Genelec 1238CF Operating Manual page 5

cated in the switch group 2. (switches 6 and 7). The switches
provide attenuation levels of -10 dB (sw. 6 ON), -20 dB (sw. 7 ON)
and -30 dB (both switches ON) The combined attenuation ranges
from 0 to -42 dB.
Functions On Switch Group 1
(Tone Controls)
Switch group 1 (the upper switch group) comprises the tone con-
trols that can be used to adjust the frequency response of the
system in stand-alone mode to match the acoustic environment.
Please note that the GLM Loudspeaker Controller allows a much
more versatile and precise set of controls to be used and sup-
ports the fully automatic system alignment feature, Genelec Au-
toCal. Use the tone control switches on the loudspeaker only if a
GLM is not available for for calibrating the system.
The controls are labelled "TREBLE TILT", "BASS TILT", "BASS
ROLL-OFF" and "DESKTOP". The factory settings for these con-
trols are all "OFF" to give a flat anechoic response. Note that these
controls have no effect when switch 1 "STORED/MANUAL CON-
TROL" on switch group 2 is set to "STORED" or when the loud-
speaker is connected to the Genelec loudspeaker control network.
Bass Roll-Off Control
Bass Roll-Off control (switches 1 and 2) affects the low frequency
roll-off of the loudspeaker and attenuates its output near the cut-
off frequency. Attenuation levels of -2 dB (sw. 1 ON), -4 dB (sw. 2
ON) or -6 dB (both switches ON) can be selected.
Bass Tilt Control
The Bass Tilt control switches (swiches 3 and 4) offer three atten-
uation levels for the bass response below 800 Hz, usually neces-
sary when the loudspeakers are placed near room boundaries.
The attenuation levels are -2 dB, -4 dB and -6 dB.
Desktop Low Frequency Control
The desktop low frequency control (switch 5) attenuates the bass
frequencies around 160 Hz by 4 dB. This feature is designed to
compensate for the boost often occurring at this frequency range
when the loudspeaker is placed upon a meter bridge, table or
similar reflective surface.
Treble Tilt Control
Treble Tilt control (switches 6 and 7) allows adjusting the treble
response above 5 kHz by +2 dB, -2 dB or -4 dB, which can be
used for correcting an excessively bright or dull sounding system
or to compensate for high frequency level loss if the loudspeaker
is placed behind a screen.
An acoustic measuring system such as WinMLS is recommend-
ed for analyzing the effects of the adjustments, however, careful
listening with suitable test recordings can also lead to good re-
sults if a test system is not available. Table 1 shows some typical
settings in various situations.
Loudspeaker Treble
Mounting Position Tilt
Flat anechoic None
response
Free standing in None
a damped room
Free standing in None
a reverberant room
Near field on
None
a reflective surface
In a corner
None
Table 1. Suggested Tone Control settings in some typical
situations.
Always start adjustment by setting all switches to "OFF" position.
Measure or listen systematically through the different combina-
tions of settings to find the best frequency balance. See Table 1
for some typical settings in various situations.
Functions On Switch Group 2
Stored / Manual Ctrl
This allows the selection between two basic methods of control-
ling the loudspeaker in the stand-alone mode. "MANUAL CTRL"
refers to controlling the loudspeaker using the controls on the
loudspeaker's back panel. The "STORED" refers to using settings
stored inside the memory of the loudspeaker. These settings are
made using GLM and the GLM Control Network. There is ad-
ditional functionality compared to that offered by the room re-
sponse correction switches on the back panel.
AES/EBU CH
This selects the audio channel(s) available on the AES/EBU ca-
ble to be reproduced by the loudspeaker. Turning both switches
on reproduces the sum of the two channels on the AES/EBU
cable. Turning both switches off has the same effect which has
been done deliberately to avoid the situation where no input
channel is selected and the loudspeaker is effectively muted.
When two channels are selected, 6 dB of attenuation is automati-
cally applied to avoid overloading the loudspeaker.
If the AES/EBU cable is operated in dual-wire mode (typically
192 kHz sampling frequency) one AES/EBU cable carries only
one audio channel. The loudspeaker detects this situation auto-
matically and the channel selection switches have no effect.
Driver Mute
These two switches allow you to mute the treble and midrange
drivers (marking DCW) or bass driver (marking "WF") indepen-
dently. This may be useful to diagnose if a transducer is faulty.
System Lvl
These switches allow scaling down of the loudspeaker output.
The signal sent to the "Thru" output connector is not affected.
The switches are additive, for example, "–30 dB" attenuation is
Bass Bass Desktop
Tilt Roll-Off
None None None
-2 dB None None
-4 dB None None
-2 dB None -4 dB
-4 dB -4 dB None
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