Mr. Erik, wouldn’t the Ulfberht solve the issues you mention due to the much lower crossover point? 200hz vs 1000hz?
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
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
63 responses Add your response
I noted the same issue. But honestly, I never listen outside the sweet spot. Even if I am outside that spot in the horizontal plane it totally destroys the sound stage/imaging for me with the DI's or any other speaker for that matter. So for me it is a total non issue. For more mobile listeners, this will be a consideration. I'll just never understand how this would be a priority for the vast majority of critical listeners however. |
I reviewed the Double Impact Monitor for hometheaterreview.com, gave them five stars out of five stars, bought the review pair to use in my smaller reviewing system and am delighted with their performance. I have had speakers in for review in this system that cost more then 6K to 8K that were easily out performed by this 2K speaker. I have had many listeners that are shocked at how beautiful the DI Monitor sounds even compared to the ULF's in my much more expensive reference system. Frankly, when I'm listening to music I'm sitting down in front of my system, therefore, believe it's mute how the speaker sounds when I'm walking around in the room. I'm always listening to music when I'm home, like now as I write this, as background pleasure, but that has nothing to do with serious listening to either of my systems. So, who cares what any speaker sounds like when your walking around the room. |
@corelli - It really depends on the buyer. I often have music playing in my home regardless of what I'm doing, so having a pleasant off-axis experience in both planes is important for me. There's much that has been written that a lot of consumers really value a wide sweet spot. Magico and Revel designs specifically for this. The DI Monitors seem to have plenty of that. I'm just super disappointed in that these appear to be a failed D'Appolito design. Part of what you get with a D'Appolito is a tighter vertical dispersion down to the mid-bass, which these speakers do not have. They are aesthetically D'Appolitos without being functional D'Appolitos. Am I being too critical? |
Terry, sorry but this is a reviewer pet peeve of mine. Mentioning that a speaker outperforms speakers costing more than 3 to 4 times its price....but then failing to name those mystery speakers. In the review, you make a comparison to the pint sized KEF LS50, a speaker that costs $500 less and the B&W 705S2, a speaker that costs $500 more... |
By the way guys, Technically, the DI Monitor is not a D'Appolitos design because it is a three way design, not a two way design. The smaller transducers sonicly function as a single point two way coaxial speaker, hence it's a three way design. In a true D'Appolitos approach you have MW/T/MW drivers that are always a two design. The reference UIF's are a true D'Appolitos were the double circle array of small transducers are the MW "drivers" flanking the tweeter between the two arrays. I nick named the DI Monitors Jr DI's because in a smaller acoustic space they are very similar to their larger siblings in performance. What surprises a lot of my listeners is the powerful bass extension and overall macro-dynamics of this stand mounted speaker. It completely disappears like all reference level stand mount monitors, but presents over all as if its a full size floor-stander. Unlike Herb, I had no problem with over loading my room with bass, and did not have any reason to stuff the rear ports with socks. I think his review says more about the limitations of his room regarding bass response, then any short-comings in the bass response of the DI Monitor. |
@teajay - On the other hand the woofer to array crossover seems rather high, around 1-2 kHz, so we can’t call the outer ring mid-woofers either. Point is, why bother with a W - (something) - W array if you are not going to get the benefits? Yeah, this is one major reason I throw Stereophile reviews in the trash. Bad rooms they refuse to do anything about, or failure to listen to manufacturer's requirements before auditioning. Their measurements are credible though, so worth looking at, especially when they completely dispute their review. :) |
Based on the impedance charts, I'm guessing the woofers cross over at around 1kHz when (based on spacing) they should have been crossed around 300 Hz. Alternatively, the designer could have done an (array) - WW design, eliminating the comb filtering altogether and providing similar output. In case it's not clear, one reason I wanted to talk about this design and measurements is that it clearly illustrates comb filtering while at the same time proving the tweeter array doesn't have any. It's pretty ironic to me. :) Best, Erik |
