directional speakers

I’ve owned those Spendors and the larger Harbeth M30. In your size room I would keep the Spendors. BTW, you should stick with the LS3/5a type of speaker. The Harbeth P3ESR is my favorite shoe box size speaker. Here is one of many positive reviews!

@yogiboy - Sorry, I should have mentioned that my wife graciously  suggested that I use our 23'x16'x8' TV room for the audio system and move the TV to the smaller room where the audio system is now.  That's why I was thinking of the larger Harbeths.

By the way, which version of the P3 do you recommend?  I've noticed that there is some difference of opinion on the XD.

What about something like a Martin Logan offering?  Those sound fantastic but have a very tight sweet-spot, in my experience. 

I have owned both. I preferred the non XD! BTW, since you are going to use a larger room the HL5 is the Harbeth I would suggest. I like them so much better than the M30! My buddy owns the M30.1 and loves them. FYI: I have owned every Harbeth minus the M40. I have also owned many Spendors including floorstanders!

@paradisecom I've actually never heard ML's but will be sure to stop by their room at Axpona.  Thanks for the recommendation.

@yogiboy Interestingly, the advice I got on the Spendor user's forum is to look into the Graham Chartwell LS6.  If I stayed in the Spendor line what would you suggest, one of the Classics?

The LS6 is rear ported so placement would be critical. How close to the rear wall will the speakers be placed and what is your budget? I can only recommend a speaker that I have owned. I have never owned any Spendor from the classic line!

If you want directional, and you are going with Mc, the Fritz with the top end ring radiators are the way to go. They sound better than their Be counterparts and the ring radiator construction naturally produces a narrow dispersion pattern.

@treepmeyer, did Theoretica give you any specific recommendations or general guidelines? Did they tell you why they recommend speakers that are "more rather than less directional"? My guess is that they want to minimize early lateral reflections, but I could be wrong.

@audiokinesis I believe that you are correct.  Here is what the Theoretica web site says:

BACCH® 3D Sound will greatly enhance the spatial fidelity of sound reproduction through any loudspeakers. Loudspeakers that have high sound directivity² will give the best and most accurate 3D imaging in a highly refelctive room with little or no sound treatment, as room reflections, which degrade imaging, are minimized by such loudspeakers.

However, even loudspeakers with low directivity (i.e. omni-directional loudspeakers) will give a spectacularly spatial soundstage with BACCH® 3D Sound in a typical listening room. As the importance of room reflections is decreased (by increasing the ratio of directed to eflected sound through room treatment and/or higher-directivity speakers and/or nearfield listening) the image’s depth and 3D imaging approach the depth and spatial characteristics of the original sound field.

An ongoing investigation of speaker directivity at Princeton University's 3D3A Lab, has shown that dipole speaker designs, electrostatic speakers, as well as speakers with horns and waveguides offer significant advantages in 3D imaging with BACCH® 3D Sound in highly reflective rooms, as they increase the ratio of direct to reflected sound. Abating early room reflections with physical room treatment (i.e. using sound absorbers on sound-reflective surfaces) in a listening room is always beneficial to any audiophile-grade sound system. For BACCH® 3D Sound the effect of sound treatment is equivalent to using loudspeakers with high directivity, or listening in the nearfield. The more directive the loudspeakers are, the less sound treatment is needed for BACCH® 3D Sound to produce a full and accurate 3D sound image.

Therefore, in a reflective untreated listening room, directive loudspeakers are more desirable. In a well treated listening room with sound-absorbing surfaces, any loudspeakers, even omnidirectional ones, will produce an excellent 3D image.²

Budget is in the neighborhood of $5000; used is fine with me.  The speakers will be placed in front of bookshelves filled with books.  I could place the speakers 18" to 24" from the wall.

I rescind those recommendations that I gave. I don’t think they are as directional that you are looking for!

@treepmeyer posted, quoting from Theoretica’s website:

"An ongoing investigation of speaker directivity at Princeton University’s 3D3A Lab, has shown that dipole speaker designs, electrostatic speakers, as well as speakers with horns and waveguides offer significant advantages in 3D imaging with BACCH® 3D Sound in highly reflective rooms..."

Very interesting. These are pretty much the same conclusions I arrived at in my own explorations of loudspeaker design and room interaction (for unprocessed two-channel stereo). I like some of the attributes of dipoles and some of the attributes of horn/waveguide type speakers.

