General description
Genelec HTS3B and HTS4B are power-
ful low frequency loudspeakers designed
specially for high quality digital 5.1 channel
Home Theater systems. Both models share
the same design layout with one active, mag-
netically shielded speaker driver mounted on
the front side of a compact cabinet and two
passive radiators, one on each side of the
cabinet. The amplifi er unit is integrated into
the subwoofer cabinet.
XLR and RCA line level input connectors
and adjustable input sensitivity provide easy
connection to all types of decoders. Bass roll-
off rate and crossover phase can be adjusted
to suit different acoustic environments and
subwoofer positioning. A “LINK OUT” connec-
tor allows coupling of two or more subwoofers
together when high sound pressure levels are
required. The amplifi ers are equipped with an
“AUTOSTART” function for automatic switch-
ing between “STANDBY” and “ON” modes.
Connectors for remote power “ON/STANDBY”
switches are also provided.
Installation
Before connecting the audio signals, ensure
that all equipment is switched off. Check that
the subwoofer voltage selector switch is set
to the correct voltage. Audio input to the
subwoofer can be made via balanced XLR or
unbalanced RCA connector. We recommend
the use of balanced cables and connectors
due to their better noise immunity. Do not use
both inputs at the same time.
The “LINK OUT” connector can be used for
daisy-chaining several subwoofers together
when high SPL is required. Simply connect
a balanced XLR cable from the “LINK OUT”
connector to the XLR input connector of the
next subwoofer. See section “Using multiple
subwoofers”.
Once all connections have been made, the
subwoofer and main speakers are ready to
be powered up.
Positioning in the room
The placement of the subwoofer in the room
affects the overall frequency response and
sound level of the system dramatically, as
at low frequencies the effects of the room
are strong. Even a slight change in the sub-
woofer’s location can cause a marked dif-
ference in the frequency balance and often
patient and methodical experimentation
and testing is needed to fi nd the optimum
placement.
The placement will also affect the bass
roll-off rate and the phase difference between
the main speakers and the subwoofer. These
effects can be compensated using the con-
trols in the amplifi er unit but we recommend
that at fi rst you leave the switches untouched
and concentrate on fi nding the position where
the subwoofer gives the smoothest response,
and only then use the controls to fi ne-tune
the balance and phase alignment between
the subwoofer and the main monitors.
Start by placing the subwoofer close to the
center of the front wall, however leaving at
least 10 cm (4”) of free space in front of the
amplifi er panel. We recommend a distance of
less than 90 cm / 36” to the wall. This position
gives increased acoustic loading and SPL
due to the proximity of the front wall and fl oor.
Cancellations from the front wall and fl oor are
also avoided. Ideally the subwoofer and main
speakers should be positioned symmetrically
and at an equal distance from the listening
position.
If the frequency balance is not quite right,
try moving the subwoofer to the left or right
along the wall so that different room modes
are excited at different levels. Positioning
the subwoofer close to a corner will boost
the bass level at lower frequencies and may
cause asymmetrical spatial imaging. If you
are using two subwoofers, try placing them
asymmetrically relative to the side walls.
Sometimes moving the subwoofers apart
into the front corners helps with problematic
rear wall refl ections and the loss of mutual
coupling is compensated by the bass boost
caused by corner positioning.
Although the HTS3B and HTS4B are mag-
netically shielded, they may cause colour
distortion if placed near to very sensitive
video monitors or computer displays. Move
the subwoofer further away or try turning the
amplifi er side of the subwoofer towards the
screen.
Soffit / Cabinet mounting
If the subwoofer is installed in a cabinet or
fl ush mounted in a cavity inside a wall, suf-
fi cient space must be left around it to ensure
amplifi er cooling and correct functioning of
the driver/passive radiator system.
The cavity must be at least 10 cm (4”)
wider and 10 cm (4”) deeper and higher than
the outer dimensions of the subwoofer. This
allows leaving 5 cm (2”) of space beside both
passive radiators and suffi cient space behind
and above the cabinet to allow cooling for the
electronics. The subwoofer’s amplifi er side
must face the back of the cavity. If the cavity
is covered with a drape or cloth, ensure that
it does not hinder the air circulation around
the subwoofer.
Setting the input sensitivity
The input sensitivity control is located on the
amplifi er panel of the subwoofer. An input
voltage of -6 dBu with a -6 dBu input sensitiv-
ity setting will produce 100 dB SPL @ 1 m in
free fi eld. To obtain a 110 dB SPL output an
input voltage of +10 dBu is required when the
input sensitivity is set to 0 dBu.
Setting the bass roll-off
switches
The acoustic response of the subwoofer may
have to be matched to the characteristics of
the room and the positioning in which it will
be used. To adjust the subwoofer to match
these characteristics use the ‘’BASS ROLL-
OFF’ control switches located on the ampli-
fi er panel. These switches provide an adjust-
ment range of -10 dB in 2 dB steps. When
all roll-off switches are ‘off’, a fl at anechoic
response is obtained.
Setting the phase control
The effect of incorrect phase alignment
between main speakers and subwoofer is a
drop in the frequency response of the whole
system at the main speaker / subwoofer-
crossover frequency. The phase difference
between the main speakers and subwoofer
at the listening position is dependent upon
the position of the subwoofer. To avoid
phase differences between the left and right
channels and the subwoofer, the subwoofer
should be placed close to the center of the
front speaker array.
Two phase matching switches in the
crossover allow compensation for incorrect
phase alignment. Four settings are provided
between 0° and -270°.
Coarse phase correction
method
• Confi gure the processor so that the main
speakers (L, C, R) are set to “small” and
check the main speaker/subwoofer
crossover frequency setting on your
processor. This frequency may be
