O 410 Operating Manual v02
O 410
Mid-Field Monitor
Operating Manual
O 410
Part Number:
Number 526312
Version: 02
Date 11-Feb-2008
uage English
Klein + Hummel
Thank-you for purchasing a Klein + Hummel loudspeaker. A Mathematically Modeled Dispersion™ waveguide
(MMD™), flexible acoustical controls, various input options and an extensive mounting hardware range allow the
loudspeaker to be used in diverse acoustical conditions, with any source equipment and in a wide variety physical
locations. The latest acoustical and electrical techniques and components have been used to ensure the most
accurate sound reproduction possible. Klein + Hummel products are designed for longevity so we hope you enjoy
many happy years of using this product.
Depending on the size, Klein + Hummel’s three-way systems are designed for use as near field monitors through
to large main control room monitors. They can be used in music, broadcast, and post production studios for
tracking, mixing, and mastering. They may be positioned used free-standing or flush mounted into a wall, and
can be mixed freely in multichannel systems.
Before reading the rest of this operating manual, review the safety and warnings section towards the back of this
book. Note that imperial dimensions are approximate.
Package Contents
The shipping carton contains:
• This operating manual
• A production calibration certificate
• Product guarantee
• The loudspeaker
• Three mains power cables (Euro, UK, and USA)
• A trimmer and switch screwdriver
Signal cables are not included. Options and accessories are listed at the end of this operating manual.
Most Common Applications and Listening Distances
The minimum, recommended, and maximum listening distances are shown below, together with their most
common application:
O 410
Most Common Application
Mid-field monitoring
1.5 m (5’)
2.5 m (8)
8 m (24’)
In multichannel systems, one should ideally use the same product for all main channels. However, as the rear
channels often contain less bass and the signals are mixed at a lower level than the front channels, the rear
loudspeakers can be smaller - table below for details. The center loudspeaker should always be of the same type
as the left and right loudspeaker. The subwoofer should be sufficient to keep up with the main loudspeakers - see
subwoofer operating manual for details.
O 410
Ideal Rears
O 410
Smaller Rears
O 300, O 300 D
Refer to subwoofer operating manuals
System Block Diagram
Below is a three-way system block diagram.
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Klein + Hummel
Refer to the detailed product specifications section for information on the crossover frequencies, amplifier power,
and driver types. In an O 410, the Low Mid / Mid control is a Mid control. As the digital option is user installable,
there is no “D” version of the O 410.
Electronics Panel Picture
O 410 electronics panel
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Klein + Hummel
Input Stage
The standard input stage is a 14 kΩ electronically balanced type on a female XLR socket.
Audio Ground
If there is a humming or buzzing sound coming from the loudspeaker, first check it is not the loudspeaker by
disconnection the input signal cables. If the noise goes away it is not the loudspeaker itself and so the noises
must be coming from the cabling or the source. There are various ways to increase the loudspeaker’s immunity
from these external noises:
Use input ground lift switch to disconnect the audio ground, on pin 1 of the analog XLR input, from the
electronics’ chassis ground. For safety reasons, the electronics chassis ground is always connected to the
mains power earth pin.
Fit an optional transformer balanced input stage to the loudspeaker. This is especially effective when
combined with the ground lift switch.
If unbalanced cables are used, they can be specially wired – see picture below. Disconnect the cable screen
from the RCA sleeve if there are still humming or buzzing sounds, and/or use the ground lift switch on the
In addition, it is possible to fit a 2424-bit,
bit, 192 kHz digital
digital input stage.
stage It has XLR and BNC inputs, and a BNC output,
so it is possible to have analog and digital signals simultaneously connected; the selector switch is used to
monitor the selected input.
coustical Controls
The acoustical controls are low-order analog filters designed to compensate for some of the acoustical issues
commonly found in listening environments. There is either a Low Mid or Mid control depending on the
loudspeaker model. The other controls are seen on all three-way systems.
Klein + Hummel loudspeakers are designed to have a flat pass band magnitude response in anechoic conditions
when all the acoustical controls are set to 0 dB. When a loudspeaker is installed into a listening environment the
response changes and thus should be corrected back to a flat response. It is therefore expected that the controls
will need adjustment to improve the in-situ response of the loudspeaker. The acoustical controls’ settings will
depend on the loudspeaker’s location and will probably be different for the same loudspeaker type installed in
different locations in the same room. In a symmetrical installation, left/right pairs (front or back) will probably
have the same acoustical settings. Suggested settings are shown after this description of the controls:
The bass control is used to compensate for the effect of loading due to nearby large solid boundaries such as
walls. Four settings are available: 0, -2.5, -5, and -7.5 dB.
The mid control (O 410) is used to compensate for strong first order reflections (floor, ceiling, side walls), that
may cause an aggressiveness in the midrange sound quality. A high mid-band reverberation time can also have
this effect and thus be compensated. Four settings are available: 0, -1.5, -3, and -4.5 dB.
