Infinity IL60 Measurements, Review System, I N F I N I T Y I N T E R L U D E I L, Sources, Cables

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stored on your favorite record- ings—and, with R.A.B.O.S., do so without obscuring the mid- bass and midrange.

But unlike a top-shelf sub- woofer, the IL60 couldn’t get down to 20Hz and below. It fell slightly short of the best bass with explosive sound effects that are meant to be felt in the stomach as well as heard, and in its ability to convey a venue- size-defining low-frequency “room sound.” But consider-

sitions. Male and female voices were repro- duced (in 2-channel mode) clearly and nat- urally: Female voices didn’t sound thick in the lower registers, and male voices weren’t chesty.

There’s a new JVC XRCD edition of the Takayuki Kato Trio’s Guitar Standards, a recent Three Blind Mice release (TBM-XR- 5041). This Japanese jazz label is known for its good sound, and Guitar Standards, recorded in analog on a 2-track Studer deck, does nothing to damage that reputa- tion. Takayuki Kato plays a Gibson acoustic

on “Estate,” accompanied by Norikatsu Koreyasu’s powerful, sometimes bowed bass and Shota Koyama’s dramatic percus- sion work. The IL60s dealt with all of this impressively, producing a credibly sized guitar image that possessed weight, tran- sient speed, and clarity. The cymbals, struck or brushed, sounded properly crisp and metallic but not hashy or edgy, and the prominent stand-up bass was deep, power- ful, and free of bloat. Switching out R.A.B.O.S. resulted in a rhythmic mess, the bass swelling and receding unnaturally.

With the EQ in, proper proportion returned, accompanied by detail and a fine sense of depth, the percussion sometimes sounding so far back it could have been in the next room.

I listen to a lot of rock, and found that the IL60 was up to that task at very high SPLs, without strain or dynamic compression. While bright, processed recordings sound- ed like just that, the speaker didn’t add its own toxic edge to the mix, and helped to keep sonic pain to a minimum.

But good as the IL60’s performance was,

ing the price, it’s almost as if the mids and highs are thrown in for free.

The midrange’s absence of

Interlude IL36c 3-way center speakerhonky or hooty colorations indicated effective driver tran-

On the other hand, if you’re musical tastes lean toward rock, this system does. Rock.

MEASUREMENTS

The IL60’s minimum impedance is 3.9Ω at

230Hz; a fair rating for the nominal impedance

would be 7Ω . (Because the impedance of most

speakers varies wildly with frequency, the nomi-

nal impedance value is always an estimate.)

The phase of the speaker’s impedance becomes

quite capacitive at 123Hz, which often indicates

a difficult load for an amplifier, particularly in

the presence of a low impedance magnitude.

But the IL60’s impedance magnitude is a com-

fortably high 10Ω at this frequency. This, com-

woofer/line-level input, Lowpass Filter On, R.A.B.O.S. On, and the three associated adjustment pots. There’s also a power switch and an IEC power jack. A front- mounted level control for the subwoofer glows green when a signal is present.

Five connection possibilities are outlined in the instructions, depending on associat- ed equipment. For home-theater use with an A/V receiver, the LFE output is routed to both speakers’ subwoofer line-level inputs using a Y connector, and the sub input is set to Line Level.

The well-written instructions (how many times do I get to say that?) advise you to turn the subwoofer levels to halfway and then listen to music. If the bass sounds thumpy, lumpy, or boomy, R.A.B.O.S. should be used. Otherwise, it can be switched out. As it turned out, there was a serious bump in my room at around 80Hz. Using the optional Infinity-supplied R.A.B.O.S. kit that includes a test CD, sound- level meter, and the Q-Finder device— which lets you correlate the Q, or width of the resonance, to a numerical value used to set the equalizer—I was able to identify the frequency, width, and amplitude of the

