Klipsch Klipschorn AK6 loudspeaker

This almost happened 13 years ago. Thinking the time was right for a Klipschorn review—2006 was the 60th anniversary of its design—I got in touch with a Klipsch representative, who requested photos of my room and details of its size and construction style. My reply was followed by a three-day lag in correspondence, after which came the disappointing news: "We're sorry: It won't work." The problem: There were baseboard radiators too near the corners of the room where the speakers would be installed; consequently, the Klipschorns couldn't be snugged all the way against those corner walls—an iron-clad requirement for their use.

I was disappointed but impressed; my contact at Klipsch, who was unfailingly cordial and eager to help, turned his back on a generous helping of free publicity, based on his and his company's integrity: They knew the Klipschorns wouldn't have worked as advertised in that setting. Good for them!

And now I live somewhere else.

That old room wouldn't have worked because the Klipschorn is the rare loudspeaker whose woofer is horn-loaded—yet that horn is completed by the adjacent walls of the 90-degree room corner in which it must be located. Without those surfaces, the horn is cut nearly in half. Why did they make it this way? By omitting from the original Klipschorn two very large, flat expanses of wood, designer Paul W. Klipsch was able to keep its weight down to approximately 150 lb; had it been any heavier—or larger—sales would likely have suffered.

Why did Klipsch bother making a full-range horn at a time when more compact full-range loudspeakers were already appearing on the market? Because among all extant types of loudspeakers, a horn is by far the most efficient—a characteristic Paul Klipsch defended in a 1954 interview: "Why efficiency? Well, amplifiers are cheap—we really don't need high efficiency in a loudspeaker system for the purpose of getting more horsepower output: We could just put more horsepower in from the amplifier. But when we achieve higher efficiency in the speaker, it achieves a lower distortion."


The mechanism, though difficult to perfect, is easy to understand: A loudspeaker driver is a notoriously inefficient thing, owing to a severe impedance mismatch between its diaphragm and the volume of air in the listening room; a horn acts as a transformer between the two, making it far easier for the vibrating diaphragm to get a "bite" on the air. The result is an increase in efficiency so drastic—from approximately 1% or 2% to nearly 50% for a properly designed horn—that the diaphragm's excursions can be kept extremely low, allowing the driver to operate within its most linear range.

The first Klipschorn, which hit the market in 1947, was a two-way, single-cabinet speaker in which frequencies below 400Hz were reproduced by a 12" woofer loaded with a bidirectional folded horn, the mouth of which was, as described above, formed by the space between the Klipschorn's plywood bass cabinetry and the user's corner walls. (In use, said cabinetry was concealed from view and thus left unfinished.) Higher frequencies were reproduced by a permanent-magnet compression driver loaded with a 24"-wide exponential horn made of phenolic-impregnated wood. In the late 1950s (footnote 1), the wooden midrange horn was replaced with a new Klipsch-designed aluminum horn—dubbed the K400—now augmented with a separate, smaller horn mounted within its mouth for the treble range; those two horns now got to share a cabinet of their own, and the bass cabinet's 12" woofer was replaced with a 15" one.

A number of running changes were made in the intervening years. During the Klipschorn's uncannily long run, its drivers have been sourced from various manufacturers, including Universal, Electro-Voice, and others. The filters comprising its crossover network were changed a few times from the gentle 6dB/octave slopes of the original two-way Klipschorn to much steeper slopes in later, three-way versions. And over the years, many small cosmetic details were altered. But according to head designer Roy Delgado, who began his career working closely alongside Paul Klipsch—and has now been with the company for 33 years—"the Klipschorn's low-frequency horn is the one thing that has changed the least. I have modified its design only slightly, only to make it easier to build consistently well—'Tab A goes into slot B' sorts of things."

According to Delgado, his ongoing work with Klipsch's five core Heritage models—the Heresy, the Forte, the Cornwall, the La Scala, and the Klipschorn—is guided by an overarching principle: "I want to do what Paul wanted, not what Roy wants."

One might safely say that recent interest in low-power tube amps has rekindled interest in those models; at the same time, the recent success of hi-fi/vinyl bars, themselves inspired by Japan's long-lived and similarly outfitted jazz cafes, has also rekindled interest in large, horn-loaded loudspeakers. One supposes this is a good time to be young, hip, and devoted to serious listening; not coincidentally, one supposes, too, that this is a good time to be Klipsch.

The company seems to think so: In September 2018, they introduced a new, easier-to-install version of the world's most long-lived commercial loudspeaker. In the new Klipschorn AK6 ($14,998/pair), the bass horn has been completed with the addition of three large MDF panels, plus additional internal bracing. Thus one can accurately describe the Klipschorn AK6, which is 45lb heavier than the standard Klipschorn—production of which has now ceased—as a corner horn that comes with its own corner.

The Klipschorn AK6 is a three-way, fully horn-loaded loudspeaker of considerably greater-than-average size and sensitivity: It measures approximately 53" high by 31" wide and 28" deep, tips the scales at 220 lb each, and is said to require only 1W of power to produce a sound pressure level of 105dB, which is on a par with a jackhammer, a gas-powered chainsaw, and a five-string banjo.