To address seanhies1 "pet peeve", Here's the speakers that have been in the same system for review that the the DI Monitors were compared to: Role Audio Enterprise Speaker 4K, Lawrence Audio Violin SE Speaker $8,500, Lawrence Audio Mandolin $5,500, NSMT Super PSM Monitor Speaker 5K. These are all wonderful music makers that I gave high ratings to and enjoyed having them in my home. However, the much less expensive DI Monitor was at least there equal and out preformed them on certain sonic parameters. erik_squires, Part of the magic of both the DI Monitor and the DI's is that the circle array with the tweeter in the middle functions as a single point co-axial driver that virtually weights nothing so it presents with horn like dynamics and yet has the speed/transparency of a planar design. So, in my experience with this speaker you get all the benefits with out short-comings. I hear no muddling of the mid-range band and the upper bass foundation, along with taut powerful lower bass extension, is excellent. |
Hey facten, Let me be very clear and precise, for my personal taste the DI Monitors did out perform the speakers that I mentioned. I could have purchased any other of the speakers I reviewed. However, I did not, but did purchase the review pair of DI Monitors for the reasons I mentioned in my review. That does not mean the other speakers are still not excellent products and fine music makers. Eric figured out something with his new design that for me sounds more like the illusion of real music in my systems. |
Hello Eric, I appreciate your critique of the Tektons from the perspective of a speaker builder. Do you believe you could produce an equal or superior speaker for the 2000.00 USD retail price of the Impact monitor? I ask this with genuine curiosity and respect (no implied snarky attitude). This speaker has received much praise based on listening which in my opinion is the most relevant factor. Thanks , Charles |
Hi Charles, My critique may be a moot point is listeners don't mind the off axis performance or plan on only listening in one fixed location. I think that for the same price, a slight re-arrangement of the woofers along with a higher order crossover could perform better. So, in that sense, yes I think I might be able to best the monitors. :) Take a look at the vertical dispersion (fig. 5) of the Tekton Enzo to see what I mean. https://www.stereophile.com/content/tekton-design-enzo-xl-loudspeaker-measurements As for the price, Tekton is getting an amazing price break from SB Acoustics in order to make those price points with seven tweeters. I think that the combination of interesting and very well behaved tweeter array plus components make the speakers a potentially very good value (assuming they sound good). If I had to sell speakers for $2k and make a profit, I'd probably try a much more traditional line array. It is quite a challenge! And not one I would attempt commercially. Best, Erik |
Listening to music is a near all day thing for me and my wife. Our listening room and kitchen/dining area is one big room. We often listen while cooking, siting at the island and moving about the space, so the ability for a speaker to sound good while standing up etc.. is very important. The days of me sitting in my dedicated cave alone with music is behind me. It is now more of a shared and living experience in my home. Sure, I still listen sitting in the sweet spot. A speaker should handle both well for our needs. |
Hey Erik, You keep referring to the DI Monitor as a "quasi' D'Appolito design" , however I politely disagree with this statement. Since it is not a D'Appolito design to begin with, therefore it by logic it can't be a "quasi" version by default. As I shared above on this thread this is a three way (co-axial single point tweeter/midrange flanked by the two woofers) all D'Appolito designs are MW/T/MW drivers, two-ways, not three- way designs. In my home the DI Monitors still sound excellent when I'm going about my business, but still want to enjoy music. Of course, when I sit in the sweet spot it's more magical, but it does not become horrible off axis at all. |
You keep referring to the DI Monitor as a "quasi' D'Appolito design" , however I politely disagree with this statement @teajay If the monitors are not attempting the same dispersion control that D'Appolitos bring, then it is just bad speaker design. Spreading out the woofers around a central array without taking into consideration the crossover point is sad indeed. On the other hand, if I think of the designer attempting to extend the focus of the tweeter array to the woofers then the intentions were good, but the execution incomplete. Either way, as good as they may sound, this seems like only a partial success. Best, E |
P.S. I reserve the right to coin a new phrase, in this case quasi-D'Apollito to mean speakers which use a Woofer - (something) - Woofer array when that (something) shares a similar crossover point that could be expected wiht a D'Appolito, around 2-5kHz. By my definition and for the purpose of this argument, the Tekton DI Monitors qualify. |
