Klipsch Forte III loudspeaker

I'm fortunate to have reviewed in recent years not one but three different pairs of horn-loaded loudspeakers. My jaw dropped when I reviewed what would prove the finest loudspeaker to ever grace my home, the Volti Audio Rival. Second came a pricey but pleasing pair from handlebar-mustache king Gordon Burwell, the Burwell & Sons Homage. Then, at the urging of occasional Stereophile contributor Steve Guttenberg, I took on the fat-boy Klipsch Heresy III. As the Beatles used to say, I was dead-chuffed.

Horn-loaded speakers achieve what few conventional cone-only speakers can: reproduce the note-perfect timing, rhythmic energy, and blood-pulsing impact of the real event. With their high sensitivity ratings and low power requirements, horns deliver music faster, like a skier blasting off a jump at warp speed: There's no drag, no lag, no confusion—just jumpin' jiminy dynamics at practically every volume level.

Though horn-loaded loudspeakers began showing up in movie theaters as early as the mid-1930s, credit goes to Paul W. Klipsch for creating some of the earliest horn designs for home use. The biggest and most famous of these arrived in 1946: the still-popular Klipschorn, for which Paul Klipsch was awarded nearly two dozen patents.

Designed and manufactured in Klipsch's Hope, Arkansas, factory, where the company's manufacturing arm remains, the K-Horn has been in continuous production for over 70 years, a feat no other speaker manufacturer can claim. The three-driver K-Horn is, or was (footnote 1), open-back, folded-horn design. When the speaker is positioned tightly in a room's corner, the floor and converging walls become part of the horn and contribute to low-frequency gain. Single-ended triode (SET) amplifiers are known for making K-Horns sing, and tube aficionados prize the speaker for a measure of efficiency—electrical sensitivity combined with impedance characteristics that ease drivability—that contributes to a lifelike dynamic range. Some of the same principles embodied in the Klipschorn—and, one hopes, many of its performance characteristics—are found in an old-new member of the company's Heritage line, the Klipsch Forte III ($3998/pair). Introduced in 1985 as the Forte and relaunched in 1989 as the Forte II, this floorstander faded from the line but was reintroduced in 2017, just in time for a new SET renaissance!

Everything old is new again
The Forte III is a three-way design measuring 36" high by 16.5" wide by 13" deep and weighing a solid 72 lb. The manufacturer's specs include a frequency response of 38Hz–20kHz, ±3dB, a sensitivity of 99dB/2.83V/m, and an impedance described as "8 ohms compatible." A newly designed steep-filter passive network crosses over at 650Hz and 5.2kHz. Tweeter and midrange drivers are, respectively, Klipsch's new K-100-TI 1" titanium-diaphragm high-frequency compression driver loaded with an ABS Tractrix K-79-T horn and a new K-70 1.75" titanium-diaphragm midrange compression driver on a new Tractrix K-703-M horn. Down low, the Forte III's 12" K-281 treated-paper cone woofer, which uses a 3" voice-coil, is supplemented with a 15" KD-15 paper-cone passive radiator affixed to the cabinet's lower backside. Constructed with a Santoprene/rubber surround, the passive driver works purely off the pistonlike air motion of the 12" woofer, addressing frequencies below 65Hz.

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"The radiator works the same as a port," explained Klipsch's principal engineer, Roy Delgado, a 30-year veteran of Klipsch Audio Technologies who initially worked under Paul W. Klipsch himself. "Because of the smaller air volume of the box, the drone (aka passive radiator) offers the advantage of allowing us to adjust compliance. If it's done right, the drone extends the bottom end. Basically you're creating a Helmholtz resonator. You cause the air to resonate at a certain frequency and that extends the bottom end. A drone does the same thing."

At a time when the US is experiencing an outbreak of measles, the Forte III remains au courant by having—you guessed it—Mumps. Literally named for the swollen salivary glands they sort of resemble, Roy Delgado's patented Mumps are curved 1" ridges that round off the interior corners within the throat of the K-703-M midrange horn. The goal, according to Klipsch's website, is "to improve coverage and control of the key mid-frequency band."

