August 2005 Reviewed by Jeff Van Dyne	Thiel Audio SmartSub SS1 Subwoofer

Description Model: SmartSub SS1 Price: $2900 USD Dimensions: 20"H x 11"W x 15.5"D Weight: 55 pounds Warranty: Ten years parts and labor Features 10" woofer with 20-pound magnet assembly	Features (cont'd) 500W (manufacturer-rated) amplifier Boundary Compensation circuit Short-coil, long-gap, copper-stabilized motor assembly Thermal overload protection RCA LFE input and output Input and output for use with a Thiel passive   crossover or Integrator DC power trigger Auto on/off power switch Optional wood veneers

Thiel loudspeakers have been on my short list of recommended components for a long time. Asked what traits I most readily associate with all Thiel speakers, I would instantly reply, "coherence, cleanness, and detail." To this I would add comments about excellent transient attack and tight bass. It was tight bass that most interested me when I learned I would be receiving Thiel’s SmartSub SS1 subwoofer ($2900) for review.

I hate bloated bass. I’d much prefer to sacrifice ultimate bass output and extension than live with a boomy, inarticulate low end. If there was one company out there that would get that aspect of a subwoofer right, I thought, Thiel was probably it.

Thiel Audio has long been recognized for the great pains it takes to ensure that its loudspeakers are among the most accurate reproducers of sound in the world. Look over the design features of any Thiel speaker and you’ll see lots of technology and attention to detail aimed purely at extracting every last bit of performance from their systems. Their signature large, rounded front baffles reportedly help reduce diffraction and thus smooth tweeter response, while the coaxial mounting of the midrange and tweeter drivers is said to improve time coherence. Many manufacturers do a few things to address the various issues impacting loudspeaker performance, but few attempt to address so many issues at once to the degree that Thiel does.

It should come as no surprise, then, that when Thiel designed its new subwoofer systems, it chose the road less traveled. They first looked at all the obstacles to reproducing great bass with a subwoofer, and then set about the task of resolving as many of those issues as they could. The result is something that still looks a little like a standard subwoofer, but a very elegant one that performs on a whole new level.

Technology and design

Thiel takes a different approach to driver design than most other companies, and the driver in the SmartSub SS1 is no exception. Key is its short-coil, long-gap design, which it shares with the drivers used in all other Thiel speakers. Thiel claims that their shorter, multilayer voice coil inside a longer magnet-and-pole assembly reduces the distortion caused by the interaction of the coil with magnetic leakage present at the ends of a conventional voice-coil-and-magnet assembly. They say that this system, though considerably more expensive to make, is capable of a tenfold reduction in distortion figures.

A 10" driver in a relatively small sealed box cannot produce 20Hz extension at any kind of reasonable output level -- not without help. The most common way of getting around this problem is to apply low-frequency equalization to boost the output of the driver at the very bottom of the subwoofer’s usable range. The disadvantage is that the subwoofer then requires substantially more power to drive the woofer at lower frequencies. To this end, the SS1 possesses a 500W amplifier that uses a switching power supply with a conventional linear amplifier to, according to Thiel, achieve efficiency gains similar to switching amplifiers.

Another problem associated with subwoofers is that the common practice of placing them in corners has the effect of inducing uneven frequency response, most often manifested as boomy, indistinct bass. According to Thiel, the degree of this effect can be calculated and compensated for if the distances of the sub from the walls behind it and to its sides are known. Thiel’s Boundary Compensation circuit does just this: The user simply sets a pair of dials on the rear panel to indicate the SS1’s distance from the side and rear walls, and the Boundary Compensation corrects the sub’s response. In the past I’ve used my Anthem AVM 20 preamplifier-processor’s boundary gain filter with terrific results, but this feature is an on/off solution. Thiel’s Boundary Compensation allows each parameter to be individually adjusted.

Also available, though not provided for this review, are passive crossovers designed specifically to work with Thiel loudspeakers; and the Thiel Integrator, designed to dramatically improve the integration of Thiel’s subwoofers with any loudspeaker. It’s likely that many people purchasing the SS1 for home-theater use will forgo the Integrator in favor of their processor’s internal bass management. While this will be a viable option for many, you must first make sure that your processor provides all the bass-management functions required to perform this task successfully -- the SS1 lacks any crossover functions. You can probably get by without the Integrator if you find that you use only your sub’s level control and can make all other integration functions through your processor. Otherwise, the SS1’s lack of crossover adjustments may dictate the purchase of an Integrator.

Setup

Thiel sent along two SmartSub SS1s, so I tried a number of setup options. First, I tried a corner placement with a single sub, which I generally find unbearable in this room for the reasons noted above. I tried the SS1 with and without Boundary Compensation, to determine how effective the filters were, and discovered that the SS1 was the cleanest-sounding subwoofer I’ve had in my theater to date, even without BC. With BC, the boominess that I normally associate with corner placement was all but gone.

I then tried placing a single SS1 just outboard of my left-hand Magnepan MC1 main speaker. Here I needed to use Boundary Compensation only for the wall behind the SS1; the sidewall was more than 3’ away. This provided incrementally tighter bass response and slightly improved integration with the Maggies, at the expense of some low-frequency output.