It seems to me the overwhelming goal of a speaker (or any audio product) is to sound good. Two professional reviewers and numerous listeners confirm they sound very good. IMO this is simply the bottom line objective. In an academic sense I get the isolated measurement concern and driver arrangement issue. It is however a moot concern if the speaker sound quality is of a high standard which it certainly appears to be. The focus on an aspect of the speaker that in the end doesn't detract from the overall sound seems irrelevant. Now if this speaker had flawless measurements across the board yet produced poor/mediocre sound quality, there's a legitimate problem. This is audio so we listen and judge. Charles |
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Hey Charles, This is one of your very well said/insightful statements that I totally agree with. By the way its been four professional reviewers that gave the DI Monitors five stars, not two. I still found it amazing what nit-picking still goes on towards Tekton speakers that give so much pleasure to scores of music lovers because they are so reasonably priced. |
@charles1dad I think as a buyer you are right on. :) One important part of the hobby and engineering though is to examine our assumptions about what sounds good (and good enough) vs. measurements. A couple of weeks ago, comb filtering was all the rage on Audiogon. It seems that the DI monitors have plenty of comb filtering and no one cares. Curious! Erik |
@erik_squires With the initial run of the Acoustic Zen Adagio speakers with the MTM arrangement, the midrange drivers were mounted flat to the front face of the cabinet. Soon thereafter, the driver mounts were changed to angle about 5 degrees. Essentially, the top midrange driver was angled slightly down. The bottom midrange driver was angled slightly up. Might this tweak help the measurements of the Tekton Impact Monitor? |
Hi @steakster I don't want to beat a dead horse, but no. The issue is the distance between the two woofers. On the other hand, as the review and others have noted, in the exact sweet spot, there is absolutely nothing wrong with the performance of the DI monitors in the sweet spot. It is really two things: 1 - Above and below 2 - The entire purpose of a true D'Appolito is to narrow the beam width of the mid-woofers, which you don't get with this design. Often angling a driver off-axis eliminates on-axis issues. Wilson did this with the Focal tweeters. :) Best, Erik |
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. |
This is why I don't think much of most reviewers. About the only thing they have above average Joe audiophile is some writing style and command of the English language. And even THAT could be debated. I would challenge any reviewer to actual listening capability and come up with as good of results with any piece of gear. Point is, I get tired of reviewers looking down on conventional music loving audiophiles. IMO. |
Hey @teajay Read my comments, from the very first posting until now. When have I assessed the sound quality of these speakers? In fact, I make it clear you should listen to them, and many replied that they only care in the sweet spot. At most, I recommend where listeners should pay particular attention. So I don't know what part of your body you type out of, but I hope it connects to the part of you that thinks a little more soon. Kristofa - I'm not sure it is even a problem, since most listeners are reporting that they listen only in the sweet spot. If your question is: Would this kind of comb filtering be in other models? Then the answer is: Depends on the crossover slopes, high pass point, and space between the woofers. Best, Erik |
@erik_squires A couple of weeks ago, comb filtering was all the rage on Audiogon. It seems that the DI monitors have plenty of comb filtering and no one cares. Curious! Truth! In that previous deleted thread, the uninformed Tekton fanboys disagreed with my statement that there is no way the Tekton designs could have ZERO comb filtering and/or lobing. This is the second measurement of a Tekton speaker, and the second to back my claim. The fanboys say to sit in the sweet spot, but there is no warning of this on the Tekton site. No one else has warned how the Tekton speakers may be a poor choice for home theater buyers. The Tekton site only talks about how Eric has "designed over 60 commercially available speaker models to-date, many for other well-known companies." He still has yet to account for these "well known companies." An average internet direct company (I'm not talking about Tekton) is nothing to brag about. |
To be clear: The tweeter array has no apparent comb filtering as a result of the array itself. All those armchair designers and array detractors were W R O N G. OTOH, the array to woofer matching shows plenty of comb filtering, none of which the A'gon pundits warned about! So I'm doubly amused. This is the sad part, and also sad because the same designer's own Enzo is relatively free of these effects. It is the insistence on a W-(array)-W arrangement that causes this. Best, Erik |