August 2009

World Premiere
Tekton Design OB45 Hybrid 4.5 Loudspeaker
Giving full range drivers the design attention they deserve.
Review By Rick Becker
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  Single driver loudspeakers have caught my attention from time to time over the past decade, primarily at the Montreal show. Often they were small floorstanding models with relatively wide baffles and shallow depth. The drivers were in the 3 to 6 inch range as best I can recall and prices were very reasonable due to the single driver design which requires no crossovers. Sometimes they have been offered as kits, making them even more affordable. The sound was usually well focused and smooth, but with a decided lack of mid and low bass. Interesting, but not interesting enough to review.

At the CES show in 2009 two things, among many, happened. First, a number of open baffle loudspeakers, most often large and very expensive, grabbed my attention. They were also very good sounding loudspeakers — much more so than an encounter I had with this breed at a New York show some years ago. My belief system was favorably altered. Secondly, I stumbled upon a very impressive single driver floorstanding loudspeaker that was among the most memorable rooms I encountered at CES.

Months later, at the Salon Son-Image at Montreal, I encountered some very impressive small stand-mounted single driver loudspeakers imported from Asia under the name John Blue, driven by some very modestly priced Tri-Path amplifiers. Given the state of the economy, these began to make a lot of sense to me. I later learned that there is a whole cult of people who relish this small, affordable high end gear — and has been for years. Forgive me for being late to the party.

First Encounter
It was late on Sunday at Montreal when I was pulled in by another small amplifier manufacturer who was using his cute, but authoritative, monoblocks to power a variety of small loudspeakers. He unselfishly dragged me around the corner of his display to show me a pair of unusual loudspeakers sitting silently on stands. It was a hybrid single driver design with two identical Fostex drivers. One was mounted on a bright blue open baffle and the second driver was firing upward, behind the baffle, mounted in a ported enclosure. I’ve heard upward firing loudspeakers before and their omni-directional sound was usually quite good. This was interesting, but I didn’t want to put the host to the trouble of hooking them up. I took a photo for the show report and we moved on. On the drive home, I began to think about this loudspeaker and recognized the convergence of the two themes from CES mentioned above. Within days, I was talking with Eric Alexander of Tekton Design in Orem , Utah .

While I originally wanted to review the $1200 Montreal sample with its thicker than standard painted baffle, when I learned the standard satin black model cost only $550, I said “Let’s start there.” It seems Eric is a master craftsman and can produce very high levels of paint and wood veneer on his products. But why not start at the entry level for this model and open the eyes and ears of young people thinking of getting started in this hobby? In fact, Tekton starts with single driver models at $200 per pair with a traditional enclosure, as well as much more expensive floor standers. But lest you think you will be getting down and dirty in this price range, the review samples arrived expertly packaged in an absolutely flawless satin black finish. This guy is a real pro.

The Roots
During the course of the review Eric completed his 500^th pair of Tekton loudspeakers, mostly in the past two and a half years, though the company was founded about four and a half years ago. For a micro-company that essentially offers a custom hand made product, that is a lot of speakers. Before that, Eric worked for a number of much larger companies and has had his hands on the design and/or manufacture of about 50 different models that have been produced in far larger quantities. One such company, Sound Tube Entertainment, I had never heard mentioned before. They make speakers for industries such as the fast food chains and we listen to music through their speakers as we supersize ourselves. This may not seem like a stellar credential for high-end audio, but work such as this exposed Eric to large scale production in Mexico , China and the USA. At the other end of the spectrum, he worked for Ray Kimber in his DiAural era. Along the way he has picked up four patents, including one for a tweeter, and he is actively pursuing several patents pending, including the design of the OB 4.5 in this review. Along the road to middle age, he has learned both the art and science of speaker building. A photo of the raw cabinets built with high quality MDF with mitered joints reveals no seams or wood putty fill, indicating perfect execution. These hard edges are routed to a smooth radius edge in his final products.

Marketing seems to be the biggest challenge for Tekton Design. They are direct sellers so CES, where manufacturers market their products to retailers, is not really an appropriate show for them. The 2009 show was their first experience at Montreal and they are looking forward to the Rocky Mountain Audio Fest in October. The AKfest show in Michigan (not Alaska ) might be another opportunity for them. These three shows are open to the public and would give Tekton the exposure they deserve.

