Tekton Design Impact Monitor loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Tekton Design Impact Monitor's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. My estimate of the Impact's sensitivity was 87.5dB(B)/2.83V/m, considerably lower than the specified 94dB. (Speakers with true sensitivities greater than 90dB tend to be rare and expensive.) The impedance is specified as 4 ohms. My measurement of the impedance magnitude (fig.1, solid trace) reveals that while the impedance does drop to 4 ohms in the lower midrange, it otherwise lies above 6 ohms for almost the entire audioband. While the electrical phase angle reaches extreme values in the midbass, the impedance magnitude is high at these frequencies, mitigating the demand for current from the partnering amplifier. Overall, as HR noted, the Impact Monitor is a relatively easy load. The impedance traces suggest that the crossover frequency between the woofers and the tweeter array lies around 1kHz.

718TekIMfig1.jpg

Fig.1 Tekton Impact Monitor, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

No discontinuities are visible in the impedance traces. Nevertheless, the enclosure's panels seemed lively when I rapped them with my knuckles. Investigation with an accelerometer found two fairly strong, high-Q resonant modes, at 500 and 617Hz, on the sidewalls (fig.2), and lower-level modes at the same frequencies on the top and rear panels, though the latter two panels were more inert. The Impact Monitor obviously uses effective internal bracing. Fortunately, both the frequencies and Q of these resonances are sufficiently high that they won't be excited by modern-temperament music. The high Q means that a resonance needs to be stimulated for a fairly long time to be fully developed; the frequencies of the Impact's resonances fall "between the notes" in the modern scale so won't necessarily be excited. However, with unpitched sounds, like percussion instruments, they might be excited and perhaps this was the cause for HR's occasional noticing what he called an "overtone of emptiness."

718TekIMfig2.jpg

Fig.2 Tekton Impact Monitor, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of sidewall (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The broad saddle between 30 and 40Hz in the impedance-magnitude trace implies that the large port on the rear panel is tuned in this region. The two woofers behave identically, and their combined output (fig.3, blue trace) has the expected minimum-motion notch at 34Hz. The port's response, again measured in the nearfield (red trace), peaks between 20 and 60Hz, but some resonant peaks are visible in its midrange output. Fortunately, these are low in level, and their audibility will also be reduced by the fact that the port faces to the speaker's rear. The sum of the nearfield outputs of the woofers and port is shown as the black trace below 300Hz in fig.3; the output is down by 6dB at the port tuning frequency, and the apparent peak in the midbass is an artifact of the nearfield measurement technique. Nevertheless, throughout the measuring, the Tekton's low frequencies sounded rather exaggerated.

718TekIMfig3.jpg

Fig.3 Tekton Impact Monitor, anechoic response on central tweeter axis at 50" (black), averaged across 30° horizontal window and corrected for microphone response, with nearfield responses of woofers (blue), port (red), and their complex sum (black), respectively plotted below 315Hz, 1kHz, and 300Hz.

The farfield response in fig.3 (black trace above 300Hz) was taken on the central tweeter axis, averaged across a 30° horizontal window. This speaker offers a superbly even on-axis output in the midrange and treble, with only a couple of small dips visible in the mid-treble. Fig.4 shows the Impact's lateral radiation pattern normalized to the central tweeter-axis response, which therefore appears as a straight line. The speaker's horizontal dispersion is commendably even below the cursor position at 3.8kHz. The tweeter array becomes gradually more directional as the frequency increases, but in a well-controlled manner up to 15kHz, above which the speaker's output drops very rapidly to the sides of the central tweeter axis.

718TekIMfig4.jpg

Fig.4 Tekton Impact Monitor, lateral response family at 50", normalized to response on central tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

In the vertical plane (fig.5), the use of two woofers spaced relatively far apart leads to major cancellations in the midrange above and below the response on the central tweeter axis, which again appears as a straight line. The Impact Monitor's vertical radiation pattern suggests that the speaker needs to be listened to within a narrow window centered on the central tweeter axis if the midrange balance is not to sound colored.