Last, I folded the second SS1 into the mix, in a position that matched the other SS1 -- just outside the right-hand MC1 -- and recalibrated the system. This increased the low-frequency output another notch, slightly smoothed the overall response, and provided the best integration with the Maggies that I’ve ever achieved.

Listening

So, what does $2900 buy from Thiel? Clean, low-distortion output all the way down to 20Hz. While many subwoofers can hit that magic number with convincing output, the vast majority that I’ve used start behaving badly long before they reach it. The SS1 never approached the distortion levels I’ve heard from other subs, even when pushed well into volume ranges that risked angry calls from my neighbors.

Running a test CD, I was able to determine that the SS1 was down about 5dB at 20Hz in my room when driven at overall sound-pressure levels of just over 100dB. You may well get different results, but my theater is a fairly typical room of medium size. The only other subwoofer I’ve reviewed that was able to achieve this level of output at 20Hz was the Hsu Research VTF-3 ($699). Some will complain that this doesn’t meet the Holy Grail of 115dB output, but at 95dB, a 20Hz test tone rattles the windows very effectively.

First up in the DVD player was U-571. Interestingly, the SS1 seemed marginally less powerful than other subs during the depth-charge sequence in chapter 15. If anything, the explosions were more sharply defined but slightly less intense than I’ve heard with other subs. Having used my Anthem pre-pro’s boundary gain EQ for some time, I had a pretty good idea of what was going on right from the start. The output of a subwoofer placed in or near a corner reinforces certain frequencies, thereby creating a dramatic increase in output at that frequency. In the case of U-571, those depth charges must have excited one or more of these frequencies exaggerated with typical corner placement. This was an excellent example of the Boundary Compensation circuit at work. The resulting explosions still shook my booty, but they were sharper and better defined.

Star Wars: Episode II -- Attack of the Clones is another interesting example of the impact that reduced distortion and proper room integration have on subwoofer performance. In the opening scene, many otherwise capable subs reduce the sound of Senator Amidala’s ship landing to a deep, indistinct rumble. With the SS1, the deep rumble was still there, but married to the distinct throbbing of engines. Other subwoofers have hinted at this, but none that I’ve tested has achieved this level of definition while simultaneously providing high levels of output and low-frequency extension.

Erich Kunzel and the Cincinnati Pops’ recording of Tchaikovsky’s 1812 Overture [SACD, Telarc 60541] is a popular torture test that I return to again and again as a consistent point of reference in testing subwoofers. Though over the years I’ve always been careful to work up slowly to peak volume levels, I’m still amazed that I haven’t destroyed at least one sub with this recording’s very-high-level, low-frequency cannon fire. Somehow, all of those subs managed to survive, though many hit their limits early in the game. The SS1 did more than just survive this test. It excelled, showing no signs of stress at levels that would normally have me running for cover.

The latest album from the power jazz trio The Bad Plus, Give [CD, Columbia 90771], is not everyone’s cup of tea, but it is original. I like the group, but this is one place where my and my wife’s tastes diverge. I was a drummer many years ago, and I’m attracted to this album’s heavy percussion and bass lines. The kick drums in "Cheney Piñata" were solid thumps I could feel in my chest, and the SS1 integrated perfectly with my Magnepan MC1s -- no small feat. I also noted that the fast, heartbeat-like drumbeats in "Velouria" were better defined through the SS1 than I’d ever heard them before. For track after track, my listening notes contain comments about the SS1’s integration with my Magnepans and its lack of boom and distortion.

Comparison

I compared the Thiel SmartSub SS1 with the Hsu Research VTF-3 ($849). Both were capable of producing ample useful output down to 20Hz, but while the VTF-3 performed well in my larger listening space, its size meant that it had to go into a corner of my somewhat smaller theater, which created some minor boom. This was never an issue with the SS1 with its Boundary Compensation switched on, and the Thiel’s dramatically smaller size allowed me to try it in both a corner and about 3’ out from the sidewall, which generally provides smoother bass response. With the BC properly set I found I was able to position the SS1 anywhere I had space and achieve very close to optimum performance -- a big plus, particularly for those who have limited space for a large subwoofer. You pay a lot more for the SS1, and you get a lot more in return.

Conclusion

The SmartSub SS1 sounded tighter and cleaner than any other subwoofer I’ve had in the house. Thiel Audio’s attention to driver distortion and their development of the very effective Boundary Compensation circuit have paid tremendous dividends in this area. The SS1’s relatively small size and considerable placement flexibility make it particularly attractive where a very-high-quality solution is required in a room of small to medium size, or where two subwoofers are needed to smooth a system’s overall response or improve integration with difficult speakers. I had high expectations of the SmartSub SS1 before the review pair even arrived, but they exceeded every one of them.

Manufacturer contact information:

Thiel Audio
1026 Nandino Boulevard
Lexington, KY 40511
Phone: (859) 254-9427
Fax: (859) 254-0075

E-mail: mail@thielaudio.com
Website: www.thielaudio.com

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