Genelec 1238CF Operating Manual

1238CF

Operating Manual
Genelec 1238CF

DSP Loudspeaker

Introduction

the interference by one or more of the following measures:

Congratulations and a thank-you for the purchase of this Genel­ec 1238CF DSP Loudspeaker. This loudspeaker is designed to
integrate easily into the digital production environment. There are
several ways to configure and operate the DSP loudspeaker for a
wide variety of high quality audio applications. The 1238CF also
has an analog input, making it a versatile and intelligent replace­ment for analog loudspeakers.

This manual addresses setting up and using the 1238CF DSP
loudspeaker in stand-alone mode without the Genelec Loud­speaker Manager GLM™ and the proprietary Genelec loud­speaker control network. Use with the GLM™ is described in the
DSP System Operating Manual.

EC Declaration Of Conformity

This is to certify that Genelec 1238CF DSP loudspeakers con­form to the following standards:

Safety: EN 60065: 2002 + A1: 2006 + A11:2008 / IEC 60065:
2001 7th Edition + A1: 2005
EMC: EN 55020: 2007, EN 55013: (2001) + A1: 2003 + A2: 2006
EN 61000-3-2 (2006) and EN 61000-3-3 (1995) + A1: 2001 +
A2: 2005

The products herewith comply with the requirements of The Low
Voltage Directive 2006/95/EC, EMC Directive 2004/108/EC and
Energy related Products (ErP) Directive 2009/125/EC.

Signed:
Ilpo Martikainen
Position: Chairman of the Board
Date: 30-September-2010

Compliance to FCC Rules

This device complies with part 15 of the FCC Rules. Operation is
subject to the following two conditions:

•  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.

•  Consult the dealer or an experienced radio/TV technician
for help.

Modifications not expressly approved by the manufacturer could
void the user’s authority to operate the equipment under FCC
rules.

Safety Considerations

Although the 1238CF has been designed in accordance with
international safety standards, to ensure safe operation and to
maintain the loudspeaker under safe operating conditions, the
following warnings and precautions must be observed:

•  Servicing and adjustment must only be performed by
qualified service personnel. The loudspeaker enclosure
must not be opened.

•  Do not use this product with an unearthed mains cable or
a mains connection without the protective earth contact as
this may lead to personal injury.

•  To prevent fire or electric shock, do not expose the unit to
water or moisture.

•  Do not place any objects filled with liquid, such as vases on
the loudspeaker or near it.

•  Note that the amplifier is not completely disconnected
from the AC mains service unless the mains power cord is
removed from the amplifier or the mains outlet.

•  Free flow of air behind the loudspeaker is necessary to
maintain sufficient cooling.

•  Do not obstruct airflow around the loudspeakers.

•  Note that the amplifier is not completely disconnected

from the AC mains service unless the mains power cord is
removed from the amplifier or the mains outlet.

•  This device may not cause harmful interference, and

•  This device must accept any interference received, including

interference that may cause undesired operation.

Note: This equipment has been tested and found to comply with the
limits for a Class B digital device, pursuant to part 15 of the FCC
Rules. These limits are designed to provide reasonable protection
against harmful interference in a residential installation. This equip­ment generates, uses and can radiate radio frequency energy and,
if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However,
there is no guarantee that interference will not occur in a particular
installation. If this equipment does cause harmful interference to
radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct
2

WARNING!

The Genelec 1238CF loudspeaker is capable of producing sound
pressure levels in excess of 85 dB, which may cause permanent
hearing damage.

System

The Genelec 1238CF DSP Loudspeaker is designed for precise
monitoring of 24 bit/192 kHz AES/EBU digital audio signal or
line level analog audio signal. The 1238CF is fully compatible
with Genelec Loudspeaker Manager GLM™ and the proprietary
Genelec loudspeaker control network and Genelec 7271A DSP
Active Subwoofer, but can also be used independently of these.
The 1238CF features high SPL output and low colouration in

Figure 1. Connectors and

2

1

ON
OFF

ON
OFF

dB

-2

-4

-8

-6

-12
0

-10

SWITCH

1

MANUAL

CTRL

-4dB

160Hz

ON+ON
OFF+OFF

-6dB -6dB -2dB

STOREDDESKTOP

-2dB -4dB

BASS

ROLL-OFF

BASS
TILT

-2dB -4dB

+2dB -4dB

TREBLE

TILT

ON
OFF

SYSTEMLVL.AES/EBUCH.

