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A K-402-Based Full-Range Multiple-Entry Horn


Chris A

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3 hours ago, gnarly said:

Oh, i've never encountered anyone using a passive high-pass for a bass reflex to prevent it from overloading below tuning.

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

 

3 hours ago, gnarly said:

Your post about folks using BR because they continue to use passives took me by big surprise.

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

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Hi Edgar, must say the comparisons you showed don't make  sense to me.

The root.....Why would i want to compare two drivers to one ?

 

Cabinet volume isn't a good reason.  I can build a 170L quality 3/4" BB box for under $100, or even two lower volume boxes (for sealed) for only a bit more $.

Each driver costs 5 -7X that..... so dollar wise, I clearly want to get the most bang per driver.

 

Excursion much below f-3 isn't a good reason, because once response is >6dB down, response is gone imo..

 

Maximum SPL surely isn't a good reason, as that's simply a function of how many drivers. 

 

The impulse responses appear to be simple Butterworth electrical filters, intended to replicate 2nd and 4th order acoustic responses, ....no?

Like i mentioned earlier for single-driver/sub-type comparisons, after you level response to the same f-3, the sealed and vented impulses ( phase traces) look very similar.

 

Of course multiple drivers can eliminate processing needs for sealed, other than having to attenuate the heck out of the high end. 

But what's the point in that. Usable bandwidth imo,  is a function of flat response, that starts from f-3. 

 

IOW, all the extra SPL of the 2x sealed blue trace in your SPL comparison is a so what, ....it's unusable.

Bring the blue trace down level to the green at 100Hz, then which one do you want ? 

Still need that low end boost with sealed, huh? 😃

 

Really, the only way your comparison makes sense to me, is if i were truly box volume constrained....(and not $ constrained at all)

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2 minutes ago, gnarly said:

The root.....Why would i want to compare two drivers to one ?

 

It was just my way of saying that it can never be an apples-to-apples comparison. Sealed boxes have an excursion disadvantage near the tuning frequency of an "equivalent" vented box, but that can be largely mitigated by the fact that you can double the cone area in the same sized box.

 

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... dollar wise, I clearly want to get the most bang per driver.

 

There is more than one way to skin a cat. There is more than one way to optimize a design.

 

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Excursion much below f-3 isn't a good reason, because once response is >6dB down, response is gone imo.

 

Except that rogue excursions below f3 cause modulation distortion, and can easily bottom-out a driver in a vented box unless a highpass filter is used. Such a highpass filter further degrades the impulse response.

 

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Maximum SPL surely isn't a good reason, as that's simply a function of how many drivers.

 

Again, if one takes advantage of the potential doubling of cone area in the same volume, maximum SPL follows. While it may not be important in a home stereo context, it can be very important in sound reinforcement context. (I come from a sound reinforcement background.)

 

Quote

The impulse responses appear to be simple Butterworth electrical filters, intended to replicate 2nd and 4th order acoustic responses, ....no?

 

A filter is a filter is a filter. Doesn't matter whether it's resistors, inductors, and capacitors, or a driver in an enclosure. It's all the same. Neville Thiele and Richard Small figured that all out something like fifty years ago.

 

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Like i mentioned earlier for single-driver/sub-type comparisons, after you level response to the same f-3, the sealed and vented impulses ( phase traces) look very similar.

 

Not possible. A 4th-order impulse response cannot be as well-behaved as a 2nd-order impulse response. The difference is quite audible.

 

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... all the extra SPL of the 2x sealed blue trace in your SPL comparison is a so what, ....it's unusable.

 

Context again.

 

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the only way your comparison makes sense to me, is if i were truly box volume constrained....(and not $ constrained at all)

 

If you want the smallest volume possible, then sealed is the way to go. 

If you want the best transient response possible, then sealed is the way to go.

If you want the simplest enclosure design possible, then sealed is the way to go.

If you want the most bang per driver (or per dollar), then vented is the way to go.

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11 hours ago, gnarly said:

...so dollar wise, I clearly want to get the most bang per driver.

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

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11 hours ago, Chris A said:

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. 

 

 

Gotcha now.  Appears both of were a little surprised by simple misunderstandings in communicating. 

I still don't understand though, why the choice of hpf (passive vs active) to the main speaker would have anything to do with whether to use bass-reflex or sealed.

