Chris A

This is either incorrect, or you forgot to add the caveats/constraints on when it might be considered true. In my experience, this comment by itself is definitely wrong. I'd like to take this discussion off to another thread on "sealed vs. bass reflex MEHs" to keep this already long thread from continuing to grow to unreasonable lengths. That new thread can be found here: I would ask that the participants here instead use that thread for their discussions of this particular "sealed vs. bass reflex" topic, since it is a diversionary subject to the basic K-402-MEH design and its implementation/DIY efforts by members here. Chris

Here are my comments on the "Hyperion" design: https://community.klipsch.com/index.php?/topic/199278-tom-danleys-hyperion/&tab=comments#comment-2605185 and... https://community.klipsch.com/index.php?/topic/199278-tom-danleys-hyperion/&tab=comments#comment-2605906 https://community.klipsch.com/index.php?/topic/199278-tom-danleys-hyperion/&tab=comments#comment-2607064 I'll warn you in advance: I'm not a fan of this design. To me, it looks like "design by committee" and by looking at Tom's past designs and reading his responses (fairly carefully) on the various forums, I know that Tom D. probably didn't initially want to go the direction he did in his latest announced design (and this is my guess alone). Chris

This is from page 420 of Toole's first edition (Sound Reproduction...): This is why. I hear it clearly in my setup, so do my "control listeners" that I invite to do A-B comparisons, in blind fashion without telling them what changed or what they're listening for. This isn't a "fixed-installation PA loudspeaker" thread. It's a build and test thread for the home hi-fi loudspeaker--the K-402-MEH. The requirements are a lot different. I chose those requirements for home hi-fi application for this thread. If you have different requirements, I welcome reading your similar thread on your own MEH builds. We also now have another thread on other MEHs (the "nearly full-range MEH" thread) that you can reuse for your projects, if you so choose. I'd like to keep this one focused on the K-402-MEHs if possible. I recommend it highly. I think there are others that have built their own K-402-MEHs that can attest to the sound quality of their bass reproduction. Chris

This is a typical diyAudio common requirement. In this thread, the implied requirement is sound quality, and being able to get the loudspeakers into the living space without sacrificing Jubilee-levels of sound quality. You can't get that kind of sound quality (including freedom from impulse and phase/group delay distortion, as well as an arbitrary reduction in realizable bass extension) using bass reflex...in my experience. I'm always amazed at those that can't hear what PWK heard, and even advised against mixing closed-box/fully horn loaded bass vs. bass reflex for his own loudspeaker models...and this hasn't changed since 1976 when he wrote the following words: https://community.klipsch.com/applications/core/interface/file/attachment.php?id=80871 I hear the difference. I'm not afraid to challenge the commonly held notion that "bass reflex is better". It isn't. It's a design compromise that I find that I don't need to make in the loudspeakers in my setup. YMMV. Having said that, of the bass reflex designs that I've heard, the Cornwall is probably the best at hiding the audible effects of that tradeoff using bass reflex. But the tradeoff PWK used is that he used a bigger box than others typically use to do it--and a lower port frequency--in order to limit the rise in phase growth and simultaneously, group delay. Modulation distortion effects of the woofer moving more or less unconstrained in its baffle vs. an acoustic suspension (sealed) design are still audible, as PWK noted. More on that subject here: https://community.klipsch.com/applications/core/interface/file/attachment.php?id=82430 and here (a good article discussing jitter, and its relevance to modulation distortion in loudspeakers--and its audibility): https://www.stereophile.com/reference/1104red/ Chris

