Infinity 4.1t User Manual
Floor-Standing 4-Way
Speaker with Powered
Subwoofer
Infinity
“Intermezzo” 4.1t
Infinity Systems, Inc., a Harman International Company, 250 Crossways Park
Drive, Woodbury, NY 11797. Voice: (800)
553-3332. Fax: (516) 682-3523. Web:
www.infinitysystems.com. Intermezzo 4.1t
floor-standing 4-way loudspeaker system
with built-in powered subwoofer. $7000.00
the pair. Tested samples on loan from manufacturer.
Editor’s Note: I hasten to point out,
before the self-righteous element in the
audio community does, that Don Keele is
currently employed by Harman/Becker
Automotive Systems, which is owned by
the same parent company as Infinity Systems, namely Harman International.
Harman/Becker and Infinity are totally
independent of each other, without any
overlap; in fact, they are located 700 miles
apart—but they are connected via Sidney
Harman’s pocket. He, or more precisely his
company, owns a significant percentage of
the audio industry, so that any one of the
limited number of truly qualified audio
engineers (like Don Keele) has more than
a small chance of falling within his
purview. It can’t be helped. As I pointed
out in one of the earliest issues of
Audio Critic, in the late ’70s, the alternative is to use reviewers totally unconnected to the audio industry, such as
audiophile dentists. O
ther magazines do
Unfortunately, said dentists don’t know the
difference between MLS and ETF, and
that matters to me more than our
reviewers’ affiliations. I can assure you, in
an event, that no one at the corporate offices of H
about this r
arman International even knew
, let alone influenced it.
eview
The
.
Introduction
o:
mezz
nter
I
a shor
t musical mo
ment separating the major sections of
a lengthy composition or work; or
termediate: one that is in a middle position or state. Both terms aptly
16 THE AUDIO CRITIC
v
in-
-
e
describe the subject of this issue’s loudspeaker review, the Infinity “Intermezzo” 4.1t, by appropriately tying
together function and music. The 4.1t
is simultaneously an intermediate
speaker in Infinity’s home theater lines,
positioned between the higher-priced
Prelude MTS and the lower-priced Interlude, Entra, and Modulus lines; and
at the same time, of course, does an excellent job playing music.
The Intermezzo 4.1t is a tall and
relatively narrow floor-standing loudspeaker with built-in powered subwoofer, packaged in a total system that
combines first-class industrial design
and handsome good looks. The 4.1t
system couples a thr
ee-way dir
ect-radi
ator system operating above 80 Hz to
a powerful subwoofer using a side-fired
very-high-excursion 12" metal-cone
woofer operating in a closed-box en-
e, powered by a built-in 850-
closur
er amplifier.
w
watt po
The upper thr
ee-way por
tion of
the design is passive and combines a
1
⁄2" cone midbass driv
6
er with a 3
1
midrange and a 1" dome tweeter, all of
which are mounted on the front of the
enclosur
e and cr
ossed o
er at a rapid
v
24 dB/octave rate. The bottom half of
the system is devoted to a rather sizable
closed-box enclosure housing the 12"
woofer, amplifier, system controls, and
connections. All driver diaphragms utilize Infinity’s sandwiched composite
metal/ceramic diaphragm material,
which is said to be light weight, quite
rigid and inert, and allows all the drivers to operate essentially as pure pistons over their respective operating
bandwidths.
I last reviewed a set of an Infinity
systems similar to the 4.1t for
magazine back in 1996. These were the
Infinity Compositions P-FR systems,
which are similar to the current Prelude MTS line. It performed excellently in all regards except for a
low-frequency response that did not
quite keep up with its upper bass and
higher-frequency performance. My
measurements of the bass output of the
Intermezzo 4.1t, described later, reveal
that it quite significantly outperformed
the bass response of the P-FR systems.
Infinity has been doing their homework! The bass improvements started
with the higher-priced Prelude MTS
line, whose subwoofer is quite similar
to the 4.1t’s. The Intermezzo line includes a separate powered subwoofer,
the 1.2s, which is equally powerful.
The Intermezzo 4.1t includes a
rich complement of controls and inputs on the r
ear panel of the subwoofer enclosure (see rear panel
graphic). The system is equally at
-
home in a complex home theater setup
or a simpler two-channel stereo situation. Inputs and controls have been
ovided for many different operating
pr
configurations, from standalone stereo
operation driven by an external power
amplifier with the system
its signal from the speakers terminals,
to a complicated home theater setup
⁄2"
driven by a Dolby Digital or DTS
processor with separate power amplifiers or a multichannel amplifier
The 4.1t’s subwoofer power ampli-
fier utiliz
es a high-efficiency switch-
Audio
s sub deriving
’
.