The treble control affects the treble driver output level and can be used to compensate for insufficient or
excessive high frequency damping in the room. The treble control is often set to suit the listener’s taste, although
in well-controlled environments there should be little reason to adjust it away from 0 dB. Four settings are
available: +1, 0, -1, and -2 dB.
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The parametric equalizer is a single stage PEQ filter with gain (+4…-12 dB), frequency (20…200 Hz) and Q (1…8)
controls designed to control nonlinearities seen below 200 Hz. These nonlinearities can come from boosts caused
by constructive interference or strong room modes. It is possible to bypass the parametric equalizer using the
bypass switch.
It is advised that an acoustical measurement system be used to set these controls in the most appropriate way
for the loudspeaker’s location. This is especially true of the parametric equalizer’s controls. In the absence of
appropriate equipment the following settings are recommended as a good starting point for further adjustment:
Acoustical Controls
Loudspeaker Location
In a corner
Next to or flush mounted in a solid wall
Next to or flush mounted in a soft wall
Free standing in an untreated room
Free standing in a well-treated room
-7.5 dB
-5 dB
-2.5 dB
-2.5 dB
O 410
-1.5 dB
-1 dB
*** This indicates that the parametric equalizer will probably need to be used. Its use will depend on the situation
so no standard recommendation can be made here.
O 410 Bass, Midrange and Treble Acoustical Controls
O 410 Parametric EQ Acoustical Controls
Note: the parametric equalizer’s response is not shown on the above graphs as it is freely adjustable within the
stated parameter ranges.
The input and output controls consist of a finely graduated control called “Input
Input Gain”
Gain and a coarse “Output
Level control. This allows the loudspeaker to be matched to a wide range of equipment outputs whilst
maintaining the desired acoustical output. As with any other component in the audio chain, it is best to use the
lowest gain for the application so as to minimize amplification of the preceding equipment’s source noise. To
check this, if the noise drops dramatically when the input cable is unplugged, the noise is coming from the source
not the loudspeaker. The default setting is “0 dB” and “100 dB SPL at 1m”. This gives an output level of 100 dB
SPL at 1m when the input signal is 0 dBu (0.775 V). The most sensitive setting (most acoustical output for a
given input voltage) is “6 dB” and “114 dB SPL at 1m”, and the least sensitive setting is “-9 dB” and “100 dB SPL
at 1m”.
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Input Sensitivity
Rotary Switch [dB]
-9 dB
-8 dB
-7 dB
-6 dB
-5 dB
-4 dB
-3 dB
-2 dB
-1 dB
0 dB
1 dB
2 dB
3 dB
4 dB
5 dB
6 dB
Acoustic output level [dB SPL] of the loudspeaker at 1m
when input signal is 0 dBu
Output Level switch = “10
Output Level switch = “11
“100 dB”
“114 dB”
100 (default)
Below are some examples of how to calculate the output level:
Input signal [dBu]
Input gain setting [dB]
Output level setting [dB SPL]
Sound Output of Loudspeaker [dB SPL at 1m]
0 (0.775 V)
+4 (1.23 V)
+6 (1.55 V)
+16 (4.89 V)
In Europe 0 dBu is -18 dBFS (EBU standard R68). In the US +4 dBu is -20 dBFS (SMPTE standard RP155). These
dBu values should equate to 85 dB SPL at the listening position. It is typical in the broadcast industry to use a
reference level of 79 dB SPL at the listening position. Near field loudspeakers can be as close as 1 m from the
listening position, whereas loudspeakers in a Dolby certified movie mixing room should be at least 5 m from the
listening position. In the examples below, it is assumed that the listener is inside the room radius and thus the
sound field decays according to 20 log10 (r), however this may not always be the case. Note that some additional
attenuation at the source (-6 or -10 dB) is required for SPL calibrated near field listening, but this facility is
always available in the console.
Input signal [dBu]
Input level setting [dB]
Output level setting [dB SPL]
Listening distance [m] (dB change)
Loudspeaker Output Level [dB SPL]
Maximum input signal before clipping
0 (0.775 V)
5 m (-14 dB)
17 dBu
+4 (1.23 V)
5 m (-14 dB)
17 dBu
The maximum input level that the input stage can accept is +19 dBu (approximately 6.9 V). To avoid clipping the
input stage, increase the input level of the loudspeaker by up to 6 dB. The maximum acoustical output of the
loudspeaker is limited by the protection system. In general, larger loudspeakers can play louder and for longer
periods than smaller loudspeakers.
Other Controls
The display dimmer is used to attenuate the display when the loudspeaker is used in low light situations. The
display can be completely turned off for use behind acoustically transparent screens. Four settings are available:
100, 66, 33, and 0 %.
The power On/Off switch turns the mains power completely on and off. There is a soft start function in the power
supply to reduce the effect of turn-on transients on the power line, thereby avoiding blown fuses.
The voltage selector switches select between 230, 120, and 100 V. Set this appropriately BEFORE applying main
power to the loudspeaker. An appropriate internal main fuse value is automatically selected. The applied mains
power voltage should be within -15% and +10% of the selected value.