Duke

Well, that’s a lot of work for BAACH. :D

It’s well known that the more reflective a room the more treatment is needed to achieve the same level of satisfaction in detail. That’s not at all new or outside of prior work in acoustics.

In a modestly treated room, the Fritz with ring radiators do pretty well, but they benefit from some treatment.

Alternatively, along the same lines of thinking, if you can put the speakers well out into the room, as well as the listening area, you achieve the same goals.

Maggie 3.7i’s should sound great with your Baach.  They don’t have a high Wife excepting index, but they really do sound nice.

All the best.

I suggest that you look into ZU speakers. They are very efficient, directional, and in your price range.  I’ve had the soul supreme for three years. I like the way they sound.

Bent

One brand that is not thought of as directional, but is is ATC. Those famous midranges are very much in waveguides and have limited dispersion.

As one who mixes dipoles, omnis', And 'directional' drivers with some ruthless abandon....

I will withhold commentary....it's 'not normal', and subject to suspicion...

...considering AXPONA, but April is already complicated for moi'...

@asvjerry The truth is I've never done "normal" well in any domain.  Why start now?

Seriously, the object of the Bacch system is to eliminate crosstalk, as I understand it.  We will see if it is worth the money.  It's an experiment, but no different than trying a new amp or DAC.

The Bacch system is going in a room as yet untreated, but I will get to that this summer.  Main reflection points on the ceiling and side walls will get primary attention.  Not sure about bass, but I have two tube traps that can be moved around.

I (and my wife!) am quite enjoying the small Spendors driven by the modded GaN1.  I just thought that now would be a good time to consider other speakers - and so I will look into the Harbeths, ATC's, the ML, the Fritz and Zu's. My read of the Theoretica info is that in a well-treated room speaker directionality is not crucial for what the Bacch does.  However, I don't want to defeat the system by getting speakers with wide dispersion.  My guess is that among the recommended speakers I can get the SQ I want and not do anything that defeats Bacch from eliminating crosstalk.

Thanks very much for all the advice above.  It's very helpful.

Tom

I think Narrow Dispersion is the wrong way to go.

Imaging, wide and precise starts with the engineering, then IF vinyl, the cartridge's wide channel separation and tight center balance make a big difference for imaging: both before you send the signal to the speakers. Digital (CD, Streaming -not me) already produces separate L/R, again, the engineering making the difference. The recorded signal is producing better or worse imaging prior to the pre/amp/speakers.

Tweeters are the narrowest dispersion, thus they need to be directed at the listening position, both horizontally and vertically to seated ear height, (slanted front face or leaning the speaker back solves this) and has the advantage of altering the initial reflections off the floor and ceiling and eventual reflections off the rear surfaces.

Horns, for tweeters and midrange typically, are designed for controlled directivity, oriented correctly, go for wide horizontal dispersion, combined with limited vertical dispersion. (as well as horns increase in a driver's output (thus high sensitivity) Check the Polar Graphs to see both horizontal and vertical dispersion.

Toe-In, and Angle of the drivers are important. As noted, tweeters need to be aimed directly at the listener. Wide dispersion will maintain better frequency balance better than narrow directivity.

Alternate Toe-In (forget spikes). For two listeners, I aim the left speaker directly at the right listener; right speaker directly at the left listener. This uses the DBX Imaging Concept: you are nearer one speaker for volume and you get more direct dispertion/volume from the other side.

Rear Wall/Corner/Ports. I am no fan of ports, if so, front. Distance from corners can be messed with, and measured via sound pressure meter and cd test tracks (not LP)

It looks like there is a divergence of opinion about how wide the speaker’s radiation pattern should be.

Given that the BACCH-SP system is using the spatial information already on the recording to present an exceptionally wide soundstage, rather than relying on strong early same-side-wall reflections to do so, I agree with Theoretica’s recommendation of speakers that are "more rather than less directional".

I pursue spatial realism in my speaker designs by a different route than what Theoretica is using, and in the course of product development I conducted quite a few controlled blind listening tests. I find a trade-off relationship between soundstage width enhancement due to strong early same-side-wall reflections on the one hand, and image precision, soundstage depth, and clarity on the other. I prefer the latter package of attributes, hence my preference for relatively narrow-pattern speakers, BUT my approach DOES give up some soundstage width relative to wide-pattern speakers.

The BACCH-SP arguably offers "you can have it all, and better than before", and in the context of what their processing does, strong early same-side-wall reflections are counter-productive.