 

11 hours ago, Chris A said:

 

 

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:

 

 

 

I think getting all the low-end extension possible is the biggest reason for using bass-reflex  in MEHs.  And DSP just makes it easier.

 

Is there any Danley SH-series Synergy that doesn't use BR ports for its woofers?  I don't know of any..

Did you see the Hyperion picts?  Looks like the dual 15" sub drivers are BR too, no?

 

It's really cool you are getting full low-end extension using dual 15"s on the K-402 horn.  Big woofers on a big horn work !

Someday I want to try 15s" or 18"s on traditional straight-sided conical MEHs.

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8 minutes ago, gnarly said:

I still don't understand though, why the choice of hpf (passive vs active) to the main speaker would have anything to do with whether to use bass-reflex or sealed.

 

If I understand this statement correctly, then the answer is that a HPF is generally not necessary with a sealed woofer, while it is often necessary with a bass reflex woofer. And, as I mentioned earlier, the bass reflex design already suffers from poorer transient response than the sealed design, and the HPF makes that even worse.

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9 minutes ago, gnarly said:

I still don't understand though, why the choice of hpf (passive vs active) to the main speaker would have anything to do with whether to use bass-reflex or sealed.

This is from page 420 of Toole's first edition (Sound Reproduction...):

 

Quote

Craven and Gerzon (1992) stated that the phase distortion caused by the high-pass response is audible, even if the cutoff frequency is reduced to 5 Hz. They say it causes the bass to lack “tightness” and become “woolly.” Phase equalization of the bass, they say, subjectively extends the effective bass response by the order of half an octave.

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.

 

13 minutes ago, gnarly said:

Is there any Danley SH-series Synergy that doesn't use BR ports for its woofers?  I don't know of any..  Did you see the Hyperion picts?  Looks like the dual 15" sub drivers are BR too, no?

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. 

 

15 minutes ago, gnarly said:

Someday I want to try 15s" or 18"s on traditional straight-sided conical MEHs.

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

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11 hours ago, Edgar said:

 

Except that rogue excursions below f3 cause modulation distortion, and can easily bottom-out a driver in a vented box unless a highpass filter is used. Such a highpass filter further degrades the impulse response.

 

Sure, of course.  I assume a hpf is a mandatory component of a bass-reflex.  

 

11 hours ago, Edgar said:

 

Again, if one takes advantage of the potential doubling of cone area in the same volume, maximum SPL follows. While it may not be important in a home stereo context, it can be very important in sound reinforcement context. (I come from a sound reinforcement background.)

 

Not sure what you are saying here regarding the importance of cone area to sound reinforcement, as it's a plain given that more drivers, more boxes any type, equals more sound.

And for live-sound its a 98% given that conventional subs will be bass-reflex, not sealed.  By conventional, I mean not horns.

 

11 hours ago, Edgar said:

 

Not possible. A 4th-order impulse response cannot be as well-behaved as a 2nd-order impulse response. The difference is quite audible.

 

 

Agreed. Tis why I only use complementary linear phase xovers....to eliminate even 2nd order (electrically)

 

One thing i still want to impart, is my experience with the sealed's final acoustic order, when response-matched to the bass-reflex. 

(Different cabinet sizes for sure, but single driver comparisons are the  context that make best sense to me.) (And same driver in both.)

I found after bringing the sealed's low-end freq response up to match the bass-reflex f-3 response,  final acoustic order was not much different from the bass-reflex. 

Reason being: Paragraphic boosts altered phase /raised group delay substantially, (albeit without excursion problems if constructed carefully ) 

A series of shelving boosts which didn't warp phase so bad, unfortunately had no limit on how low they boosted and could cause thermal  problems...requiring a hpf just like the bass-reflex.

Both EQ techniques for bringing up the bottom, took away the sealed's  natural second order advantage .

11 hours ago, Edgar said:

 

If you want the smallest volume possible, then sealed is the way to go. 

If you want the best transient response possible, then sealed is the way to go.

If you want the simplest enclosure design possible, then sealed is the way to go.

If you want the most bang per driver (or per dollar), then vented is the way to go.

 

I'd add:

If you want the lowest extension possible, then bass-reflex is the way to go.

If you want lower end extension with less amp power required, bass-reflex is the way to go.