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The 12 V trigger is used to turn the loudspeaker on and off remotely without having the use the mains power
switch. This may be useful in a large facility where the whole room is powered-up using a single switch.
Equipment can be time-delayed using simple low-voltage circuitry so there is not a mains power surge, although
there is already the soft start function to reduce this effect. Note that loudspeaker’s electronics are fully powered
on and off with this control, so the startup time is subject to the same on/off muting delays as if the loudspeaker
had been turned off and on using the main power switch. There are two modes of operation, which are selected
using an internal switch (see picture below):
Remote Power
Switch Position
Away from
Applying 12 V across the remote terminals turns OFF the loudspeaker
Removing the 12 V from the remote terminals turns ON the loudspeaker
Applying 12 V across the remote terminals turns ON the loudspeaker
Removing the 12 V from the remote terminals turns OFF the loudspeaker
The factory default mode setting is “12 V TURNS OFF”. In both modes and with either applied voltage levels at
the terminals, switching the mains power switch to “OFF” will turn off the loudspeaker.
To change the remote power mode to “12V TURNS ON”:
Turn off the loudspeaker and disconnect the mains power and signal cables.
Open the electronics panel (located in the cabinet or remote electronics kit).
Locate the large switch on the mains power circuit board and move the switch towards the backplate.
Close the electronics panel and reattach the mains power and signal cables.
Power up the loudspeaker, apply 12V to the remote control terminals, and check that the appropriate lights
are illuminated.
Using 4th order filters, the crossover divides the input signal into three bands for reproduction by the appropriate
sized driver. Time alignment ensures that the sound from each driver around the crossover frequencies is emitted
at the same time. In addition to this an extensive protection system ensures that the loudspeaker is not
damaged if a large signal is applied to the input. The red “PROTECT” lights up when the protection system is
active. If this happens, reduce the input signal. If this happens regularly, use a larger loudspeaker with a higher
SPL output, or add a subwoofer to handle the high-level low-frequency energy. The protection system consists of:
thermal and peak limiters for the amplifiers, thermal modeling of the drivers, and an excursion limiter for the
The protection system is not a compressor, it is designed to protect the loudspeaker from damage, and the red
light tells the user it is active. The protection cannot protect against sustained abuse of the loudspeaker, i.e.
consistently playing the loudspeaker for long periods of time with the protect light on, so avoid this to ensure a
long life from this product.
There are also production trimmers in the crossover section which are hidden from view to avoid “accidental”
adjustment. These should only be adjusted by qualified personnel with specialized measurement equipment. If a
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Klein + Hummel
component critical for sound quality, e.g. bass driver, is changed, the loudspeaker should ideally be recalibrated in
a Klein + Hummel Continental Service Center, i.e. one equipped with an anechoic chamber.
Hybrid class AB amplifiers are used because, for full range loudspeakers, the overall performance is still better
than any other solution. Harmonic and intermodulation distortions, and noise are all consistently low in welldesigned class AB amplifiers. Heat dissipation is reduced by using class H techniques for each amplifier channel to
seamlessly lower the amplifier power supply voltage when the input signal is low. Even so some space (5 cm, 2”)
is required around the electronics panel.
Accelerated Heat Tunneling™ (AHT™) is a technique designed to ensure equally effective cooling of the
amplifiers, whether the cabinet is mounted vertically or horizontally. The “funnel effect” accelerates cool air into
the lower heatsink aperture and expels heated air from the upper heatsink aperture. It is recommended that the
amplifier heatsink is checked for any build-up of dust and fluff at least every six months. The heatsinks can be
cleaned without having to open the electronics panel: simply blow clean compressed air into the vents on the side
of the electronics panel and across the external heatsink. Failure to do this may limit maximum SPL output.
If the cabinet is flush mounted it is highly recommended that the electronics panel be mounted on a Remote
Electronics Kit – see Accessories and Options section. Although no damage will result, insufficient cooling will
cause the amplifier protection to activate prematurely thereby limiting the system’s maximum output level.
The drivers are the best available for their application. Long throw, efficient, low distortion drivers ensure a clean
sound quality even at high replay levels. The bass driver is loaded by the internal volume of the cabinet. The mid
and treble drivers have their own self-contained back cavities. All drivers are magnetically shielded for use next
to CRT screens. The system’s SPL output and the cabinet volume can be seen in the specifications section below.
O 410 Mathematically Modeled Dispersion™ Waveguide (MMD
The midrange and treble drivers are mounted into a Mathematically Modeled Dispersion™ waveguide (MMD™).
The MMD™ is made from the same acoustically excellent material used in the O 300, LRIM™. It has been
mathematically modeled and experimentally verified in an anechoic chamber to give optimum control of the
directivity of the midrange and treble drivers. The benefits are increased driver loading, reduced edge diffraction
and room reflections, a smoother power response and a wide useable listening area. The result is a reduced audio
distortion and a corresponding sound quality improvement. The MMD™ has 80° x 60° dispersion and so, if the
loudspeaker is horizontally mounted, must be rotated 90° in either direction from the position it which it was
supplied. A rotated waveguide allows the bass driver to be placed either side of the MMD™. If the cabinet is
positioned upside down, the MMD™ should also be upside down to maintain an optimum midrange-bass
crossover region. As the display text is then upside-down, please contact K+H in Germany directly to get a
replacement display sticker with upside-down text. In all cabinet orientations, the acoustical axis should point
towards the engineer’s listening position, or the center of the listening area, in both the horizontal and vertical
planes – see Cabinet section for a definition of the acoustical axis.