Manufacturer’s
Specifications
Type: 4-way, floor-standing, with
powered closed-box subwoofer
Drivers: 12" cast-frame woofer
with 3" voice coil, 6
1
⁄2" cone mid
-
ISSUE NO. 28 • SUMMER/FALL 2002 17
mode tracking po
wer supply powering
a class-AB amplifier. The power
’s output voltage tracks the
supply
audio signal in such a way as to mini
e output device power dissipation.
miz
Quoting the 4.1t’s owners manual:
“The result is an extremely efficient
audio amplifier that does not compromise audio performance.” The
tracking power supply is not unique
with Infinity, however; it first started
out primarily in the professional audio
field (Crown International and Carver
were among the first to offer the feature on their amplifiers) and then
trickled down to the home market.
The 4.1t includes a single parametric subwoofer equalizer in its bass
electronics, intended for smoothing
the subwoofer’s response in its listening
environment. As is well known, the listening room heavily influences what is
heard from a loudspeaker in the bass
range below 100 Hz. The equalizer, if
set properly, can effectively optimize
the Intermezzo’s subwoofer response to
complement most listening environments. The parametric equalizer can
provide a variable-width cut or dip of
arbitrary frequency and depth, which,
if matched to a room peak, can considerably smooth out the system’s in-room
response. As pointed out by Infinity,
this also improves the system’s transient
esponse
r
because
the low-frequency
speaker-to-room response is essentially
(Techno-geek com-
minimum
phase.
ment: If a system is minimum phase
and its frequency response magnitude
minimum-phase
a
with
flat
ed
equaliz
is
equalizer, its phase response will follow
and also be equalized flat, and hence its
transient response or time behavior will
be optimized.)
This theory is all well and good,
w does the user know how to set
but ho
his equaliz
er for optimum r
esults? On
the one hand he/she could hire an ex-
e acoustical engineer to come in
pensiv
with his one-third-octave real-time
spectrum analyzer, noise generator, and
-
R.A.B.O.S. Sound Level Meter
calibrated microphone, and properly
set the equalizer after doing some measurements. Or, on the other hand—
tuh da!—the user could employ
Infinity’s slim LED sound level meter
(see Sound Level Meter graphic) and
the accompanying test CD with detailed instructions, which are supplied
with the 4.1t to accomplish the same
task. Gee, Infinity thinks of everything! Infinity calls their adjustment
system R.A.B.O.S. or Room Adaptive
Bass Optimization System (love that
acronym!). It comes with documentation and bass response graphs that the
user fills in, along with a circular
hinged clear-plastic protractor-like
gizmo, called a “Width Selector” by
Infinity, that allows the user to rapidly
determine the Q or r
esonance width of
the dominant peak in the system’s response (see Width Selector graphic).
Matching a speaker/room response
peak by adjusting the parametric filter’s
notch depth and frequency is relatively
easy; ho
the Q adjustment. M
wever, this is not the case with
e on this sub-
or
ject later, in the use and listening section.
Measurements
o 4.1t
zz
nterme
The I
response was measured using two different test techniques: (1) nearfield
measurements to assess the low-fre-
s fr
’
equency
Width Selector Graphic
quency response of the subwoofer, and
(2) windowed in-room tests to measure mid-to-high-frequency response.
The test microphone was aimed
halfway between the midrange and
tweeter at a distance of one meter with
2.83 V rms applied. One-tenth octave
smoothing was used in all the following curves.
The on-axis response of the 4.1t,
with grille on and off, is shown in Fig.
1, along with the response of the subwoofer. Without grille, the response of
the upper frequency portion of the
curve (excluding the sub) is very flat
and fits a tight 3-dB window from 95
Hz to 20 kHz. The woofer exhibits a
bandpass response centered on about
50 Hz and is 6 dB down at about 25
and 90 Hz. In the figure, the woofer’s
response has been level adjusted to
roughly match the level of the upper
frequency response. Averaged between
250 Hz and 4 kHz, the 4.1t’s 2.83 V
rms/1 m sensitivity came out to 86.2
’s 87
dB, essentially equaling I
nfinity
dB rating. The grille caused moderate
response aberrations above 4 kHz, with
een 3 and 11
eduction in lev
a r
el betw
kHz, a slight peak at 12.5 kHz, fol-
y a dip at 17 kHz.
ed b
w
lo
The grille
can be easily removed for serious listening if required. The right and left
systems were matched fairly closely, fit-
±1.5 dB window above 150 Hz.
ting a
18 THE AUDIO CRITIC
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