Long before such observations became fashionable, Paul Klipsch was known for suggesting that the sound of music resides mostly in the midrange; for reproducing the approximately 3.25 octaves between 450Hz and 4.5kHz, the AK6 uses a compression driver with a 2" phenolic diaphragm, loaded with an exponential horn molded from rubber-impregnated ABS plastic, with a 16.5" wide by 5.5" high mouth. Installed just above that horn is a far smaller horn—its mouth is 4.25" by 1.75"—molded from fiberglass-impregnated ABS plastic in a Tractrix flare, driven by a compression driver with a 1" phenolic diaphragm. The midrange and treble drivers are mounted inside a 12"-tall upper cabinet, the four stiff rubber feet of which engage with recesses made for them in the top surface of the bass cabinet.


And what a bass cabinet it is! For the most part, the listener sees only a large, unblemished expanse of wood, beautifully veneered, but behind it is a front-firing 15" woofer loaded by an 8'-long exponential horn. The horn's throat begins with a comparatively narrow slot—to increase pressure as well as to conform to the mathematical requirements of the horn's predetermined rate of expansion—before directing the woofer's front wave both straight up and straight down, prior to traveling through the remainder of the horn, which is constructed with dozens of precisely cut plywood and MDF pieces. Portions of the cabinet interior are accessible via side-mounted grillework—as with the grille for the midrange/treble cabinet, these are held in place with magnets—behind which one sees conduits for the internal wiring, as well as the crossover's output and input connectors, respectively, for the midrange and treble driver cables and the cables from the user's amplifier.

My review pair appeared very well-made, their cherry veneer—visible mostly on the front of the bass cabinet and the top of the midrange/treble cabinet—having been expertly flip-matched between the left and right speakers. I have neither the vocabulary nor the color perception to accurately describe the Klipschorn AK6's gorgeous, vintage-inspired grille fabric; suffice it to say, I never tired of gazing at these speakers, with or without a soundtrack. Their styling is as timeless as anything from Stickley, Jaguar, Rolex, or Savile Row.

Installation and setup
I'll draw the curtain of charity over my experiences receiving, unpacking, and assembling the Klipschorn AK6s: On the day they arrived, I was the only one at home, and none of my able-bodied neighbors were available to help. With rain a possibility and nightfall a certainty, I didn't have the luxury of waiting for assistance, so I worked alone, countering the speakers' considerable bulk and weight with a few 105dB outbursts of my own, none suitable for children. The worst of my profanities were directed at the flimsy and unwieldy cardboard cartons in which the bass cabinets were packed, and which are surely good for only a single ride.

Suffice it to say: Unpacking and setting up a pair of Klipschorns requires two able-bodied people and a home in which all doorways between the delivery truck and the listening room are at least 29" wide. Trust me on this.

It took about an hour and a half to get the four separate cabinets unpacked and in the door, after which things went reasonably well. I put felt sliders under the assembled speakers as an aid in positioning them and soon found that the closer they were to the corners of my room, the better these new Klipschorns sounded. This observation is corroborated in the AK6's slim owner's manual, which states: "The Klipschorn (AK6) has a fully enclosed low frequency horn and no longer has to be flush to the corner in order to operate properly. The Klipschorn can now be toed in or toed out to obtain the best imaging. The corner still serves as an extension of the low frequency horn, improving low frequency performance. For best results, Klipsch highly recommends the Klipschorn be placed in the proximity of a corner."

A note about my listening room: It occupies the major part of a single-story addition to my 1936 brick house. Two of the room's four walls are exterior walls, and a third—the wall that adjoins what was once the house's brick back wall—is effectively an exterior wall, making this an extremely sturdy, stiff-walled room. The room measures 17' long by 12' wide, with an 8' ceiling.

I began with the backs of the Klipschorn AK6s a short distance from the front wall—their front surfaces, measured at the centers of the cabinets, were a little more than 3' from that wall, and a little more than 8' apart from each other—and with the speakers slightly toed-in toward the center listening seat. At first, I relied on my reference Shindo Haut-Brion power amp, which uses push-pull 6L6 tubes, operated as pentodes and without feedback, to deliver 20Wpc.

Footnote 1: Actually the early 1960s.—Editor
Klipsch Group, Inc.
3502 Woodview Trace
Indianapolis, IN 46268
(317) 860-8100

Ortofan's picture

... the First Watt SIT-3 and the Quad II Classic.

gcvanwinkle's picture

Many eons ago at a LA NAMM (National Association of Music Merchants) show I was listening to some pro Altec horns that were time aligned playing brass band music at serious SPLs. I turned to the guy next to me and saw that it was none other than Paul Klipsch! The Altec guys noticed Paul so they turned down the volume and motioned him closer as he obviously had some questions. After he left they cranked it up even louder as if to say to Paul "these are what horns are supposed to sound like!". Very impressive demo.

Needless to say, I too would love to see how the modern K-horns would measure properly DSP'd - but I would also like to request that John try to measure a vintage Klipschorn in good condition to see how that compares to the modern version.

jeffhenning's picture

He brought it up, but I said the same thing on a different sight about the Klipsch Forte.

They measured dynamic compression/linearity, frequency response and distortion. They were all very good, but they didn't measure temporal performance.

I expected the temporal performance of this speaker to be very poor and it is. That passive crossover (like all passive crossovers) severely handicaps the design.

Some serious DSP and tri-amping would help this beast out immensely.

There still seems to be some issues with the mid driver that need to be hashed out. The spectral plot shows a lot of break up above 4kHz. Also, the bass cabinet vibrations are a bit concerning as well.

Even so, if you bypassed the crossover and used a digital speaker processor and Dirac Live or DEQX or a Legacy Wavelet, a pair of Benchmark AHB-2 amps for the mids/highs and beefy class D mono blocks for the woofers, you would have a incredibly potent system for around $25K.