This is how to rotate the MMD™:
Lay the loudspeaker cabinet on its back on a soft flat surface so the drivers are facing upwards.
Undo the four Allen head bolts on the MMD™ using a T4 Allen head screwdriver.
Carefully lift the MMD™ out of the cabinet, avoiding scratches on the paintwork and damage to the sealing
Reposition the MMD™ in the new orientation and centre it in the front panel cut-out.
Tighten the four Allen head bolts on the MMD™ to a torque setting of 2.8 Nm (0.74 lbf-ft).
Test the cabinet sealing by playing a reasonably loud (so you can feel some wind through the ports) sine
wave with a frequency equal to the loudspeaker’s -3 dB low frequency cut off (see specifications below).
Then listen for any hissing sounds around the edge of MMD™ and its drivers. If there is a hissing sound, the
sealing has been compromised and should be repaired.
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Klein + Hummel
The wooden cabinet is painted using a standard RAL color. An appropriately colored pen can be used to touch up
the paintwork if it is scratched during transport or use. The following RAL numbers correspond to K+H standard
cabinet colors.
K+H Color Name
RAL Number
Combined with the cabinet volume, the ports load the bass driver to extend the low frequency response of the
loudspeaker. The ports have a high capacity to move air without inducing turbulence and associated
nonlinearities that degrade the sound quality.
The acoustical axis is a line normal to the loudspeaker’s front panel along which the microphone was placed when
tuning the loudspeaker’s crossover during design. Pointing the acoustical axis, in the horizontal and vertical
planes, towards the listening position or centre of the listening area will give the best measured and perceived
sound quality. For three-way loudspeakers in the Klein + Hummel range, the acoustical axis is located on the midpoint of the midrange and tweeter drivers.
O 410
x dimension
16.5 cm (6 1/2“)
y dimension
51 cm (20 1/8“)
O 410 Acoustical Axis
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System Use
Klein + Hummel loudspeakers should only be used indoors and in these ambient conditions:
• +10° C to +40° C (+50° F to +104° F), <90% relative humidity, non-condensing
During transport or storage the ambient conditions can be:
• -25° C to +70° C (-13° F to 158° F), <90% relative humidity, non-condensing
Before connecting the mains power cable, ensure that the correct mains voltage is selected on the electronics
panel (230, 120, or 100 V) and that the mains power switch is off. Next connect the input signal cable (analog,
digital, or both as appropriate) and power up the loudspeaker. There will be a five second delay before sound can
be heard from loudspeaker so as to avoid noises (pops) from preceding equipment turned on at the same time.
Conversely, turning off the loudspeaker immediately mutes the audio. The K+H logo should light up together
with either the green or yellow light to indicate an analog or digital signal. If there are no lights, check the mains
power supply and the display dimmer (ensure it is not set to 0 %).
In a studio application, the loudspeakers should be placed according to the ITU-R BS.775-1 recommendations so
there is consistency of reproduction when compared to other listening environments. For movie applications,
ANSI/SMPTE 202M is the preferred standard for system setup. For home use, as materials are mixed in ITU style
rooms, one should get as close as possible to this configuration to maximize replay authenticity.
Loudspeaker Name
Left Surround
Right Surround
ITUITU-R BS.775BS.775-1 Angle
An array to the left
An array to the right
For two-channel stereo, ±30° should be used. There are currently no internationally agreed standards for 6.1 or
7.1 formats. However common practice is to use one or two loudspeakers in the centre back location of a 6.1
system. In a 7.1 system common practice is to place side loudspeakers at ±90° and to push the surround
loudspeakers back to ±150°.
For the best stereo imaging the loudspeakers should be placed symmetrical in a symmetrical room where objects
have been placed symmetrically. This ensures the same response from each loudspeaker at the listening position
and thus good imaging. Sound reflected back to the listening position should also be minimized using surface
angling or acoustical treatment. The acoustical axis point towards the listening position or centre of the listening
area in both the horizontal and vertical planes.
The loudspeaker should be placed on a circle to ensure equal time of arrival of the audio from all loudspeakers.
Failing this, appropriate electronic time delays should be added to compensate for time of flight differences.
If the loudspeaker is used free standing, good quality loudspeaker stands and suitable accessories (see
Accessories and Options section) are recommended.