In the Video Rig
Listening began with the OB4.5 speakers up on concrete blocks topped with a cotton wash cloth to protect the finish. Using them in the video rig allowed the most rapid break-in and right from the get-go it was evident these were good loudspeakers. It took a bit of getting used to the missing deep bass, but I reveled in the smooth presentation and high degree of midrange focus that surpassed my Coincident Partial Eclipse II loudspeakers which now cost more than eight times as much as the Tekton OB4.5. The adventure had begun and I soon discovered the pleasure of late night listening at low volume while my wife slept peacefully. Even at low volume, the midrange clarity was sustained and drew me into the music. Had I been listening to my Kharma loudspeakers in the big rig at this volume, I likely would have shut it down, answering the question “Why bother?” At low volume, the highs trickle off and the bass fades — a consequence of how our ear/brain has evolved from the good old “hunting and gathering” days, but the listening experience continues to invite. If you live in an apartment or have small children you don’t wish to awaken, this is a valuable asset.

The OB4.5 is an efficient loudspeaker being a dipole on top and a ported design on the upward firing driver. The two Fostex FE 127 drivers are wired in parallel. Sensitivity is rated at 92dB/W/m. Impedance is rated at 4 Ohms and it is claimed to handle 90 watts. The integrated amplifier in my video rig is a vintage Tandberg 3012A rated at 100 wpc into 8 Ohms, much of that biased in Class A. Obviously, I didn’t try and test the limits with this kind of power on tap. The Fostex drivers sounded very good, but with paper cones and a stamped steel cage, they were not the most robust drivers I’ve seen, nor should that be expected at this price range. (A single driver retails for less than $50 on the web). With the baffle placed two feet in front of the wall behind them, a reasonable soundstage appeared in spite of the TV and the cabinet placed between them. A second cabinet supporting the electronics sat just off to the left. It was not a pinpoint soundstage, but sufficient for video based listening.

In The Big Rig
Pushing the Kharma aside and replacing them with the Tekton loudspeakers seemed almost ludicrous — the Tekton being a few percent of the total cost of the system. Placed out into the room where my Kharma normally reside, creating a roughly 60-degree triangle with the listening chair, a full pinpoint soundstage developed. Within the frequency limitations of the Fostex driver, the focus was superior to the Kharmas. Likewise, the transparency of the Tekton easily surpassed the Kharma. And again, within the limitations of the Fostex drivers, seamlessness matched the Kharma from the midrange on up.

Tonal balance, however, was a different experience. The frequency response of the Tekton is said to be 45 Hz to 20 kHz (no limitations given). Now, 20 kHz is way above what my aging ears can cognitively perceive, yet I often sense an openness or airiness of loudspeakers equipped with super-tweeters that play far above these limits. That said, the Tekton seemed to have an upward tilt to the treble upon initial listening. But was it really so? Curiosity led me to pull out my analog Radio Shack SPL meter to check it out. Overall, the frequency response measured at the listening position was very smooth, although there was a slight drop in the midrange at 300 to 400 Hz, followed by a smooth, but elevated upper midrange through the mid-treble. I would guess it is this slight elevation coupled with the outstanding transparency that gave me the impression of a small upward tilt in the treble. For those less familiar with response curves measured in room at the seating position (rather than on-axis in an anechoic chamber), this is a very good reading for this type of instrumentation. At the upper and lower extremes, the Radio Shack SPL meter is known to be inaccurate, so take them with a grain of salt. The black line shown here is with the speakers aimed straight ahead. Later I toe’d them in which gave the red line readings, as explained further below.

And the bass? Right below the midrange the upper bass took a 10 dB leap that peaked at 91.5 Hz and then rolled off practically in a straight line all the way to about 55 dB at 20 Hz. The hump no doubt contributed to the satisfying perception of bass in the upper bass region, and the smoothness of the roll-off ameliorated the fact that the useful bass extended only into the mid-bass region. Usually this type of hump is attributed to room resonance interference. For a loudspeaker of this size and cost, this is far from shabby. More important than the actual frequency response in the bass region is the quality of the bass which was not only tuneful, but almost as well focused as the midrange and treble. While the peak at 91.5 might suggest a one-note bass, this was not the case. While it surrendered volume as the frequency declined, it did not surrender quality. It was musical throughout its useful range down to about 50 Hz.

