On the upper end, distortion seems to limit the DMB-A to about 4500hz. Super low distortion until about 5khz, then up it goes, dramatically. Is this breakup, or is something wrong with my test set-up? There is a few dB dip in FR around 4300hz
Have others noticed the rapid rise in distortion? I wonder: Could it be my settings in ARTA? I have checked advanced Windows settings for mic and speaker through Sound blaster card, are all at16bit/96khz.
I am OK with crossing to a tweeter at 4500hz, I just wonder why I see distortion rise so quickly.
I did get it to roll-off well enough, but that was by using a parallel notch filter---1.5uF/.14mH/30ohm. For some reason, the calculator I used gave very different values than these, so these are the result of trial and error, with measuring.
For others working with the DMB-A: To tame/roll off the low end resonance/ response; here is a starting point that looks good for an 800hz high-pass: 20uFseries cap plus a series notch filter (parallel with the driver): 40uF/1.2mH/3.3ohm
This looked good after measuring/swapping parts; I did not do a simulation.
Too bad it is hard to find “acoustic suspension”(compliant suspension, Fs/Qes below .5) woofers like the vintage AR units nowadays. Seems like Dayton could sell an 8" steel frame for $40-$50 retail, if they wanted to. Maybe the cones/spiders/surrounds that are easily available overseas don't have the characteristics required?
Ported speakers are popular, but I find that sealed lets me hear the deep bass notes more clearly, even though the mid bass may not be so powerful. Dayton, and others, have drivers that work in sealed boxes without DSP, but they roll-off earlier on the low end, and most have more breakup in their upper range. Highly successful vintage 2ways, with larger woofers, tended to have woofers that rolled-off more gracefully on the top end. They did tend to have less distinct mid-range sound though, likely due to more internal damping of the cone material.
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Very interesting project! Will you work out a crossover for a widely available and not expensive 8" bass unit and tweeter? I like the idea of a sealed cabinet.
andyjevens: "Very interesting project! Will you work out a crossover for a widely available and not expensive 8" bass unit and tweeter? I like the idea of a sealed cabinet."
That is a good idea. I know that would be more useful to folks than modifying this old speaker.
I have had these speakers around a long time with a blown tweeter, and they cost very little money when I got them. I re-foamed the woofers, which is typically a very satisfying project---bringing new life to old.
Using two 8" woofers each in sealed 2.5way towers, my friend is getting great bass, but the enclosure is 2x the size of the AR-16, at least. The bass is especially clear and not boomy or boxy. His woofers are (NLA) Vifa poly cones. There should be something similar available now. He used a (to me) novel filling material to achieve lower Fc: activated carbon. It had to be enclosed in cloth bags!
I should first get these boxes working well. I hope to find the time to do it soon. The HIVI DMB-A mid-driver band-pass is the toughest part of this build. The stock AR-16 woofer is very well behaved. The woofer low-pass is not "textbook" 2nd order, it uses a large air core coil to accomplish baffle-step compensation, then has a capacitor shunt to ground near the crossover point. The response drops steeply to 1500hz.
Almost any new tweeter could work OK. I plan to use the SB Acoustics SB19ST-C000-4 3/4" Textile Dome Tweeter- 88mm- 4 ohm. It has smooth response, and generous x-max for a 19mm tweeter. It is inexpensive for what it is. I hope the directivity of the dome mid and this tweeter are similar at 4500hz crossover point. If not maybe a typical 1" dome, or even one of the small "horn loaded" dome tweeters would be good.
That is a good idea. I know that would be more useful to folks than modifying this old speaker.
I have had these speakers around a long time with a blown tweeter, and they cost very little money when I got them. I re-foamed the woofers, which is typically a very satisfying project---bringing new life to old.
Using two 8" woofers each in sealed 2.5way towers, my friend is getting great bass, but the enclosure is 2x the size of the AR-16, at least. The bass is especially clear and not boomy or boxy. His woofers are (NLA) Vifa poly cones. There should be something similar available now. He used a (to me) novel filling material to achieve lower Fc: activated carbon. It had to be enclosed in cloth bags!
I should first get these boxes working well. I hope to find the time to do it soon. The HIVI DMB-A mid-driver band-pass is the toughest part of this build. The stock AR-16 woofer is very well behaved. The woofer low-pass is not "textbook" 2nd order, it uses a large air core coil to accomplish baffle-step compensation, then has a capacitor shunt to ground near the crossover point. The response drops steeply to 1500hz.