AB

WF COAX

DRIVERMUTE

SWITCH

2

-10 -20

dB

-30

SUMA ANDB

MADE IN FINLAND

1238CF DSP TRI-AMPLIFIED
MONITORING SYSTEM

MAGNETICALLYSHIELDED

SERIALNUMBER

MAINS INPUT 230 V~
50/60Hz 330 W

DIGITALIN

AES/EBU

www.genelec.com

292-1238T-6

ANALOG

IN

DIGITAL THRU

AES/EBU

12 V

REMOTE

STAND-ALONE USER
INTERFACE LEVEL CONTROL

STAND-ALONE USER
INTERFACE SWITCH
GROUPS 1 AND 2

GLM CONTROL

NETWORK

CONNECTORS

MAINS POWER

SWITCH

MAINS INPUT
CONNECTOR

ANALOG INPUT CONNECTOR

DIGITAL THRU CONNECTOR

DIGITAL INPUT CONNECTOR

12V REMOTE
CONNECTOR

controls on the back panel
of the 1238CF.

a small enclosure size. It is suitable for a wide variety of tasks,
such as near field monitoring, mobile vans, broadcast and TV
control rooms, surround sound systems and home studios. The
advanced Directivity Control Waveguide™ (DCW™) technology
provide excellent frequency balance even in difficult acoustic
environments.

Amplifiers

The amplifier unit is mounted in the rear of the loudspeaker en­closure. The unit incorporates special circuitry for driver thermal
overload protection. Variable input sensitivity allows accurate
level matching to console output section.

Using the Loudspeakers in Stand-Alone
Mode

The 1238CF accepts both analogue line level input signals and
AES/EBU formatted digital input signals.

When the loudspeakers are not connected to a Genelec loud­speaker control network, they operate in stand-alone mode.
However, settings made with the Genelec Loudspeaker Manager
software can be saved into each loudspeaker and applied even
when the network is disconnected by setting switch 1 “STORED/
MANUAL CONTROL” on switch group 2 of each loudspeaker to
position “STORED.”

This manual concentrates on using the loudspeakers without the
control network. All issues concerning use with the network are
explained in detail in the System Operating Manual provided with
the GLM™ Loudspeaker Manager software kit.

Connections

Each loudspeaker is supplied with a mains cable, one 5 m GLM

network cable and an operating manual. Before connecting up,
ensure that the mains switch is off.

“MAINS INPUT” Connector

Connect the mains supply to this connector.

“DIGITAL IN AES/EBU” Connector

Use this female XLR connector for AES/EBU formatted digital
audio input signals. This input is selected automatically when a
valid digital audio signal is present, and overrides the analogue
input.

Depending on the digital 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 level, it may be
advantageous to lower the level control either on the GLM soft­ware interface or the loudspeaker’s back panel controls rather
than the source device, which in turn will force the use of more of
the digital [bit] resolution in the volume control.

If the digital input is used, audio levels are referenced to 0 dBFS
(digital Full Scale, the largest level that may be represented in
the AES/EBU signal). Genelec DSP loudspeakers produce 100
dB SPL at 1 meter in free space for a digital input signal of –30
dB FS. It is advantageous to keep the digital level as high as
possible.

“DIGITAL THRU AES/EBU” Connector

This male XLR carries an unaltered copy of the digital signal fed
into the “DIGITAL IN AES/EBU” connector. It can be used for
daisy-chaining up to four loudspeakers together.

3

“ANALOG IN” Connector

Use this connector for analog audio signals. When operating an
1238CF in the analog mode the A/D converter must not be over­loaded, otherwise distortion will be heard. The maximum input
level is +22.0 dBu RMS. When A/D converter input clip occurs
the front panel light turns momentarily red, indicating the over­load condition.

If the “Level” control on the back panel is reduced (turned
counter-clockwise), the acoustic output will be reduced. This
control decreases the output from the D/A converters. Ideally
the Level control should be set to force the use of more of the
input range of the A/D converter without overloading it. Re­member, there is no headroom above the maximum input to
the A/D conversion.

456 mm

17 15/16”

235 mm
9 1/4”

CLIP
PROTECT
(FAULT)

READY

a

“CONTROL NETWORK” Connectors

Use these RJ-45 sockets to connect the loudspeaker to the pro­prietary Genelec Loudspeaker Manager™ (GLM™) network
only. This connector is not Ethernet LAN compatible. Do not con­nect to Ethernet LAN.

“12 V REMOTE” Connector

You can set up remote controlled powering up and down of the
1238CF with 12 V 60 mA trigger voltage connected to this con­nector.

Front Panel Warning Light

Normally the light on the front panel of a 1238CF loudspeaker
is green, indicating that the loudspeaker is in normal operational
mode.

The overload light (red) is activated by several events,

•  exceeding the maximum input range of the analog input

•  exceeding the maximum input range of the digital input with

large probability

•  exceeding the output capacity of the power amplifier
(clipping in the power amplifier) and thermal
overload of the power amplifier or loudspeaker drivers
(thermal protection has activated)

•  if an error is detected in the AES/EBU audio data

If a red warning light appears, turn the source down! If the levels
are already modest and a digital signal is being used, ensure that
there are no bit errors in the AES/EBU digital audio data.

