K2 Audio KLABPLUS Operating and safety instructions

KLABPLUS
Overview
The KLABPLUS is a compact, powerful stereo amplier built onto a standard size UK double gang
wall plate. It provides 20W (RMS per channel) of amplication eliminating the need to make space
for a conventional amplier. It is powered by an externally located mains adaptor and can controlled
by push buttons integrated into the front panel membrane or by infrared remote. It can be switched
between four audio sources; an integrated FM radio, rear line input (analogue or digital), bluetooth
and a front panel 3.5mm jack input. The amplier uses class D digital circuitry for maximum eciency
and generates very little heat. The amplier only requires 25mm depth and so may be either ush or
surface mounted. The KLABPLUS can be customised prior to installation using the free KLABSETUP
software, allowing many parameters including Bluetooth ID to be changed. The software requires use
of an optional programming cable (code KLABLINK).
Installation & Connection
Installation should only be carried out by a qualied installer or electrician, as a certain amount of
electrical knowledge is assumed.
Mounting
The 25mm depth will allow installation into standard UK 2-gang boxes, which may be galvanised
metal for installation in solid walls, or plastic drylining (with lugs) or surface mount box or trunking
system.
Important - please read!
The front panel membrane has two tabs that can be exed outward to allow
access to the panel xing screws. Once fastened in position and tested the
backing paper can be peeled o and the tabs xed down ush to conceal the
screws. ONLY perform this operation once the installation has been tested
and found to be satisfactory. Once stuck down these tabs cannot be removed
without damage to the front panel.
Replacement front panels are available, (part number KLABPLUSFP)
Wiring
In order to make a reliable and safe connection without short circuits it is recommended that the
speaker cables and line input signal cables are prepared and tinned prior to connection, with no more
than ¼” or about 7mm of tinned wire extending out of the insulation.
Power
The amplier requires a power supply of 12v to 18v DC centre positive and a minimum current of
3500mA. If you are not using the recommended psu please verify that the supply is correct BEFORE
connection. If using the recommended supply we suggest that it is connected in accordance with
current wiring regulations. The amplier can also be powered from a 12v car battery but NOT directly
from a car battery charger as this would damage the circuitry. Do not install near any heat sources
such as radiators, stoves, or other apparatus that produce heat. The mains connection should be via
a fused and switched mains outlet.
Environment
The KLABPLUS is not IP rated for use in a damp environments but if due care is given to positioning
of the amplier and supply then it can be used in zone 3 installations. Please use a qualied
electrician operating to current regulations if you intend to use this unit in a bathroom.
Setup and installation guide

Left speaker
connection
DC input
socket
KLABLINK
connector
FM Aerial
connector
Rear line input
jack socket
(analogue or
digital)
Right speaker
connection
Connections for Power, Line Input and Loudspeaker Outputs
are located on the rear PCB.
Note that the loudspeaker and line input screw terminal blocks can be pulled
upwards and detached from the PCB to make connection and installation easier.
Rear line input
The rear line input is multi-functional 3.5mm jack socket. It can accept both analogue OR optical
audio signals and will automatically route the signal accordingly. If you are using a surface mount
pattress you may nd a right angled adaptor useful as sometimes the moulded section of an optical
cable plug can be quite a tight t.
Aerial
The FM radio requires a 75ohm aerial for operation. The bare wire ends of the supplied aerial cable
should be connected to the terminals on the PCB and the other end arranged in a “T” shape as best
as possible within wall or ceiling. If the cable needs to be extended then use similar sized 75ohm
impedance cable. If you wish to connect to an external FM loop aerial then use coaxial aerial cable.
Polarity of the supplied aerial is not important, although if using coaxial cable then connect the
screen (ground) to the right hand terminal closest to the PCB screw.
Loudspeakers
Connect the loudspeakers being careful to keep both left and right phase connections the same.
For example if you’ve connected the left speaker positive to “A” and negative to “B” make sure
that the right speaker positive also goes to “A” and negative to “B”. Please note that the amplier is
fully bridged so there is NOT a common ground or return connection. The recommended minimum
speaker impedance is 4 ohms on each channel. If driving 2 speakers or more on each channel
use them in series if they are both 4 ohms or in parallel if they are both 8 ohms. Note the speaker
corresponding to the left input is actually on the right hand terminals in the amp as viewed from the
front.

