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OPERATING INSTRUCTIONS
LEHLE LITTLE DUAL II
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Dear Musician!
Thank you for purchasing your LEHLE
LITTLE DUAL II!
I have been building units that switch,
split and route signals with no technical
compromises and with maximum musical
fidelity since 1999. Your new LEHLE
LITTLE DUAL II comprises only the very
best components.
Every assembly of your LEHLE LITTLE
DUAL II has been made and tested in
Germany.
Your LEHLE LITTLE DUAL II is of extremely
robust design and construction, to make
sure that you get absolutely years and
years of enjoyment from it. If you should
nonetheless have a problem, or simply a
question, just mail me or a member of the
Lehle team at: support@lehle.com
I wish you the very greatest pleasure and
success using your LEHLE LITTLE DUAL II!
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CONTENT
Introduction
4
Technical data
6
General description
7
Selecting the operating mode
12
Selecting the foot switch mode
13
Restoring factory setting
14
Typical uses of the LEHLE LITTLE DUAL II as
amp-switcher
15
amp-switcher for stereo eects and 2 amplifiers
16
amp-switcher in a wet/dry system
18
amp-switcher for one instrument with piezo and magnetic pickup to two amps
20
amp-switcher for one instrument with piezo and magnetic pickup to one amp
21
and a mixer
tuner mute box
23
LEHLE LITTLE DUAL II signal flow diagram
24
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INTRODUCTION
The LEHLE LITTLE DUAL II is the successor
to the Lehle Little Dual and is a maximum
signal-fidelity amp switcher for two amps.
By using the soft-touch switches you can
switch between two connected amplifiers
hum-free and without sound loss.
Two dierent operating modes are ready
for you. You decide if you want to activate
or deactivate every output individually or
if you want to switch between the amps
and activate the remaining one.
The LEHLE-Switches work with a microcontroller and an intelligent True-BypassRelay-Circuit with active pop noise suppression circuit. Thereby they switch the
LEHLE LITTLE DUAL II even faster than
mechanical switches and in addition to
that wear- and noise-free.
The easy-action mushroom-shaped buttons characteristic of LEHLE products are
mounted in the cover, so that your foot
pressure is transmitted indirectly only, via
a spring. Thus the electronics board is not
exposed to mechanical loads, making the
LEHLE LITTLE DUAL II virtually indestructible and guaranteeing years of troublefree switching.
High-intensity LEDs make it easy to read
o switching state A or B, or both, even
under high-power spots.
The centrepiece of the LEHLE LITTLE
DUAL II is its high-end LEHLE TRANSFORMER HZ, which galvanically isolates
output A from output B, making history
of hum loops - permanently! The LEHLE
LITTLE DUAL II features a gold-plated
contact phase inverter and a gold-plated
contact ground switch. The two inputs
can also be routed in stereo to outputs
A and B, if you use the stereo signal of
an eects unit as the input, for example.
This also makes it possible to route instruments equipped with two pickups, including many acoustic and hybrid guitars,
and also double basses, via two amplifier
systems - with no complications.
Additionally the LEHLE LITTLE DUAL II is
equipped with a TRS switch. Therewith it
is possible to send in above-mentioned
stereo- or dual-mono signals via a TRS
jack or “stereo-jack”.
These signals can be operated either in
alternation or in parallel - without hum,
and without sound losses, needless to
say.
The LEHLE LITTLE DUAL II - small, but so
utterly eective!
We take care of your signal so that you
can take care of the music.
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TECHNICAL DATA
Weight 540 g
Length
Width
Overall height
Supply voltage
Current consumption
Max Level
Total harmonic distortion
Frequency range
Input impedance
(transformer load impedance)
3.9“
4.8“
1.85“
9-15 V DC
63 mA
+20 dBu (THD < 1%, 50 Hz - 20 kHz)
0.003 % (0 dBu, 1 kHz)
20 Hz – 100 kHz -0.1/ +0.4 dB
(source 600 , load 1 M)
min. 2 M at 2 kHz
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GENERAL DESCRIPTION
2
345678
1
9
A
10
LITTLE DUAL
MADE IN GERMANY
11
1. TRS SWITCH
TRS
Press this switch to distribute a stereo- or
dual-mono-signal, provided by a TRS
jack, to both outputs A and B.
If you have a mono-signal (TS jack), or
a stereo-signal via two TS jacks, use the
A/B input or input A/B and A respectively.
However some instruments oer a TRS
output, where e.g. the separated signals
of a magnetic pickup and piezo pickup
are supplied or e.g. separated signals of
B
B
TRS
ABAA
the neck- and bridge-pickup.
Now you can insert these signals via a
TRS-TRS cable into the LEHLE LITTLE
DUAL II, by pressing the TRS switch, so
the signal is distributed to both outputs
A and B.
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2. A/B-INPUT SOCKET
AB
Connect your instrument or the output
from an eects unit or DAW here.
