Buggtussel Amygdala loudspeakers. (Equipment).
Source: Manufacturer loan
Reviewer: David R. Moran
And we're back. Thanks to all who emailed over the last year-plus asking Wassup and when I would review again; alas, I've been busy with other things. Then one day these tall heavy cartons arrived, and I knew I had taken possession of a pair of Buggtussel Amygdalas. While the model sounds like a subcommittee of the Imperial Senate in Clones, Buggtussel is a Michigan loudspeaker company whose founder and engineer/designer, Kevin Blair, is trained in zoology and neuroscience to the doctoral level, with extra-academic excursions into recording, driver analysis, and LP cleaning.
The Amygdala (the part of the brain "understood to coordinate the emotional expression of stress and aggression," explains the company) is a fairly conventional 2-way, its low end unconventionally loaded with a quasi-transmission line. The woofer/ midrange is nominally a 7" driver, and there are two of them (actually they're significantly less wide than 7"). Each is loaded by its own q-TSAL (quasi-Thiele/ Small Actuated Labyrinth), the "pinnacle of transmission line evolution." Each is centered on a phase plug/"heat pipe."
The tweeter is a one-incher, about which similarly extravagant claims are made; it is Buggtussel's Aual design, a viscous-gold-damped metal-dome unit with a disperser in front. Crossover is specified as 3kHz.
The claim for transmission-line designs, which, like vented ones, make use of the speaker's rearward radiation (whereas sealed systems discard it), is extended and somehow improved bass playback. The "line" is a chamber (typically folded) behind the driver whose total distance is a quarter-wavelength (typically) of the driver's resonance or rolloff starting point. That rear wave eventually gets added to some of the forward radiation, with the same polarity (in "phase," in other words) at a given frequency, and all is good. Damping material lining the interior of the path gets rid of any audibly interfering higher-frequency rearward radiation.
Even such brand names as Joe D'Appolito and George Augspurger have signed off on transmission lines. The former: "The advantages of TLs are well-known. They are essentially non-resonant enclosures, producing a deep, well-controlled bass response. For a given driver, bass response will extend well below that produced with either a vented or sealed enclosure using the same driver. Above a few hundred Hz, the line-filling material completely absorbs the driver back wave, giving the TL an open, non-boxy sound." The latter: "Such a system can dramatically improve the quality of neutrality in contrast to a comparable vented box or even an acoustic suspension design."
It would be fascinating to know how TL bass--open, non-boxy, neutral-quality--sounds "improved" when compared with the output of a properly implemented sealed or vented design.
Turning to higher frequency ranges, any expensive high-end speaker that you hear positive rumors and reports about almost certainly has superior midrange sound, as I learned while preparing my last T$S review, of the estimable Eggleston Fontaine and its exceptional real-world, in-room midrange performance. There may be variables in the bass in high-end models and, with so many single-tweeter designs, there may be airlessness in the treble. But the midrange is where many of these companies thrive. And there's nothing wrong with that. So yes, when I fired up the Amygdalas, it was immediately clear that a--perhaps the--chief excellence of this loudspeaker was its mid: smooth and clean, wideband and flat.
First off I listened to some of the same midrangy material as with the Fontaines: Schubert (this time the expansively intense String Quintet, performed on a BBC Music CD by the Vellinger string quartet with the great cellist Bernard Greenhouse) and Mary Carpenter (various albums). Very natural, very lifelike, and I seldom write down those kinds of comments.
I also played some DVD movies: The Big Lebowski sounded detailed and otherwise fine overall. LF-based transients in all the bowling (and violent) scenes were handled very well. Was there a little bit of a boom? Maybe that was the room and my seating position, though maybe not, too.
I next fed it some lower bass, including my own test killer, the humongous 20Hz shudders that occur a couple of minutes into the Braveheart track of the Boston Pops/ Keith Lockhart Celtic Album (RCA). These clip almost everything in their path: the biggest amps, the biggest subwoofers, and of course, and as with other speakers, the Amygdala. (This CD cut is not on anyone's death-wish bass list, for some reason, probably because it's too quiet overall.) The Amygdala clearly needs a subwoofer for serious home use today. What bass there was was just fine, though I could not distinguish it in any way from other designs competently implemented. It seemed to reach to near 35Hz when kept at more-moderate levels, as with a CD set I recently produced of historic (1960s) Anton Heiller organ-recital recordings of Bach et al. on Harvard University's then-new Fisk.
