November 2009

World Premiere
Tekton Design S12 Subwoofer
Achieving greatness at just a few percentage points of far higher cost models.
Review By Rick Becker
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First, Let Us Recap The OB4.5 Monitor Review
After submitting the review of the OB4.5 monitors Steven R. Rochlin asked a couple of questions. Did I mean to write $5500 as the cost? And was I submitting them to the Superior Audio section of Enjoy the Music.com? Both were legitimate questions. No, the cost was indeed only $550 per pair. And no, I asked him to put the review in the regular review magazine because I wanted it to be read by as many people as possible—particularly those of limited financial resources and folks who might shy away from Superior Audio, thinking it was the haunt of ultra-expensive gear. But it certainly qualified. Its chief limitations were the maximum volume capability (about 92dB peaks at the listening position in a mid-field listening triangle in a large room), and its polite, but tuneful bass with limited depth. Other than that, it is a spectacular sounding loudspeaker that begs the question: How can it sound this good for only $550? Part of the answer to that question is the black satin finish that borrows a page from the Harley Davidson palate. For some, it will cry out for a custom paint job or an eye-catching veneer, while others will be too busy discovering the music they thought they knew so well.

Eric Alexander is obviously aware of the shortcomings of his design. For those who wish a more splendid treble he offers a very modestly priced tweeter with a minimal crossover. And for those who can't live without a powerful bass he has built upon his earlier acclaimed success with subwoofers and out-performed himself with a new patent-pending design, the S12. The custom paint jobs and optional veneers he offers for both the OB4.5 and S12 should quell the apprehension of the design conscious.

The Design Theory
Without pretending to be a physicist let me explain the basic principle of the S12.  There are two 12-inch Danish Sound Technology woofers mounted coaxially. The front-facing driver is mounted on an open baffle held in place by six pillars connected to the cube. The second driver, directly behind the one on the open baffle, facing the same direction, is mounted in the sealed cabinet that also houses the Canadian built BASH 300S subwoofer amplifier that is in common usage today. It can be fed a full-range line level signal directly from your preamplifier, or a full-range speaker level signal directly from the amplifiers that power the monitors. In a home theater system, it would be fed a line level signal from the LFE output of your processor. The line level inputs are single ended RCA only. There is a 180 degree phase switch and a variable crossover as well as a switch to take it in and out of the circuit without having to turn the power off.

The two drivers are wired so they both push and both pull together. There is no compression behind the front driver because the rear driver is sucking the air from behind. The rear driver compresses the air behind it in the acoustic suspension box. Likewise, there is no compression from the rear driver when it pushes forward, because the air in front of it is moving into the void created by the forward moving front driver. Thus, the only effective compression recreating the sound wave comes from the front surface of the front driver. The S12 is essentially an open baffle monopole subwoofer, a patent pending design. The back wave of the front driver is nullified and the music comes from the front of the open baffle. Placing my head behind the front baffle of the speaker I experience a relative musical void, hearing only what is coming around the edge of the front baffle. The advantage of this design is the front driver works with greater transient speed and accuracy without having to deal with the compression on the back wave. The upper end of the subwoofer's range is intentionally rolled off at 24dB/octave.

This tandem arrangement in the subwoofer is not unlike the use of the second full range driver in the OB4.5. In the monitor, the upward facing driver mounted in the cabinet behind the open baffle essentially performs a similar function, primarily in the bass. A ported enclosure is used to reinforce the bass with this particular Fostex driver. Because the drivers are at right angles to each other, the mid and high frequencies are permitted to continue rearward in typical dipole fashion, thereby creating a sense of spaciousness as I mentioned in the earlier review.

The Listening
Adding the S12 to the OB4.5 monitor was an immediate and obvious improvement. Optimum integration of subwoofer and monitor was achieved when the subwoofer was brought forward to the plane of the monitors in proper time alignment. By itself, the OB4.5 was absolutely delightful with music that had only modest bass content and I became fully adjusted to the purity of the music with this open baffle design. It makes perfect sense for apartment dwellers or families with young children that retire to bed early. But adding the S12 brings the OB4.5 to full range status. It also resolved much of my ambivalence regarding how loud the OB4.5 is able to play. Adding the subwoofer brings more total energy to the performance. Even thought the SPL meter might still be peaking at only 92dB, it feels like the music is playing louder with the extra energy and extended deep bass from the subwoofer. The music is much more gratifying.

On small group acoustical music the S12 brings a more realistic sense of space with added room tone. The importance of this was demonstrated at the Montreal show this year when Graeme Humphrey from Coup de Foudre demonstrated the new Wilson Audio subwoofer, Thor's Hammer, in conjunction with the Maxx III. The effect is primarily qualitative. Switching Thor's Hammer in and out of the system showed how a good subwoofer improved the quality of the midrange and brought a more real sense of being there to the music. The Maxx III certainly didn't need help in producing the fundamental musical tones, but the addition of the Hammer reproduced the room tone of the recording and brought the experience closer to that of a live performance in a room that was several times the volume of my listening room.