This is a problem. Jubilees are corner horns--and not really "quarter space horns". (This would affect midbass and deep bass SPL response.) Did you take a measurement of each loudspeaker (using something like REW or other shareware and a $100 microphone) to see the effects of each placement to verify what you were getting? You have revealed what kind of microphones were used (...unfortunately...). The Blumlein Pair is about the only way that you're going to hear anything even distantly resembling what occurred in-room. Otherwise, a video is not useful, but a merely a distraction. The lossy format of YouTube videos (AAC) immediately takes away the possibility of hearing any differences in upstream electronics--or even the real recording quality. You're already down to a small subset of things to convey vs. an in-person audition. You have to work hard to minimize the damage of just what YouTube is doing to the audio. I think that these two pieces of information (i.e., in-room measurement results, location and type of video microphones) should be a requirement for all videos of loudspeakers so that the people watching them can understand a little about the effect of room placement and recording microphone dependencies on the demonstration. (But I find most sales-related offerings don't do that...unfortunately for potential customers.) Hence, my first post in this thread. Out of respect for Roy's original wishes, I think most Jubilee owners have abstained from attempting this sort of thing and especially because of this outcome that you now lament. (Apparently...you didn't get that memo.) So the best outcome here is the realization by potential buyers that "gee, I really do need to listen to these in person, and in well-set-up condition". Sorry to appear to join the other voices on this subject, but getting to a fair comparison condition for a YouTube video (if, in fact, that can actually be done--which I have never believed was actually possible), the bar is high for loudspeakers that have these performance levels, but which require proper placement in-room. A poor demo is a good way to influence the outcome any way you wish, but the work done by the engineer(s) of each loudspeaker is not really given a fair treatment. Chris

This isn't actually what I was referring to (passive high pass filtering). I'm actually a little surprised that you took my comment to mean "passive high pass filter for the woofer circuit", since I've rarely seen that, too. I was talking about upstream (usually preamp) hi-pass filters. Virtually all manufacturers of home hi-fi ported bass loudspeakers tend to say in their owner manuals to add an additional hi-pass filter to the incoming signal to preclude driving the bass reflex design below port resonance frequency. Here is a JBL manual that recommend that for the LSR708 and 705 series monitors (toward the bottom of pg. 6). This is typical advice given in JBL's literature: https://jblpro.com/en/site_elements/7-series-set-up-guide I really don't see a reason to use bass reflex designs with DSP crossed loudspeakers, especially MEHs, which enjoy flat phase and group delay response without using reflex ports. In fact, this entire thread is for a "full-range" MEH based on the K-402 horn that doesn't use bass reflex ports, along with rationale: https://community.klipsch.com/index.php?/topic/161404-a-k-402-based-full-range-multiple-entry-horn/page/51/ and... https://community.klipsch.com/index.php?/topic/161404-a-k-402-based-full-range-multiple-entry-horn/page/38/&tab=comments#comment-2485972 Chris

Cory/Jason/Trey needs to invest in something like this at the listening position: Chris

Xmax is much less useful in a sealed (acoustic suspension) design than in a ported enclosure design, precisely because the air inside the sealed box acts as an additional opposing spring force at all frequencies where larger movements of the woofer occur. Xmax is a "large signal parameter" from the Thiele/Small (T/S) list of parameters, and its usefulness was created by the use of bass reflex designs (as are all parameters in the Thiele/Small papers), but not really sealed box (acoustic suspension) bass bins. If a bass reflex box is given a strong bass signal below the port frequency, only the suspension in the woofer stops it from going over its travel limits, as there is no effective back air pressure from the box to resist the woofer motion (i.e., below the tuned port frequency). So it is very easy to "unload" a woofer from its normal position if trying to boost its output below the port resonant frequency (which is the reason why most manufacturers recommend high pass filters for their bass reflex-ported loudspeakers--which further raises the effects of the audible phase growth at low frequencies). The only reason why people use bass reflex is because they continue to use passive crossovers without EQ embedded in them (i.e., low-Q notch filters). They use bass reflex to get a extra 3 dB of output in a very narrow frequency range just below the resonant frequency of the woofer/box system--without having to use correcting EQ in the passive crossover circuitry (which also decreases the effective sensitivity of the entire design using passives). But they pay a high price for this, however, and it generally shows up as increased phase and group delay response growth. It also limits the low frequency extension of the reflex ported system vs. the sealed system, because as the frequency descends below the woofer+port resonant frequencies, the phase of the backwave coming out the port(s) begins to cancel the frontwave energy by increasing amounts. In a closed box system, EQing the box SPL response below resonance doesn't result in this phase cancellation. In fact, the sealed box system loses SPL at nominally 12 dB/octave below resonance, while the bass reflex loses SPL at 24 dB or more per octave below resonance. Also, in order to get more SPL output below resonance, many/most loudspeaker manufacturers use higher "Q" woofers with higher mass, which also increases the phase and group delay growth growth, and limits high frequency output capability of the woofer/box system. So you pay a high price for that "extra" 3 dB of extremely limited bass extension from a bass reflex design. I don't use bass reflex designs for these reasons, simply because I don't use passive crossovers anymore. It's much better and easier just to add 3 dB (or more) of EQ boost below the sealed box's resonant frequency with a DSP crossover. Bass reflex also typically doesn't sound very good to my ears. Chris