"Studying various data," Delgado noted, "I noticed that when the directivity index tends to drop, right before the horn starts to lose control of the coverage pattern, it beams, the coverage pattern becomes narrower and starts to wrap around itself like a cloverleaf effect, and the output comes down. I wanted the waves to stay in contact with the horn walls so that when they exit the horn that beaming is eliminated. Working with modeling clay, I noticed that the more clay I put into the corners of the horn, that tended to eliminate that beaming. Usually you avoid that by raising the crossover point, which isn't the most efficient use of the horn. The Mumps allow me to use the horn in a wider bandwidth."

Like versions I and II, the Forte III couples to the floor via a 1" wood base to which four 1/8"-thick round metal footers are attached, one for each corner.

Setup
The Forte III is the most amplifier-sensitive loudspeaker I've reviewed: Careful upstream choices were essential. The Kuzma Stabi R turntable and 4Point tonearm/Hana EL cartridge handled analog; the Tascam CD-200iL CD player with BorderPatrol DAC SE spoke digital, connected by a lm run of Triode Wire Labs Spirit II interconnect. The Kuzma 4Point's dedicated Crystal Cables tonearm cable connected to a Musical Surroundings Phonomena II phono stage, its signals flowing to either a Parasound Halo HINT 6 integrated amplifier, Shindo Allegro preamplifier with Shindo Haut-Brion power amplifier, or Schiit Ragnarok integrated amplifier, through a pair of Shindo interconnects. A lm pair of Triode Wire Labs Spirit II interconnects joined the BorderPatrol DAC SE to amplification. Auditorium 23 and Triode Wire Labs American speaker cables provided juice to the Forte IIIs.

You'd think a stout loudspeaker with two large bass radiators per cabinet would present a setup nightmare, but finding the optimum location for the Forte III proved rather easy. Firing the speakers almost straight ahead, with the grilles off, created the widest and deepest soundstage ever experienced in my Greenwich Village penthouse pad, with absolutely zero honk or nasal whine, common horn complaints. The Forte's rear panel wound up two feet from the front wall.


Footnote 1: After 70 years, Klipsch is retiring the open-back Klipschorn. The most recent model, the AK6, has a fully enclosed basshorn to free users from having to snug their speakers into the corners; a review of the Klipschorn AK6 will appear in our pages later this year.
COMPANY INFO
Klipsch Audio Technologies
3502 Woodview Trace, Suite 200
Indianapolis, IN 46268
(317) 860-8100
ARTICLE CONTENTS

COMMENTS
Bogolu Haranath's picture

May be KM could also review the JBL L-100 Classic speakers ......... L-100 Classics are also about the same price, $4,000/pair :-) .........

Indydan's picture

According to one review.

https://www.hifinews.com/content/jbl-l100-classic-loudspeaker

Bogolu Haranath's picture

I read that Hi-Fi News review ......... We don't know what amp that reviewer used ........ Hi-Fi News measurements of JBL don't look bad ........ Hi-Fi News gave that JBL 'editor's choice' award, anyway ....... It would be nice to get a 'second opinion' from Stereophile :-) .........

Jason P Jackson's picture

On one hand, I'm surprised JBL are satisfied leaving a $4k design measuring that way. On the other hand, I've worked with a manufacturer who insisted on limiting the performance of a less-expensive design, as to avoid the design being "intrusive" toward the upmarket models. Why else would JBL be satisfied with a 5db uptick at 2k? Ouch.

Bogolu Haranath's picture

Those measurements were taken with the MF and the HF controls set at 0 db ......... KH mentions that in the measurements section ......... L-100 comes with HF and MF adjustable controls ....... Listeners can adjust those to suit their preference :-) ...........