The best thing I listened to was conductor Kurt Masur's farewell performances as head of the New York Philharmonic, live from Tanglewood over Boston's WGBH-FM. These concerts comprised Beethoven, Brahms, and Mahler. Masur kept things unusually cogent and light, rhythmically propulsive, with plenty of power too. The Eroica and Emperor Concerto (with Yefim Bronfman) were really something even if you've heard them too often, and the Brahms Double Concerto (violin and cello, with Philharmonic chairs Glenn Dicterow and Carter Brey) was strikingly supple but still oddly uninteresting to this Brahms-lover, even with Michael Steinberg's brilliant notes right at hand. (As they were for all four pieces. I cannot recommend highly enough for T$S classical-music readers Steinberg's gold-standard listener guides, the Symphony and the Concerto.)
Mahler's Symphony no. I was for me the high point of the Masur/NYP weekend, again even if you've heard its manic and motley moods too often as well (bumper-car crashes alternating with expanses of the most poignant song). It too was light on its feet, forward-moving, and just beautifully organized (this is so rare in that symphony and in Mahler in general). Like the other pieces it was extraordinarily well-played: you also would have thought that the Phil was some other orchestra--silky and exact, zippy, utterly ensemble--and you would been muttering, "Why is this guy leaving?" What a live thrill it all was!
With these broadcasts the Buggs did a very good job. The GBH BSO miking (and sound) are rather close and dry, but such imaging as there is--kind of omni--was plainly, and more or less specifically, laid out by the Buggs. This is no mean feat; I had already noted a level of imaging precision with Schubert and M-C Carpenter. If I say that the Amygdala imaging was not just mostly stable but also wonderfully floaty and, best of all, disconnected from the cabinets, and if I have noted these qualities before with a few other speakers, it's only because I don't review enough bad designs for The Sensible Sound. This is the kind of thing the Bugg Amygs do best.
The high highs were on the dry side and also a tad tizzy, I wrote in my notes. Applause sounded natural but without quite enough of that lifelike spacious feeling. I often observe the relative airlessness of speakers without enough, or without small-enough, tweeters. You probably will not notice it particularly unless you listen a lot to classical strings, or are a drummer and know what cymbal crashes and splashes really sound like. Also it should be noted that the majority of loudspeakers sound that way: comparatively unspacious, meaning they deliver insufficient treble into the reverberant field. Smaller and/ or more tweeters (or panel designs open in the back) help enormously. (So do more channels, which is another reason why no one complains today about the lack of air to the highs. Indeed, if more stereo speakers had been airier the last decade or two, the appeal of multichannel for stereo music would have been much less.)
It is odd historically. Midranges and woofers are omni (unless you take them too high, as an ignorant designer might do), and so are tweeters in their lower range. So why should it be a good thing that the natural increasing beaminess of a 1" tweeter in the last audio octave or two (depending on its baffle) be a goal, be desirable? Why not see it as the limitation it is and overcome it, so any speaker system's room output in the upper treble is the same as its output everywhere else? Why are there almost no high-end (or other) designs with an extra tweeter somewhere, even if on the back panel? Talk about turning a design necessity into a virtue (and a cheaper parts decision)! Some of the reason must be that so few people in audio listen seriously to classical music anymore.
The Amygdalas may try to make up for their treble beaminess (1" tweet on a fairly wide baffle) by being run slightly on the hot side, as I thought I detected.
Altogether, though, a superior job from Buggtussel. The bass didn't stand out, to my ear, despite the claims, though it was perfectly fine as far as it went. My notes spoke of possible boom, too. There also may have been a little "absence" in the lower midrange, which is generally the case with all off-the-floor designs (the woofers in this speaker are effectively on stands in terms of their midrange performance resulting from typical room loading). And the very top may be a touch hot. Whether such costly designs as the Amygdalas owe consumers better performance than something similarly configured but much less expensive (from, say, Boston Acoustics), well, that's for them to judge. But now I understand why Buggtussel has some of the buzz it does.
The fit and finish of the product was just fine; one of my teen children looked at the dramatic rosewood grain and said, "Wow." The magnetic-hold grills are the cleverest and most efficient such design I have ever seen, and this is a notorious problem area for many speaker companies. But the tall cabinets are very heavy, with all that internal TL bracing, and worse are top-heavy: these are not speakers for a house with little children, or rearing and bumping pets. The units come with very substantial and hefty (nicely machined) screw-in brass knoblike feet with flat-bottom tips that won't damage anything. I heard (in sighted tests) and measured no playback difference with and without them.
The bad news is that the Buggtussel manual and the website both betray a decidedly garage-shop feel, and certainly do not inspire confidence if you're spending kilobucks for something. The manual is surprisingly brief, although not unhelpful, yet nowhere does it mention--and, as with most manufacturers, it's likely they do not know--that for most full and accurate lower-midrange playback the distances from the midrange/woofers to the floor, side wall, and front wall (the one behind the speakers) must not be the same or close to it. Worse, the equilateral triangle specified as the optimal listening arrangement is illustrated with one that's clearly not (at least it's isosceles!).