Mounting Considerations

Figure 2. The location of the acoustic axis is on the center­line of the enclosure at the given height.

Maintain Symmetry

Check that the loudspeakers are placed symmetrically and at an
equal distance from the listening position. If possible, place the
system so that the listening position is on the centerline of the
room and the loudspeakers are placed at an equal distance from
the centerline.

Minimise Reflections

Acoustic reflections from objects close to the loudspeakers like
desks, cabinets, computer monitors etc. can cause unwanted
colouration and blurring of the sound image. These can be mini­mised by placing the loudspeaker clear of reflective surfaces. For
instance, putting the loudspeakers on stands behind and above the
mixing console usually gives a better result than placing them on
the meter bridge. Symmetrical positioning of the reflective objects
is also importent in order to maintain a balanced soundstage.

Minimum Clearances

Sufficient cooling for the integrated amplifier must be ensured
if the loudspeaker is installed in a restricted space such as a
cabinet, or integrated into a wall structure. The surroundings of
the loudspeaker must always be open to the listening room with
a minimum clearance of 5 centimeters (2”) behind, above and on
both sides of the loudspeaker. The space adjacent to the loud­speaker must either be ventilated or sufficiently large to dissipate
heat so that the ambient temperature does not rise above 35
degrees Celsius (95°F).

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 loud­speaker.

4

Setting the Input Sensitivity

The loudspeaker level sensitivity functions for both analog and
digital input. The sensitivity can be matched by adjusting the ro­tary Level control together with the System Level switches lo-

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 con­trols 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 sup­ports the fully automatic system alignment feature, Genelec Au­toCal. 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 con­trols are all “OFF” to give a flat anechoic response. Note that these
controls have no effect when switch 1 “STORED/MANUAL CON­TROL” on switch group 2 is set to “STORED” or when the loud­speaker 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 cut­off 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 atten­uation levels for the bass response below 800 Hz, usually neces­sary 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 recommend­ed for analyzing the effects of the adjustments, however, careful
listening with suitable test recordings can also lead to good re­sults if a test system is not available. Table 1 shows some typical
settings in various situations.

Loudspeaker
Mounting Position

Flat anechoic
response

Free standing in
a damped room

Free standing in
a reverberant room

Near field on
a reflective surface

In a corner

Treble

Tilt

None None None None

None -2 dB None None

None -4 dB None None

None -2 dB None -4 dB

None -4 dB -4 dB None

Bass

Tilt

Bass

Roll-Off

Desktop

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 combina­tions 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 control­ling 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 ad­ditional functionality compared to that offered by the room re­sponse correction switches on the back panel.

AES/EBU CH

This selects the audio channel(s) available on the AES/EBU ca­ble 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 automati­cally 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 auto­matically 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”) indepen­dently. 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

5

achieved by turning on the “–10 dB” and “–20 dB” switches. The

Genelec Oy 1238CF (dBr) vs freq (Hz) 3 Mar 11

0°

60°

15°

30° 45°

50

100

55

60

65

70

75

80

85

90

95

d
B

r

A

Hz

Genelec Oy 1238CF (dBr) vs freq (Hz) 3 Mar 11

80

85

90

d
B

r

A

DESKTOP LF

BASS TILT

BASS ROLL-OFF

TREBLE TILT

80

85

90

80

85

90

effect of these switches is combined with the effect of the rotary
level adjustment control. This results in total possible attenuation
of 42 dB, 30 dB by the system level switches and another 12 dB
by the rotary control.

Using 7000 Series Analog Subwoofers
with the 1238CF DSP Loudspeakers

Genelec recommend the use of DSP subwoofers (7200 Series)
with DSP loudspeakers. However, it is also possible to use ana­log subwoofers. Please follow the steps below to integrate an
analog subwoofer into a system of DSP loudspeakers:

•  Connect cables carrying analog audio to the 7000 Series
analogue subwoofer first.

•  Connect the subwoofer outputs to the analog inputs of the
1238CF DSP loudspeakers.

•  Connect the GLM Control Network to the loudspeakers.

•  Make a System Setup in GLM. It will consist of only

loudspeakers as this is all the network can see, so suitable
Rapid Cabling Presets are “Stereo Pair (Analog)” and “5.0
Surround System (Analog)”.

•  Run AutoCal and review and the results to check for large
dips at or above 85 Hz. Move the loudspeakers and repeat
AutoCal if there is a problem.

•  Press “Finish”, then in the Main Page select “Menu | Store
Acoustic Settings to All Online Loudspeakers” and close GLM.