I've been in that room next to the chamber listening to Jubilees over the course of a couple of days. It's got a left-right asymmetric ceiling height and drywall construction, following the contour of the building's roof itself--which has a low pitch characteristic of metal-and-concrete floor construction industrial buildings of this part of the world. It is fairly well damped in the bass bands--ostensibly through its inherent membrane absorption construction--and the left-right ceiling height difference wasn't a big remaining factor at midrange frequencies--apparently using foam-type absorption to control reflections, but placed asymmetrically within the room left-right. Roy mentioned that they did a lot of work in that room acoustically to get it right, but the resulting visual presence wasn't really indicative of that work, I have to say. It looked like the placement of the absorption was almost random, and not nearly as much absorption as I would have guessed was necessary. But listening along the side and rear walls (farthest from the loudspeakers) was not as problematic as I've experienced in other similar-sized rooms. Pretty much the entire room was usable as listening positions. Chris

1) The MEH probably is able to handle room acoustics issues better than almost anything else (albeit, you may lose boundary gain if you move them away from the walls/floor at some frequency, and depending on the dimensions of the listening room). Having directivity control and co-axial output without disruptions in the directivity down to 100 Hz (where boundary gain begins to kick in) is the reason for this. Even more so than Jubilees, etc. (Perhaps more on this discussion to come.) 2) I think that the real issue is watching the reverberation times (RT30, in particular) between 100-250 Hz. If you lose control of this band's total absorption (usually provided by bass traps), you get a booming sound when the SPL gets to some point--that you can't do anything about. 3) You don't want something like this: listening to a live rock concert in a place like the G. Rollie White Coliseum (the former basketball arena on the Texas A&M campus--a structure since torn down). I never heard any FOH guys able to handle mid-bass "boom" in that horseshoe-shaped arena, because the entire back wall just behind the stage was corrugated steel with no absorption. You have to control the ringing of these kind of surfaces. If that back wall was covered with anything acoustically absorptive in the 100-250 Hz band, the problems would be been manageable, I believe. (Of course then they couldn't call it "the Holler House on the Brazos" if they did that, however.) Deep bass can be a problem if you're up against solid brick masonry walls--like in a basement or a solid masonry structure with no wood, plaster lathe construction, or drywall--where the walls basically don't flex. Most rooms rely on that flex to do membrane absorption below 70 Hz, and there aren't enough people in the audience to substitute for deep bass absorption. If the walls don't flex at all, you've got a real problem, and it takes really big absorbers to do anything about it. I think about the Beatles' most notable early venue--the Cavern Club--which was basically in the catacombs of Liverpool--and solid as a rock. They apparently had to develop a "new sound" in order to avoid the booming sound, mostly devoid of Mr. McCartney's deep electric bass range (which they carried forward in their early recordings, and almost anything below 100 Hz was basically attenuated out): Chris