Not cheap, but it would outperform the most systems regardless of cost.

I'd love to see what measurements JA would get with an active, DSP'd Khorn.

JHL's picture

DSP is an immensely powerful tool, however its absence in no way conflates with any assertion that passive filters are inherently defective. Put another way, rendering this speaker flat in the amplitude domain is no guarantee that half a dozen key criteria - which are in effect why horns exist - would be improved, if even addressed.

Unless we grasp all aspects of loudspeaker behavior we can't begin to assert that DSP is the panacea armchair advocates claim.

jeffhenning's picture

You are making some inferences about my post that were not implied. So let me elaborate.

• While flat frequency response is preferable, it is not nearly as important as the ability to equalize the group delay and eliminate the phase distortions of a speaker. DSP can do that. Passive cannot.

• Once you have addressed the temporal issues with DSP, the remaining speaker and room related issues are much easier to address with EQ in DSP

• When you are talking about a speaker like the KHorn, the room is part of the equation for its sound. That's what makes it such a brilliant design. Instead of fighting the room acoustics, it works with it. The proviso being that the room has to sound good before you put the speakers in it.

• Passive speaker systems have very little left to offer in improvement. We've watched as the refinements in passive speakers that are affordable have made them really good in the last 40 years. We've also seen idiotic designs like that Wilson Chronosonic monstrosity that move nothing forward in the realm of speaker tech. I own KEF LS50's for my mains in my system. They are fantastic for what they are. Can they be improved upon? Sure. Will it be as great as their active, DSP'd siblings? I doubt it. KEF understands that and they know more about speaker design than anyone who writes here.

• Passive speakers, no matter how good they are, have serious flaws that can never be fixed without DSP. If you are some type of purist who wants to stay with obsolete technology, are you also willing to state that CRT screens and video tape are as good or better than Blu-rays and OLED? That analogy is valid.

• I think that a fully DSP'd, tri-amped KHorn would be awesome and I'd love to hear it after they also bolstered that front panel and got a better mid driver.

• Unfortunately, my basement theater can't accommodate KHorns because of the odd stairs and the weird shape of the room. Neither can my project studio in my dining room.

• A DSP'd, multi-amped KHorn would be mind blowing and further validate a truly great design that should be improved upon for future generations. This speaker's potential has not yet been fully exploited.

• Paul Klipsch was a genius, baby!

JHL's picture

Your points corrected, in order:

-If group delay and phase ever become reliably and commonly moored to sound the field will advance and DSP may cease being the conjectured wonder it is today. Until then assumptions about DSP vs analog filters naturally remain just such conjecture.

-Whether rooms are as critical as conventional wisdom assumes is another argument compounded by conflicts in Objectivist dogma. Whether DSP is easier is therefore moot. Whether it genuinely sounds better is not.

-Axiomatic, although fine horns in theoretically terrible rooms are much better than average speakers in very good rooms, which leads back to the current schizophrenia over speakers in rooms in general. As with measuring speakers, we'll have to solve how we feel about such things in a relative and meaningful sense before we can expect to progress.

-Passive speakers are hardly a comprehensively understood phenomenon, and they're even less a well-developed phenomenon in the casual eye, which casts doubt on the assumption they will automatically be surpassed by moving their filters into another type. Ignorance about real aspects of real things like the very large WMTMW you mention is proof of such assumptions. The same can be said of miniature coaxial speakers. Contrasting them poorly is absolute proof.

-All speakers have serious flaws. A meaningful hierarchy of those flaws - which doesn't exist yet - will naturally run in parallel to a meaningful hierarchy of their respective sound. It just won't replace it, which along with not speculating about either is a key truth.

-Me too. Migrate back up-thread and catch the mention of PK attending a proper horn setup. This is no small thing.

-Whether a DSP'd KHorn would blow the mind is unknown. Whether some would immediately grant it super-speaker status anyway is somewhat less in doubt.

-Fortunately others continue on, with excellent effect.

jeffhenning's picture

A dilettante has given me his dubious expert opinion.

I've now wasted enough bandwidth on this subject.

Have a nice life in your incomprehensibly understood world.

JHL's picture

Expending a small dictionary is one way to appeal for acclaim, but good audio really only asks for reasonable proofs of reasonable concepts. Those who can, do.

The fun part is that while one may simply observe the obvious, he gets to hear it too. I did and I do.

Bogolu Haranath's picture

Some of the listening impressions AD had with these K-horns, could have been due to the required corner placement of these speakers ........ If AD could have listened to the some what similar looking Klipsch La Scala AL5 speakers (reviewed recently by HI-Fi News), his listening impressions might have been different ....... La Scala AL5 don't require room corner placement ..... See also, Klipsch website :-) ........

Bogolu Haranath's picture

The K-horns have more demanding low impedance loads in the mid and upper bass region (see measurements) ....... The La Scala AL5 are not that demanding in this region as per Hi-Fi News measurements :-) .........

Bogolu Haranath's picture

Another choice, without using DSP could be, using SS amp(s) which can handle low impedance loads for bass frequency, and SET tube amp(s) for the mid and high frequencies :-) .........

Bogolu Haranath's picture

AD was trying to drive a fully loaded 18 wheeler Mack truck, with a four cylinder engine, so to speak :-) ........

Jim Austin's picture

Some of the listening impressions AD had with these K-horns, could have been due to the required corner placement of these speakers

As was made clear in the article via an extended quote, corner placement for the new K-horns is not required, according to the company.

