Infinity Kappa 600 floorstanding loudspeaker. (Components).

Manufacturer: Infinity, 250 Crossways Park Drive, Woodbury, NY 11797; 800/553-3332; www.infinitysystems.com

Price: $2,499/pair

Source: Manufacturer Loan

Reviewer: Glenn Strauss

This handsome, beautifully crafted loudspeaker is capable of highly focused, accurate musical reproduction. It has bass extension into the low 30s, flat amplitude response, and excellent horizontal and vertical response. Its high frequency response is very extended and linear, so it will need to be carefully matched to the room for best results.

The Kappa 600 tops Infinity's latest incarnation of the Kappa moniker, which has graced speakers in the top echelon of the marquee's line for many years; today, it stands below the Prelude MTS and the Intermezzo in the Infinity pecking order. Although the new Kappa line has only been offered in the USA since the summer of 2002, it has been available in Europe and Asia for quite a while. It is a good example of the value that a vertically integrated manufacturer like Harman International can offer: French drivers from their Audax facility, a beautifully sculpted design with choice of three real wood veneers, and precise woodworking and assembly in Denmark.

The sample pair was finished in a flawless cherry (black ash and lightly stained maple are also available). Each has a titanium-colored faceplate that wraps partially around the top and sides, and a matching grille which minimizes sonic interference. The cabinet is nicely rounded to the sides of the front firing midrange and high frequency drivers to reduce diffraction: only the back and bottom are squared off. The vented box is made of 3/4" MDF, with a 1 1/2" front bezel, and is well braced and damped, passing the knuckle rap test with a solid thud.

The midrange and tweeter are separated from the woofer, housed in a separate section which takes up the upper half of the box. Open-cell foam is used for internal acoustic damping, and the drivers are shielded for use near video monitors. Unusually, the crossover is also housed in the upper section, and my examination revealed it to be made of high quality parts: metallized polypropylene 5% film capacitors for the mid and tweeter networks, non-inductive power resistors, etc. The internal wiring is 12-gauge rope-lay cable. The rear-mounted port is three inches wide and six inches long, flared on the outside, and located at the top of the bass chamber. Infinity specifies frequency response of 30Hz - 27kHz +/- 3 dB, dimensions of 37-3/8"h x 8-11 /16"h x 16-3/4"d, and shipping weight of 72 pounds.

All of the drivers in the Kappa 600 use Infinity's Ceramic Metal Matrix Diaphragm material, a ceramic sandwich with an aluminum filler. Infinity's excellent White Paper on these drivers claims they provide ideally pistonic behavior without energy storage side effects. Bass is handled by a 10" side-mounted woofer with a thick roll surround and generous excursion capability. The side mounting requires a fairly low crossover to the midrange, in this case 100 Hz, since a crossover point into the lower midrange would compromise dispersion and image specificity. Mids are handed off to a 6.5" midrange, while highs above 3kHz are rendered by a 1" dome tweeter. Crossover slopes are 4th-order. The side-mounting of the woofer allows for a narrow front panel, while the depth of the cabinet provides adequate volume (about 1.1 cubic feet) for deep bass with reasonable sensitivity 90 dB/2.83v/ 1M). The impedance is rated at 6 ohms.

The speakers are supplied with 8mm spikes. For cosmetic improvement, I utilized a set of StarSound Audiopoints (I do not subscribe to the "spikes changed my life" club). Spikes do provide stability and leveling capability on thick carpet or sagging floors, and the Audiopoints are beautifully made, and made to last.

Listening Tests: I performed my listening tests before measurements, as I always do to minimize any techno-geek biases. Associated equipment included the InnerSound pre-amplifier and amplifier, rated at 300 wpc/8 ohms, as well as a mid-line JVC A/V receiver with 100 wpc.

It was apparent from the outset that the Kappas had outstanding dispersion laterally and vertically, and it was easy to get acceptable imaging and tonal balance in numerous placements. I ended up placing them with only a few degrees of toe-in, about 36" from the front wall, 48" from one sidewall, 30" from the other (all measurements relative to tweeter center); the speakers were 7' apart, and 10' from the listening position. My listening chair puts my ears at about 36" height, a typical distance. This placement yielded an unusually panoramic sonic picture, the best I have achieved in listening room 2. Images were high and wide, particularly satisfying on orchestral material, yet capable of subtle audio placement cues from well-recorded jazz--a great start.

I was also impressed with the focus and transient detail of the Kappa 600s. They excelled at preserving the transient demands of piano, harpsichord, vibraphones, and the like--those C.M.M.D. drivers really do seem to deliver the goods in avoiding the smearing effects of cone flex while adding no artifacts of their own. Bass was powerful, a bit plump perhaps, but satisfyingly deep and smooth, with excellent mid-bass detail. Some might prefer less bass extension and a tighter damping profile, however. I was particularly impressed with the midrange driver, as it had to cover nearly 5 octaves, and did so with a seamless quality and no sense of strain, although I did note some minor compression effects in the upper bass on loud, sustained classical organ pieces.

