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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. 

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 

Loudspeaker  

Mounting Position

Treble 

Tilt

Bass 

Tilt

Bass 

Roll-Off

Desktop

Flat anechoic 

response

None

None

None

None

Free standing in 

a damped room

None

-2 dB

None

None

Free standing in 

a reverberant room

None

-4 dB

None

None

Near field on 

a reflective surface

None

-2 dB

None

-4 dB

In a corner

None

-4 dB

-4 dB

None

Table 1. Suggested Tone Control settings in some typical  
situations. 

Summary of Contents for 1238CFM

Page 1: ...Genelec 1238CF DSP Loudspeaker Operating Manual 1238CF ...

Page 2: ...to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures Reorient or relocate the receiving antenna Increase the separation between the equipment and receiver Connect the equipment into an outlet on a circuit different from that to which the receiver is connected C...

Page 3: ...ital hardware transmission of a 192 kHz sample rate is achieved using a double speed single channel cable interface This is called dual wire mode In this case one cable per channel is used and no channel selection is required Dual wire mode is automatically detected by the input stage If the digital source device has a digital level monitor pot or graphical volume fader that controls the digital l...

Page 4: ...rs in the AES EBU digital audio data Mounting Considerations Align the Loudspeakers Correctly Always place the loudspeakers so that their acoustic axes are aimed towards the listening position see Figure 2 Vertical placement is mandatory to maintain cooling behind the loud speaker Maintain Symmetry Check that the loudspeakers are placed symmetrically and at an equal distance from the listening pos...

Page 5: ...ing 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 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 Ta...

Page 6: ...ck of each loudspeaker to enable the internal Acoustic Settings and then turn it on again To set the phase control on the subwoofer connect the Center channel output of the subwoofer to the loudspeaker to be used to align phase Follow the instructions in the subwoofer user manual for setting phase and level Maintenance No user serviceable parts are to be found within the loudspeaker enclosure Any ...

Page 7: ... 1238CF Bass amplifier short term output power Midrange amplifier short term output power Treble amplifier short term output power Long term output power is limited by driver unit protection circuitry 150 W at 4 Ohm load 120 W at 8 Ohm load 120 W at 8 Ohm load Slew rate 80 V us Amplifier system THD at nominal output 0 05 Signal to Noise ratio referred to full output Bass Midrange Treble 100 dB 100...

Page 8: ...S please contact Genelec Inc 7 Tech Circle Natick MA 01760 USA Phone 1 508 652 0900 Fax 1 508 652 0909 Email genelec usa genelec com In China please contact Beijing Genelec Audio Co Ltd Jianwai SOHO Tower 12 Room 2605 D 1504 Chaoyang District Beijing 100022 China Phone 86 10 8580 2180 Fax 86 10 8580 2181 Email genelec china genelec com In Sweden please contact Genelec Sverige Ellipsvägen 10B P O B...

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