 

If you want the very best with no constraints, get as many sealed as it takes to get the f-3 response you want.....without needing any low end boost.

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44 minutes ago, gnarly said:

Did you see the Hyperion picts? 

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

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35 minutes ago, gnarly said:

If you want the lowest extension possible, then bass-reflex is the way to go.

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

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  • 1 month later...
On 5/3/2021 at 10:14 AM, gnarly said:

I have not found ports in the center to degrade consistent polar directivity/coverage.  Surprisingly not, given the nearly universal opinion that they would.

Some words from Mr. Danley in another forum:

 

Quote

...What i can say is that by comparing measurements of the horns with and without ports, the size and locations were established. It turns out that the corners of the horn are in a low pressure or shadow zone at higher frequencies compared to mid wall locations...

 

This is the conformation that I was expecting to report on several years ago when I designed the K-402-MEH that you see in this thread.  All the Danley Unity™ and Synergy™ horns have the port locations in the corners of the horn, and as I had suspected--there was a reason for this placement--consistently seen in their designs.

 

Chris

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On 6/20/2021 at 12:35 PM, Chris A said:

Some words from Mr. Danley in another forum:

 

 

This is the conformation that I was expecting to report on several years ago when I designed the K-402-MEH that you see in this thread.  All the Danley Unity™ and Synergy™ horns have the port locations in the corners of the horn, and as I had suspected--there was a reason for this placement--consistently seen in their designs.

 

Chris

 

Hi Chris, 

 

I was really glad to see that post of Tom's.  It comes right when I've been exploring port placement and sizes, in another in-depth round of prototyping.

 

The "low pressure zone" in the corners.....

I'm thinking i can take a 1/4" measurement mic and stick it through 1/4" holes in the horn,  located in a corner and in the center, equidistant from the CD.

This will be on a horn alone with no ports it it.  Seems i should be able to measure a SPL difference to get a sense of the low pressure zone effect.

Make sense to you?  Any suggestions?

 

I'm particularly interested in this for the use with smaller mids, to go along with larger low drivers....like in a traditional Danley Synergy.

I'm guessing port location for small mids, may be considerably more critical to the CD's response, since they are so close to the CD.

 

When going straight from a CD to larger cones (12"s, 10", etc), I've measured horns without ports, and then again with ports, for both corner ports and centered. Similar to what Tom described doing.. but by measured, I mean mag and phase, on and off-axis. Like in the Nearly Full Range MEH thread 

 

 

These larger cones, whether ports are in the corners or the center, have required the ports be about 6" inches from the CD.

I simply have not measured any significant advantage of corner ports over centered ports. 

Neither port location,  that far out from the CD,  seems to effect CD response all that much.

 

Mouth termination has had a consistently  much greater effect on CD response.

One big caveat to all that........ those comments are based mainly on horizontal polars....vertical polar experience is much more limited .  

 

i hope to explore verticals more with this new round of prototyping

.

And i must say, the idea of using small mids is intriguing, even when i can go straight from a CD to larger cones.

My gut says the tighter the acoustic packing, the greater the synergy effect. I'd like to tighten up the physical spacing of the 2-300hz to CD xover range.

And then also, using small mids would allow putting the larger low cones further out in the horn for lower loading. (I currently have to keep the low ports within about 6 inches to be able to reach the CD. 

 

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(Please remember that the subject of this thread is the K-402-MEH--and not all MEHs or all design trades.  There is another thread for those discussions.)

 

2 hours ago, gnarly said:

I'm guessing port location for small mids, may be considerably more critical to the CD's response, since they are so close to the CD.

 

I saw the effects of the woofer ports in the K-402-MEH, crossing between 400-500 Hz to the 2" compression driver:

 

K-402-MEH horizonal normalized sonogram.jpg

 

Of course, this was before I knew how change my approach to crossover filters between "ways" on an MEH, so the effect you see above is not what I'm actually seeing in the K-402-MEH nowadays.  This is apparently a "worst case" condition--minimal frequency overlap between drivers via higher order filters. 

 

I now use much more frequency overlap and lower order (actually "zeroth order" without phase growth through the crossover region--then I add back 90 degrees of delay to the woofer channel)--because I can do this without the negative effects of overlapping crossover interference bands in the MEH horn aperture like you get with non-MEH horn designs (i.e., using multiple horn apertures--one per driver--in the traditional sense).