The website is bush-league by any standards, even those of high-end garage shops: pocked with typos and misspellings and common misusages ("compliment" for "complement," e.g.). It badly wants proofing, spellchecking, and grammatical, punctuational and common-sense editing by someone ... anyone. It also is full of high-end marketing bunk: the Buggtussel "dipolic" tweeter (sic, and it's not "dipolar" in any sense either) is alleged to be superior in several ways to "monozygotic" tweeters (this is the voice of a zoologist?). Naturally, "fast, articulate" bass is praised, and sure, we can all agree that it's way better than that slow, tongue-tied bass. Adhesives are said to be 100% solids (no solvent)?
If I had not listened these units at length, I might be leery of approaching this Michigan company based on their promo materials. No matter. The Amygdala is a substantial achievement, with expert crossover design.
Now to the measurements. It's always a concern that they won't jibe with perceptions. What did mine show? Thankfully, they seemed to show good correlation with the listening notes.
I was particularly concerned about this because I took more repeat measurements outdoors than usual, since it wasn't easy to get sufficient levels (loud enough above breeze and background noise) without having the excursion of the midrange/woofers seem worrisome. These drivers are unloaded, you see, unlike the case with most full-range designs, and they were really popping back and forth with high-level input (pink noise). I wanted not to be unfair to them or stress them unduly, so I also took several measurements at lower levels, with excursions that looked more typical and less scary, and/or closer than my protocol.
I hasten to add that I did not notice any spl limitations with the Amygdalas in use in my two listening rooms: they went loud enough, and I noticed no audible problems above the low bass. I did not try them as PA-type systems, though, or at the highest home-theater levels. In any case, since these parameters are comparatively unimportant, I do not measure for TH or IM or similar distortions (nor, for that matter, for any of the so-called time-related behaviors, nor for impedance).
Before getting to the curves, let me review my protocol, since it's been a while. I use a 1/2" AKG mike compensated to match several 1/4" and 1/2" B&Ks. I also use an intermittent B&K 1/4-incher when it's working, and sometimes a half-inch B&K. Measuring precision-generated, ruler-flat pink noise, the mike feeds a dbx pro RTA-1, a third-octave, extremely steep-filtered PC-based unit that features temporal averaging (also memories, arithmetic manipulations, export capabilities, etc.). Temporal averaging is absolutely essential for measuring loudspeaker performance; I was pleased to see its key importance recently underscored by famous audio engineer Tom Holman in his Surround Professional magazine in a series of articles on how to measure and equalize speakers correctly.
I measure speakers in a couple of typical rooms, as mentioned, one large with a peaked ceiling, one a conventional living room. Speaker placement and listener (measurement) positions are entirely normal. After positioning trials for balance and imaging, I experiment with staggered boundary distances to get smoothest results through the lower midrange. The mike takes its data while being slowly moved within a cubic foot or two where the listener's head would be, with the dbx rta set to continuous (cumulative) averaging. I measure the speakers separately and together, playing both mono and "stereo" (two uncorrelated channels) pink noise.
In addition, I take one speaker outside to look at its horizontal radiation. The yard I work in is large, flat, and quiet. (Dare I repeat the joke of the former speaker-engineer colleague who said I was "out standing in my field?") The load on the speaker outside is half-anechoic, an anechoic room, if you will, i.e., one with a real floor but no walls or ceiling. Grass turns out to be quite close to carpeting in treble absorption. While the dbx rta continuously averages, I measure the speaker system playing pink noise with the mike slowly moved through a solid space 7-9 feet away, at seated ear height, up and down, forward and back, and side to side a few inches. I do this measurement on axis (plus or minus a few inches), then repeat it at -30, -60, -90, -135, and -180 degrees (which is directly behind). What we hear from a sound source in an enclosed space, way more than anything else, is its frequency response as a function of horizontal radiation pattern. Not only do these individual horizontal outputs create the playback imaging in a room, as they reflect off side and front walls, and form image sources, but in toto they become the bulk of a speaker system's in-room power response.
To get the clearest possible sense of horizontal radiation and of any crossover problems (a big seam or stitch in the off-axis response), I also normalize the on-axis response to flat and graph the other horizontal responses as the difference or deviation from flat. This starkly shows driver/baffle directivity and scallops or "flare-in" at crossovers, where the lower driver begins to get beamy at the top of its range and the upper one comes booming in within the omni lower part of its range.
I have been following this protocol for 15 years now (having had it vetted back then by several highly regarded designers), and it offers good correlation with what is audible, not to mention being notably consistent. It is quaint compared with the myriad impulse-based systems everyone else uses, which have the easy potential to be less accurate or at least more misleading (though more and more reviewers do look at horizontal radiation). That's one reason why I was so glad to see someone like Holman finally insist on the necessity of the key component of my protocol: precision temporal averaging, the kind that will show pink noise not as a bouncy signal but as quickly settling to an unchanging flat line.