Ortofan's picture

... a full-range horn-loaded design.
As mentioned in the review, a "steep-filter passive network crosses over at 650Hz and 5.2kHz" to the horn-loaded mid-range and tweeter.
So, the main radiator of frequencies up to 650Hz - about one and one-half octaves above middle C - is the 12" paper cone woofer.
In that event, how much of the apparent sound quality from the Forte III is a function of the horn-loaded mid-range and tweeter versus the relatively conventional passive-radiator-loaded paper cone woofer?

Bogolu Haranath's picture

May be 'best of both worlds' :-) ........

Bogolu Haranath's picture

JBL also has several different models, which use similar type of cone woofers and horn midranges and horn tweeters ....... JBL also uses that 'hybrid' type of configuration in several of their pro models :-) ......

Ortofan's picture

... rave reviews of such "hybrid" speakers because they are horn-loaded, when that applies to just the tweeter (and midrange) driver(s).

Bogolu Haranath's picture

Ortofan, La Scala is for you ......... Fully horn loaded .........Talk to Anton ....... See below :-) ........

Ortofan's picture

... the following speaker is the one for me:
http://www.vacuumtubeservices.net/TDL_Reference.pdf
http://www.vacuumtubeservices.net/TDL_Reference_2.pdf

Bacek's picture

LaScala bass horn works only till about 100Hz. Below that works like "direct" radiator.

David Harper's picture

kind of amazing that in 2019 an old fashioned conventional horn loaded dynamic speakers-in-a-wooden-box can be described by a reviewer in such wonderfully imaginative terms of sound quality. And only four grand! For 700 bucks a pair of the new maggie LRS speakers would,I suspect,reveal the primitive nature of the aformentioned Klipsch horns.

Bogolu Haranath's picture

We're talkin'about LOUD speakers heer :-) .........

Anton's picture

It's nice to see Klipsch regarded as "Hi Fi" again.

In the millennium prior to this one, Klipsch was anathema among the Hi Fi hoi polloi.

I don't have precise recollection of when Klipsch was welcomed back into the fold, perhaps when Sam Tellig heard a pair during his travels and mentioned it in a column?

I root for Klipsch. Horn loading and high efficiency strike me as the beating heart of getting at 'the absolute sound.'

Thanks for a fun review!

I impulse bought a pair of new Heresy's last year to use in a small loft and love them (observations in the press about occasional HF intensity are correct, by the way,) and my son uses a pair of La Scala speakers with a PS Audio Sprout to FABULOUS EFFECT.

It's nice seeing Klipsch back in the pantheon.

ken mac's picture

Glad you enjoyed the review. I love the Forte IIIs.

Anton's picture

I wanna go hear the new Klipshcorns and La Scala AL 5 speakers, as well!

I also lurk at the Klipsch forums, they have a very dynamic tweak/upgrade community!

About 5 years ago, our club played with a pair of Klipsch corner horns and we attacked two large plywood "corners/wings" to the back of the speakers and then played then in free space, it worked very well!

I am on the Klipcsh website's mailing list...if they ever discount the heritage line like they do the regular line, I am taking a deep dive!

Cheers!

David Harper's picture

and best of all they're really really LOUD!!!! So loud that you may not ever want to listen to anything again.

Bogolu Haranath's picture

May cause 'hyperacusis'? :-) .........

Robert Francis's picture

Nicely written article Ken, I remember hearing a set of Klipschorns at Kenny's Castaway's on Bleecker St., back in the late 80's. From the first note to the last, wow, those babies really sang out and opened my ears to a new level of reproductive high fidelity sound that I didn't think was possible at the time. Of course the living musical waves that resonated out from the large plywood cabinets could only be amplified by a fine vintage, sweet-sounding, and artfully crafted McIntosh tube amp that was well cabled.

The Klipsch/ McIntosh combo creates a sublime depiction of a musical landscape that still lives on within my inner ear. I'm grateful for holding dear to those beautifully sounding sense memories that I recall when an occasion arises. Plain and simple, music, I mean high quality sounding music makes life truly enjoyable in this paradise known as earth. Thanks Ken. You truly are a gifted writer, and you really helped me out all those years ago. Kudos, to you my friend.