Performing this same exercise with the S12 and the OB4.5 I experienced the same result to a somewhat lesser degree with the additional benefit of a tonal shift of the epicenter of the music to a point lower in the midrange. In this case, the S12 was contributing additional fundamentals that the monitors could not effectively produce. The music had more weight, better tonal balance and even the treble seemed better resolved — go figure! But one shortcoming became apparent, though not particularly annoying. While the soundscape of the upper bass on up was beautifully portrayed and three-dimensional, the mid and lower bass seemed more one-dimensional. Not "one note", mind you — it was definitely very tuneful, but the music lacked the colorful life-like feeling coming from the monitors. If it was a TV set, I would have said the chroma had been turned down. With great loudspeakers such as the Coincidents that I've reviewed in the past year, I wrote that I could "taste the skins" of the drums. That wasn't happening with the S12. The notes were fast and focused, and they integrated perfectly with the monitors, but something was missing. Was it the fact that the bass from the left and right channels were summed in this monaural subwoofer? I shot an email to Eric and made an unreasonable request for a second S12. He came back with an apology for not having sent two to begin with.

Dual Subwoofers
The problem with dual subwoofers is you need an additional power cord and either a long set of interconnects or a second pair of speaker cables. I also didn't have a second Symposium Acoustics Svelte Shelf and an extra set of Boston Audio TuneBlocks for the second subwoofer. I "made do" with what I had, only to discover that merely "making do" was pretty phenomenal. The left and right subs were not identically positioned relative to the monitors, but they seemed to sync up pretty well with their cones crudely time aligned along an arc in front of the listening chair …or perhaps there is a whole other level I've yet to experience. Whatever the case, it was not difficult to find two spots where they sounded very good indeed. And, yes, I could taste the skins of the drums.

Like the OB4.5 reviewed previously, the subwoofer exhibited outstanding transparency, tonality, transient speed and absence of box colorations. This is a bit unnerving at first and takes some getting used to. There is no warm, fuzzy feeling here. Nor is it cold or clinical. Such neutrality merely conveys what's on the source. My LPs took a jump up to the kind of focus, transparency and bass response that I was previously experiencing with CDs. As a side bonus, adding the deeper bass seemed to minimize my awareness of the clicks, pops and surface noise previously enjoyed. Possibly this was because the acoustic center of the now full-range loudspeaker had been lowered to the acoustic center of live music — further below the frequency of the clicks and pops. My CDs, in similar fashion, were reincarnated a generation closer to the holy master tape. Keep in mind we are talking about the contributions of a frequency range of about 60 Hz, from 20 Hz to 80 Hz, while the monitors cover a range of thousands of Hz. The point here is that the perceived contribution was substantial and continuous with the monitors. I simply enjoyed the music with the subwoofers a whole lot more than with just the monitors. In a blind test, I would have guessed they cost thousands more than they do. Bass fans can rejoice; the adjustable volume on the back allows you to choose the tonal balance that pleases you (within reason, of course). I achieved what I thought was a relatively flat response, relative to the midrange, without using any measurements. When I switched the bass out, the effect was subtle for most music, affecting the sense of ambient space in the recording. Yet the few instruments producing bass fundamentals were more prominent by virtue of the transparency and focus of the open baffle design and the tightness afforded by the BASH amplifier. Following bass lines in the music was simply a matter of wanting to. More frequently my attention was captured by the interplay of the instruments, but most of the time I was mesmerized by the gestalt of the music.

One problem became evident when I played "Master Tallis's Testament" from Pipes Rhode Island. The subterranean organ notes broke up the little Fostex driver in the monitors while the S12 handled them with aplomb. Turning off the monitors and playing only the subs showed me that the subs were doing just fine.

Then, out of a sense of obligation, not evil, I cranked up the volume. The subs playing alone broke up when playing back the deepest organ notes at 100dB in my large listening room. This probably correlates to the affordable drivers, not the design. Those organ notes were probably below the free air resonance of drivers. With more normal listening material, including rock and classical, it was rare to experience any break up of the monitors and never was the rule with the subwoofers at listening levels peaking at 92dB at the listening position.

Combining the two S12 subwoofers with my full-range Kharma loudspeakers was also a revelation that was mostly positive. The additional fullness in the mid and lower bass was especially welcomed. It was also evident that the mid-bass of the S12 was more clearly focused than that of the Kharma 3.2c even though the driver in the ported Kharma was more "high-tech". In fact, the bass from the S12 was more highly focused than the rest of the music which had a very pleasing, but warmer presentation. Of course, part of the reason is that I was driving the Kharmas with the relatively low powered Manley Mahi monoblocks in triode mode, albeit somewhat tweaked for considerably better focus than stock. The other part of the reason was the 300 watt BASH digital amplifier in the S12 that undoubtedly had a better grip on the driver than a Mahi could ever hope to muster in the bass region. I crossed over at about 80 Hz to give the mid-bass a little stronger presentation. The more highly focused signal from the S12 seemed to mask the warmer sounding low frequency output of the Kharma without apparent problem. Remember, both the S12 and the Kharma were being driven full-range, although the S12 is rolled off sharply at the top end.