The blending of the drivers was first-rate, indicating care in driver selection, placement, and crossover design. My acid tests for driver blend include pedal steel guitar and vibraphone, where the frequencies rapidly slide over the mid to tweeter crossover points with lots of harmonic content. Any anomalies here will be perceived as a change in timbre, a movement of the instrument in the virtual soundscape, or a "phasey" quality, as if the leads were reversed. The Kappa 600 did very well in the stand-up, sit-down test, and provided an outstanding sense of center fill even when sitting well off the center point. This would be a terrific speaker for use in a home theater, as it will provide acceptable spatial information even for those sitting on the end of the couch.

Measurements: The vented box is tuned to about 32 Hz, with a slightly under-damped profile. The woofer minimum excursion point is in the mid-30s, and the port's maximum output is around 50 Hz. The summed bass response at a number of close proximity measurements locations is admirably flat and extended, with useful output just below 30 Hz. This is excellent performance for a reasonably sized floor-standing loudspeaker with moderately high sensitivity (I estimated 89 db/1W/1M). It is an easy load for any good amp or receiver capable of driving a 6-ohm load. Impedance peaked at 19 ohms at 50 Hz, and reached a minimum of 3.5 ohms at 280 Hz. Over the range 75-250 Hz, impedance was in the range of 4-6 ohms; in the upper and extreme treble, it stayed in the mid-4 ohm range.

I measured the speaker both in-room and outside using several techniques: near-field bass measurement of the woofer and port, 1-meter frequency response sweeps using 1/12 octave FFT, and warble-tones using sine wave and warble tones measured with a precision SPL meter. The speaker measured beautifully, within the limits of my measurement system, which is about 1.5 dB. From about 1 kHz to the high treble, the room-averaged FFT measurement showed the system to be commendably flat, although the treble range above 3 kHz was a bit higher in level relative to the 400-500 Hz range.

The power response was also quite excellent. The overall response profile stood up well out in excess of 45 degrees off-axis horizontal, and to about 15 degrees vertical, with only a small dip at the treble high-pass.

Distortion measurements at 90 dB at 50 Hz looked fine, but not earth-shatteringly low. Distortion in the higher ranges was totally inconsequential. The crossovers were extremely close to the specified points, indicating a well-designed and tightly controlled network.

I did detect some cabinet resonance in the 100-120 Hz range. This might be explained by the observation that the mounting baffle is thinner here than the rest of the cabinet in order to allow the grillcloth to fit flush. It also may account for the somewhat overripe bass quality I noted in the listening tests.

I found the treble range somewhat more prominent than other speakers used in Listening Room 2, which is moderate in size and somewhat sparse in its furnishings. Well-engineered speakers like this one can be challenging due to their uniform power response, which may result in an excess of room energy in the treble unless your room is very large or has lots of furniture. (Indeed, my reference Waveform Mach 17s warn of this in the owner's manual, suggesting the speaker can be too bright if the listening room is not properly damped. With the Mach 17, it is a simple matter to dial back the treble control on the electronic crossover, which attenuates the frequencies in the mid treble and above). With the Kappa 600, one can either use a light hand on the treble tone control or equalizer.

As a control, I also auditioned the Kappa 600s in Listening Room 1, which contains my reference Waveform Mach 17 loudspeakers. This room has extensive acoustic treatment, and is considerably longer than Room 2, which puts my listening position closer to the far-field. Here, the treble balance was nearly perfect, with the added detail on quality recordings only occasionally offset by the sibilance of "juiced" pop recordings. Compared to the Waveforms, the Kappas acquitted themselves well in terms of frequency balance and soundstage, a testament to their outstanding dispersion characteristics. The Waveforms were free of any compression effects, and simply provided a clearer window to the music, with the effortless resolution of dynamics and revelation of fine detail that separate great loudspeakers from very good ones. By comparison, the Kappas sounded a bit more veiled. But at their price, that is as it should be. The fact that the Kappas also filled this large room with clean, solid musical reproduction validates their engineering competency and fitness for use in an excellent music or theater system.

The strengths of this speaker are formidable: beauty, quality of materials and assembly, very high performance, and part of a line which includes a center channel and smaller companion speakers to form the basis of a topnotch music and video system. While I made a point of the tweeter voicing issue, it is one that varies in criticality from one person to another, but is part of the musical range that can be the deciding factor between a decent loudspeaker and an outstanding one. I can comfortably recommend the Kappa 600 with the stipulation that you listen well and long before making your decision. Rest assured that it is a properly engineered and crafted transducer, free of the audiophile "tweak" protocols: no bumped-up mid-bass, no shelved mid-treble to add "depth," no excesses of construction that only drive up cost. The Kappa 600 bears the fruit of Harman International's global resources, including its esteemed human resources under the leadership of Dr. Floyd Toole. One wonders what Infinity has in store for us in the future ...