Jim Austin, Editor

Bogolu Haranath's picture

May be Jim Austin can tell AD to keep the K-horns for a while, and send him some amps like darTZeel NHB-468 mono-blocs, McIntosh MC462 and may be even the new Parasound Halo JC-5, and tell us how they sound with the K-horns ....... AD could do some follow-up reviews :-) ........

Jim Austin's picture

Too late: Because we needed to take photos for the cover--and also because Art needed to return to his reference system in order to review other stuff, the Khorns were removed promptly and shipped out.

I too noticed that Hervé likes the La Scalas with his big amps (a review of which, by the way, is forthcoming). However, it seems from the measurements, to me at least, that when used with a low-impedance SS amp, the Khorns would be pretty hot. You can see this quite clearly in Fig.5 in the measurements, but it's implied in the impedance plot and is also quite clear fro Fig.4. I don't think the answer lies in using a typical SS amplifier. Rather, that might be the answer, but not by itself. After all, the only other answer is hit-or-miss matching with various tube amplifier impedance curves; try 'em until you find one you like.

This is just speculation, but I'm with those who say that this speaker probably still needs very tight corner placement (despite the new back panels and in contrast to the company's recommendations) and is best used in large rooms where you're mainly listening to the reverberant field. Isn't that how they're usually deployed?

Jim Austin, Editor

Bogolu Haranath's picture

Like you mentioned, the K-horns probably work better with big tube amps like Audio Research reference line or McIntosh tube amps :-) ......

Bogolu Haranath's picture

Since we are talking about tube amps, you could ask AD to review the new 70th anniversary McIntosh MC2152 tube amp ......... MC2152 looks gorgeous ........ Most likely it will sound gorgeous, as well :-) ..........

georgehifi's picture

Those measurements are not what you expect from a $15k speaker, good luck selling these Klipsch today at that price, back in the 50-60's maybe

johnny p.'s picture

..like the Volti Rival speaker. Sub-par test results, great sound, IF driven and set up right.

JA has a long history of (disconnected) test-results and sound.

John Atkinson's picture
johnny p. wrote:
JA has a long history of (disconnected) test-results and sound.

If you have read Robert Heinlein's "Stranger in a Strange Land," you will be familiar with the concept of a "Fair Witness" - someone who describes how things actually are. That is the case with the measurements that accompany the magazine's reviews. They describe what the product is actually doing regardless of whether or not the reviewer likes or dislikes the sound.

The question then becomes: is the reviewer's opinion of the sound due to the measured problems or despite them? To pretend that the measurements must somehow be flawed evades that question and serves no-one.

John Atkinson
Technical Editor, Stereophile

johnny p.'s picture

..there is no constant-correlation between tests and sound. (Many) wide gaps remain. The darTZeel amp -high distortion, best amp ever.

I brought this up at Audio Asylum in a thread called "Those darn measurements" about 2 years ago. And without my intention, posters there said you didn't measure the Volti Rival speaker correctly.

Audio Perfectionist mentioned your cherry-picking style of measuring many years ago.

So, if you're not doing it right OR the debate's been settled, why bother ? What are you trying to prove, decade after decade ?

Bogolu Haranath's picture

Well .... Let me try to defend JA1's various audio products' measurements ........ There are numerous products listed in the Stereophile magazine in the past and present, that measure well and also sound great ....... Most likely that trend will continue for many more years to come ........ Of course, there are going to be some products that don't measure well but can sound great ....... If I have to choose, I will choose those products that measure well and also sound great ........ Stereophile is one of the very few magazines that measures and also listens to the audio products :-) ..........

John Atkinson's picture
johnny p. wrote:
I brought this up at Audio Asylum in a thread called "Those darn measurements" about 2 years ago. And without my intention, posters there said you didn't measure the Volti Rival speaker correctly.

I read the thread. Yes, if someone liked a speaker that didn't measure well, they do say that the measurements weren't performed correctly. There was a comment that said that the Voltis should have had their in-room response measured. However, that wasn't possible.

John Atkinson
Technical Editor, Stereophile

JHL's picture

Given that a loudspeaker will exhibit a dozen key behaviors, its isolated amplitude response and related metrics naturally comprise an incomplete yardstick. This is an absolute surety. A loudspeaker is no more a plot than an automobile is.

Therefore, amplitude responses have without question become sighted bias. These threads of remarks are proof thereof.

This in no way excuses the potential for ham-fisted design, but it is also not the casual critic's claimed authority on good design. The authority on good design is sound, even as annoying as the human element has become of late.

To date Stereophile has done a good job separating hearing from the microphone. The distinction is as notable and important as is the *contrast* between sound and plot. I hope, for the sake of fine audio, that this remains the case. A loudspeaker simply cannot be snap-shotted like too many of us seem to want to believe.

johnny p.'s picture

..but possible to show sub-par results. Like Greg says below, "if you want a speaker that measures the way JA says it should, there are plenty".

In other words, good plots don't equal good sound. Or the reverse with horns, a popular speaker these days. God forbid you review Emerald Physics.

No distortion tests, no polar plots, no tone-bursts, no cavity-noise in db. And now more complaints at Asylum, in thread "Klipshorn's/Art Dudley".

With respect, it seems your goal for the last 30 years is to deceive and confuse, and that you have accomplished..

Bogolu Haranath's picture

As a side note ..... Emerald Physics top of the line speakers can be used with optional manufacturer supplied DSP/EQ/ crossovers ........ They also can be bi, tri and quad amped, and used with subwoofer(s), according to the manufacturer .......... See Emerald Physics website :-) .......

