Adjustable Response Contour
le frequency dividing network of the 4311 is provided
L?
fth front panel controls to allow separate regulation of
output in the 1.5 kHz to 6 kHz “presence” range and the
“brilliance” region above 6 kHz. Controls are continu-
ously variable from maximum to full off. With suitable
settings of the two controls, the frequency response con-
tour of the 4311 can be altered to compensate for almost
any acoustical environment, or to achieve the tonal bal-
ance desired. Control scales are clearly marked so that
special settings can be logged and easily reset when
needed.
Performance Characteristics
The accompanying graph and specifications were
compiled from measurements made under standard
laboratory test conditions. The loudspeaker system was
mounted flush in the center of a large, flat baffle m an
anechoic environment. a calibrated condenser micro-
phone was suspended at a known distance from the
sound source, sufficiently far to be safely out of the near
field; and all electronic equipment was checked and
calibrated before tests were run.
The on-axis frequency response of a typical 4311 does
not vary more than *3 dB from 45 Hz to 15 kHz. Due to the
wide-angle characteristics of the midrange and high
frequency units and their physical orientation. response
measured up to 45’ off axis, horizontally or vertically,
I,
,es not deviate more than 6 dB from on-axis response
t
2 kHz nor more than 10 dB at 8 kHz. The 431 l’s lack of
distortion is equally outstanding. Distortion is inaudible
even at high power levels and at very low frequencies,
as shown in the photo at right.
While specifications indicate that the 4311 has impres-
sive performance characteristics. they cannot convey
the full impact of an extended listening evaluation
Clean, crisp, wide-range performance, even at very
loud levels, powerful bass fundamentals without dou-
bling and lifelike voice projection are qualities found in
few loudspeaker systems, regardless of size or price.
When heard from a monitor occupying less than 7 1 litres
(2.5 ft’), the effect is little less than awesome.
35-Hz Output
This unretouched photo shows the acoustic output of the system when driven by a
50-W sme wave sIgnal at 35 Hz A laboratory microphone was used to pick up the
sound from the 4311 The slgnal from the mlcrophone was connected directly to an
oscilloscope and the trace photographed
SustaIned performance at this lntensay would not be encountered during normal
use A50-W s~newave represents afar mored~fficuli lob for the loudspeakerthan ,ts
rated capacity of 75 W program material particularly I” the very low frequency
range Even so It can be seen that the 4311 produces an almost perfect sine wave
(Note Below 50 Hz most loudspeaker systems produce substantial dIstortion with
an Input of only a few watts
)
c
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