The benefits of flush mounting are reduced cabinet edge diffraction (smoother midrange), increased bass driver
loading (reduced bass distortion), and elimination of rear wall cancellations (smoother bass response). It is a
good idea to employ an experienced acoustic engineer to design an effective flush mounting wall. Recommended
acoustical control settings are shown in the Acoustical Controls section and a Remote Electronics Kit, shown in the
Accessories and Options section, is highly recommended to avoid heat dissipation problems and allow easy
adjustment of the controls. If the loudspeaker must be covered, use a thin open weave cloth. Two layers of very
thin material will improve opacity.
Before trimming the levels, calibrate each loudspeaker’s response:
In studio applications, the response of each loudspeaker at the listening position should be flat.
In movie applications, the response of each loudspeaker should be one of the X-curve shapes, depending on
the size of the room (see ANSI/SMPTE 202M).
In home applications, the response of each loudspeaker should be set for subjective audio quality. This is not
necessarily a flat response, but generally, with time, a gently downward sloping response with increasing
frequency is often preferred.
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Absolute acoustic level calibration is achieved using a sound level meter set to ‘C’-weighting and a “slow”
integration time. Play a broadband pink noise test signal set to -18 dBFS (Europe) or -20 dBFS (USA) on the
console meters and measure the sound pressure level at the listening position. Then adjust each channel’s level
(can also be adjusted on all loudspeakers for a specific channel) until the desired level is achieved:
85 dB(C)
79 dB(C)
Engineer’s preference
For information on setting up a subwoofer with these main loudspeakers, please refer to the operating manual
supplied with the subwoofer.
Technical Specifications
-3 dB free field frequency response
Pass band free field frequency response
Self-generated noise
Sine wave output with a THD < 0.5 % at 1 m distance
Max. SPL In half space at 3% THD
Averaged between
30 Hz … 24 kHz, ± 3 dB
32 Hz … 20 kHz, ± 2 dB
≤25 dB(A) at 10 cm
95 dB SPL (>100 Hz)
120.0 dB SPL
100 Hz and 6 kHz
Woofer amplifier, cont.(peak) output power*
Mid amplifier, cont. (peak) output power*
Tweeter amplifier, cont.(peak) output power*
Controller design
Crossover Frequency
Crossover Slope (dB/oct.)
Equalization: Low cut
Parametric Equalizer:
Time of Flight adjustment delay
Protection circuitry
Infrasonic filter frequency; slope
340 W (400 W)
160 W (190 W)
180 W (210 W)
analog, active
600 Hz/2.2 kHz
0, -2.5, -5, -7.5 dB
0, -1.5, -3, -4.5 dB
+1, 0, -1, -2 dB
+4 … -12 dB
20 … 200 Hz
Limiter: low, mid, high
15 Hz; 12 dB/oct.
Analog Input
Impedance, electrically balanced
Impedance, transformer balanced
Input sensitivity
XLR, 13 kΩ
XLR, 4.7 kΩ, optional
-8 dBu / +6 dBu
-9 … + 6 dB
>60 dB @ 15 kHz
Digital Input/Output
Format XLR (Format BNC)
Impedance XLR, balanced
Impedance BNC, unbalanced
Input switching
Digital converter: resolution, design
sampling rate
Displays and Mains Power
Displays and indicators: power on
Mains power
Power consumption - Idle
Power consumption - Full output AC
O 410 Operating Manual
(AES3id, S/P-DIF)
110 Ω
75 Ω (input and output)
Analog/Digital A, B, Mono
16 … 24-bit DAC, ∆Σ
20 … 216 kHz (SRC)
K + H logo “red”
Green (Analog signal),
Yellow (Digital signal, error)
230, 120, 100 V AC
36 VA
1300 VA
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Height x width x depth, mm
Internal net volume
Mounting points
Mounting hardware included
Cabinet surface finish
Color: standard
Color: custom at extra cost
Baffle cover
*THD+N < 0.1 % with limiter deactivated
645 x 330 x 444 mm
25 3/8” x 13” x 17 1/2"
42 liters
36.0 kg (79.2 lb)
Magnetically shielded
10", 250 mm
3", 76 mm
1", 25 mm
Threaded inserts on rear
Anthracite or silver
Optional metal grille
Acoustical Measurements
Below are acoustical measurements conducted in anechoic conditions at 1 m. Color versions of these graphs can
be found on the appropriate product page of the klein-hummel.com web site.
O 410 freefree-field response
O 410 group delay
0ø Grad
O 410 horizontal directivity plot
O 410 vertical
vertical directivity plot
O 410 harmonic distortion at 95 dB SPL
O 410 intermodulation distortion at 95 dB SPL
O 410 Operating Manual
0ø Grad
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Accessories and Options
In this section is a description of the options and accessories that are available for the products covered in the
operating manual. Note that options and accessories are fitted at the user’s own risk and that safety and
warning instructions should be observed.
Transformer balanced input module option (TIM 1)
This option changes the electronic balanced input into a transformer balanced input for increased noise
immunity, especially when used in conjunction with the ground lift switch. The circuitry is based on a current
transformation with a THD less then -100 dB @ 16 dBu input level, even down to 20 Hz. It can be used in
conjunction with the digital input option when “Analog” is selected.