•  For each DSP loudspeaker, turn it off, select “Stored” on the
back 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 maintenance or repair of the loudspeaker should
only be undertaken by qualified service personnel.

100

200

20

50

500

1k 2k

5k

10k

20k

Hz

Figure 3: The upper curve group shows the horizontal direc­tivity characteristics of the 1238CF measured at 1 m. The
lower curve shows the systems power response.

100

200

20

50

500

1k 2k

5k

10k

20k

Figure 4: The curves above show the effect of the “bass tilt”,
“treble tilt” , “desktop” and “bass roll-off” controls on the free
field response.

Guarantee

The Genelec 1238CF is supplied with two year guarantee against
manufacturing faults or defects that might alter the performance
of the loudspeakers. Refer to supplier for full sales and guarantee
terms.

Accessories

A wide selection of accessories is available for Genelec loud­speakers. Consult the Accessories Catalogue on www.genelec.
com or your local distributor/dealer for up-to-date information.

6

Figure 5: Horizontal directivity of the 1238CF. Figure 4: Vertical directivity of the 1238CF.

SYSTEM SPECIFICATIONS

1238CF

Lower cut-off frequency, –3 dB < 55 Hz

Upper cut-off frequency, –3 dB > 20 kHz

Free field frequency response 57 Hz – 20 kHz (± 2.0 dB)

Maximum short term sine wave acoustic
output on axis in half space, averaged from
100 Hz to 3 kHz

Maximum long term RMS acoustic output
in same conditions with IEC weighted noise
(limited by driver unit protection circuit

Maximum peak acoustic output per pair with
music material

Self generated noise level in half space at 1 m
on axis (A-weighted)

Harmonic distortion at 90 dB SPL at 1 m on
axis

Freq: 60…100 Hz
> 100 Hz

Drivers

Bass
Midrange
Treble

Weight 42 kg (93 lb)

Dimensions

Height
Width
Depth

@ 1 m > 117 dB SPL

@ 1 m > 107 dB SPL

@ 2 m > 124 dB

< 15 dB

< 1 %
< 0.5 %

2 x 210 mm (8") cone
125 mm (5”) cone
25 mm (1") metal dome
All drivers are magnetically
shielded

610 mm (24”)
470 mm (18
257 mm (10

1

/2”)

1

/8”)

AMPLIFIER SECTION

1238CF

Bass amplifier short term output power
Midrange amplifier short term output power
Treble amplifier short term output power

150 W at 4 Ohm load
120 W at 8 Ohm load
120 W at 8 Ohm load

Long term output power is limited by driver unit
protection circuitry

Slew rate 80 V/us

Amplifier system THD at nominal output < 0.05 %

Signal to Noise ratio, referred to full output

Bass
Midrange
Treble

Mains voltage
Mains voltage operating range

>100 dB
>100 dB
>100 dB

100/200 or 115/230 V

-10 to +10 %

Power consumption (average)

Idle
Full output

23 VA
330 VA

SIGNAL PROCESSING SECTION

1238CF

Digital signal input connector
XLR female 110 kOhm

Digital signal output / Thru connector
XLR male 110 kOhm

Analog signal input connector
XLR female, balanced 10 kOhm

Digital audio

Word length
Sample rate

Control network

Type
Connection

Crossover frequency

Bass/Mid
Mid/Treble

TM

GLM

software frequency response adjust-

ment *

Notch filters
Shelving filters

System calibration Auto Cal™, Stand-alone

AES/EBU Single Wire or
Dual Wire

AES/EBU Single Wire or
Dual Wire

pin 1 gnd, pin 2 +, pin 3 -

16 - 24 bits
32 - 192 kHz

Proprietary GLM™ network
2 RJ45, CAT5 cables

420 Hz

2.8 kHz

4 LF and 2 HF
2 LF and 2 HF

* The notch and shelving filters adjustments, AutoCalTM and GLM

TM

manual system calibration features are part of the Genelec Loudspeaker Manager (GLMTM) software

7

1238CF Operating Manual

Genelec Document D0100R001 Copyright Genelec Oy 10.2010. All data subject to change without prior notice

International enquiries:

Genelec, Olvitie 5

FIN-74100, Iisalmi, Finland

Phone [phone]

Fax [phone]

Email [e-mail]

In the U.S. please contact:

Genelec, Inc., 7 Tech Circle

Natick, MA 01760, USA

Phone [phone]

Fax [phone]

Email [e-mail]

In Sweden please contact:

Genelec Sverige

Ellipsvägen 10B

P.O. Box 5521, S-141 05 Huddinge

Phone [phone]

Fax [phone]

Email [e-mail]

www.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 [phone]

Fax [phone]

Email [e-mail]