Duke

@audiokinesis The tradeoff you describe is very interesting.  I,too, would choose imaging precision, soundstage depth and clarity over soundstage width.  We'll see if Bacch allows me to have my cake and eat it too.

Thanks

@treepmeyer, in my experience interaural crosstalk cancellation works; it significantly expands the soundstage in width and depth, and enhances the sense of being within the acoustic space on the recording.

I owned an electronic interaural crosstalk cancellator in the early 80’s and it worked but colored the sound, and Theoretica has addressed the coloration issue.

In the mid-80’s I made a passive interaural crosstalk cancellator using large foam wedges which worked but was impractical. Theoretica has addressed the practicality issue.

Polk Audio made, and I believe still makes, speakers that use a secondary array of drivers to provide interaural crosstalk cancellation. Ime their approach works too.

But Theoretica’s processing goes beyond interaural crosstalk cancellation; it also uses de-correlation, which ime further improves perception of the acoustic space already on the recording. And since the BACCH processing is extracting information from the recording itself, the sense of spaciousness won’t have the "sameness" from one recording to the next that can arise with synthesized spaciousness contributed by upmixing to delayed rear channels.

To the best of my knowledge, techniques for interaural crosstalk cancellation only work within a fairly small listening area, typically one person wide and maybe two people deep. So there is that limitation. My understanding is that some versions of the BACCH system do head-tracking and therefore work from a wide range of listening locations, but still only for one (or two) people at a time.

(I have no affiliation with Theoretica.)

Duke

@audiokinesis Everything you say is consistent with my understanding.  I'll report back in a month or so when I get the Bacch system up and running.

By the time we get enough money for good equipment, and good source material, and enough free time: we are old enough that our lack of sensitivity to high frequencies has begun, and will continue to diminish, thus the distribution of the narrowest frequencies are the ones we want to preserve, perhaps boost a bit and a bit more as we age.

Ignore the Space (at first)

One Listener, always dead center, narrower may be beneficial.

A bit OFF Center (i.e. two listeners): narrower may be detrimental.

..............................................

Measurements, published specs:

frequency balance (i.e. 45 hz to 35000 hz +/- 3db)

sensitivity (1 watt/1 meter away i.e. 89db)

are taken directly facing the speaker. (i.e. direct toe-in), most often in a space with zero reflections.

On/Off Axis (infrequently given by maker, mostly revealed by reviews with test reports). Polar graphs of individual drivers, and assembled speakers exist.

On/Off Axis shows the ’drop off’ of various frequencies as you sit off axis (off center), the narrower frequencies ALWAYS dropping sooner off center, and producing less volume than other frequencies. Horns, multiple tweeters, acoustic lens ... are meant to minimize horizontal drop off of narrow frequencies (often controlling/limiting vertical distribution)

Sit Dead Center: toe-in: aim the speakers other than directly at listening position,

narrow frequencies will be weaker in volume than wider frequencies. Detrimental to both frequency balance and Imaging.

Sit a bit off center:

narrow dispersion: the highs are weaker than other naturally wide frequencies, and Imaging is altered detrimentally.

wide dispersion: the highs are closer to the other naturally wide frequencies, and Imaging will be better than narrow dispersion.

Alternate Toe-In. DBX Wide Imaging System.

Aim left speaker directly at right position. Aim right speaker directly at left position. Each position gets ’more’ volume via directivity combined with ’more’ volume via distance to nearest speaker. Wide imaging is created. Great for 2 listeners and very important for home theater

....................................

Imaging (not frequencies)

2 channel stereo: All is phantom, the engineers varying volume side to side, phase, other engineering methods.

narrow dispersion: successful imaging will be limited to dead center

wide dispersion: successful imaging will be extended a bit off center as well as center.

You, wherever you are, are not aware of whether distribution/imaging is from narrow or wide dispersion drivers, you only hear what that specific position receives. IOW, you are not aware if the distribution is narrow or wide, just whether the imaging is poor or good.

……………………………………..

Now Consider the Space (reflections off floor, ceiling, side walls, rear wall)

and Toe-In as it relates to the speaker’s directivity, and the space’s alteration of the speaker’s measured dispersion, NOW in a space with reflections..

.................................................

Get thee a SPL Meter, Tripod, and a Test Tone CD (not LP). Know what you are dealing with, what you are getting, at that location, in that space.