718TekIMfig5.jpg

Fig.5 Tekton Impact Monitor, vertical response family at 50", normalized to response on central tweeter axis, from back to front: differences in response 45–5° above central tweeter axis, reference response, differences in response 5–45° below central tweeter axis.

In the time domain, the step response on the central tweeter axis (fig.6) indicates that the tweeters and woofers are all connected in positive acoustic polarity, the good integration between the drive-unit outputs correlating with the well-managed crossover in the frequency domain. The cumulative spectral-decay plot on the central tweeter axis (fig.7) is very clean.

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Fig.6 Tekton Impact Monitor, step response on central tweeter axis at 50" (5ms time window, 30kHz bandwidth).

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Fig.7 Tekton Impact Monitor, cumulative spectral-decay plot on central tweeter axis at 50" (0.15ms risetime).

When I first saw the Impact Monitor's array of seven 1" dome tweeters, I wondered how it could possibly work. But its measured performance shows that this unusual design is not compromised—I keep coming back to that superbly even on-axis response—and that the array works well to control the speaker's treble dispersion.—John Atkinson

COMPANY INFO
Tekton Design LLC
Orem, UT 84058
(801) 836-0764
ARTICLE CONTENTS

COMMENTS
Bogolu Haranath's picture

"Will It Go Round in Circles"? ............. Billy Preston :-) ..........

tonykaz's picture

What phraseology, it takes my mind and imagination to Schonbek Silver Chandeliers in Clear Swarovski.

Mr. HR always seems to toss the readership a GODIVA Truffle in his various writings.

I'll have to return to this review after the prose dissolves.

I took a further glance at this loudspeaker and it's siblings wide range of paint offerings. Phew

Stonehenge tweeters & Orange seem at odds. My Eyes are demanding a Grill ( or at least requesting less impact ). I could cover these things with a Silky Cloth and a Statue of Vlad. Putin on one with Mr.Orange on top the other.

Tony in Michigan

ps. Keven Deal just did a YouTube Review of the Tannoy Cheviot ( which wants $6,500 up front and Funeral Home setting back home )

FredisDead's picture

to cancel my subscription.

Catch22's picture

I don't think I've ever seen a disparity that great in sensitivity measurements vs manufacturer's specification. What gives?

Bry_E's picture

That gives me more pause than anything else about Eric's speakers. I don't think any of them have ever matched his sensitivity claims which are as high as 99dB on some models.

es347's picture

..hasn’t McIntosh been doing this for decades?

Anton's picture

Very very similar in appearance!

Ortofan's picture

... get a Frost King F1524 window air conditioner filter and use the open-cell foam to plug the port.

Bogolu Haranath's picture

Kinda looks like "Cyclops" :-) .............

tonykaz's picture

there ain't no dam chinesium in any of this outfit's products. ( I can easily forgive 'em for bee-n mormons if that's what they are ). Romney is a good guy and trump a jerk for dissing him.

Tony in Michigan

dalethorn's picture

Trump is a forward-looking progressive and Romney a luddite.

Edit: This might be a good time for a quick historical overview of hardware quality and work ethic. I started with HP proprietary computers several years before IBM entered the PC business. An HP computer could run in a tent in 110 degree F temps when the IBM PC would shut down before temps reached 90. Then in 1985, HP introduced IBM compatibles, and their quality dropped like a stone. I have many specific examples, FYI.

Articles concerning HP's mil-spec industrial-grade quality in the years before they produced PCs raised awareness about their production plants and quality control. In Corvallis OR and Fort Collins CO, the workforce was described as consisting of "Mormons and born-again Christians". I have no reason to believe that their work ethic was dependent on any given cult, but I do believe that the monocultural aspect of their societies in those locations was a huge factor, as it was in the rapid industrialization of Japan and Germany after the war, when they became legendary for high quality. A man named Deming held the key to some of that.