Anton's picture

Art found plenty of sonic issues, do we need to complain about that, too?

"If you want a speaker that sounds the way Art says it should, there are plenty..?"

John Atkinson's picture
johnny p. wrote:
No distortion tests, no polar plots . . .

Meaningful distortion plots are difficult without access to an anechoic chamber, as I have explained in the past. And no polar plots? You are perhaps unaware that every Stereophile loudspeaker review includes a full analysis of the speaker's horizontal and vertical dispersion, in a form that I feel is more informative than a polar plot.

johnny p. wrote:
With respect, it seems your goal for the last 30 years is to deceive and confuse, and that you have accomplished...

Apparently hell hath no fury like an audiophile whose speaker he likes the sound of is shown to have sub-optimal measured performance :-)

John Atkinson
Technical Editor, Stereophile

Bogolu Haranath's picture

".... to deceive and confuse" ......... Oh please JA1, don't run for public office ........ We need you here at Stereophile :-) .......

johnny p.'s picture

..don't do it at all. Why measure speakers in a driveway when it can have a VERY different response than a room ? Same for impedance, the Klipsch shows a scary drop, but is this what happens in a room ?

Toole/Keele/Geddes say that polar plots (or early-reflection directivity index) are important.

Where's the tone-bursts ? And how honest can it be to use (1) amp then blame the speaker ?

But tests are limited -no way to test depth of field, speed, coherence, instrument separation, coloration, etc.

People already struggle with understanding measurements and what you're doing causes controversy. The last thing we need here. (Try DARKO KIH #25 "what do measurements really tell us").

John Atkinson's picture
johnny p. wrote:
Why measure speakers in a driveway when it can have a VERY different response than a room?

It is universally accepted that anechoic or quasi-anechoic measurements are necessary to characterize what a loudspeaker does without it being influenced by the arbitrary and unknown room acoustics.

johnny p. wrote:
Same for impedance, the Klipsch shows a scary drop, but is this what happens in a room?


johnny p. wrote:
Toole/Keele/Geddes say that polar plots (or early-reflection directivity index) are important.

As I said, rather than publish polar plots, I show in detail a loudspeaker's dispersion in both horizontal and vertical planes. This shows the same information as a polar plot in what I feel is a more easily comprehensible manner.

johnny p. wrote:
Where's the tone-bursts?

Every Stereophile loudspeaker review includes the measured step response.

johnny p. wrote:
And how honest can it be to use (1) amp then blame the speaker?

Please reread the measurements. You will note that although I used the same amplifier for this review as I do for all the magazine's speaker reviews, for consistency, I also used Art's Shindo amplifier for one test. Art himself used 3 amplifiers for his auditioning.

johnny p. wrote:
But tests are limited -no way to test depth of field, speed, coherence, instrument separation, coloration, etc.

That's why Stereophile's reviews include both measurements and auditioning comments. Neither on its own gives the full picture of a product's performance.

And FYI, you should check out the Hi-Fi News measurements of the Klipsch La Scala AL5 at www.hifinews.com/content/klipsch-la-scala-al5-loudspeaker-lab-report. Similar to my own findings with the AK6.

John Atkinson
Technical Editor, Stereophile

johnny p.'s picture

Using a second amp for only (1) test, then not renting the use of a semi-anechoic room. This is not science. If your readers think it is, then that's fine.

A step response is not the same as tone-burst or group delay. And for what you do measure, you gave up using a room with smoothing and averaging. Art's driveway, Mike's driveway, even simple science is gone !!

JHL's picture

Great audio has a long history of disconnected test-results and sound. The high end frontier is figuring out how and why.

Anton's picture

Wow, the body disappeared.

I had wondered whether the different amps Art used would have produced difference measurements in JA1's protocol.

It would be interesting to see if there was any correlation between what Art heard and what JA1 would measure.

Scintilla's picture

I had the same thought about using DSP-implemented crossovers as I read through the review and then John just nailed it. Apparently we are all beginning to not just accept the value of DSP in real-world implementations as being an outlier, but that it is becoming "normal." I would add to that though: shame on Klipsch for not seeing that themselves. In this age of cheap silicon and relatively mature off-the-shelfs, c'mon Klipsch, get with the damn program for a $15k speaker! At least offer an in-house designed and optimized optional unit. That's just a shameful lack of vision for such a storied company. What would Paul Klipsch say?

jmsent's picture

......Bullshit! He may have said that in this case. Face it, this is a 1950's era speaker and it shows. It was resurrected to appeal to people who remembered if fondly when it was current, but couldn't afford it. Klipsch already builds far superior speakers to this one, and I'm not all that convinced that a DSP crossover will propel this speaker into SOTA territory. There are inherent problems in the drivers and cabinet that DSP can't fix.

jimtavegia's picture

for telling it like it is, and explaining what a great solution might be. Regardless of the flaws, to me the one thing is that someone could drop serious money on this speaker and never know that their amp is not a great match for this new model. Now they at least know that the amp they use will matter greatly.

The other issue of time delay between units can be corrected and it would be good for Klipsch to be the ones to offer a box solution for their customers, but that is a marketing decision they will have to address.

I trust there are many owners who are not audiophiles who may be enjoying them regardless of the flaws as there are millions who are still content with MP3s and worse. They won't have the EQ problems solved, but to each his own. Now they know what the issues are if they are subscribers.

Still a beautiful product with a solution in sight. I hope someone had the ability to market it.