Oh yeah, old fashioned features: a balance control, tone controls, equalizer, or my beloved speakers with level controls combined with those features.

Then, adjust for your preferences and/or needs i.e. your hearing ability as revealed in testing.

Lastly, remote balance, a gift you give yourself.

...........................................

@elliottbnewcombjr Thank you for the detailed response.  I have already adjusted the toe-in to try your "Adjusted Toe-in" method to enhance imaging. 

In your comments, however, it occurs to me that you do not make them in the context of a Bacch implementation, which I made quite clear in the OP is what I am doing.  Your recommendations may be valid generally, but I'm not so sure of their validity in a Bacch implementation.   Could you confirm that your recommendations hold within a Bacch implementation?  Have you familiarized yourself with the Theoretica literature so that you know what Bacch does?

Thanks in advance for your clarification.

treepmeyer

thanks for acknowledging my input.

I don't know anything about what you are doing, I just write for you and others I imagine who are following: to share what I have experienced, perhaps to get you to try that alternate toe-in for instance, try leaning your speakers back to aim the tweeters, and alter the floor and ceiling reflections, perhaps buy a sound pressure meter, test cd, a tube tester, i.e. give yourself tools to get the most out of what you have or might buy.

Especially speakers, always the biggest difference, and understand you have to find how they best fit 'that' space.

I try to be organized and clear enough when I write, perhaps comes off as 'you should', but it is really 'you might want to try this'.

treepmeyer

"I just bought a Bacch4Mac bundle and am thinking of upgrading speakers.  Theoretica recommends speakers that are more rather than less directional.".

Perhaps you could summarize the beneficial theory you are pursuing.

treepmeyer

I apologize, I now realize the importance of the specifics of your post. My responses are related to 2D and Front Imaging: not ‘3D from 2D’ which is Bacch4MAC’s objective.

I just looked it up and realized Bacch4MAC is what my friend wanted me to go to a demo of in Princeton (45 minutes from us). After a glance, I declined, thus I have never heard/experienced their solution in use.

@treepmeyer Directionality is an important concept when it comes to room interaction. The more omnidirectional a speaker is the greater is it's room interaction which always creates problems. Ideally the speaker would project sound only to the listening area and there would be no early reflections in the room. The types of speakers that manage this best are horns and line source dipoles. Dipoles always need the wall behind them covered in sound absorption tile. 

I do not like the term "tight" is regards to imaging. Imaging is either focused or blurred. To hear a system that is perfectly focused or rather focused at the state of the art is an eye opening experience Really well focused imaging will have two distinguishing characteristics, the sweet spot will be extremely obvious and balance will shift between recordings. Gain is never exactly equal between channels of a recording. It is adjusted by ear on systems that can easily be 1 dB in one direction or the other. For most systems balance has to shift over 1 dB to make an obvious difference in perceived balance. With a super focused system 0.2 dB will do it and there will be a tendency to adjust balance with many if not most recordings. Every system that I have ever heard that was this focused was highly directional with one exception and this fellow's listening room was covered in bean bags. I did not count, but there must have been 20 of them. To check balance listen with your eyes closed. Pick an instrument or voice you know is mixed to the center, spin yourself a little back and forth (it helps to have a listening chair that rotates) an stop with that instrument dead ahead. Open your eyes and look where you are facing. If to the left you need to increase gain in the right channel. If to the right increase gain in the left channel. With some recordings especially symphony orchestras you sense more energy coming from one side or the other. You adjust gain so it is equal. 

I prefer the line source dipole. Line sources project acoustic power better than point sources which is why you see them at stadium concerts. They also form a larger, front row image. Line source dipoles project sound in a figure 8 pattern that is exactly as tall as the loudspeaker. There are no reflections from the side walls, middle of the front wall, floor or ceiling. ESLs in particular are extremely directional. Dispersion is controlled by curving the speaker. As an example Sound Labs ESLs come in two curvatures, 45 and 90 degrees. The 90 degree units are for very large rooms. They sell way more 45 degree units. 

If you want a point source system Klipsch Cornwalls are an amazing speaker for the price. If you want to try a line source dipole look at the Magnepan range. If you are a rocker or prefer smaller amps go with the Klipsch's. If you prefer jazz and classical and have plenty of power go with the Maggies. The 3.7i with subwoofers can be the basis for an exceptional system. 

@elliottbnewcombjr Fair question about the theory behind Bacch.   I'll respond as best I can, but the truth is I'm close to being over my head.

