116 August2019nstereophile.com
KLIPSCH FORTE III
measurements, continuedthat you don’t want to resonate,” Delgado said. “Raising
them up will tighten the bass.”
I sourced six BXI Anti Vibration Isolation Pads—these
measure 6" by 6" by 2" and weigh 12 ounces apiece (Ama-
zon, $22.99 per two-pack)—and placed three of these chunky
rubber-and-cork squares in a triangle pattern under each
Forte III. Experiencing one of those epiphanies that
occur when the Gods must be crazy, everything snapped into
focus. I could now hear minute differences in bass-frequency
textures, with some recordings presenting finely layered
slabs of well-defined bass drum, acoustic bass, synthesizer, or
Hammond B3 organ. From classic rock to modern electron-
ica, the Forte IIIs forged beautiful bass waves, defining what
seemed nearly subsonic frequencies with ease.Listening
Pianist Russ Lossing’s Motian Music (CD, Sunnyside SSC
1532) pays tribute to master drummer Paul Motian, joined
by the pianist’s longtime compatriots Masa Kamaguchi
(bass) and Billy Mintz (drums). Like Motian himself, Loss-
ing’s interpretation of Motian’s music is playful, even ram-
bunctious. The Forte IIIs revealed the excellent engineering
of Paul Wickliffe and the acoustic space of his Charlestown
Road Studio in Hampton, New Jersey. Panned right, the
entire drum set had its own distinct stage, each decay,
cymbal ring, and drum resonance part of a larger percussive
whole that poured forth from the Forte IIIs with exhilara-a Parasound Halo HINT 6 integrated amplifier, Shindo Al-
legro preamplifier with Shindo Haut-Brion power amplifier,
or Schiit Ragnarok integrated amplifier, through a pair of
Shindo interconnects. A 1m pair of Triode Wire Labs Spirit
II interconnects joined the BorderPatrol DAC SE to ampli-
fication. 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.
As I played different recordings, I kept thinking the low
end should be better defined, given the woofer’s high cutoff
frequency. The Forte III’s thin footers practically embedded
themselves into the floor, so I slid four 2" by 2" by^7 / 8 " Anti
Vibration Isolation Pads (ribbed rubber with cork center,
Amazon $6.99/4)under each cabinet. General focus im-
proved, as did low-end definition.
A drummer (in his spare time) who well understands how
bass frequencies can bloat, Delgado gave me his blessing to
go further. “You don’t want the speaker to couple too much
to the floor because it will cause some things to resonate
out in the crossover region gets deeper
to the speaker’s sides. However, the
speaker’s radiation pattern is otherwise
well-controlled and even up to 12kHz,
above which the tweeter becomes
fairly directional. In all but small rooms,
this will tend to balance the slight ex-
cess of top-octave energy seen in figs.
3 and 4. In the vertical plane (fig.6), the
on-axis crossover-region suckout ap-
pears to fill in 5° below the tweeter axis
but deepens above it. As the tweeter is
just 32" from the floor and the average
(seated) listener’s ears are 36” high,
the Forte III might benefit from a slight
amount of tiltback. However, as the
suckout is very narrow, it might not be
too much of an issue when it comes totreble sound quality.
Turning to the time domain, the
Forte III’s step response (fig.7) is com-
plicated. All three drive-units appear
to be connected in inverted acoustic
polarity, with the tweeter’s output—
the sharp down/up spike at 3.8ms—
arriving first at the microphone. The
output of the midrange unit is the lazier
downward spike just before 4.5ms fol-
lowed by the slow rise of the woofer’s
output. The decay of the midrange
unit’s step smoothly blends with that of
the woofer, suggesting optimal cross-
over design. The difference in arrival
times of the tweeter’s output and that
of the midrange unit can also be seen
in the Klipsch’s cumulative spectral-decay plot (fig.8). This is fairly clean in
the region covered by the tweeter, but
some delayed energy can be seen at
lower frequencies.
Multiway loudspeakers with
horn-loaded upper-frequency drivers
but a flat baffle can’t be made time-
coincident without the use of digital
signal processing. Does this matter?
Perhaps a more conventional speaker
with time-aligned drive-units would
give better-defined stereo imaging, but
I keep coming back to the Forte III’s
astonishingly high sensitivity, one of
the highest I have encountered. At typi-
cal listening levels, the drive-unit dia-
phragms will hardly be moving, which
implies low distortion.—John AtkinsonFig.6 Klipsch Forte III, vertical response family at
50”, normalized to response on tweeter axis, from
back to front: differences in response 15–5° above
axis, reference response, differences in response
5–10° below axis.Fig.7 Klipsch Forte III, step response on tweeter
axis at 50” (5ms time window, 30kHz bandwidth).Fig.8 Klipsch Forte III, cumulative spectral-decay
plot on tweeter axis at 50” (0.15ms risetime).Time in msData in Volts