All of this says the OB4.5 fairly begs for a subwoofer and this fact has not escaped Eric Alexander who has developed a unique patent pending design that will hopefully be headed my way in the very near future. Likewise, at the upper extreme, Eric offers an exclusive 1-inch soft dome add-on tweeter ($50/pair) to fortify the upper treble for those with good hearing in that range.

Can’t Get No Satisfaction?
If you love to listen at head-banging, ear shattering levels, this is not the loudspeaker for your aural suicide. Nor is it wimpy. I experienced great satisfaction in my large, 6000 cu. ft. listening room (that opens up into another large family room) at levels peaking from 87 to 92 dB as measured from the listening chair. Listening levels depended a lot on the dynamic nature of the music being played, however. A modest overall level might contain a drum whack that would bottom out the driver. Music that was a lot fuller and more demanding might not fly at that level, but music of all genres was certainly very engaging and satisfying at reasonable listening levels. When over driven, you get clicks and pops that send you scrambling for the pause button to give you a chance to adjust the volume. A rig with a remote controlled volume would have come in handy to adjust for different recording levels and exceptionally dynamic passages. Once you learn to respect the limitations of playback level of the loudspeaker you open the door to appreciating its qualities. The outstanding focus and transparency delivered music at a level I have heard with precious few other loudspeakers — most of which are priced for the very rich. Placed in a smaller room, it may very well play louder, though I expect that like most loudspeakers, it needs to be well out from the wall to maximize its soundstage capability. Likewise, side and ceiling reflections in a small room may not allow you to achieve quite the level of focus I experienced. With the wide dispersion of this dipole design, I expect it will play best when placed along the long wall of a room. Moving it back closer to the front wall will give you more bass at the expense of soundstage depth. Plan accordingly. Be prepared to play with positioning a bit, but it is not difficult to get good music from this loudspeaker.

It responds to changes in position with rather obvious results. Likewise, changes in gear up stream are easily revealed.

Dumbing It Down
The above comments were written based upon listening in my main room with a high level rig. But how likely is it that a person with such a rig would buy a $550 loudspeaker? For comparison, I dumbed my rig down with a vintage Musical Design SP-1 preamplifier and Manley Mahi monoblocks. Both pieces have been treated with AVM which improved their focus, but no vibration absorbing devices were used under the preamp. I retained my JPS Labs power cords and speaker cables, and Kharma commercial grade interconnects as well as my analog and digital front ends.

Predictably, the quality took a step down. There was only a slight loss of transparency, but the overall focus took a moderate step down in quality. The bass, in particular, suffered from the smaller transformers in the Mahi monoblocks. Bass was more bloated and had noticeably less control, hence less focus than the TubeMagic monoblocks. Much of this was undoubtedly due to the more diffuse signal coming from the Musical Design preamp. Was it horrible? No, but anyone reading my laudatory comments above might question my judgment if they heard these loudspeakers with lesser electronics.

I also began thinking about a minor dissatisfaction with the treble region at this time. In checking out the frequency response chart for the FE 127 on the Madisound.com website, I noted a rather significant drop-off in treble response at 30 degrees off axis, which is about where I had the speakers positioned. With conventional dynamic loudspeakers with separate tweeters I invariably aim them straight ahead for smooth treble response, so that is what I did with the Tekton. After experimenting with toe-in I settled with them aimed at each shoulder. The treble smoothed out beautifully, albeit at the cost of a small loss of soundstage depth, most notable at the outer corners. Right down the middle the soundscape remained deep and clear. The frequency trace on the graph showing the results in the toed-in position (red line) doesn’t convey the improvement in smoothness and focus in the treble. It was sounding very, very good at this point, so I decided to up the ante and put TuneBlocks under the Musical Design preamp. The resulting improvement brought the “dumbed-down” rig embarrassingly close to the results with the CAT preamp and TubeMagic monoblocks. We’re talking serious High End quality, here. Although this music was extremely well focused, among the best I’ve heard, it was easy to listen for long periods. The outstanding detail of the music and transparency of the soundscape were very inviting and often tricked me into believing I was at the venue of the recording, particularly with female vocals and music with fewer instruments that had less bass content.