Digital input module option (DIM 1)
This option is a 16…24-bit, 20…216 kHz digital input stage that can accept AES3-2003 (commonly known as
AES/EBU), AES3id-2001, and S/P-DIF (with a suitable impedance adapter or connector converter) signals. XLR
and BNC connectors ensure good interconnectivity options. A buffered BNC output is provided for connecting
additional loudspeakers to the same cable – a user supplied 75 Ω BNC terminated coaxial cable is required for this
(same cable type as used for word clock signals). The BNC output provides an electronically buffered copy of the
input data, but in AES3id format. The BNC input stage has an internal 75 Ω termination so T-pieces and
terminators are not required. A four-way switch allows selection of:
nalog input (electronic, or transformer if it is fitted)
Digital subframe “A
Digital subframe “B
Digital subframes A and B simultaneously “M
M” (mono). Note: output level is automatically attenuated by 6
dB to avoid clipping and have the same loudness as a single channel reproduction (A or B).
It is possible to have an analog and a digital cable simultaneously connected to the loudspeaker. The input
selector switch is used to monitor the selected input. Only one of the digital inputs (XLR or BNC) should be
connected at a time. A clock input is not required because loudspeakers are not audio sources and the clock signal
is locally regenerated from data contained in the bit stream.
User-bit volume control (IEC 60958-1) is supported so that the source can directly control the output level of the
loudspeaker whilst using digital signals normalized to full scale. The digital volume control occurs in the analog
domain, thereby offering full bit resolution and improved reproduction at low replay levels. The source must also
support this standard for it to work – see information provided by the manufacturer of the source to see how it
has been implemented.
De-emphasis is supported on 32, 44.1, and 48 kHz sample rates.
An interconnection example is shown below. To listen to the analog source, set both loudspeakers to “Analog”. To
listen to the digital source, set the left loudspeaker to “A” and the right loudspeaker to “B” (note the signal
routing in the source).
If the analog input is selected (Analog), the green light on the MMD™ display illuminates. If the digital input is
selected (A, B, or M), the yellow light on the MMD™ display illuminates. The yellow light does not illuminate if
there is no valid word clock on either digital input (note: the green light will also be off in this state as a digital
input has been selected). If there is an error in the digital signal, the yellow light will flash. If this happens check
the cables and connectors, and the source equipment. If there are no lights on, check that mains power is applied
and that the display dimmer switch is not set to 0%. Always use good quality cables with the correct impedance
to achieve these maximum cable lengths:
Format (Connector)
AES3id (BNC)
O 410 Operating Manual
75 Ω
110 Ω
75 Ω
Cable Length
up to 10 m (30’)
up to 100 m (300’)
up to 1000 m (3000’)
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Klein + Hummel
Warning: The digital input option’s BNC connectors protrude from the rear panel. If the O 410 cabinet is placed on
a flat hard surface with the drivers facing upwards, the circuit board will be damaged. Find a soft surface, such as
bubble wrap, packing foam, or a folded blanket, or angle the cabinet slightly to avoid applying pressure to the
BNC connectors.
Remote electronics kit option (REK 1)
This is a hardware kit to allow the electronics panel to be located up to 30 m (90’) away from the loudspeaker
cabinet. The benefits enjoyed when loudspeakers are flush mounted are: lack of heat dissipation problems, easy
adjustment of the controls, and easier electronics servicing. An 8-pole Speakon terminated cable carries the
driver signals and a CAT-5 cable carries the display signals. Additional space is not required behind the cabinet as
the connectors face downwards when installed. The connections are as follows (note: “Bass 2” is not used when
there is only one bass driver in the cabinet):
Bass 1-/+
Bass 2-/+
Midrange -/+
Treble -/+
Speakon Pins
1 -/+
2 -/+
3 -/+
4 -/+
K+H Logo -/+
Red -/+
Yellow -/+
Green -/+
RJRJ-45 Pins
The cabinet’s serial number is printed under the bass ring – pull it gently by hand to remove it – so it is visible
when the cabinet is flush mounted. This number should be matched to the serial number printed on the remote
located electronics panel.
O 410 Operating Manual
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Klein + Hummel
Cable pack (CP nn)
A CAT-5 and 8-core driver cable of length 2, 5, 10, 15, 20, 25, and 30 m (6’, 15’, 30’, 45’, 60’, 75’, and 90’) are
available from Klein + Hummel (Cable Pack 2, 5, 10, 15, 20, 25, or 30), or industry standard cables may be
sourced from a third party. The Klein + Hummel cables use flame retardant materials and high-quality metal
connectors (Neutrik EtherCon NE8MC and Neutrik Speakon NLT8FX). The conductor specification is shown in the
table below:
<=20 m (60’)
>20 m (60’)
Wire Gauge
2.5 mm2 (14 AWG)
4 mm2 (12 AWG)
Mounting hardware (LH nn)
A collection of hardware for mounting the loudspeaker:
LH 28
LH 29
LH 36
LH 37
LH 41
LH 42
LH 43
LH 44
LH 45
Tripod stand adapter – used to fit the loudspeaker onto a standard 1.4” tube tripod stand (external fit
with screw thread).