Final Checks
Double check all connections and, if all is well then fasten the panel into the mounting box. Switch
on the power source and observe the LED’s. On rst receiving power the KLABPLUS will perform
an initialisation routine and the LED’s will ash in sequence. Once the initialisation is complete the
amplier will default to standby. Press the “power” button on the front panel once (or press power
on the remote control) and the standby red LED will change to a slow ashing blue LED ready for
bluetooth pairing. Use the front panel controls or infrared remote to cycle through the other inputs.
If there are no unexpected sounds then it’s probably all connected correctly and it should be safe
to proceed to the operation instructions. Do not fasten down the tabs until you are certain that
everything is working as it should!
Operation - front panel overview
Stores the current
radio station to the
current location
Switches between
Bluetooth, radio, PCB
line input and jack
Mutes the output
Switches between
Standby and On
Seeks up to the next
radio signal
Switches between
stored radio stations
Volume Up
3.5mm jack socket
front auxiliary input
Volume Down
Receiver window
for the supplied IR
remote control
Status indicator LED’s
Notes
When the klabplus is switched on from standby
it will revert to the last used input. In the
event of a power failure the amp will self test
then revert to standby mode. The last stored
parameters will be preserved.
It is safe to leave the amp in standby as very
little current (less than 100mA) is used in that
mode. In standby only the Red power LED will
be illuminated. This is the normal method of
switching o.
Volume
There are 64 steps to the volume control from a minimum volume of 0 to a maximum volume setting
of 64. These are accessed by pressing the volume up and volume down buttons. The 10 number
keys from zero (minimum) to 9 (maximum) provide quick way of selecting a range of preset volumes
within this range. Please note that the volume control system used does not go to absolute zero
volume, the mute button is provided for when you require the unit to produce no sound.

Standby
Increase / decrease
volume
Cycles through the
inputs: bluetooth,
radio, rear line, front
jack
Bluetooth next and
previous track.
Radio station preset
up/down.
Adjust parameters
when in setup mode.
Power on/o
F5 then number key
= got to radio preset
Numbers 0 to 9
give pre-set volume
levels
Mute
F6 toggle loudness
on/o
Bluetooth mode
In Bluetooth mode a slow ashing blue LED indicates that no Bluetooth device is connected. Switch
your device’s Bluetooth function on and go to the Bluetooth settings. Scan for new devices and
select KlabPlus (or the name was assigned during setup). Your device may display a pairing code
in which case accept. If a specic PIN was specied during setup this must be entered. Once
connected the LED will stop ashing and you can now play music through the KLAB. F1 sends a
play/pause command to the device. F2 sends stop command to the device. The large up and down
buttons (above/below mute) send next and previous track command to device.
When switching the amplier back from standby or from another source to Bluetooth mode it will
attempt to reconnect to the last paired device. Please be aware that not all Bluetooth devices will
automatically reconnect and if this is the case you may need to select the amplier again from the
list in your Bluetooth settings.
The factory set Bluetooth ID is KlabPlus. It can be changed to any desired name (up to 14
characters) by using the klabsetup software program in conjunction with the klablink cable, details
at www.info.keene-electronics.co.uk
Important - when you scan for Bluetooth devices the ID is usually stored along with its unique MAC
address. When you change the ID from say Klabplus to Kitchen it may still appear in your device list
as Klabplus if this had been previously scanned and discovered. This may be the case even if you
have not previously paired with it. To force the name to change you will need to pair to the device,
then perform a “forget this device” or “unpair”, then rescan and re-discover it under the latest
device ID.
F1 radio seek (up)
F1 bluetooth pause
F2 enter/exit setup
F3 radio seek (down)
F4 next / store

Radio mode
In normal operation you can either press the front panel “preset” button or the up or down arrow on
the remote (above/below the mute button) to cycle through the FM presets.
To store a radio station rst choose a memory location, for example to store to location four, press
F5 then four. This makes number four the current active memory location. Now press seek (F1
up or F3 down) until the tuner settles on the station you like. Now press and hold F4 until the FM
radio LED ashes green and the current station will then be stored to location four. Repeat for each
location (0 through 9) storing as desired. Presets can also be listed edited and stored using the
klabsetup software program details at www.info.keene-electronics.co.uk.
Adjustment procedure for bass, treble, balance and loudness:
To enter setup mode press F2 and hold for 8 seconds. All 4 LEDs will illuminate briey then one
will go out ready to change the rst parameter.
F4 cycles through these parameters and the radio preset up/down (above/below mute) will adjust
the levels. To exit setup procedures press F2 again. To store the current settings to memory so they
will be saved when the KLABPLUS is switched o and on again exit setup mode by pressing F2 and
then press F4. Note - setup mode will be exited automatically (without storing) if no key is pressed
within four seconds.
When in setup mode the LED’s will illuminate as follows:
When making adjustments in setup mode:
The “mute” key will reset the parameter
being adjusted
The “F1” key will reset all four parameters
In setup mode
press up / down
to adjust then F4
to move to next
parameter then
store and exit
Adjust bass
Adjust treble
Adjust balance
Adjust loudness