Almost any new tweeter could work OK. I plan to use the SB Acoustics SB19ST-C000-4 3/4" Textile Dome Tweeter- 88mm- 4 ohm. It has smooth response, and generous x-max for a 19mm tweeter. It is inexpensive for what it is. I hope the directivity of the dome mid and this tweeter are similar at 4500hz crossover point. If not maybe a typical 1" dome, or even one of the small "horn loaded" dome tweeters would be good.
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The frequency response looks much like what I measured. The distortion in the HIFI Compass graph does not show the steep rise that my measurement had. There is likely something amiss in my measurement set-up. Thanks.
The dip at 4300hz seems very stubborn, so 4500hz remains a promising spot to cross.
Does anyone have experience crossing from a 2" dome around 4500hz? Generally speaking, would a 19mm or 3/4" be as good of a directivity match as a 1" dome? HIVI has a really sweet, inexpensive, 1" (or is it 28mm) dome in the Q1R. I do like the smaller faceplate of the 19mm SB, becasue it brings centers closer, and my baffle space is limited.
Looking more at the HIFI compass directivity/off-axis info, it looks like beaming sets in strongly at 4300hz. So this may be an answer to my earlier question about breakup above 4500hz. The shape of the curves do not so much look like breakup. I am not really sure if the power response does/does not rise above 4500hz, but the beaming seams responsible for the increase in the on axis response above 4500hz. Due to the increase in directivity, it does seem like 4000-4500hzwould be a good place to cross to a tweeter.
I have come up with a 3way passive crossover for my 8” AR-16 speaker rebuild, using the HIVI DMB-A dome-mid. I used the previously mentioned series-notch, but not the parallel-notch for the higher frequency hump. After many, evolving, iterations the speaker now sounds coherent and “relaxed”; or maybe I should say, I feel relaxed listening to it.
The DMB-A was the most difficult mid I have worked with, especially rolling off the top end. I usually try to pick drivers that are easy to work with. I am learning a little bit more about manipulating stubborn areas in drivers though.
Early iterations did not sound right, even when the frequency response looked basically OK. The latest sounds really coherent; and the frequency response in room at 40” is +/- 2dB bumpy, but basically flat. The baffle has some physical time alignment built in, as well as some mild wave-guiding---I am hoping that the imaging characteristic works out OK. I added lots of bracing/stiffness to the stock cabinet.
Sensitivity must be well below 85dB, but the bass is clean and solidly there, at least in my room, which has a mode-related 40hz boost at the listening position.
The DMB-A was the most difficult mid I have worked with, especially rolling off the top end. I usually try to pick drivers that are easy to work with. I am learning a little bit more about manipulating stubborn areas in drivers though.
Early iterations did not sound right, even when the frequency response looked basically OK. The latest sounds really coherent; and the frequency response in room at 40” is +/- 2dB bumpy, but basically flat. The baffle has some physical time alignment built in, as well as some mild wave-guiding---I am hoping that the imaging characteristic works out OK. I added lots of bracing/stiffness to the stock cabinet.
Sensitivity must be well below 85dB, but the bass is clean and solidly there, at least in my room, which has a mode-related 40hz boost at the listening position.
Why do you want to crossover the midrange and tweeter so high? I hardly know any tweeters that can't be separated lower.
In this case, a few reasons:
The mid dome is physically like a big dome tweeter that plays to 800hz without stress. On the upper end it has a big on-axis notch, or dip, at about 4300hz, that may have to do with the shape and height of the dome. It also starts to beam at this frequency.
I wanted to have the mid covering as wide a range as it could,until it started to beam, which looks, from a HIFI Compass article,to be about 4300hz.
Here a quote (from profiguy) from another thread,
https://www.diyaudio.com/community/threads/the-dome-midrange-thread.407105/page-52
which agrees with my design choices on this project. He likes to use an 8” cone below about 800hz for lower mid-range substantiality (my choice of adjective):
“Its important to aim for at least high 100s to 4k coverage by a smaller cone or large dome. Having this critical part of the spectrum come from one driver allows for smoother phase. I do this for all of my 3 way builds and its the main reason I don't usually build anything with a crossover point between 1k to roughly 3.5 - 5k.”