TV spigot adapter – used to fit the loudspeaker onto a standard TV spigot used in broadcast studios
(internal fit).
Tilting adapter – used to add a tilting function to a tripod stand or TV spigot.
Tripod stand adapter – used to fit the loudspeaker into a standard 35 mm (1.4”) flange fitting.
Base plate – used to fit the loudspeaker onto a tripod stand. Adding an LH 36 gives a tilting function.
Ceiling system (Vertical) – used to suspend the loudspeaker from a ceiling when the cabinet is oriented
vertically. The maximum angle is 30°, selectable in 2.5° increments.
Surface mounting plate – used to mount the LH 42 onto a flat surface such as a ceiling.
Ceiling system
system (Horizontal) – used to suspend the loudspeaker from a ceiling when the cabinet is
oriented horizontally. The maximum angle is 30°, selectable in 2.5° increments.
Wall mount ‘L’ bracket – used to suspend the loudspeaker from a ceiling when the cabinet is oriented
horizontally. The maximum angle is 30°, selectable in 2.5° increments.
LH 28 – Tripod stand adapter
LH 29 – TV spigot adapter
LH 36 – Tilting adapter
LH 37 – Tripod flange adapter
LH 41 – Base plate
LH 42 – Ceiling system
system (Vertical)
O 410 Operating Manual
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Klein + Hummel
LH 43 – Surface mounting plate
LH 44 – Ceiling system (Horizontal)
LH 45 – Wall mount ‘L’ bracket
Suitable combinations of the above hardware are:
Location of Loudspeaker
Hardware Combinations
Flush Mounted
On a Floor Stand
(tripod, TV spigot, or with a
5/8" thread)
REK 1 and CP nn for electronics
LH 41 + LH 28
LH 41 + LH 36 + LH 28
LH 41 + LH 29
LH 41 + LH 36 + LH 29
LH 41 + LH 37
LH 41 + LH 36 + LH 37
LH 42 + LH 45
LH 44 + LH 45
LH 42
LH 42 + LH 43
LH 44
LH 44 + LH 43
LH 42 + LH 29
LH 44 + LH 29
On a Subwoofer
(fitted with a flange)
On a Wall
Off a Ceiling
Off a Lighting or Truss Bar
Detailed mechanical drawings of these accessories can be found on line at www.klein-hummel.com.
Metal grille (GO 410)
A metal grille (pictured below) can be attached to the front of the loudspeaker to protect the drivers. It simply
clips into the grooves on the long sides of the cabinet. It is damped to avoid rattles and has been designed for
acoustic transparency. The grille is available in black and silver.
Flight case (FO 410)
As the original packing is primarily designed to get the loudspeaker from the factory to the end user, it is highly
recommended that a flight case (pictured above) is used if the loudspeaker is regularly moved between locations.
One O 410 can be packed in each flight case.
O 410 Operating Manual
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Klein + Hummel
Safety and Warnings
In addition to specific warnings throughout this document, please observe these additional general instructions.
The term “loudspeaker” includes the case when the electronics of an active loudspeaker is installed into a Remote
Electronics Kit, or when it is still located in the back of the cabinet.
This symbol means that a high voltage is to found nearby. Take appropriate precautions to avoid
electric shocks.
This symbol means that hot parts of the product may be found nearby. Take appropriate
precautions to avoid burns.
• Keep these instructions in a safe place for future reference.
• Failure to follow the safety and warning instructions contained in this document voids the warranty.
• This product should be used for the intention for which it was designed and as described in this document.
• Ensure that the room in which you use this product is wired in accordance with the local electrical code and
checked by a qualified inspector.
• A correctly earthed mains power connection should always be used.
• If access to the interior electronics is required, disconnect it from the mains power and allow electrical energy
storage devices, such as capacitors and transformers, to discharge.
• Other electronic products may generate sufficient heat to require ventilation.
• Do not block or cover heatsinks, fans, or vents.
• Unless otherwise stated, this product is designed to be used indoors only.
• Do not expose this product to water, any other liquids, moisture, or naked flames.
• Do not install this product into hot, humid, or excessively dusty locations, or into direct sunlight.
• Avoid installing this product into locations where it will experience externally generated vibrations or heat
(e.g. radiators).
• If the product is moved from a cold environment into a warm one (such as from a vehicle into a building), it is
possible that condensation will form. Please allow the product sufficient time for acclimatization to room
temperature before using.
• Wherever an amplifier is located, a free flow of air should be maintained by leaving a gap of at least 5 cm
(2”) around it. A flush mounted cabinet with the electronics panel still installed should be well-ventilated to
avoid heat build-up and possible risk of fire.
• The equipment should be mounted by a suitably qualified professional in accordance with local, national, and
international regulations and standards.
• Falling equipment can damage itself, people, and other objects, so do not place this unit on any unstable
platform, cart, trolley, stand, table, or mounting hardware.
• Do not use accessories and options with this product that are not approved by Klein + Hummel.