Ortofan's picture

... Roy Delgado - and, if it's still known, Paul Klipsch - used during the development of the Klipschorn.

kenkirk's picture

I visited the Hope Ark factory back in the early 70's as a teenager. I saw Paul in a sound room working. He was not a super friendly kind of guy. I was hoping to meet him. But I remember seeing the distinct blue faceplate and huge meters of McIntosh gear in the room. And they were playing. And one of the best stereo demos I have ever heard in my life was from a pair of Klipschhorns with a Belle Klipsch center channel driven by McIntosh tube amps, McIntosh preamp and a nice turntable of the day. I think it was a Dual.It was a stereo store in Texarkana Texas. I am sure Paul probably helped them set up the system as they were close to Hope. They played for me ZZtop La Grange at live levels. I will never forget the sound of the drums then the bass and guitar come in and just exploded. Goosebumps on goosebumps. Klipsch done right can be a window into live music. Just huge fun. I had Klipschorns for years. I moved on to Sonus Faber when heard a 3d soundstage from Extremas that just moved me in a different way. But still have a set of Hereseys for parties. :) Very cool Stereophile reviewed these speakers! Ken

Bogolu Haranath's picture

May be they were darTZeel NHB-468 mono-blocs for this latest version of K-horns ...... Who knows? ...... See AnalogPlanet's visit to darTZeel facility :-) ........

May be AD could borrow a pair of NHB-468s, and tell us how the K-horns and darTZeel sound together :-) .........

Bogolu Haranath's picture

Of course, it would be lot less expensive to use McIntosh MC462 (reviewed by Stereophile), if AD chooses to use it, for a follow-up review :-) .........

Bogolu Haranath's picture

Any amp(s) with the first two numbers 46 may work fine :-) ........

Ortofan's picture


Bogolu Haranath's picture

Volti Audio Vittora, reviewed by AD without measurements, looks very similar to Klipsch La Scala AL5 reviewed recently by Hi-Fi News :-) .........

georgehifi's picture

"If I have to choose, I will choose those products that measure well and also sound great ........ Stereophile is one of the very few magazines that measures and also listens to the audio products"

And that's the way all mags should be, not just the reviewers opinion.
After all any audio equipment is made with test measurements and ee calculations, if not, I wouldn't even spit on it, it'll be rubbish.

Cheers George

Lars Bo's picture

Thanks Art. What a gutsy conclusion. Thanks for telling it like it is.

Thanks John. Excellent, informative report. Thanks for telling it like it is.

If body, soul, and musicality were essentially to be found in a lab, things would be different. They're not. I'm not so sure this is a bad thing, really.

SpeakerScott's picture

First let me be clear..it's tough measuring a corner horn like this. But if you're going to do the review...and then publish these measurements....you've got to do better than what was published here.

1. The bass response shows the dramatic ripple associated with too small a mouth area. Keele's work on optimum mouth size (AES Convention 46, 1973, preprint available on his website) shows great examples of the ripple here. While Klipsch has added the back panels meaning the speaker doesn't have to be flush against the wall it still needs the corner loading to finish the horn flare. By measuring it in a driveway you've robbed it of a huge portion of it's bass In a perfect world if you found a large building exterior in the shape of an L and stuck the speaker in the corner you could maintain the flare, and then measured ground plane you would have gotten much closer to the actual capabilities of the speaker. While I understand the practicalities, this should be mentioned in the review.

2. The impedance of a horn speaker depends greatly on the horn loading....it's not clear in the review text if the impedance was measured in room or in the driveway. I suspect you'd have a different result if you measured it in room.

I can't help but suspect they would have significantly better results if they changed the horn flares to account for some of Geddes work on higher order mode creation. There are tractrix flairs available that have significantly better performance than the ones measured here. That would stay true to Paul's desire for good acoustical matching while maintaining better wavefront propagation in the horn resulting in fewer internal reflections and the ragged response shown.


Anton's picture

Thanks for posting that.

Volti's picture

I think JA's testing of the Rivals was pretty much spot on, and looked very much like my own tests. I suspect his testing of the Khorn was also pretty well done, although one would think that a speaker designed to be in a corner should also be tested in one.

I could easily modify the design of the Rival speaker to test better, and it would change the sound of the speaker if I did that. I like the way they sound, and it's not worth it to me to change that sound so that the measurements look better. There are choices I made during the development of the Rival, and the sound I wanted took precedence over the measurements.

Not one single Rival customer would have me tweak the design of their speakers and therefore change the sound, in order for them to test better.

Many of the tests used to test loudspeakers have baselines that are subjectively derived. Someone, at some time in the past, said that a speaker should be more or less flat in frequency response across the bandwidth to be considered "correct". That's a subjective evaluation.

If you want speakers that measure the way JA and others say a speaker should measure, then go buy some. There are plenty of them out there, new and used. Khorns are not that speaker.

All this talk of DSP and tri-amping to change the Khorn into something it is not just seems foolish to me. I would no more try to make a big horn speaker sound like a Tidal/Wilson/Sonus Faber/Magico speaker than I would try to make a Tidal/Wilson/Sonus Faber/Magico speaker sound like a big horn speaker. They are two entirely different things, and if one doesn't suit your tastes, you should buy something different.

Life is too short to messing around with DSP and tri-amping. All that complication does is make you focus more on the equipment and less on the music. Keep it simple. Have Fun!