 

But it is instructive to see that the polar coverage effects of off-axis port is scalable with frequency.  Just because they're woofers doesn't mean that the effect is any less important--in fact, it may be more important at the 400-500 crossover region because this is where the ear is apparently most discerning of discontinuities in polar coverage---and one of the reasons why I don't understand why virtually no one pay attention to directivity below ~1 kHz--even Danley seems to be paying only lip service to "full-range" directivity control.  In my listening and (and others at Klipsch in Hope, etc.) it makes a huge difference in sound quality (i.e., much better sound quality) to be able to control directivity below 500 Hz.

 

I have to say that I'm not really that interested in investigating port placement across horn mid-wall areas. Mid-wall is where most of the acoustic wave energy transmission is occurring, while the corners of the horn are somewhat shielded from the effects of acoustic waves. Also, the fact that Danley only uses ports in the horn creases (over a period of 20+ years) tells me something, too. 

________________________________________________

 

Personally, I would rather see a trade on the size of the ports and the acoustic efficiency/flatness of the lower frequency driver response.  In my measurements of the SH-50 drivers (with and without crossover networks), I saw interesting behavior in terms of the SPL response (vs. frequency) that I compared to the K-402-MEH, and found that the K-402-MEH actually exhibits flatter SPL and phase response than the SH-50 drivers do. 

 

2 hours ago, gnarly said:

These larger cones, whether ports are in the corners or the center, have required the ports be about 6" inches from the CD.

This is four and a half inches for the 15" woofers in the case of this thread's subject--not six. 

 

I don't really see the point you're trying to make. It feels like you're going in a direction that I wouldn't choose to go with full-range MEHs ("full range" as defined by myself in this thread).

________________________________________________

 

With the Celestion Axi2050 on a horn the size of a K-402, the crossover could easily be an octave lower than the ~500-550 Hz it is in the case of the prototype K-402-MEH (again to the point--the actual subject of this particular thread...not all MEHs in general). 

 

This means that the woofer ("off axis") ports can be placed 8-10 inches away from the horn throat--which not only pushes down the effects of polar coverage perturbations an additional octave into a much less critical listening band (in terms consistent polar coverage), but it also results in better loading of the woofers within the horn, per this type of effect that Tom D. pointed out in his white paper on Synergy™ horns and tapped horns where placing the woofer and midrange ports a bit further away loads them much more effectively due to the slower taper rate found in the straight-sided horn profile:

 

striaght-sided horn off-axis port loading curve.JPG

 

This is a win-win design trade in my experience.  One apparently wins in two different ways by crossing over an octave lower. The only tradeoffs I see are slightly increased FM distortion of the compression driver (which is still vanishingly low--apparently below audibility) and the reduced ultimate SPL from the loudspeaker due to the increased travel requirements of the diaphragm to reach down to 200 Hz.  The plane wave test results of the Axi2050 leads me to believe that there is still unrealized low frequency performance that's available there (note the overall SPL in this plot from Celestion):

 

AXi-PWT-1.jpg

 

In fact, it may the reason to explore horns with greater depth than the 17" of the K-402, i.e., scaling up the size of the K-402 horn very slightly to see the effects of better woofer loading and pushing down the effects of the crossover frequency to an even lower listening band, perhaps to ~200 Hz . 

 

JMTC.

 

Chris

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I've meant/tried to respect your desire to keep this thread about your 'K-402-Based Full-Range Multiple-Entry Horn'.

 

I guess when you quoted me, when you brought up TomD's post about ports in corners, it seemed like an invitation to discuss that here.

Maybe it would have been better raised/quoted  in the "Nearly Full-Range MEH'  thread ???

 

Anyway, I  completely agree with your assessment of the benefits of lower pattern control (and lower loading). 

And i like the idea of expanding the size of the K-402 a bit to do so.

That was the design goal of my 'syn7' version that tried to copy the K-402's flares, albeit larger in size.  It has 225 Hz horizontal control by Keele's formula, and is 21" deep, mouth to throat.