By and large, you pays your money and you takes your choices, but it's good to know which companies make high-quality products, the era in which those are produced, and the backgrounds that lead to such things. In Apple's case for example, large-scale Chinese manufacturing and the legendary iron-fisted dominance of Steve Jobs turned what could have been tons and tons of schlock into a wealth of useful and durable products.

Bogolu Haranath's picture

May be it is a good idea to stay "in the zone"? :-) ..............

dalethorn's picture

Who is not in the zone? Who violated the zone first? Don't some people always violate the zone? What zone are you in? The twilight zone? Speak plainly.

Bogolu Haranath's picture

High-end (high performance) audiophile zone :-) ............

dalethorn's picture

There is much controversy about the high end zone. With all of the pressures to remaster the world's catalog in MQA, to end downloads in favor of streaming, and to install listening ("music") devices in every home, you might want to think about what exactly is your high-end zone preference. The world is changing, and where is hi-fi going?

Bogolu Haranath's picture

Yeah ...... That is the fun part of the whole thing .......... That is what keeps us all interested :-) ..........

Indydan's picture

By "the zone", do you mean a polite way of staying on topic? If so, I agree.

Bogolu Haranath's picture

"Deming Circle" :-) ............

Bogolu Haranath's picture

Stuffing socks or air conditioner filter is some thing similar to "heuristic" solution to the problem of over blown bass :-) .............

Ortofan's picture

... foam bungs that some manufacturers ship with their speakers to allow the user to tune the bass response by either partially or fully blocking the port?

This is an example from B&W:
http://www.hi-fiworld.co.uk/images/stories/Loudspeakers/Knowledge/bw686.gif

Maybe Tekton should consider employing the same method.

Bogolu Haranath's picture

Agreed ....... I am familiar with that option ......... I also, mentioned another option like acoustic suspension (closed box) design .......... Another possible solution could be using a separate subwoofer and take away the bass duties from these (book shelf type of) speakers. Of course separate subwoofer costs extra money. The advantage with separate subwoofer is flexibility of room placement for best possible bass response :-) ...........

Bogolu Haranath's picture

May be acoustic suspension design is a better solution :-) ..........

Indydan's picture

Interesting speaker design. Though, probably not for people who suffer from trypophobia.

Bogolu Haranath's picture

Or, neophobia :-) ......... Some of the audiophiles have that problem :-) ...........

Indydan's picture

True. And some audiophiles have the opposite problem: they always need something new or different in their system!

Bogolu Haranath's picture

"Something New" ........... Album by The Beatles :-) .............

Bogolu Haranath's picture

Also, "Dora the Explorer" :-) .........

AllanMarcus's picture

Very very cool that you are reviewing an internet direct. Affordable, audiophile lovely set of speakers. May I suggest you listen to the BMR philharmonitors http://philharmonicaudio.com/BMR%20Philharmonitor.html

JBLMVBC's picture

"The classic two- or three-way woofer/midrange/tweeter design contains shortcomings, because the mass relationship is wrong when compared to the recorded source [eg, a violin string]."

One wonders how they explain not multiplying woofers in order to keep up their mass mojo for kettle and bass drums, piano etc...
LOL

Bogolu Haranath's picture

Great idea ......... How about 7 woofers surrounding 7 tweeters? :-) ............

scottsol's picture

I’m not sure it makes sense to call these three way speakers. At the least, this would only make sense if the center tweeter was fed by a separate high pass filter so it did not share lower frequencies with the six outer tweeters. Otherwise this could at best be called a two and a half way.

rzr's picture

When are the Stereophile reviewers going to get a decent room to review speakers? In this review, Herb mentioned that the bass was "bloated and boomy". He blamed it on his 11' room depth. DUH!!! My bathroom is bigger than 11' and our master bedroom closet is bigger than that. IMO, all reviewers should be required to get a decent size room so they can evaluate a speaker without pointing out that the speaker is performing badly, mainly because of the room being used. If I was a manufacturer, i'd be pi$$ed that a terrible room was used to evaluate my speaker. Also, I don't want to hear that Herb's room sounds great because no 11' room will sound as good as a treated bigger room.

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