In a nutshell, Bacch is a specialized time-domain DSP intended to eliminate crosstalk without coloration.  Theoretica claims that their customized Bacch filters do not have the spectral coloration added by previous attempts at crosstalk elimination.  A Bacch implementation includes calibration using in-ear mics and Webcam head tracking so that the sweetspot follows the listener's head, within reason.

That's about the best I can do.  There is more on Theoretica's website under FAQ, but you may want to look at Edgar Choueiri's book Immersive Sound on Amazon.  Choueiri is quite willing to talk to people about Theoretica's work so I would encourage you to reach out to him, or stop by Princeton if you are close.  If you do have a conversation with him I for one would be very interested to hear your reaction.

Regards, Tom

from their site (emphasis by me):

**BACCH-ORC is the most advanced room correction technology today. Unlike any other commercially available room correction system, BACCH-ORC relies on quick in-ear (binaural) acoustic measurements, millimeter-resolution head tracking, and cutting-edge algorithms derived from years of psychoacoustic research, to produce and apply individualized optimal room correction (ORC) FILTERS: that elevate any stereo loudspeaker playback system to its ultimate level of transparency".

"BACCH-dSP is a 3D audio powerhouse application for mixing and rendering 3D binaural audio over loudspeakers and headphones.

At the heart of BACCH-dSP is BACCH® 3D Sound, a proprietary technology developed at Princeton University that allows the listener to experience stunning virtual reality 3D imaging using only two loudspeakers."

the in-ear microphones are : "used to generate personalized digital filters for BACCH® 3D Sound". (from those speakers, in that space, at the in-ear microphone's specific location.

.......................................................

Without reading about Theoretica, I presume, by OP's statement, that NARROW DISPERTION speakers are recommended i.e. narrow is best for the in-ear microphones reception NEEDED to produce the filters to create Individualized optimized room correction.

Playback via those filters want to be reproduced by the same narrow dispertion speakers.

This is definitely designed for 1 person, centered, keeping their head/ears where they were when the in-ear microphones received the in-room signal to create the filter for that specific room.

Audio Presentation: 2D Stereo; 5.1 Directional; 3D Enveloping

Live sound is generally ‘front stage based’ (except ‘surround theater’ like Cats), presenting 2D directionality (varying greatly with seat location). Conveying the sense of a particular space, but almost never experienced as surround sound.

I listen to ‘Front Stage Based’ 2D (live and recorded/reproduced). Quality equipment and speakers for fidelity. Two Speakers to provide Stereo Imaging. (great Mono fidelity already existed). The Stereo Imaging is greatly affected by the Space the Speakers are in.

Bacch4MAC (3D from 2D). Nyet, a blunt no from me. I lived thru the era of unsuccessful ’enveloping sound’ attempts, Quad etc.

I have never liked or wanted ’stereo everywhere from 2 speakers’, like Bose and others attempt, and not a big fan of attempts of 3D from 2D, like Bacch4MAC is.

It should be noted: 3D Immersion from 2D is different than Dolby 5.1 ‘directional sound’ (developed for Video).

Video’s Sound: I used to grab the speaker wires out of old CRTs, hook up better speakers, realizing the audio signal was far better than what we heard from the dinky speakers within. I was thinking about improved fidelity, not directionality

Dolby 5.1 is ‘improved front imaging’ via center speaker along with better front speakers spaced widely apart: combined with directional effects of specific sounds, placed here or there by programming, to be produced by separate additional directional speakers, for often unseen sources i.e. helicopter from rear left …. The ‘.1’ adding a sub-woofer for a Dinosaur Stomp. Dolby is enhanced directionality, not 3D immersion. (excepting battle scenes, earthquakes, ... still created by specific programming for INDIVIDUAL directional speakers, not 2. Individual Room Correction is adjusted by specific locations of 5 speakers and 1 sub, volume matched by ear or automatically volume matched by ’In-AVR’ signals and microphone provided. Those adjustments are based on and re-produced from/to the center listening position: 1 person, dead center.

‘Sound Bars’ attempt, like Dolby 5.1 to produce improved directionality (not 3D immersion) via ‘processing tricks combined with special drivers within.’

Note: omitting a center channel speaker while listening to 5.1 totally eliminates the sounds specifically programmed for the center speaker, i.e. most dialog compromised). No Center Channel Speaker: 5.1 content: Changing the AVR to 2 Channel Stereo very often improves the primary sound as center programmed sounds are added equally to both FL and FR

Now, I watch a lot of Video on my small Dolby 5.1 Home Theater.

