Tekton DI Monitors


Finally got to see the measurements for the Double Impact monitors. I’m a little disappointed.

https://www.stereophile.com/content/tekton-design-impact-monitor-loudspeaker-measurements

This woofer - tweeter - woofer configuration is similar to the style named after the esteemed Joseph D’Appolito. Done well this configuration functions like a single large woofer in terms of dispersion. Less floor and ceiling bounce yield better detail at the listening position. 

Interestingly, the Audiogon craze of criticizing the tweeter array for possible comb filtering is not what I’m sad about. In fact the array appears to be the least of the issues. Look at figure 4. The horizontal plots are superbly clean. Any comb filtering from the tweeter array would be displayed here, and it’s not. Those critics going nuts about the array’s poor performance can apologize for their uninformed criticism right now.

The problem is really the vertical response. It is terrible. Here we do have evidence of comb filtering! See the plot closest to the viewer in figure 5? See the regularly occurring hills and valleys completely absent from figure 4? That my friends is comb filtering. However it’s not coming from the tweeter array, but from the two widely placed woofers. There’s also a great deal of hash above 5kHz on this same plot. This makes me so very very sad.

Part of this is fixable. As Dr. D’Appolito discovered, the designer should have used a higher order crossover slope, which would have taken care of the hash above 5 kHz. However the comb filtering below this is not easily remedied. The issue has to do with how far away the two woofers are from each other. They are so far, and cut in so high that they can’t help but interfere with each other and this woofer to woofer distance is ultimately controlled by the size of the tweeter array.

Should you buy this speaker? I think you should listen to it. See how it sounds to you as you move around your listening space. If you find yourself enamored of the mid-treble resolution and detail, I would encourage you to listen to other Tekton designs that don’t attempt a D’Appolito design, because I'm afraid that the main benefit of this type of design, narrow mid-woofer dispersion, is lost.  A simpler 2-way would avoid these issues and be as good at detail and resolution 
erik_squires
Well if you asked Joe what his D'Appolito design is,  he would tell you that he made the MTM design to reduce lobing and improve midrange output on a standard 2 way.  To do this properly,  the driver spacing & Crossover frequencies are critical as they work hand in hand with each other.  Originally Joe's MTM's used 18db per octave slopes period, he has now adopted 24db slopes.  I have built MTM myself with 12/18 slopes and 24/24 slopes both with outstanding results..  I do understand Erik's term, because Joe calls the MTM, the D'Appolito himself, but in reality,  the array along with variable frequencies in the crossover on the tweeter array along with spacing that Joe would never have used in his designs make this nothing like a D'Appolito design.  The tekton's only get away with the driver spacing so far apart because of the crossovers being so low in frequency... Overall a very different speaker. 
Yes, I get that D’Appolito array is different, but as far as the woofer to woofer spacing and lobing, along with the integration to the drivers, they are the same problems.

The reason D’Appolito now prefers 4th order filters is exactly why they DI monitors have horrible vertical response above 1 kHz. The reason Joe tried to keep the woofers together and pick a low enough crossover frequency is exactly why the DI monitors show gross combing between 300 Hz and 1 kHz.

Everything Joe did right, the Tekton’s do wrong, regardless of whether it is a 2 or 3 way or 3 way coaxial. The core issues which D’Appolito deals with are exactly why I’m complaining but also why I feel the D’Appolito design is the perfect example against which to compare the DI monitors to.

Best,

Erik
In simple terms, could this phenomenon explain why, in some of my initial listening with multiple amps and multiple rooms, but with perhaps not as much attention to the vertical as needed (but as much as with other speakers), I sensed sometimes male voices sounded recessed and female voices sounded slightly forward?

 Regardless how they measure, they are fun and easy to listen to.  I ended up keeping them even though I never could get the bass to sound right.  Crossed them over at around 80hz and did my best blending them with a sealed sub to avoid the problem--short of banding them to half ton stands with couple of sandbags on top.

The measurements also indicate that the 91/94db rating was optimistic, which my ears and gear told me, but disappointing nonetheless.
stfoth - 

Possibly. The reflections on the floor and ceiling from them will be complicated. I would definitely attempt a lot of absorption on the floor all around these. Between them as well as between them and you. 

Best,

Erik
Is this issue only relevant to the DI Monitors, or does it pertain to the DI Floorstanders as well?