was easy to do this in my setup by inadvertently selecting the (TosLink) digital input coming directly from the LD player while a DTS laserdisc was playing. Fortunately, I understand that in the latest version of DTS encoding, this noise currently at reference level (0 dB)-is at -12 dB. You still hear noise, but at a much lower, less startling level. A better solution would be automatic switching; the processor should recognize whether the source is Dolby Digital or DTS and automatically switch to the right decoder. The SSD-66 cannot do this.

As is my normal practice, I also used the SSD-66 in stereo mode in my high-end, two-channel music system, again using its digital input. The result was fully satisfying. The ADA exhibits a sweet, clean, detailed top end with no edginess or brightness, and a tight soundstage with fine depth. Compared with a Mark Levinson No.36s driving a Rowland Consummate preamplifier, the SSD-66 Is less open and detailed on top, with a little less inner resolution, and it is less punchy and defined in the bass. None of these shortcomings is very pronounced, especially considering that the Levinson/Rowland combination costs three times as much as the basic SSD-66. I could happily five with the ADA in my stereo system.

Finally, I found the video switching circuits to be fine. I never felt the need to bypass them for critical viewing.

 

Conclusions

In Dolby Pro Logic, the SSD-66 is at least the equal of any surround processor I have evaluated to date. Sonically, it most resembles the Chiro C-800; perhaps it's not as sweet on top as the Chiro, but not far from it. While this analogy could be extended to the bass as well, the SSD-66's bass seems marginally more full-bodied. It has a little less clarity and detail, but it is still impressively deep and powerful. In Dolby Digital, only the Meridian 565 is likely to challenge the SSD-66 for supremacy in the ability to do full justice to AC-3 soundtracks while minimizing the slightly brittle top end these soundtracks can exhibit on some processors.

As for DTS playback, the SSD-66's performance is striking. While the outboard nature of the DTS-1 adapter makes this a relatively expensive proposition, it also lets you make the decision to acquire it after you have determined that the available software justifies the expense.

On the downside, you might not need or want all the bells and whistles available for the SSD-66, but adding them results in an expensive piece (and a cumbersome one, with all those outboard boxes). Most users will definitely want to replace the remote with something better. There is also the matter of excessive LFE bass level, which you can get around by selecting the "SUM-10" mode during setup (although you shouldn't have to). And finally, I strongly recommend that the SSD-66 be professionally installed.

That said, no surround processor I have heard to date is without some sort of foible or idiosyncrasy. While its far from the easiest processor to set up and use, I can definitely recommend the SSD-66 to readers who are not easily fazed by the expense and/or a few ergonomic wrinkles. More than that, the SSD-66 (5.1) has not been bettered in overall sonic performance by any surround processor I have yet auditioned.

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