Tekton Design Moab

It’s funny: springs (most prominently those offered by Audiogon gadfly Geoff Kait) and the more-sophisticated Townshend Seismic Pod (and related products) have been mentioned and recommended here on Audiogon numerous times in that past few years. I felt it was falling on deaf ears, and gave up. The ol’ "Wasn’t invented here" phenomenon? ;-) Anyway, glad to see the use of springs for isolation becoming trendy.

I can enthusiastically second squeak_king_77’s recommendation of select-hifi for those interested in the outstanding Townshend Seismic product line. Select-hifi’s John Hannant is a Townshend family member, and THE source for all of Max Townshend’s brilliant designs (I am a longtime Rock turntable owner). The best prices, excellent customer service.

Just for the record, there are other designers who have used multiple very small drivers to reproduce the midrange. Danny Richie at GR Research for one has offered a number of line-source loudspeakers for years, employing both dynamic drivers and magnetic-planars. It is arranging them in a co-ax arrangement (a center tweeter surrounded by multiples of same for the midrange) that makes the Tekton's unique.

Peter Walker's created an ESL variant on that theme with his Quad 63. The 63 reproduced sound beginning in the middle of the panel, with delay lines sending the signal to surrounding areas of the Mylar driver. Considerably less moving mass then even the lowest mass dynamic drivers. 

The Tekton models with a single group of tweeters (Impact, Double Impact, Electron) may behave as a co-ax, but those with two tweeter groupings and a single tweeter between the two groupings (Encore, MOAB) create an M/T/M D’Appolito output.

For great tutorials on loudspeaker design and measurement, watch the GR Research Tech Talk Tuesday YouTube videos. All is revealed: on and off axis frequency response, the spectral decay "waterfall" plot, the cumulative phase characteristics of multiple drivers and it's effect on FR, enclosure and driver resonances, and how to deal with all of those in the crossover, a Danny Richie specialty.

A loudspeaker with a large enclosure lacking "sufficient" bracing leads me to question the talent (and/or knowledge) of the loudspeaker’s designer. The sound produced by large unbraced enclosure walls is a very big deal, a serious design weakness that should not be left to the consumer to correct. That is way beyond a tweak.

I designed sealed enclosures for the DIY Rythmik F15HP subs I built, putting braces every 6" in each plane: front-to-back, side-to-side, top-to-bottom, 0.75" x 1.5" Baltic Birch ply doubled (each brace then being 1.5" square). Every 12" may have been sufficient, but what the hell. Each brace is bolted together where it passes another brace of a different plane: cross-braced, in other words. The enclosure walls are therefore unable to expand enough to make any sound.

The baffle of the Moab (and all other speakers and subs), if insufficiently braced, will be very resonant, producing lots of sound not fed it by the amplifier. That resonance can be seen in a waterfall plot (which reveals "stored energy")---and most likely in the loudspeaker’s impedance curve---and will be heard as smearing, a lack of transparency, and perhaps "chesty" coloration and congestion. You can’t fool mother nature. ;-)

Looks like I hit a nerve. ;-)

Some of the big UK loudspeaker designers believe in having enclosures that contribute to the total sound of their speakers. The other extreme is Wilson, Magico, Von Schweikert, and Salk, who endeavor to create enclosures that remain unheard. To see a very well-braced enclosure, take a look at what Jim Salk puts inside his custom Rythmik subs.

Ric Schultz (ricevs) didn’t mention it in his post above, but he was in the past offering a loudspeaker/sub combo built to Herculian standards. He installed the great NEO magnetic-planar drivers (whose availability is now uncertain) as a line array on a baffle made of three layers of 3/4" MDF, securing each layer to the others with Green Glue. He made his baffles for the GR Research/Rythmik OB/Dipole Sub the same way. His suggestion to "mod" the Moab in that same fashion reflects his approach to loudspeaker design.

If the Moab’s enclosure is, as has been reported, left largely unbraced, I’m not sure adding bracing to it is advisable. The sound of that enclosure may be part of the synergistic whole. I consider adding internal bracing a redesign, not a tweak. Quad stiffened the frame of the ESL63 after reports of it’s audible resonances became commonplace, and that change was very well received. Some people are more bothered by that type of imperfection than are others. The sound produced by large unbraced sheets of MDF (whether CNC cut or not) is not something I want to hear coming out of a loudspeaker. But then I prefer a line source loudspeaker to a point source, so I'm not a potential Tekton customer anyway. There appear to be enough customers for every design available to keep a good number of companies in business, and Tekton seems to be doing better than most. You can't argue with success!

Regarding color: if anyone does any DIYing, John Deere (the tractor company) offers spray paint in a color they named Blitz Black. It has a sheen similar to indoor house paint often called "eggshell". It looks like the black that greasers paint their hotrods with---between primer or flat black and satin. Looks cool with pinstriping details.

There is a Bob's Big Boy right on the border of Burbank and Toluca Lake. It is of interest for a few reasons: 1- Every Friday night hotrodders take over the parking lot, showing off their customized rides (lots of dropped Mercs and Chevys). For years my gal and I went there regularly, after margaritas and dinner at Don Cucos, just around the corner, and the best Mexican food in L.A. 2- This Bob's is where David Lynch went for coffee and pie during the extended filming of Eraserhead, sitting for hours observing people and listening to their conversations while working on scripts. 3- Bob's is open 24 hours a day, so musicians go there after their gigs. No beer, but pretty good coffee and bacon/lettuce/tomato (or avocado) sandwiches and fries.