I really didn't have any time for hi-fi audio tinkering, etc. when the kids were growing up and I was working "for the other guy" to foot the bills. I was a hi-fi enthusiast before marriage, however. I just put it on hold for 22 years. Only when the last one went off to college did I invest in Jubilees (2007). I've never regretted spending the time with the kids growing up, however. Chris

That sounds like a marital issue to me... (i.e., domestic living with kids). But I do understand the need for escaping the kids from time to time if they're in the mid-late teens. But it still dilutes the funding for a better (single) setup. Chris

A simple switch between amplifiers is a much better solution, acoustically. Now if you have marital problems..that's something different altogether. Think about it--you're diluting the funds that you could spend on one really good setup--on two not so good setups. Chris

I find it's not needed. In fact, a system set up for very high quality surround sound also simultaneously performs as a two-channel system. The notion that you need different rooms and setups really hearkens back to a time when home theater systems were of lower quality and were mostly related to sound effects, and "music setups" were selected based on stereo playback (only). The fact of the matter is that multichannel music recordings of the best kind available blow away stereo-only recordings (at least in my listening room). With typical direct radiating-type loudspeakers having poor or no directivity control (i.e., not Klipsch loudspeakers) the problem arises in trying to control the early reflections from just around these type of loudspeakers by using a lot of absorption in-room (RT30 times of 0.2 seconds and below). However, using loudspeakers with better loudspeaker directivity enables the use of a lot less absorption in-room (RT30 of 0.4--0.6 seconds) which also makes the room good for stereo playback. Good stereo relies on the phantom center imaging via lateral reflections in-room to fill the "fundamental flaw of stereo" hole in the perceived response around 1.8-2.2 kHz (also see here). Chris

I'm sure that this is information that people need to understand the difference between these two loudspeakers. However, I'm also sure that it isn't always welcome by all that have held the Khorn out to be the loudspeaker that started PWK's company in ~1946--and is still going 75 years later. I do believe it's worthwhile to point out that the Klipsch Jubilee that they are listening to is also PWK's design (with Roy apparently doing the "elbow grease" duty with PWK's recommendations on which way to go). So the Jubilee is reportedly PWK's last loudspeaker design, and I think that should be remembered in this context. When the Jubilee bass bin was completed, PWK was in his mid-90s. Roy was able to assist Mr. Klipsch in realizing the last instance of his corner horn design with "all the bells and whistles" learned after more than 50 years of design knowledge in how to improve it poured into it. That's what these two guys are listening to. Chris

To the OP: there are "experts" that abound in this subject area. The reason why I posted the information that I did is because you don't have to take my word for it--there are many sources of information that have been vetted by many people. I trust Toole and to some degree, Linkwitz, who were fairly well calibrated on this subject. Paul Klipsch is another that I generally trust (although a great deal of psychoacoustic research has been conducted since 1970, before which PWK wrote most of his articles). I highly recommend Toole's book as a reference: https://smile.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering/dp/113892136X/ Chris