Aesthetics
The pair I saw at Montreal, with their bright blue baffle attracted me as a modern design suggesting Mondrian’s paintings. The larger front baffle eclipses the box behind it from straight on, but from any other angle the box of this hybrid design is visible. The combination of the two elements — box and baffle — is anything but traditional. My friend Tom, whose wife has their home decorated in constant anticipation of photographers from Traditional Home magazine, thinks they’re ugly. I, on the other hand, see them as a blank slate waiting to be hand decorated by artistic young mothers with small children or plastered with stickers from indie bands and musical instrument companies by young dudes who have somehow “got it” that sound quality matters. I can envision the speakers sitting just as they are in my music room — atop cinder blocks, perhaps spray painted satin black to match the speakers, with maybe a red tinted patio paver or two to bring the driver up to ear level. Tekton offers custom designed, sand fill-able speaker stands for $200 as seen in the photo of the blue OB4.5. Certainly, the OB4.5 deserves a solid foundation to achieve its highest potential, and I have to admit I’ve been using Sound Dead Steel Isofeet beneath the box to absorb the faintest trace of cabinet vibration. For more sophisticated contemporary settings consider a colorfully hand painted baffle like the one shown here on a Tetra 105 loudspeaker or an elegantly veneered one like this bubinga pair from the factory.

You might even squeak into a traditional setting with a giclee of a French impressionist painting, though you might have to find an outside craftsman to pull off that feat. Even at $1200 with the thicker, color accented baffle, the OB4.5 is an incredible value if you have quality electronics and home décor that require a more upscale look.

Hybrid Design
So, what’s going on here? Why the two drivers? And why is the one in the box facing upward? As best I understand the explanation, Eric begins with a single full range driver that is positioned in the classic open baffle configuration. He then uses a second identical driver mounted in a ported enclosure firing upward, right behind the open baffle driver. With the drivers wired in parallel and in phase, this creates an acoustical short circuit path which nullifies the bass energy radiating from the rear side of the open baffle driver. He wrote:

“We must remember that the power radiating from both the front and rear of an open baffle dipole system is equal and opposite in nature. So… if we nullify (i.e. short-circuit) the low frequency power being radiated from the rear side of the open baffle, we now have an open baffle radiator that is totally compact, and effective in presentation. And because we're dealing with longer wavelengths here, the low frequency power disperses evenly throughout the entire room [from the front of the baffle].”

Regarding the vent located on the open baffle: “It might seem a bit counter intuitive to vent a system like this. And I do produce models that have no vent; however, the full-range transducer I’ve chosen to use here is really quite conducive to the classic vented alignment, so we’ve gone with the vent to further augment the performance of the overall system.”

“My primary design objective here was to offer a compact open baffle system (with high wife acceptance factor) that is 100% compatible with a pure analog system! I felt that a giant baffle, complex manifolds and labyrinths, equalization, and DSP processing must be avoided at all cost. I've also taken the creative license to integrate the full-range potential of the upward firing driver into the potential of the overall presentation. In my opinion, the result is best described [as a] hybrid that is closest in relation to an omni-directional polar type loudspeaker."

Eric told me the upward firing driver is padded down about 10 dB in the mid and high frequencies and acts much like a rear-firing driver typically found in Von Schweikert and Vandersteen loudspeakers to create a deeper soundstage and more three dimensional sound. Simple and elegant. And that is what I heard. It does not achieve the true omni-directional effect I’ve heard from much more expensive loudspeakers costing well into five figures, such as various mbl models, among a few others. A centrally positioned musician or singer will follow you as you move left or right and then be positioned at the loudspeaker as you move even further off stage. But in comparison with the exceptional soundstaging, which is slightly recessed due to the volume limitations, this lack of true omni-directional effect is trivial. From the listening chair, the three dimensional soundstaging is about as good as it gets from even the best known manufacturers.

Shortcomings
So what are the shortcomings? The Fostex 127E is a shielded driver with a banana fiber paper cone sourced from the Far East. It is pretty amazing by itself, and even more amazing in this hybrid application, but there are better full range drivers out there. Lowther and AER come to mind, but these would totally destroy the price and size of this design concept. A larger driver should produce a more satisfying bass, but this might also compromise the excellent imaging of the smaller driver. A larger, higher quality driver might also be able to deliver more dynamics and handle more power, hence play louder overall. The absence of deep bass limits the excellent midrange and treble by stripping the music of the subtle room tone cues that, when present in the recording, give us the sense of “being there”. These are not criticisms of the OB4.5, merely shortcomings of what you can expect for $550 or even more money if it were not available factory direct. The shortcomings could be seen as opportunity for future development of larger, more expensive variations of this design. They also keep me lusting for an opportunity to hear the $650 Tekton subwoofer. Stay tuned to this station.