Fine Tuning
In the review of the OB4.5 there was an SPL chart of the monitors pointed straight ahead along with an overlay of the response with the monitors aimed directly at each shoulder. For the chart presented here I took measurements from 200 Hz down with the subwoofers active and used the line representing the monitors aimed toward me. When I took my first set of measurements with the subs crossed over at about 80 Hz and turned up to about 2/3 full volume as I had tuned by ear, I was disappointed in the measured results. Now, granted, these are crude in-room measurements taken from the listening position and the Radio Shack analog SPL meter is known to be less accurate at the frequency extremes, but I really expected to see a more convincing graph.

I adjusted the crossover down to 50 Hz and pumped the volume up to maximum. The measurements of this adjustment are what you see here with the difference between the monitors + subs and the monitors alone shaded in red to give you an idea of the energy contributed by the subwoofer. More than producing a better looking curve at the low end, minimizing the overlap of the sub and monitor cleaned up the mid-bass, improving the focus even further in that region. Increasing the volume gave me a stronger bass response than to what I was accustomed. The stronger bass sometimes buried the vocals in the midrange deeper into the music. For several late night/early morning hours I revisited key recordings, reveling in the qualitative improvements and getting accustomed to the stronger deep bass. The fine tuning made a great sounding musical presentation even more outstanding. The hump in the upper bass region is a room node which doesn't bother me since it has been there with every piece of gear I've reviewed. I'd probably think something was dreadfully wrong if I installed a room correctional device. The important thing here is the bass below 70 Hz was dramatically improved.

Aesthetics And Value
Like the OB4.5 monitor, the finish of the S12 subwoofer is a satin black. The front baffle mounted in front of the acoustic suspension box largely conceals the second driver mounted behind it. The un-polished chrome plated bolts running through the six pillars supporting the front baffle give it a rather industrial look. Four high quality adjustable spikes are mounted at the corners of the box, but with the 12-inch front driver cantilevered on the open baffle it is a little front-heavy. I didn't experiment with additional vibration absorbing support beneath the open baffle, but it could be interesting to do so. The subwoofer and the monitor appear to be cut from the same cloth and the idea of stacking the monitor on top of the sub, separated with some vibration absorbing devices, crossed my mind more than once. Unfortunately, the cables I had on hand precluded this arrangement and I had to suffer with a rather unsightly arrangement with each sub offset a different distance to the right of each monitor. With the necessary lengths of cables, a symmetrical arrangement would have improved the visual presentation considerably. My amplifier stand and a row of large jade plants across the front wall also precluded trials with the subs backed up to the front wall.

While the subwoofer by itself is relatively innocuous, it didn't take me long to come up with the idea of using a sock around the pillars (ala Vandersteen and Von Schweikert) to conceal the back side of the driver on the open baffle. Eric liked this idea and it may be implemented in the future. If not, a quick trip to a fabric store and a little sweet talk with a seamstress should get the job done. Pick your favorite color, pattern or texture; everything goes with black.

After living with this gear for several months, I pretty much ignored its presence. It will not contribute to the elegance of your room unless you paint it up like an object d'art, but that's not what it's all about. The OB4.5 and S12 are cutting edge technology and Job 1 for Eric Alexander is to get it out there and show the world that it works. Dressed in black, it's all about the music. And it that form it is one of the very highest value full range loudspeakers I've ever heard.

Summary
It is no overstatement that I nominated the Tekton Design OB4.5 monitor and Subwoofer for the Blue Note Award. I've been privileged to hear many of the best and most expensive speakers loudspeakers over the years, often valued near and above the six-figure dollar amount. That the Tekton combo achieves much of their greatness at just a few percentage points of their cost is a stunning achievement. Playback volume is the chief limiting factor here. Peaks of 92dB were pretty much the limit imposed by the monitors in my large listening room in a mid-field listening configuration. The Subwoofer can play much louder than the monitors and a pair of them in my large room could reproduce the lowest organ notes with authority you could feel in your body at moderate volume. The S12 could make a substantial contribution to even very expensive, but not quite full-range loudspeakers. The sacrifices made by these Tekton models were primarily for cost, not for the quality of the music. That the combination achieves such excellence with modest stamped frame drivers and cabinets that vibrate to the touch is mind boggling. It also begs the question of how much better might this technology be if implemented at a higher level of construction. I'll be the last one to underestimate the talent of Eric Alexander.

Specifications
Type: Subwoofer with 300-watt amplification
Drivers: Two 12-inch transducers (Danish Sound Technology)
Frequency Response: 27 Hz to 120 Hz (20Hz in-room)
Sensitivity: 92dB/W/m
Power: 300 watt RMS, BASH300S subwoofer amplifier
Adjustments: Variable frequency X-over, LFE input, phase, high level inputs
Weight: 52 lbs
Dimensions: 18 x 14 x 19 (HxWxD in inches)
Grille included
Custom finishes available
Price: $650

Company Information
Tekton Design LLC
272 South Ridgecrest Drive
Orem, Utah 84058

Voice: (801) 836-0764
Email: tekton_design@yahoo.com
Website: www.tektondesign.com