The mid-dome crosses from the woofer near 800hz (this is an approximation), so even at 4300hz cross to the tweeter, the mid is only covering about 2.3 octaves. The mid is almost acting like a "filler mid-driver", overlapping significantly with both the woofer and the tweeter in the mid's range. Also it has proven tough (for me) to get this mid to roll off on the top end with a low passive-components count---I don't like to use lots of parts if I can help it.
One other factor, that I did not anticipate, was that the SB Acoustics 19mm tweeter had a big peak 1000-2000hz (probably boosted by my wave-guide baffle) near it's resonance, when the tweeter had a 2nd order high pass. The peak was very noticeable in the overall FR around 1500hz. Crossing lower would have necessitated a steeper cross, and related to earlier comments here, it was hard to get the mid to roll off quickly to meet the tweeter for a steeper hand-off. The tweeter filter section now has 3 reactive components and a resistor.
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Here is an update after a few weeks of tweaking, and the making of a second prototype:
The box has 19 liters internal volume. 50hz is at the same level as 1000hz (there is a 2dB mid-dip built in, and the cabinet has a bass bump, starting at about 120hz and centered on 65hz; 65hz is about 3dB above the 1000hz level). Because it is sealed, the roll-off is 12dB/octave. Being sealed, 30hz is way down in level, but is still perceivable in music---no port output to mask the really low tones. Bass is tight and articulate. It does not play super loud, but is plenty loud for HIFI use in smaller rooms.
The sealed design seems to integrate nicely with a vintage NHT1259 sealed sub located on the side wall, using only the basic controls on the plate amplifier.
WAVEGUIDES
This current build utilizes a unity wave-guide---which is simply a surround made from a low angle molding that meets the baffle plane at about 1.5” away from the dome mid, and a little closer to the tweeter. It looks more like a picture frame than anything else. The moldings cause the mid to be physically recessed,and thus protected. The woofer is on its own .75" thick, arch top, supra baffle; the top of which forms the bottom side of the “picture frame”. The picture frame side and top moldings simply extend to the edge of the cabinet, with no corner radius. The drivers are fairly close to being physically “time-aligned”, with the mid flange sitting on top of the tweeter flange, which is also covered by a small “waveguide extension” which is part of a 5.2mm panel that also forms a rebate for the mid. There are no flanges exposed----all drivers are in rebates.
Response is very flat through the mids at 10 degrees off axis horizontal, with on axis and 20 degrees horizontal having complementary variations of +/- 1.5dB between 2khz and 7khz. 3khz is down on-axis, and up at 20deg off axis. Adjusting the toe-in should be able to give great results.
I liked the way my mono prototype sounded, but was unsure if a stereo pair would image well. I now have two prototypes that make a really nice sound-stage. There are surely systems that image more precisely, but I find all to be well placed,deep and enjoyable.
No major edge diffractions have been noticed, unless the above mentioned variations between 2khz and 7khz are a result of the "unity-waveguide" features). I had much more trouble with mid dome wave guides that were 7" round and had throats that were close to the dome. I first experimented with loose moldings on a flat baffle and noticed good results in measurements, and no big problems, so the "picture frame" idea came into being. I did something similar on another build, but did actually use a round waveguide for the Dayton DC50FA dome mid.
I had made a 7” round wave guide that worked well on the (no longer available) Dayton DC 50 FA (was the DC50FA a copy of a Dynaudio mid?). I tried the same WG on the DMB-A mid. Due to the fact that it boosted the area below the (stubborn) on-axis dip of the raw driver at 4300hz, it promised to make the DMB-A harder to work with.
I think that the crossover is close to being fully tweaked, but----??? I wanted to cross at 4khz but ended up substantially lower, due to trouble getting the DMB-A to roll off smoothly on the top end.
Take aways:
Moderate sized box, nice bass, but lower sensitivity, maybe 84 or 85 dB. Moderate power handling in the bass.
Very clear mids and highs, not fatiguing. Monitor like detail, with "BBC dip" type response curve.
Approximate physical time alignment of drivers.
Recycled woofers/cabinets, (nice) inexpensive mids/tweeters (SB19STC0004). If all new materials were used, cost might be about $350.00; but since sealed box woofers that play low in small boxes are hard to get now, the cabinet size/extension situation would be different. A rear mounted passive radiator system might come close, though the bass might not be as tight and natural sounding. A PR system would cost more, use a larger box, but would probably be more sensitive and play louder.