 

best,   mark

 

 

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Well, usually the trigger for me is when the discussion turns to midrange drivers on MEHs.  That's squarely in the other thread, I think.  Otherwise, this thread is going to continue to grow past its already sizeable portions.  I've found that there really is never a reason to use midranges in MEHs--just substitute a 1.4-->2" compression driver instead and avoid the midranges altogether.  The SH-50 almost doesn't need a midrange--and if Tom D. had used a 1.4" compression driver instead, he wouldn't have needed the midrange drivers (except perhaps for extreme SPL output--which is what he was exclusively designing to).

 

I plan to talk about a Cornwall-sized MEH (the entire front baffle and horns are replaced by a single MEH with probably 1.4-->2 inch compression driver, thus eliminating the need for midrange drivers.  I'll probably put that into it's own new thread--when I can finally get enough "round tuits".  Lately, life hasn't really allowed for any MEH design or building, but I hope that will change in the next month or so.

 

If you read carefully on Tom D.'s comments over on that "other forum" (the one with "science" in the name), you'll see that he started with a SM-60 as the top portion of his new design (basically unchanged) as a home project, and that's the basis of his new "Hyperion".  So I don't believe that he started from scratch with an idea to control directivity from (nominally) 100 Hz, all the way up to 18-20 kHz. That design started on "reuse".  He acknowledges that it loses directivity control below ~500 Hz.  I calculated it might lose directivity at ~400 Hz, but I guess that's in the "splitting hairs" category.  That 400 Hz loss of directivity control is still at too high a frequency for my needs (and those that listen to them, I would bet). Here's the beam width EASE data (-6 dB) for the SM-60M:

 

image.thumb.png.8f33182bbc64c4b9083a0c872973adee.png

 

Here's the same horizontal beam width data for the SH-96 (-3, -6, and -9 dB curves):

 

SH96.png

 

In this thread, the K-402-MEH design started on reuse of the K-402, and leveraged the idea of a larger MEH based on SH-96 proportions, but definitely without using 11 drivers--rather using 3 drivers (two 15" woofers and a 2" compression driver).  The reasons should be clear by now why I took that course. 

 

However, if I were to start with a "clean sheet of paper" design, I'd probably try both a slightly smaller MEH--the size of the Cornwall (discussed above)...and one larger size that's a little larger than the K-402 in order to eliminate the need for extra subwoofers+woofers (i.e., horns can be designed to get about 3.3 octaves of passband, and for woofers, that could be sub-20 Hz to 200 Hz), and use the amazing capabilities of the Celestion Axi2050 full-range driver--at least down to 200 Hz to cover the rest.  That MEH design would get me out of bed in the morning to design and build.  But I get ahead of myself...

 

Chris

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Well, maybe this is a question for another thread.

Since the word "phase" is also used in MEH design, I will post it anyway.

 

On his recent youtube channel Amir from audioscienceforum explains that phase shift is actually inaudible in our room (out of anechoing chamber).

 

Is it really true?

 

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4 hours ago, parlophone1 said:

On his recent youtube channel Amir from audioscienceforum explains that phase shift is actually inaudible in our room (out of anechoing chamber).

 

Is it really true?

Not true in my listening room. 😎  But there are acoustics differences that loudspeakers having "full range" directivity in-room have over what the guy that you mention doesn't listen to.  Three properties are needed to hear phase in-room:

 

1) loudspeakers having excellent directivity control down to ~100-200 Hz,

2) loudspeakers having essentially flat "excess phase" response,

3) room treatments (mostly absorption) just around the loudspeakers--within the first 3-6 feet (1-2 metres) that significantly reduce early reflections within the first 4-8 milliseconds from the direct arrivals from the loudspeakers, and no acoustic reflectors around the listening positions.

 

...then you can "hear phase" in my experience.  More on that subject here: 

 

Chris

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Hi Chris and Mark (Gnarly)

 

This is a very interesting discussion, and also a bit complicated to discuss, depending on what trade-off´s are made/intended?! 

 

14 hours ago, Chris A said:

and one larger size that's a little larger than the K-402 in order to eliminate the need for extra subwoofers+woofers (i.e., horns can be designed to get about 3.3 octaves of passband, and for woofers, that could be sub-20 Hz to 200 Hz), and use the amazing capabilities of the Celestion Axi2050 full-range driver--at least down to 200 Hz to cover the rest.

 

That would be one set af trade-off´s as, I see it. A two way horn-system with a set of woofers to do the 20-200 Hz duty. A. That requires bigger ports to go low. B. the "big 402 horn" does not provide optimal loading for the woofers in the lower octaves, meaning that the modulation distortion can go up!? These are my assumptions, they may not be correct.