room bump. Then, using the three poten-
	REVIEW SYSTEM
tiometers, I was easily able to flatten the
bump. Infinity recommends that you then
use music to set the woofer level as you	Sources
please. The whole process took about 15	Pioneer CLD-D606 LD player
minutes. Though the IL60 is a large speaker,	Camelot Technologies Round Table
I ran my pair as Small, sending everything	DVD player
below 80Hz to the powered sub section	RCA DTC-100 HD digital tuner
through my receiver’s Subwoofer Out jack.	Display
	Philips 55PP9701 55" HD-ready RPTV
Listening	A/V Receiver
Listeners accustomed to the peaky outputs	B&K AVR307
of lesser speakers might at first confuse the	Cables
IL60’s smooth, relatively flat response with	TosLink: Kimber
a lack of transparency, air, and detail. How-	Speaker: Sumiko OCOS (L/C/R,
ever, the more you listen, especially to well-	surrounds)
recorded music, the more you’ll come to	Video: AudioQuest S-video, component
appreciate the IL60’s subtly impressive abil-	Digital: Wireworld, Wireworld Eclipse
ities—especially if you’ve tamed a trouble-	Gold, XLO Reference
some room bump for the first time. While	Misc.
you might hear less bass than you’re used	Audio Power Industries Power Wedge
to, there will be better, more articulate,	116 line conditioner
more tuneful bass from kick drums, and	Terk Pi indoor powered FM antenna
greater timbral and textural accuracy from	Terk AM Advantage AM-1000 indoor
acoustic and electric bass. With the excep-	AM antenna
tion of the lowest organ pipes, the IL60’s
low-frequency response of down to 28Hz
will deliver all the musical bass information

bined with the powered subwoofer, should	Fig.1: Infinity IL60, pseudo-anechoic horizontal
make the speaker suitable for use with most	response at 45° (red) and 60° (blue) relative to tweeter
	axis.
competent amplifiers. The IL60’s sensitivity mea-
sured about 89dB/W/m.
The pseudo-anechoic response of the IL60 at
tweeter height, averaged over a 30° forward
angle and combined with the nearfield
responses of the woofer, is shown in Fig.1
(violet). This is one of the flattest speaker
response curves we have ever measured. The
off-axis curves are also very well controlled—
another sign of a well-engineered speaker.
While the vertical response curves in Fig.2
show a good response at or slightly above the
tweeter axis, below the tweeter (an unlikely lis-	Fig.2: Infinity IL60, pseudo-anechoic response at +15°
tening location for serious listening) a suckout
	(red) and –15° (blue) relative to tweeter axis.
centered at 4kHz begins to appear. The effec-
tive bass response (–10dB) extends down to	at tweeter height, averaged over a 30° for-
30Hz.
	ward angle and combined with the nearfield
The IL36 center-channel’s minimum imped-
	response of the woofers, is shown in Fig.3
ance of 3.3Ω falls at 320Hz, and its sealed

cabinet is tuned to 56Hz. A reasonable nomi-		(violet). While not as strikingly flat as the IL60’s
		curve, it is nevertheless a very competent result.
nal impedance rating would be 5Ω	. The IL36

should not be a difficult load, though the	Just as important, the off-axis curves show little
	sign of the sort of serious response dips com-
amplifier should be comfortable driving 4Ω .
	mon in horizontal center-channel speakers—
The IL36’s sensitivity measured about
	thanks to the 3-way design and its vertically
88dB/W/m.
	configured midrange and tweeter. The vertical
The pseudo-anechoic response of the IL36c

Fig.3: Infinity IL36c, pseudo-anechoic horizontal response at 45° (red) and 60° (blue) relative to tweeter axis.

Fig.4: Infinity IL36c, pseudo-anechoic response at +15° (red) and –15° (blue) relative to tweeter axis.

All figures: Violet: pseudo-anechoic response on tweeter axis, averaged across a 30° horizontal window, combined with the nearfield woofer response.

response curves in Fig.4 also show a solid result, despite a small dip that develops below the tweeter axis and suggests that the IL36c should be tilted down when mounted atop a big-screen TV. The speaker’s effective low-fre- quency limit (–10dB) is 45Hz.—Thomas J. Norton

88 Stereophile Guide to Home Theater • January 2002 Stereophile Guide to Home Theater • January 2002 89