Ken? Hmm... I think I subleased your place back in 1990 on MacDouglal Street, I remember a roommate who played a great jazz trumpet as the aroma of Mamoun's spicy fried falafel balls wafted through your place enticing me to indulge... Though, perhaps you're a not the Ken I once knew. Anyway, keep up the great work. I too love the fine art of audiophile grade music as much as you and your esteemed colleagues at the venerable Stereophile magazine enjoy. Cheers.

ken mac's picture

That was surely me, and my apartment, then, thankfully I no longer reside above Mamouns. And the trumpeter was Ken Watters, a fine musician. I remember your name but not your face. Sorry. Thanks for the kind words. I never knew Kenny's had that setup!

Robert Francis's picture

Yeah, it took me awhile to figure out where that amazing sound was coming from at Kenny's. As one walked through the set of double doors, the bar was on the left, and on the right was the jukebox that connected to the McIntosh amp that was tucked discretely on a lower shelf in the sound booth area.

The speakers were up on a platform toward the ceiling at the end of the bar... What a bunch of misfit characters at that place, it reminded me of an old pirate ship. I worked the day bar, and served hot dogs and a beer for a buck, and at night I managed the floor at the Bitter End, a couple blocks to the east. That was a really fun time, we were saving the Bitter End from a rogue outfit of real estate scavengers from Long Island who had plans to suck the life's blood out of Bleecker by gentrifying the spirit out of the place. Needless to say we were set to make a final stand and so Kenny Gorka, Paul Colby and the crew called in reinforcements in a successful attempt to make the Bitters into NYC's only official landmark status dive bar. People like Bonnie Raitt, David Crosby, Judy Collins, Joan Biaz, Kris Kristopherson, Bill Cosby, George Carlin, etc... all showed up night after night to attract the needed PR and I was lucky enough to have been there at that time. What a blast of great memories from the past.

Ortofan's picture

... work/sound with the First Watt SIT-3?
https://www.stereophile.com/content/first-watt-sit-3-power-amplifier

ken mac's picture

would know.

Ortofan's picture

... doesn't like - save for some speakers he once owned several decades ago.

Bogolu Haranath's picture

Is he the opposite of Mikey? :-) .......

ken mac's picture

...products he doesn't like. If he gets in something for review that truly stinks, he returns it. He doesn't want to waste his or the reader's time. I believe that is a correct characterization....

Bogolu Haranath's picture

Wonder how they sound like with the new darTZeel NHB-468? ........ See AnalogPlanet :-) ..........

Bogolu Haranath's picture

SIT-3 may work even better with 101 db sensitive Klipsch La Scala AL5 ........ See Hi-Fi News measurements :-) ..........

Bogolu Haranath's picture

AD could review the La Scala AL5 ....... Should work well with his favorite SET tube amps :-) ........

Timbo in Oz's picture

No, not true.

cyclebrain's picture

"which implies low distortion."
Why don't you do speaker distortion measurements?
Would be interesting to see speaker efficiency vs distortion.
Maybe don't want to show orders of magnitude of distortion between speakers and electronics.

Bogolu Haranath's picture

Hi-Fi News does speaker distortion measurements in addition to the other speaker measurements :-) .......

smileday's picture

I guess it is difficult to measure in low frequency without an expensive anechoic chamber.

Bogolu Haranath's picture

You can read JA1's previously published articles in Stereophile about how he does loudspeaker measurements ....... You can also watch JA1's previous video presentation of how he does loudspeaker measurements at the RMAF :-) ..........

johnny p.'s picture

I just wonder if Ken ruffled any feathers with those who own the O/93. Several on the 'phile staff do and Ken reports that the Forte is more transparent than the Devore. I believe it, but this would be amazing, at the Forte's price.

ken mac's picture

...the generous warmth and easy soul of the O/93s. Those are major qualifiers.

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