• Mounting hardware must be attached to the appropriate hardware and attachment points rated and
intended for such use.
• Ensure that the operating voltage of this product matches that of the local mains voltage.
• Use the power cable that came with this product as this has been manufactured to international safety
standards. If it has been damaged obtain a similarly certified and specified mains power cable.
• This product should be unplugged from the mains power and the signal sources if is not to be used for an
extended period of time, or during lightening storms.
• The power switch on this product should be set to off before applying mains power via the mains power
• Some parts of this product, particularly power amplifier components, can become hot to the touch. Do not
touch these parts until they have cooled down.
• Never touch the loudspeaker’s drivers.
• Loudspeakers are often capable of producing a sound pressure level in excess of 85 dB. This may cause
permanent hearing damage so user caution is recommended. Noise exposure is a function of SPL and time, so
observe local regulations when listening at high levels for a long time. Hearing protection may be required.
O 410 Operating Manual
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Klein + Hummel
• Repairs, maintenance, or other servicing of this product when its interior compartment is exposed should
only be performed by Klein + Hummel authorized service engineers familiar with the equipment and risks
involved in handling electronics.
• Servicing may be required in the event of exposure to unfavorable environmental conditions, such as liquids,
excessive heat, or a lightning strike.
• Amplifier outputs may carry high voltages so take appropriate precautions, for example, connect the cables
before powering up.
• When replacing a fuse, ensure that a brand new fuse is used. It must be exactly the same type, value, and
voltage as the original, as stated in the product’s technical specifications or on the circuit board.
Maintenance and Servicing
There are no user serviceable parts inside the standard version of this product. Repairs should only be
undertaken by Klein + Hummel certified service engineer.
Options and accessories are fitted at the user’s own risk.
Products may be cleaned using a non-abrasive cloth lightly damped with water. Disconnect the mains power
cable when cleaning to avoid risk of electric shock. Do not use alcohol-based cleaners.
The electronics should only be opened by non-“Klein + Hummel certified service engineer” for the installation
of user installable options as described in the product’s operating manual. The mains power cable should be
disconnected whenever the electronics panel is opened.
If the main fuse blows, the product should be checked by a Klein + Hummel certified service engineer.
This product comes with a guarantee, a copy of which is enclosed with this product.
Attention to product quality in the design phase ensures, firstly, that products have a long life and that, secondly,
all parts of a product may be reused or recycled at the end of that life. An extensive product servicing network
ensures that products can be repaired in the event of the premature failure of a part, or as a way to prolong the
life of a product that would otherwise be considered a candidate for landfill. Eventually there comes a time when
a product is considered beyond repair (for economic reasons or lack of parts), so the parts must be disposed of in
a suitable manner. The disposal should conform to local environmental regulations and be conducted in an
authorized recycling facility.
Loudspeakers and electronic products consist of some or all of these components:
Loudspeaker Cabinets
Damping Materials
Electronics Panel
Remote Electronics Kits
Cables and Connectors
Packing Material
User Manuals and Sales
O 410 Operating Manual
Wood (MDF), steel, aluminum,
polyurethane or a combination
Aluminum, copper, paper and plastics
Sheep wool
Steel and some electronics
Metals and/or plastic
Cardboard, wood and/or plastics
Paper and cardboard
Recycling Instructions
Separate materials then recycle
Separate materials then recycle
Remove electronics and recycle
Recycle in an approved recycling facility
Separate materials then recycle
Reuse or recycle
Separate materials then recycle
Page 17
Klein + Hummel
EC Declaration of Conformity
This equipment is in compliance with the essential requirements and other relevant provisions of Directives
89/336/EC and 73/23/EC. The declaration is available on the internet site at www.klein-hummel.com. Before
putting the device into operation, please observe any respective country-specific regulations.
For loudspeakers fitted with digital inputs: Compliance to FCC Rules
This device complies with part 15 of the FCC Rules and with RSS-210 of Industry Canada. Operation is subject to
the following two conditions:
• This device may not cause harmful interference, and
• This device must accept any interference received, including interference that may cause undesired operation.
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 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.
Consult the dealer or an experienced radio/TV technician for help.
This class B digital apparatus complies with the Canadian ICES-003
Changes or modifications to this equipment not expressly approved by Klein + Hummel may void the FCC
authorization to operate this equipment.
O 410 Operating Manual
Page 18
The following are trademarks of K+H Vertriebs- und Entwicklungsgesellschaft mbH.
• “Low Resonance Integral Molding” and “LRIM”
• “Mathematically Modeled Dispersion” and “MMD”
• “Accelerated Heat Tunneling ” and “AHT”
Other company, product, or service names may be trademarks or service marks of other organizations.
Klein + Hummel reserve the right to change product specifications without notice. Exceptions and omissions
K+H Vertriebs- und Entwicklungsgesellschaft mbH
Auf dem Kessellande 4a, 30900 Wedemark, Germany.
Phone: +49 (5130) 58 48 0
Fax: +49 (5130) 58 48 11
E-mail: enquiries@klein-hummel.com
Web site: www.klein-hummel.com
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