Here is a picture of your model showroom: Here is Siegfried Linkwitz's listening room: I think it could be an outstanding listening room, as shown. For one thing, it has enough volume to avoid the issues that I see with many other listening rooms, and a high ceiling. I think you're going to really like listening in there. That room is pretty similar in dimensions to my listening room (15.5 x 40 x 9--5500 ft3). Having a ~6300 ft3 room and lots of lateral reflections outside a 6 feet radius of the loudspeakers will significantly increase the listening pleasure, I've found, especially in two channel mode. Of course Cornwall IVs are not dipole radiators like the loudspeakers Linkwitz used (above), but the Cornwalls can be accommodated quite well by positioning them near the front wall, like you've shown, above, to take advantage of room boundary gain. I also recommend a third Cornwall IV instead of a "horizontal array of woofers" center loudspeaker, which never really work very well (perhaps if you stand them up on end, they will behave like D'Appolito array loudspeakers. (I would not use it horizontally, in any case.) I'd avoid that type of center loudspeaker. I've found that having a center whose performance matches or exceeds the front (left, right) loudspeakers is not just desired--it's really a requirement. The only reason why people seem to gravitate toward those long horizontal arrays of direct radiating woofers is because they don't really understand how important the center channel is in multichannel music and HT reproduction. It makes a huge difference, IMHE. Side surrounds would probably work much better if they weren't so high off the floor. In fact, they could be placed at slightly above head level while sitting (about a foot or two at most), and preserve the timbre and ambience of the front loudspeakers. Here is the ITU-R-BS-775-1 standard for surround sound showing the lateral and vertical suggestions for loudspeaker placement. I've found that it is right on, in terms of height above floor: I've found that it is easy to set the surrounds too high. When you listen to multichannel music albums (SACD, BD, DTS, etc.) having the surrounds emulate the fronts in terms of their placement greatly increases the impression of true surround music and HT experience. The side surrounds can easily go in front of the 90 degree (lateral) line of the listening position(s). In fact, their effectiveness actually increases when you do this: Chris

Horizontal horn orientation is preferred, but they can be used vertically without any issues since they are point source loudspeakers. Floor and ceiling bounce are the major issues with vertical orientation, and if your ceiling isn't like ~10 feet (3 metres), that ceiling/floor bounce is going to be accentuated in vertical orientation. They will go very low--but with PEQ boost (just like almost all direct radiating subwoofers are set up to reach the lowest frequencies). In general, they will tend to roll off below ~45-50 Hz if EQ boost is not used. I think that @rickmcinnis indicated that point was close to his crossover frequency (...or was it higher frequency...?). It's usually a juggle to match room dimensions and relative dimensions (i.e., room modes) and where the loudspeaker is placed. In my room, I place the MEH in the center, and since I don't have a sub in the center of the room, extending the bass response of the K-402-MEH prototype adds greatly to the low bass coverage (like "filling up" the room modes at the nodes and anti-nodes characteristic of the room's dimensions). Chris

The current status of loudspeaker specifications (in my opinion) isn't terribly good-especially if applied to fully horn-loaded loudspeakers. I'd add that the reason why a lot of people prefer the sound of horn-loaded loudspeakers--those measures (modulation and compression distortion levels) aren't even mentioned in their specifications--relative to direct radiating loudspeakers (fully horn loaded loudspeakers effectively have zero modulation and compression distortion relative to direct radiators, and virtually no one understands or remembers this point). The efficiency of horn-loaded loudspeakers isn't well suited to voltage sensitivity measures, and as Mark(?--Gnarly) has pointed out, nowadays each channel needs to be EQed flat to compensate for controlled directivity horn efficiency swings over their passbands. That's why I don't like to use sensitivity ratings since I don't use passive crossovers in my setup any more--everything is bi-amped or tri-amped, and EQed (very carefully) to flat response on-axis at 1m. The typical sensitivity ratings of loudspeakers is not actually measuring the bass bin channels in their measurements, only assuming that the bass bin channel has enough woofer diaphragm area (or bi-amping) in order to keep up with the midrange/high frequency drivers. So the whole subject of loudspeaker efficiency becomes a bit subjective even though objective measures are being used. In general, the MEHs that I've had my hands on have efficiencies that vary between 2-20% on the bass channels (i.e., on the same channel, same MEH, as a function of frequency), and between 4% and close 100% on the high frequency channels. If using midranges, the efficiency varies between 3-50%. You can see this by the number of drivers used on the high frequency, midrange, and woofer channels in the Danley SH-96 (which is almost the same dimensions as the K-402-MEH, and has the same horizontal and vertical coverage): The SH-96 is a fixed PA loudspeaker (not arrayable) that is used mostly as a center stage loudspeaker (or one each on the side of the stage). It has 90 degrees of horizontal coverage and 60 degrees vertical coverage in order to cover the full audience in a PA or music reinforcement application. The SH-96 uses 11 drivers...not because it needs all those drivers for home hi-fi duty, but because it has to play at 133 dB continuous (music power) output to full audiences in large auditoriums and outside venues--without boundary gain. Danley very conservatively rates this loudspeaker at 101 dB/2.83 V into WHOLE space (no boundaries close by--as if elevated far above ground level outside). If that same loudspeaker were rated into half space, it would jump 6 dB in sensitivity rating, another 6 dB if in quarter space (e.g., wall/floor interface) and another 6 db in eighth space (full corner loading). So it is 101 dB /1 m @2.83v elevated far above ground, and nearly 118 dB/1m @2.83v in a room corner. The K-402-MEH needs to play at much less overall SPL than that. It can use three drivers (a good 2" compression driver and two 15" woofers) instead of the one 1.4" compression driver, 6 compression midranges, and four 15" woofers of the SH-96. If you need the MEH to play louder at the same input power, add drivers. Of course, this isn't what I need at home, so for me, three drivers are more than "good enough". Chris