The box has 19 liters internal volume. 50hz is at the same level as 1000hz (there is a 2dB mid-dip built in, and the cabinet has a bass bump, starting at about 120hz and centered on 65hz; 65hz is about 3dB above the 1000hz level). Because it is sealed, the roll-off is 12dB/octave. Being sealed, 30hz is way down in level, but is still perceivable in music---no port output to mask the really low tones. Bass is tight and articulate. It does not play super loud, but is plenty loud for HIFI use in smaller rooms.
The sealed design seems to integrate nicely with a vintage NHT1259 sealed sub located on the side wall, using only the basic controls on the plate amplifier.
WAVEGUIDES
This current build utilizes a unity wave-guide---which is simply a surround made from a low angle molding that meets the baffle plane at about 1.5” away from the dome mid, and a little closer to the tweeter. It looks more like a picture frame than anything else. The moldings cause the mid to be physically recessed,and thus protected. The woofer is on its own .75" thick, arch top, supra baffle; the top of which forms the bottom side of the “picture frame”. The picture frame side and top moldings simply extend to the edge of the cabinet, with no corner radius. The drivers are fairly close to being physically “time-aligned”, with the mid flange sitting on top of the tweeter flange, which is also covered by a small “waveguide extension” which is part of a 5.2mm panel that also forms a rebate for the mid. There are no flanges exposed----all drivers are in rebates.
Response is very flat through the mids at 10 degrees off axis horizontal, with on axis and 20 degrees horizontal having complementary variations of +/- 1.5dB between 2khz and 7khz. 3khz is down on-axis, and up at 20deg off axis. Adjusting the toe-in should be able to give great results.
I liked the way my mono prototype sounded, but was unsure if a stereo pair would image well. I now have two prototypes that make a really nice sound-stage. There are surely systems that image more precisely, but I find all to be well placed,deep and enjoyable.
No major edge diffractions have been noticed, unless the above mentioned variations between 2khz and 7khz are a result of the "unity-waveguide" features). I had much more trouble with mid dome wave guides that were 7" round and had throats that were close to the dome. I first experimented with loose moldings on a flat baffle and noticed good results in measurements, and no big problems, so the "picture frame" idea came into being. I did something similar on another build, but did actually use a round waveguide for the Dayton DC50FA dome mid.
I had made a 7” round wave guide that worked well on the (no longer available) Dayton DC 50 FA (was the DC50FA a copy of a Dynaudio mid?). I tried the same WG on the DMB-A mid. Due to the fact that it boosted the area below the (stubborn) on-axis dip of the raw driver at 4300hz, it promised to make the DMB-A harder to work with.
I think that the crossover is close to being fully tweaked, but----??? I wanted to cross at 4khz but ended up substantially lower, due to trouble getting the DMB-A to roll off smoothly on the top end.
Take aways:
Moderate sized box, nice bass, but lower sensitivity, maybe 84 or 85 dB. Moderate power handling in the bass.
Very clear mids and highs, not fatiguing. Monitor like detail, with "BBC dip" type response curve.
Approximate physical time alignment of drivers.
Recycled woofers/cabinets, (nice) inexpensive mids/tweeters (SB19STC0004). If all new materials were used, cost might be about $350.00; but since sealed box woofers that play low in small boxes are hard to get now, the cabinet size/extension situation would be different. A rear mounted passive radiator system might come close, though the bass might not be as tight and natural sounding. A PR system would cost more, use a larger box, but would probably be more sensitive and play louder.
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People here say a lot of things, most if it sounds right on paper but in reality things often play out differently. I hear this claim made a lot about having one driver reproduce the "critical band" for various reasons and I really feel it's a hold over from days past. IME I find really no basis for this claim to be true and it seems like it still permeates as a way to fulfill ones obsession with a particular speaker metric, while ignoring others.
The best sounding and I'd argue most accurate speakers I've heard come from brands like Genelec, Nuemann, March Audio, KEF, Dutch and Dutch, and a few more. All of these speakers are very highly regarded and exhibit performance that backs up the subjective experiences people have with them. Speakers from these companies have their crossover points within that "critical band" and yet they simply sound phenomenal and very coherent.