 

I have just begun to understand the implication and importance of (inter-)modulation-distortion in my own experience with two big basshorns in my listening-room years ago, due to knowledge conveyed by you (Chris), an the article called "The Mud Factor". I called it the effekt of invisible/weightless bass back then. Today I know/believe it is the absence of modulation-distortion I heard back then! I liked that invisible/weightless bass so very much, in fact I strive to have it in my future system.

 

Therefor I have been thinking of an other set of trade-off´s, a three way system: A "big 402 horn" with Axi2050´s with smaller off-axis ports (and smaller woofers I guess) crossed at maybe 80Hz to some sort of horn-sub-bass that is more optimized for that region of bass, i.e. 20-100 Hz, length and flare-rate. Of course placed in a corner, and it will fill some more space!.  With this set of trade-off´s I would still have full-range directivity with less disturbance from the off-axis ports and lover modulation-distortion in the bass.

 

I do assume that the ports in a MEH do have to be "oversized"/made bigger, to be able to play down to 20 Hz without chuffing. This has been one of the things I have been thinking about for some time. And I guess it has to be remembered here, that the "original K402 MEH" was developed to be a center-speaker, and not for corner-placement! That must must have influenced the choice of woofers and porthole-dimensions? I have often wondered how a K402MEH, optimized to be supported by a Jubilee-bass-bin would have to be constructed?

 

Also I have been wondering, if the woofer-section of the K402MEH is approaching direct radiating bass-reproduction due to less and less hornloading as frequency goes down? I know the K402 is a conical horn and hence has no cut-off as an exponential horn does. You, Chris, have shown illustrations about that before, but is there a point, where the woofers see no hornloading anymore?

 

All that said. The "big 402 horn" as proposed by Chris might just be a very fine and balanced compromise!

 

Regards

 

Steffen

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On 6/23/2021 at 5:28 AM, Supersteff said:

These are my assumptions, they may not be correct.

For reasons I can explain--these assumptions you state just above are not right--if the MEHs are placed within boundary gain in-room.

 

On 6/23/2021 at 5:28 AM, Supersteff said:

I do assume that the ports in a MEH do have to be "oversized"/made bigger, to be able to play down to 20 Hz without chuffing.

No larger in cross sectional area than an equivalent ported subwoofer needs--but MEHs typically use two ports per woofer (except the SH-96, which uses one long port per woofer). The other thing is, MEH ports are very short--not like subwoofer ports, which typically require some length--like a tube.  MEH woofer ports need to be as short as structurally possible.

 

On 6/23/2021 at 5:28 AM, Supersteff said:

...I have been thinking of another set of trade-off´s, a three way system: A "big 402 horn" with Axi2050´s with smaller off-axis ports (and smaller woofers I guess) crossed at maybe 80Hz to some sort of horn-sub-bass that is more optimized for that region of bass, i.e. 20-100 Hz, length and flare-rate. Of course placed in a corner...

I currently own K-402s on top of KPT-KHJ-LF Jubilee bass bins, just in front of 14 Hz TH subwoofers in the room corners, crossed at 40 Hz.  What I found is that the center K-402-MEH, EQed to a -3 dB point of 18 Hz in its elevated center position adds about 2x to the infrasonic bass experience, probably due to being able to "fill up" the anti-node midwall positions of the room with deep bass response. Having 5 K-402-MEHs, each with ~18 Hz (EQed) response would likely be even better, and is still what I'm aiming to do in my listening room. 

 

On 6/23/2021 at 5:28 AM, Supersteff said:

Also I have been wondering, if the woofer-section of the K402MEH is approaching direct radiating bass-reproduction due to less and less hornloading as frequency goes down? I know the K402 is a conical horn and hence has no cut-off as an exponential horn does. You, Chris, have shown illustrations about that before, but is there a point, where the woofers see no hornloading anymore?

That point is about 18 Hz in my listening room, with the K-402-MEH in the elevated above floor center loudspeaker position.  It does even better than my TH subwoofers in terms of freedom from harmonic distortion and phase shift. 

 

Having them in room corners would add significantly to the low bass response and probably deepen the -3 dB frequency.

 

Chris

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