At a more detailed level, the standard binding posts were too thick to accept my JPS Labs speaker cables, so I was forced to insert one prong into the hole of the post and tighten it down in that position. Eric explained that his products are custom made and that he stocks both Cardas and WBT binding posts for those who need a thinner post. Likewise, he offers different internal wiring for those who prefer something better than the standard 18 gauge stranded copper he uses. I also had concern for mounting the binding posts on top of the enclosure. This raises the speaker cables into a position of greater visibility and vulnerability. It also puts them closer to eye level for small children with big curiosity. The danger of heavy, stiff cables pulling on a relatively light loudspeaker is also greater with cables protruding straight off the back, rather than draping straight down toward the floor. As a father with young children, Eric said he would give these views some consideration for future development.

Hearts Of Space
It is no secret that I love to listen to Hearts of Space on National Public Radio on Sunday nights. Tonight I listened to program #844. I started listening when they were in the 400’s. That’s like eight years ago. Virtually everything I review gets evaluated during this show on at least one Sunday night. Earlier in the evening I swapped out the Plinius solid state amplifier for the tube powered Mahis just for this show. Often times I multi-task with audio magazines while I listen. With the OB4.5 now toe’d in, the “slow music for fast times” was much better than previous weeks. I put the magazine down and turned out the light to listen in the dark as I often do. The listening experience took me to a level I’ve reached only with the Gemme Audio Green Gem loudspeakers, a $37,000 model. The OB4.5 lacks the frequency extremes and the ultimate refinement of the Green Gem, but the heart of the music was right up there in that league.

New Age music is often computer generated and sometimes lacks the timbral cues of conventional instruments hence I listen with no expectations of what a note should sound like. Deep bass is not a prerequisite for this genre, either. The music often just happens with the predictability of a kaleidoscope imparting a feeling of floating in space. Listening in the dark, the excellent focus afforded by the OB4.5 permitted the attack and decay of notes to suggest space as deep as our solar system. Had I been using my better amplifiers and had my power conditioner been in the rig I would have experienced an even better signal to noise ratio which would have imparted a more galactic experience. The OB4.5 completely disappeared and there was seemingly no correlation between the modest drivers in that loudspeaker and the expansive music I was hearing.

The Larger Soundscape
One of my friends, with deep roots in the history of audio, wrote to me about single driver full range loudspeakers:

In my listening arsenal I have several full range drivers from the last 60 years including a pair of Fostex, albeit a rarer type.

As all crossovers degrade time coherence, a top class full range system with one full range driver is a crucial reference for hearing. In many aspects the best of breed ones can not be equaled or eclipsed in their homogenous portrayal of music.

Advancing full range driver design is the biggest challenge in speaker design as it demands profound knowledge of the sonic signatures of materials and other less travelled avenues of insight.

In the 1960s we had the famous "Exact" full range drivers from Japan (used as reference nearfield monitors at the legendary French harmonia mundi studios), which had cast paper membranes with variable thickness profiles — an art no one is expert in today. We had spider-less designs on the better Telefunkens and Isophones — reducing parasitic secondary agitation effects by magnitudes....

Maybe some day full range drivers will get the design attention they deserve and we may get the ultimate speaker technology with them....

The Tekton OB4.5 certainly seems to be a step in that direction.

Wrap it up? For Now...
The OB4.5 gives you an incredibly transparent and focused view into the recording venue that opens the door to the upper level of High End audio at an entry level price. Its shortcomings insure that you will not likely break your lease or your marriage. With even modest gear and attention to detail and set up, it should help flood our ranks with new believers and elevate jaded old timers to the status of Born Again Audiophiles.

My wise friend who builds very expensive audio gear on another continent warned me:

     Be careful not to fall in love with the full-range idea for yourself. The
     best of them are so good that they may move upwards the tolerance
     threshold of future reviews of conventional products...or even spoil it.

That, folks, is pretty much what happened here.

Specifications
Type: Full-range single-driver hybrid loudspeaker
Frequency Response: 45 Hz to 20 kHz
Drivers: Two 4.5-inch Fostex 127E
True full-range-no crossover
Sensitivity: 92dB/W/m 
Impedance: 4 Ohms
Weight: 21 lbs
Dimensions: 22 x 13.25 x 12 (HxWxD in inches)
Custom finishes available
Price: $550, optional grills adds $45/pair
          Tweeter addition adds $50/pair 

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