My personal expereince with filter design does show that taking a xover point too high has some pretty audible negative effects, and lowering it if possible provides some fairly obvious benefits. DSP crossovers makes for pretty easy comparisons if one has that available.
I have crossed some 4" cone mids as high as 3500hz, often so that I could use a 19mm tweeter and be able to play the system loud. The most successful used a tweeter wave-guide to (hopefully) match dispersion around crossover.
In the case of this present build, it looks like the cross is about 3300hz, from the 14dB dip in response when the tweeter is reversed. The dip is not very sharp, more U-shaped than V-shaped, so I guess that I might want to investigate phase a little further??? It was sharper until I rolled off the woofer earlier/faster and also raised the level of the mid-dome substantially. I do really like the way it sounds now, but maybe it could get better.
@wafflesomd I've learned the hard way to keep my distance from specific individuals who tend to antagonize others based on whether they agree or disagree with those who have strong opinions. Evenso, I'm going to add my 2 cents here.
I have experience with most of the monitors and speakers you list, some of which are touted as being "best" sounding and accurate. I've owned the KH120s and didn't care for their "processed" sound, particularly in the mids. They also weren't very reliable (besides the point) and didn't respond well to any larger amount of dynamic material.
My so called obsession with one speaker metric is based on the identification of the most significant flaws and shortcomings of most modern 2 way monitor designs. The same goes for speakers designed mainly for casual listening,, where a certain flavor of FR deviation is acceptable or even preferred. With that said, I'm going to mainly focus on 2 way, monitor type speakers.
On your typical 2 way with 6"+ woofer and 1" dome having the crossover right smack in the mids between 1 - 3k is a major problem. For someone who knows what to listen for, this is highly audible at higher playback levels, regardless of how well the tweeter measures distortion wise. One reason for this is the tweeter's lack of a double suspension. At higher excursion levels closer to Fs, most dome tweeters start to show rocking behavior and other non linear motion. The only fix for this is either a higher crossover point or lower the playback volume.
The above applies to most 2 way systems with a 1" HF dome that crosses under roughly 3k, regardless of filter being employed. A WG can help, but only if its used to support a set crossover point and not for pushing the tweeter HP further down. Of course the WG corrects the directivity mismatch, which is the reason it should be used in the first place. When designing any speaker, the highest priority should be placed on the midbass or midrange. Some people choose the tweeter first, which makes little practical sense for a several reasons and makes for a more complicated crossover design. This also can lead someone to choose a midbass driver that has a rather compromised FR which needs to be hammered into shape with DSP. What most people overlook is the tendency for sharp breakup resonances and other weirdness to remain audible after flattening the FR. That usually ends with a monitor design that has ear fatiguing qualities and harsh midrange as the SPL goes up, even if the resonances are deemed as being linear in nature. This could be avoided by selecting the midbass first and focusing on a flat FR with minimal resonances or other hard to correct anomalies.
As far as my main point goes, I can guarantee that just about any well designed 3 way system that avoids crossing in the 1 to 4k range will outperform most 2 ways that cross between 2 - 3k. This is considering the use of similar quality drivers which perform equally well in their chosen band of operation with similar distortion specs along with similar off axis linearity. The performance comparison becomes much more evident as the output levels go up. In most monitor settings this is at least equally as important of a requirement as is a reasonably wide listening window.
If anyone is obsessing with one specific metric over anything else, it always appears to be off axis linearity. On your typical 2 way 6 + 1 monitor, that usually means sacrificing midrange dynamics, power compression and poor transient response (especially when using steep filters).
Placing priority on one specific parameter of performance means compromising in other areas. There's no way around this. Everyone has their own specific pet peeve they tend to focus on. For myself, that's the typical cookie cutter 2 way speaker that falls flat on its face in the mids when asked to play loudly. The problem worsens with larger LF drivers, further pushing the tweeter to its limits. Larger domes can help, but these sacrifice top end extension and dispersion.
All this and more is why I don't bother building 2 ways anymore that use 1" domes and woofers larger than about 5". The exception is being able to cross at or above 3k, which means sacrificing a reasonably minor amount of directivity and dealing with a small depression in the mids. That at least doesn't sound nearly as bad as an audibly complaining tweeter.
All this is why I prefer to build 3 way systems which allow for crossover free 1 - 4k. And yes, having that range come from one driver with minimal phase error and vanishingly low distortion is a big deal, much more so than perfect directivity.