In Figures 1 and 2, observe how flat the 60- and 90-degree off-axis responses are! This is not an easy achievement.
[FIGURES 1-2 OMITTED]
Is the sonic hole centered on 200Hz real? Yes and no. It is real because the floor reflection can and will readily cancel the direct output around that frequency if allowed to do so, which is most of the time. But this valley can be filled in, at least partly, in a room, by ensuring that the distances from the speaker to the front and side walls are not the same as the drivers are off the floor. (If the three distances are the same, then yes, for sure, you will have a big ol' suckout somewhere in the octave below middle c.)
I was concerned about the apparent ramp-up in the last octave shown in Figure 3, thinking perhaps my half-inch AKG was compensated too much. Mikes vary greatly in this highest range and the smaller the mike the more potentially extreme the results. They also vary in the high treble as a function of pickup angle, whether it's directly into the mike diaphragm (normal incidence) or at a grazing angle. (When measuring I move my mikes around to help average out their various angular pickup responses.) I don't display anything above 16kHz because I don't trust those data.
[FIGURE 3 OMITTED]
Here I took the 1/4" B&K and, at its own flattest angle, measured the system on-axis, with slightly up and down spatial averaging only (nothing side to side or to and fro). I measured at three distances, the two cited above and also at the standard 1 meter. The graph is from 400Hz to 16kHz and the three curves are offset for clarity. Conclusion: The last-octave (8k-16k) ramp-up appears quite real and presumably correlates with the tizz I noted. This is an odd tweeter-design issue, or decision. But it is not hugely significant.
In Figure 4, I have normalized the axis response to be ruler-flat, to show the deviation by angle of the horizontal responses. What one wants here is even, smooth and congruent striation of the outputs, meaning that the images formed from the side and front wall reflections don't suddenly get wider and narrower depending on their frequency range. (If you don't care about imaging, this curve set is unimportant.) Here the -30[degrees] output is not perfectly uniform, but the other ones sure are. And flat to boot. Do note again the absence of a crossover stitch at 3kHz. That's something you don't see very often.
[FIGURE 4 OMITTED]
Let's now look at Figure 5. I felt I should try to measure this special TL bass, but did not know how. With subwoofers you can measure a few feet away and really crank it to get good data (if they are up to it and if you have the amp, that is, in order to get at least 10dB above any continuous environmental noise at 20Hz, which ain't easy). But the Amygdala is too weak in the very low bass to do that. So I set the mike a foot away and a couple of inches off the ground to clear the grass--almost what is called a ground-plane measurement. It yielded a good-looking result, more impressive than I could get in my rooms, with the quiet 20Hz only 8dB below 40Hz. The ramp-up above 70Hz is unfortunately real, I discovered.
[FIGURE 5 OMITTED]
Figure 6 is something new: I averaged all the horizontal output and weighted it appropriately by angle to see if I could predict the in-room response. Of course vertical radiation is not included, so this curve will not be totally accurate. One cool thing about that "inaccuracy" is that if the in-room response looks and sounds a lot rougher, it shows anomalies in the smoothness of the vertical radiation. Depending on your ceiling height and how high you sit, these could matter (or not). Finally, with savvy (staggered distances) placement experimentation, the lower-midrange valley will not be that bad; this is worst-case for sure.
[FIGURE 6 OMITTED]
Figure 7 is the average of all responses taken in the room that yielded the better smoothness (the big peaked-ceiling family room), although the 50Hz dip is clearly room-caused (and the peak an octave above is not). The Buggs were set across the corner (diagonal) at various distances from the wall behind. Stereo pink noise: Again observe the smooth crossover work around 3kHz. The sheer number of the responses that were averaged (and the various positions) flatten out the tweeters' top octave, plus this was using a third mike, a B&K 1/2-incher with a slightly softer top octave than the other B&Ks.
[FIGURE 7 OMITTED]
Figure 8 is the same as 7 but with mono pink noise, which is always a little less smooth.
[FIGURE 8 OMITTED]
Figure 9 shows good consistency and inter-unit quality control, as it is of each of the two speakers placed in a different spot in the room, and they're within +/-1.5dB or so of each other.
[FIGURE 9 OMITTED]
Conclusion: In my "reviewer" opinion, Buggtussel could pay more attention to issues of mid-bass boom, lower-midrange loading, and upper-treble spaciousness, all in typical customer usage. Overall, though, the Buggtussel Amygdala is a fine loudspeaker with smooth, natural-sounding response and steady imaging. It has pleasingly flat response broadband, strikingly so around the important, ear-sensitive crossover region. The company's high-end reputation is altogether understandable.
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|Date:||Dec 1, 2002|
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