Jim Austin's picture

It raises several interesting questions, but I'll exercise restraint and keep this reasonably short. First, though, I'll mention that according to the manufacturer, the new K-horn does not require corner placement. Here's the language from the manual: "The Klipschorn (AK6) has a fully enclosed low frequency horn and no longer has to be flush to the corner in order to operate properly. The Klipschorn can now be toed in or out to obtain the best imaging. The corner still serves as an extension of the low frequency horn, improving low frequency performance. For best results, Klipsch highly recommends the Klipschorn be placed in the proximity of a corner." This is precisely what Art did.

Now for the question--I'll limit myself to one. Are you willing to share an example of a specific design choice you made that resulted in worse measurements and better sound? Please don't read skepticism into this, and don't assume it's some kind of loaded question--it's not. I'm merely curious, and I think it would be interesting to others as well.

Quick anecdote: A few months ago, I was with John Atkinson. We were chatting just after hearing a demo of an excellent, modestly priced loudspeaker. I said to him, "It seems to me that the problem of designing a classically well-behaved loudspeaker is basically solved." With heavy MDF cabinets and good engineering, you can have a resonance-free enclosure and excellent frequency response on and off-axis. (I'm talking about frequency-domain; adding in time-domain challenges further complicates things.) And here I'm not assuming any use of dsp. If my observation is correct, then the frontier moves either to fine-tuning--raising the bar on classical performance--or in designing interesting alternatives to the "classic" design.

To be clear, by "classical" I mean not traditional but orthodox from an engineering standpoint: resonance-free enclosures, even, flat frequency response, uniform dispersion, etc.

My Best,

Jim Austin, Editor

Ortofan's picture

... that a heavy resonance-free cabinet was unnecessary if the resonances were relatively low in frequency and amplitude such that they would be masked by the program(me) material?
A few British speaker makers still employ that lossy-jointed, thin (and damped) wall concept of cabinet design.

Jim Austin's picture

That's one approach to speaker design that has stood the test of time, but the "classical" approach I'm referring to is more Floyd Toole.

Jim Austin, Editor

JHL's picture

The constant power, uniform directivity philosophy, coupled with the standard approach to lowering resonance and hopefully distortion, has delivered many a nicely theoretical loudspeaker. Many sound pleasant enough, as they should. There's no evident reason not to seek that goal.

This is because they're roughly the equivalent of raising the automotive bar by way of the onboard computer - instant EFI, timing curves, boost and traction control, and even racer telemetry if you like. Who wouldn't want that; it's all for the good.

And indeed the industry is presently enamored by the average speaker's equivalent of onboard computing in an era when so many speakers are average. The problem arises when everything it appears in ranges only between Toyota and Lexus. There are no outliers, few exceptional exceptions, and especially, less consideration given to all available technology.

Like speakers, this is also fine for cars: We all more or less drive standard transportation (even though we bench-race everything but). We can't be questioned when we listen to $1000 production loudspeakers, even when they run a few times as much. It's the current thing.

Yet for speakers there is an alternative to that school, and it doesn't hinge on brief demos of Accords vs Corollas to teams of amateur listeners in an office park.

Combing the experience of audio pros reveals and confirms that historical audiophile preference has indeed identified good-sounding speakers and for very specific reasons, and not the current trend of what they do in directions other than at the listener. There's a good reason the experienced audiophile prefers what s/he prefers and statistically the audio pro with his decades of hearing agrees.

The speaker field hasn't been entirely well-served by the so-called science of how uniformly the average, frequency-centric speaker energizes a room specifically suited to it. It has, however, been well-served by seeing speakers as transient energy devices, which is how music manifests.

Bogolu Haranath's picture

May be Ortofan likes all those 'Good Vibrations' :-) ...........

Bogolu Haranath's picture

Next thing Ortofan is gonna say is, those 'damping rings' around the vacuum tubes are not gonna make any difference :-) ........

Bogolu Haranath's picture

Well ...... Speaker cabinet vibrations and vacuum tube vibrations are not the same thing, not the same principle :-) ........

Anton's picture

Please don't get yourself too worked up.

Bogolu Haranath's picture

The other Bogolu is my evil twin :-) ........

johnny p.'s picture

...someone got it right, the new editor of Stereophile, no less.

And maybe we're close to a new paradigm. We only lack the light to show us the way...

timbo69's picture

i was a subscriber from 1983-1999,went to 2 Stereophile shows(Santa Monica 1st & San Francisco) K-horn owners were always asking for a review,but JGH&J.A. weren't for it.I bought my Pair in 1983 for 2383.00 tax included.Thanks Art(I know u weren't with the magazine back then)for FINALLY doing the review,BTW wish u had tried with solid state amp or av receiver.that's where the BASS is

Robin Landseadel's picture

Back in the mid-90's, I hung out with a man who installed custom audio systems, had bulk Van den Hul solid-core interconnect. I managed to use some for internal re-wiring of some vintage gear. Another friend gave me a Marantz 8b. I was never all that happy with the amp, the dude with the wire [sorry, can't recall his name, he lived in Berkeley and wasn't Ric Schultz, another 'wirehead'] happened to have a pair of Kilpschorns in an [tiny] acoustically inappropriate room. If you wanted to hear the lower octaves, you had to go to the next room. In any case, he wound up with the Marantz 8b. I still heard everything I didn't like about the amp, but it worked better with the Klipschorns than any thing else on hand to hook up to the horns. I get the feeling that Klipsch speakers want a lot of room. Like maybe a motion picture theater. I think earlier remarks concerning room reinforcement to be pretty on point, and I'd add that the lowest octaves for this speaker really need a big room. I wonder how a minty Marantz 8b would work out with the updated Klipschorn?