Here is the raw response of the woofers in the K-402-MEH, SPL and phase response (i.e., very close to the MEH variants discussed in this thread): and the high frequency (TAD TD-4002 channel) raw response on the same K-402 horn: Where do I select the output SPL to calculate sensitivity? One kHz? Bass bin frequencies? Here is a quote from another audio forum: So , using that method, the voltage sensitivity (not power) is artificially boosted by about 8-12 dB. I find that the idea of using a single number for sensitivity, and not using power, but RMS voltage input from the amplifier, further points to the uselessness of the measure. Loudspeakers are current-drive devices, not voltage driven (which is a common misconception). And in this case, a single sensitivity number isn't valid, because I'm bi-amping (actually tri-amping in the case of the dual-diaphragm BMS 4592ND presently). So each channel has its own SPL response. I think it's a little better just to post the SPL response at a certain RMS input voltage for each driver on its horn. Then the customer (a hypothetical, in this case, since no one here is apparently buying anything) can make the final decision. The above measurements are apparently -13 dB for the high frequency plot (and unknown for the woofer channel--likely close to 0 dB), down from the 2.83 reference voltage that is usually reported, and would be extremely loud in my listening room, and would in fact annoy my neighbors if I tried testing it outside at that drive level. I think it's easier to let the reader figure it out for themselves, since the measure itself has no real meaning except as a poor guide to the efficiency of the loudspeaker (which should be the measure, but has to be reported as a function of frequency). I can say this: the subjective sensitivity of the K-402-MEH is about the same as the Jubilees on each side (reportedly "105 dB/1m" loudspeakers). If I didn't use the DSP crossover to extend the bass response of the center K-402-MEH (because I can...and the difference is spectacular in-room listening), their subjective sensitivity for the bass channel only (since I'm bi-amping) is within ~3 dB of the Jubilees. Does that answer your question? Chris

If you're looking for raw SPL output for live sound, I'd recommend Danley's offerings as they offer robust PA levels of output and generally (such as many in the Synergy series...except the SH-96) arrayability, as well as road ruggedness. [One Jericho per side of a stage is said to be sufficient. See https://www.youtube.com/watch?v=AkrZplo9xgM, replacing 11-box line arrays on each side.] But for home hi-fi use, the loudspeakers we're talking about in this thread are much more suited in terms of their design requirements...and affordability. Chris

If that's true, then there is apparently something else occurring, since the plots do not appear to be symmetric but opposite in polarity. How did you take the measurements? Chris