Trying to argue about what levels of HD are acceptable or audible when deciding on how low the tweeter HP can be pushed is highly arbitrary. Some people are more bothered by specific amounts or combinations of HD than others, so what's "good enough" for one person can be unacceptable to someone else. I don't need the so called "experts" telling me what I'm supposed to like or tolerate based on questionable statistical averages or group studies. That sort of thing borders on the line of politics, which I choose to not participate in.
I have experience with most of the monitors and speakers you list, some of which are touted as being "best" sounding and accurate. I've owned the KH120s and didn't care for their "processed" sound, particularly in the mids. They also weren't very reliable (besides the point) and didn't respond well to any larger amount of dynamic material.
My so called obsession with one speaker metric is based on the identification of the most significant flaws and shortcomings of most modern 2 way monitor designs. The same goes for speakers designed mainly for casual listening,, where a certain flavor of FR deviation is acceptable or even preferred. With that said, I'm going to mainly focus on 2 way, monitor type speakers.
On your typical 2 way with 6"+ woofer and 1" dome having the crossover right smack in the mids between 1 - 3k is a major problem. For someone who knows what to listen for, this is highly audible at higher playback levels, regardless of how well the tweeter measures distortion wise. One reason for this is the tweeter's lack of a double suspension. At higher excursion levels closer to Fs, most dome tweeters start to show rocking behavior and other non linear motion. The only fix for this is either a higher crossover point or lower the playback volume.
The above applies to most 2 way systems with a 1" HF dome that crosses under roughly 3k, regardless of filter being employed. A WG can help, but only if its used to support a set crossover point and not for pushing the tweeter HP further down. Of course the WG corrects the directivity mismatch, which is the reason it should be used in the first place. When designing any speaker, the highest priority should be placed on the midbass or midrange. Some people choose the tweeter first, which makes little practical sense for a several reasons and makes for a more complicated crossover design. This also can lead someone to choose a midbass driver that has a rather compromised FR which needs to be hammered into shape with DSP. What most people overlook is the tendency for sharp breakup resonances and other weirdness to remain audible after flattening the FR. That usually ends with a monitor design that has ear fatiguing qualities and harsh midrange as the SPL goes up, even if the resonances are deemed as being linear in nature. This could be avoided by selecting the midbass first and focusing on a flat FR with minimal resonances or other hard to correct anomalies.
As far as my main point goes, I can guarantee that just about any well designed 3 way system that avoids crossing in the 1 to 4k range will outperform most 2 ways that cross between 2 - 3k. This is considering the use of similar quality drivers which perform equally well in their chosen band of operation with similar distortion specs along with similar off axis linearity. The performance comparison becomes much more evident as the output levels go up. In most monitor settings this is at least equally as important of a requirement as is a reasonably wide listening window.
If anyone is obsessing with one specific metric over anything else, it always appears to be off axis linearity. On your typical 2 way 6 + 1 monitor, that usually means sacrificing midrange dynamics, power compression and poor transient response (especially when using steep filters).
Placing priority on one specific parameter of performance means compromising in other areas. There's no way around this. Everyone has their own specific pet peeve they tend to focus on. For myself, that's the typical cookie cutter 2 way speaker that falls flat on its face in the mids when asked to play loudly. The problem worsens with larger LF drivers, further pushing the tweeter to its limits. Larger domes can help, but these sacrifice top end extension and dispersion.
All this and more is why I don't bother building 2 ways anymore that use 1" domes and woofers larger than about 5". The exception is being able to cross at or above 3k, which means sacrificing a reasonably minor amount of directivity and dealing with a small depression in the mids. That at least doesn't sound nearly as bad as an audibly complaining tweeter.
All this is why I prefer to build 3 way systems which allow for crossover free 1 - 4k. And yes, having that range come from one driver with minimal phase error and vanishingly low distortion is a big deal, much more so than perfect directivity.
Trying to argue about what levels of HD are acceptable or audible when deciding on how low the tweeter HP can be pushed is highly arbitrary. Some people are more bothered by specific amounts or combinations of HD than others, so what's "good enough" for one person can be unacceptable to someone else. I don't need the so called "experts" telling me what I'm supposed to like or tolerate based on questionable statistical averages or group studies. That sort of thing borders on the line of politics, which I choose to not participate in.