+
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+
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speaker
terminal
+
-
+
-
speaker
terminal
+
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+
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speaker
terminal
speaker
terminal
+
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+
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+
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+
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How to safely connect more than one pair of speakers
Parallel wiring
Series wiring
8 ohm 8 ohm
8 ohm 8 ohm
8 ohm 8 ohm
8 ohm
8 ohm
amplier load approximately 4 ohms per channel
amplier load approximately 16 ohms per channel
In short:
2 x 8 ohm speakers in parallel = approx 4 ohm = OK
2 x 4 ohm speakers in parallel = approx 2 ohm = Too low
3 x 8 ohm speakers in parallel = approx 2.66 ohm - Too low
3 x 4 ohm speakers in parallel = approx 1.33 ohm = Too low
2 x 8 ohm speakers in series = 16 ohm = OK
2 x 4 ohm speakers in series = 8 ohm = OK
3 x 8 ohm speakers in series = 24 ohm = Too high
3 x 4 ohm speakers in series = 12 ohm = OK
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+
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speaker
terminal
+
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Series / parallel wiring
8 ohm
8 ohm
amplier load approximately 8 ohms per channel
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8 ohm
8 ohm
+
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+
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speaker
terminal
+
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+
-
8 ohm
8 ohm
8 ohm
8 ohm

Series Parallel wiring explained
If you want to drive two pairs of loudspeakers from the output of one amplier you can either
connect them to a switchbox or wire them directly. If you use a switchbox then you can have the
exibility of listening to either or both pairs as required. If you always want both pairs to be active
then it is possible to wire them directly as long as you are careful with the connections. There are
two ways to wire the loudspeakers; either in series or in parallel.
Wiring in series increases the impedance and will give a lower acoustical output. Wiring in Parallel
has the opposite eect of lowering the impedance and increasing acoustical output. When deciding
how best to connect have a look at the impedance of the loudspeakers you are using and also at
the specications for the amplier. Most ampliers will not work correctly with a load of below
4 ohms so if in doubt, always wire in series. These example use only two pairs of loudspeakers. It
is possible to combine more than 2 Speakers per channel. If connected in Parallel, (and assuming
each loudspeaker has the same impedance) then the net impedance of the load is equal to the
impedance of the one loudspeaker divided by the total number of loudspeakers.
For example 3 x 8 Ohm loudspeakers in parallel would equate to 8/3 (2.667) Ohms. If connected
in series (and assuming each loudspeaker has the same impedance) then the net impedance
of the load is equal to the impedance of the one loudspeaker multiplied by the total number of
loudspeakers, for example 3 x 8 Ohm loudspeakers in series would equate to 8x3 (24) Ohms.
A quick note about testing ceiling speakers.
It can be a temptation to take your newly purchased ceiling speakers out of the box and connect
them straight-away to see how they sound before tting them into place.
Be aware that all open back ceiling speakers will sound terrible if you simply connect them whilst
they are just sitting on a table. This is because they have been designed to be xed into a panel.
The panel (ceiling) acts as a
bae, and if there is no bae
then air can simply spill around
either side of the cone with next
to no resistance. This means the
front and rear waves are able to
cancel each other out, resulting
in a complete lack of bass and
a sound that is pretty awful. It is
not unknown for people to test
newly purchased speakers like
this and then send them straight
back to their supplier leaving
both parties somewhat disappointed.
If you want to have an idea of how they will sound before you mount them in place the simplest
solution is to use a couple of large cardboard boxes. Simply cut the appropriately sized hole in each
box, push the speakers into place and test them that way. They still won’t sound exactly the same
as they will in the ceiling, but the box will at least provide some semblance of a bae and give you a
much more realistic indication of their performance. If you don’t have any boxes then even mounting
them into large at sheets of card (or other material) will suce as long at the sheets extend at least
30cm from each edge of the speaker.
In fact a at sheet is what’s known as an open bae and in reality you’d need a sheet nearly 8m in
diameter to get a sub-50hz bass response! But the purpose of this is not to get into the ne detail
of loudspeaker enclosure design (fascinating a subject as that is), its simply to help you avoid any
disappointment before you nish your installation.

Contact us www.k2audio.co.uk [email protected]
Designed and manufactured in the UK!
Customisation
The KLABPLUS can be
customised using the free
KLABSETUP software.
This allows you to program your
own options for:
• Bluetooth ID and pairing
codes
• FM station presets
• Tone, balance Loudness
• Maximum Volume Limit
• Time-out
The software requires use
of an optional programming
cable (code KLABLINK) and
the parameters should be set
BEFORE installation as the programming port is not easily accessible afterwards.
The software can be downloaded from www.info.keene-electronics.co.uk
Care of the keypad
The KLABPLUS uses a special membrane keypad. When installing the amplier care must be taken
not to damage the connector ribbon between the keypad and the circuit board. If replacing a front
panel hold the plastic connector at the end of the ribbon when inserting into the circuit board so
as not to fold or crease the ribbon cable. The ribbon cable is designed to be bent into shape but it
must never be sharply folded or creased.
Part numbers you may nd useful:
KLABPLUSFP Replacement front panel with membrane keypad
KLABPSU Power supply (input: 100-240v AC, Output: 15v DC 4.0A)
CMS5U Architectural Cavity Wall / Ceiling mount loudspeakers 5 1/4” 25W
CMS8U Architectural Cavity Wall / Ceiling mount loudspeakers 8” 30W
KRC1 Additional remote control