It turns out that the Cornwall cabinet is about the right size for a slightly smaller (but still full-range) MEH than the full K-402. The K-402 horn itself can be accommodated inside the Cornwall box, with perhaps a small amount sticking out on the front (like Ron's [NBPK402]) or back, (like a Khorn or La Scala K-55/K-400 midrange) to get the full 17.5" depth of the K-402 horn. The compression driver depth (whatever that happens to be for your application) would attach to the horn throat, and increase the depth of the total stack by that amount. So you can say that the K-402 is actually a 36" x 21" horn...with extra mouth flanges that make it easy to seal against a box mounting. If you don't need or use that flange, then the full-size K-402 is 36" x 21" x 17.5". If you are thinking about trying passive crossovers and mono-amping...I think that designing and implementing a correct passive crossover that EQs properly, etc. will take much more effort than the DSP crossover/bi-amping solution. The effort to build a "correct" passive for any controlled directivity horn loudspeaker is non-trivial. Note that PWK built collapsing polar midrange horns (a.k.a., a "pattern flip" midrange horn) in order to avoid having to put EQing (low-Q notch filters) into his passive crossovers because DSP crossovers weren't really available back then. DSP crossovers have really become the preferred approach in terms of affordability and really superb performance within the past 10-12 years. Chris

The off-axis ports apparently affect both axes of polar coverage by similar amounts...according to my measurements. Chris

Yes. That's a good definition of a "full-range MEH". The K-402 (...which isn't 46" wide...) does that, in spades: K-402-MEH horizontal directivity sonogram, normalized to on-axis: Note where this 36" x 21" horn (without flanges) actually loses horizontal directivity (the -6 dB point is the light blue-green color corresponding to ~-9 dB on the right-hand scale). This is a hybrid straight-sided/tractrix mouth flare horn that is sold by Klipsch (i.e., this forum's sponsors). So the answer is that the horn needs to be perhaps 32-35 inches wide x 19-21 inches tall to fit my "full-range MEH" criterion. That size horn will fit into a Cornwall cabinet (see the K-402-MEH thread for a layout from Waslo's Synergy Calc spreadsheet, dual flare). More discussion on that here and here. THere are a lot of people that own Cornwalls, and like them a lot. Here is the loudspeaker type that I own (these are prettier than mine): Note the horns on top. I needed a center channel between two of these, but my room will not permit a third Jubilee in the center (fireplace hearth gets in the way). The K-402-MEH came from that need for a center channel between these two loudspeakers. I found that the K-402-MEH works a lot better than planned. More people are building these now, and we currently have four installations of these loudspeakers, seen to grow to a greater number. I own an SH-50, and have used it between the two Jubilees (which is where I got that data). It sounded good--just like the Jubilees, in fact--but its apparent source width (ASW) is far too narrow to match the Jubilees. My room is 15.5 feet wide, 9 feet tall, and 40 feet long. With the K-402-MEH, anywhere you choose to listen inside the room is good--outside of a 3-feet radius of the loudspeakers at the very front of the room. I think others also see the advantages of that, and they are building their own K-402-MEHs. I think your definition of linear phase is more like "flat phase" instead of what I'd call linear phase. If you look at the excess group delay plot, its really quite flat for a passive crossover horn-loaded loudspeaker (full range). A couple of more plots of the SH-50 vs. the IIR-only Jubilees using a Xilica XP-8080 crossover: That's clear. I don't define what an MEH is. I've merely defined what I mean to be a "full-range MEH" instead. (You can do what you like--as can anyone else.) I'd like to retain my definition because it conveys what I need it to convey-especially to the members in this forum that own and prefer Klipsch products. If you believe that your definition is more valid than mine--then you can certainly feel secure at the forum you post to. I freely share my detail designs and data with others here, not to increase my own standing, but so that others can enjoy what I enjoy listening to. There are very good reasons for defining a "full-range MEH" the way that I have. It's a short hand way of saying that you most likely get the same level of performance as what I listen to each day (all day). If that bothers you, I don't know what to say, except, "go listen to some K-402-MEHs" and/or Jubilees. Chris