VIDEO: I concentrate on Improved Front Imaging: 2 or 3 persons sitting on a couch: (3 persons: the Majority or 2 persons the Entire audience off-center.

Or, 1 person, i.e. proximity to an end table). the entire audience off-center, Important for both front 2D Imaging (stereo: no center or rear speaker/content) and the improved front 2D of Dolby 5.1. 2.1 simply adds a subwoofer to 2D Stereo. .

My Vintage DBX 100 speakers, are designed specifically to create a wide front stereo image. (I call the DBX 100 solution ‘cross toe-in’). Aim the Left Speaker toward the right side/Aim the right speaker to the left side. Stereo Imaging is widened based on: relatively equal volume l/c/r via opposite side increased directionality combined with volume from near side proximity. DBX 100’s have 3 tweeters (front/side/rear) to solve highs that have too narrow dispersion to work via ‘cross toe-in’.

Pseudo 5.1 (created from recordings that were not specifically made for 5.1) very often sounds better when the AVR is changed to 2 Channel Stereo. Often selecting ‘direct’ changes Pseudo 5.1 to 2 channel. I find much content is Pseudo Surround.

ATC is not directional.  They do have very small waveguides but it's a very small mid and they are very wide dispersion.  They are very much set and forget, not varying a lot by location.

@jon_5912 Thanks for the heads-up on ATC directionality.  I will, of course, take advantage of any opportunity to hear them as they have a great reputation but they are probably not ideal for my application.

Regards.

ATC is not directional. They do have very small waveguides but it’s a very small mid and they are very wide dispersion. They are very much set and forget, not varying a lot by location.

My comment was based on the specs for those mids with those waveguides. I stand by that statement.

That's not to say they don't have excellent off-axis imaging. 

Regarding the radiation pattern of ATC speakers which use that big 3" dome midrange on a shallow waveguide -

As a general ballpark rule of thumb, a horn or waveguide starts to lose directional control below the frequency where its dimension in a given direction is less than 1/2 wavelength, though it still has some directional control down to the 1/4 wavelength frequency.

It looks to me like the round waveguide is about 3" in radius (6" in diameter) and maybe 1.75" deep. The 1.75" depth is the limiting factor. Assuming these numbers are correct, theoretically the waveguide will start losing directional control around 3.8 kHz, and it won’t have much effect below about 1.9 kHz. The directional control won’t fall off a cliff because the radius of the wageguide is still large enough to impart some control, but it’s being largely short-circuited by the shallowness of the waveguide.

You can see the off-axis response out to 40 degrees in the measurements made by Troels Graveson, scroll down about 1/3 of the way:

http://www.troelsgravesen.dk/ATC-SM75-150.htm

It looks to me like useful pattern control is maintained down to about 1.6 kHz, so a little bit lower than my calculation.

In the SCM40 the upper crossover point is 3.5 kHz, so the shallow waveguide is narrowing the radiation pattern from there down to about 1.6 kHz, a range of a little over an octave.

I would expect the direct radiator dome tweeter that takes over north of the 3" midrange to have a wide radiation pattern in the crossover region, narrowing of course as we go up in frequency and the wavelengths become shorter. So even if the midrange dome’s waveuide was large enough to exert serious directional control across its range, the tweeter would still have a wide pattern.

I used to be a dealer for ATC, and remained one up until the time I started manufacturing loudspeakers. I think very highly of ATC, and in particular I think very highly of that dome midrange, but "directional" is not a term I would have used to describe ATC speakers.

Duke

dealer/manufacturer

This has off axis response graphed.  

"Despite the significant size, the 30 degree lateral output is almost as good as the on-axis trace, as is the 45 degree response. Only by 60 degrees laterally off-axis does this enclosure begin to become directive at higher frequencies."

Hi-Fi_Critic_SCM50PSL_WEB.pdf (atc.audio)

Thanks for providing better source materials than my poor memory, @audiokinesis and @jon_5912 - It seems I was very much mistaken.  My bad.

I will say that I don't think "directional" is a bad thing, so I certainly didn't mean it as a negative, but in this case my expectations of the objective behavior of those speakers was clearly wrong.  I apologize.

@erik_squires, when the day comes that it's MY bad memory in the spotlight, I hope to remember your example and be half as gracious as you.  Mad respect.

Duke