There was a shop in Ferndale California, really beautiful all-wood construction, probably built in the early 1900's. The ceiling was two stories high, the floor-plan was open, about 30 feet wide by 50 feet deep. This store had Heresys mounted 12 feet up, made a glorious sound in that room. Not a lot of bass, but everything else was right in place.

I managed to find a pair of bookshelf Klipsch speakers from the 1990s at a yard sale, $15 for the pair. leaner than usual on the bottom but more dynamic than than anything else in the house. There were a lot of speakers to be found at these yard sales, also found Paradigm Titans and a/d/s L400's, but the Klipsch speakers were easily the most dynamic of the bunch.

As it turns out, Klipsch makes my favorite earbuds. The MRSP for the X11i earbuds is $350, BLINQ had them for closer to $100. These are the smallest earbuds I have encountered, designed to go further down the ear canal than typical, with tiny and lightweight drivers. Sound is wide-range and very detailed, possessing nothing like what I would call the Klipsch "House Sound". I find it ironic that the company that produces these monster horn speakers makes tiny, audiophile earbuds.

Anton's picture

Regarding the amps sounding so different...perhaps the screws on the cases were set too tight or too loose?

Jonathan Scull noticed that back in the day, as well! I forget which amp, I think it was a big beast with 17 screws on top?

Bogolu Haranath's picture

Was it 'screw loose'? :-) ........

Anton's picture

Eeerily similar to a J-10 review from the foggy past!

Glotz's picture

and his funky chair and lover?

Great writer...

Anton's picture

Regarding speakers, especially horn speakers, we are likely all familiar with how people talk about being far enough away when listening to allow for better "driver integration," where sounds no longer seem to becoming from drivers that can be spaced pretty far apart.

I think Art and JA, and Mike Fremer in his recent impressions from listening at, was it darTZeel? all landed with noting problems with timing issues. (But they all seemed like rather near field listening experience for this big ass speaker!) I agree with the person above who was suspicious about Art's room size (no matter that Klipsch 'approved') being to small to let the timing issues integrate more favorably. These really aren't, to me, small room speakers. In a big room, the timing issues are masked by the room reflections, etc.

Also, despite the speakers no longer 'needing' a corner...it's pretty obvious that a real corner will extend their predicted bass boundary to a greater extent than a nailed on baffle does. perhaps some accessory wings to expand the new artificial corner the back baffle provides would go a long way to improving the new sonics.

I say all this as a Klipsch lover - I have a pair of heresy and a pair of La Scala speakers and they are lovely.

Tesla one's picture

One paragraph from Mr. Atkinson's measurement section interests me in particular:


I wasn't too surprised by the Klipschorn's limited low-frequency extension despite its size. I was reminded of the impact Acoustic Research's first loudspeaker, with its relatively small sealed enclosure and "acoustic suspension" woofer, made in the mid-1950s. "My measurements showed that my little prototype had better bass and less distortion than anything on the market, yet it was one quarter the size," wrote AR's founder, Edgar Villchur, adding "I thought, 'This has got to be the future of loudspeakers.'" (footnote 3) It was.

It's surprising as it isn't to see JA effectively siding with Mr. Villchur's statements, when the latter is the man promoting his own invention to cater to buyers who're mostly concerned with size and looks. Going on to further claim sonic superiority from a 1/4 size package with low sensitivity is really wanting to have your cake and eat it too. There's no denying the success Mr. Villchur's design spurred for years to come, in that regard certainly the future of loudspeakers, but what's the benchmark here? Realistic sound reproduction, or certainly its approximation hinges on physics of which size, sensitivity and ease are core parameters, and I don't see any of those apply to the AR1 and its same-principle descendants. My gripe with JA (and Mr. Austin) on this is that he fails to realize a smaller, low(er) efficiency and direct radiating speaker isn't an exhaustive reference in and by itself (well-behaved it may measure - "well-behaved" being the operative word here), but a different principle with its own set of compromises.

In all fairness I believe Mr. Atkinson's closing remarks on DSP-compatibility with the K-horn is a constructive approach, but as Greg of Volti Audio pointed out it also takes away "the juice" of what really defines these speakers and has for over 70(!) years now. It's not that I don't welcome improvements made to a design; my own speakers are exactly that of the Klipsch Belle.

Bogolu Haranath's picture

Just another suggestion ......... One or two powered subwoofer(s) could be considered for use with the K-horns ....... The crossover with the subwoofer(s) could be set at 100-150 Hz ......... In that situation tube amp(s) could be used for the mid and high frequencies ....... Those mid and high frequencies would be easier loads for the tube amp(s) .........That configuration also allows for more flexible room placement for the K-horns .......... See Stereophile review of Volti Audio Vittora for example :-) ..........

Bogolu Haranath's picture

The above mentioned configuration could also be used for the Klipsch La Scala AL5 ....... La Scala AL5 was reviewed with measurements by Hi-Fi News :-) ........

Anton's picture

A pair of La Scala speakers mated to a pair of SVS woofers is a thing to behold!

m_ms's picture

With the La Scala's I'd mate them a pair of horn subs - the operative word with this combo being integration! Tapped horns in particular I find to be very successful augmenting the folded bass horn of the Klipsch's. I previously used an SVS SB16-Ultra with my Uccello's (derived from the Klipsch Belle), and shifting to a pair tapped horns has been bliss ever since.

Anton's picture

What brands are there?