5. PHASE SWITCH
Here you can invert the phase of output
A if necessary.
The mono input signal is fed into this
socket; should the input socket A (3) be
used as well this signal will be routed to
output B only.
If the TRS switch (1) is pressed, a stereoor dual-mono-signal can be distributed
to both outputs.
3. A-INPUT SOCKET
A
Connect the second pickup of your instrument or the second stereo output from an
eects unit or DAW here.
The signal from this input socket is routed
to output A only. Stereo signals such as
the signals from stereo eects pedals or
dual-mono signal from dierent pickups
can be switched individually to the outputs A and B, which could be 2 separate
amplifiers or PA channels.
4. B-OUTPUT
B
Connect your amplifier or the input of a
mixing desk here.
The signal is routed to output B directly
via a microcontrolled relay-switching-circuit with no semiconductors. The LEHLE
LITTLE DUAL II, and therefore the instrument connected, is grounded via this
socket. This output should therefore always be occupied.
This switch can be used to invert the phase
of the input signal from the A output socket by 180°. Splitting signals to two amps
may sometimes cause phase cancellations, resulting, for most musicians, in a
“thin” sound. Inverting the phase eliminates this problem. Experiment to find
out which position you prefer - as always,
your individual taste is what counts.
6. A-OUTPUT
A
Connect your amplifier or the input of a
mixing desk here.
Output A is galvanically isolated from
output B by the LEHLE TRANSFORMER
HZ - so hum loops are impossible, even if
A and B are switched on simultaneously.
A balanced or an unbalanced signal is
possible, irrespective of the type of signal
fed from the input, this way you can connect any guitar or bass amp as well as
balanced inputs on a mixing console.
If both input jacks A/B (2) and A (3) are
occupied, but not output jack A (6), a
passively summed signal will be sent out
of output B (4). This way you can easily
sum down a stereo signal to mono, in
case you don‘t have enough space for
your second amp or it‘s simply too loud.
Please keep in mind that the stereo signal
has to be sent out of one device. If the
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signals are coming from two dierent devices, an impedance mismatch can occur
and the mix won‘t sound balanced. In this
case, for active summing of two dierent
signals we recommend using the LEHLE
PARALLEL SW II.
7. GROUND SWITCH
Connect the grounds of output sockets A
and B if necessary.
If this switch is not pressed (standard), the
ground of output A (6) is disconnected
from the pedal.
It reconnects the chassis of outputs A and
B when it is pressed since connecting the
ground conductors can help in some situations, depending on the units connected
and on their power supplies. Actuate the
ground lift switch to find out for yourself
the position in which noise is minimised.
8. EXTERNAL POWER SUPPLY
Connect a power supply with a voltage
of 9 – 15 V.
In order that the LEHLE LITTLE DUAL II
can work flawlessly, it needs a current
supply. This should supply a minimum of
9 V and a maximum of 15 V. Polarity is
of no importance. The supply voltage is
internally rectified and stabilized in order
to guarantee trouble-free operation. In
order to avoid noise it‘s recommendable
to use a single power supply or an output
of a multi power supply oering galvani-
cally isolated outputs for the LEHLE LITTLE DUAL II.
9. LEDS FOR SWITCHING STATUS
If the left (A) LED shows green, the output
A (6) is active, if the right (B) LED is red, a
signal is routed through output B (4).
The high-intensity LEDs under the lenses
clearly indicate switching State A or B,
even under stage lighting.
Output A (left) is GREEN and output B
(right) is RED.
10. TRUE-BYPASS-SWITCH
Here you can switch.
The LEHLE LITTLE DUAL II switches all
audio signals controlled by a microcontroller and an intelligent True-Bypass-Relay-Circuit with an active pop suppression
function.
Triggered by the easy-action mushroomshaped buttons characteristic of LEHLE
products, mounted in the cover so that
your foot pressure is transmitted indirectly
via a spring. Thus the circuit board is not
exposed to mechanical loads, making the
LEHLE LITTLE DUAL II virtually indestructible and guaranteeing years of troublefree switching.
According to the operating mode following configurations are given:
- Classic Mode:
Left switch: alternates between outputs A
and B
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Right switch: adds in the other output, so
both outputs are active, press again to
remove it
- Manual Mode
Left switch: activates and deactivates output A
Right switch: activates and deactivates
output B
The LEHLE LITTLE DUAL II is shipped in
the Classic Mode. How to change the operating mode can be found in the chapter
“Selecting the operating mode” on page
10.
You can reprogram the LEHLE-Switches
(for the Manual Mode) from latching
(switch) to momentary (button) with ease.
You will find out how to do this in chapter
“Selecting the footswitch mode” on page
11.
spacers of the Mounting Kit.
Attach the cover and tighten the four
housing screws - done!
For flexible solutions we recommend using 3M Dual Lock™ instead of Velcro for
stability, which you can also find in handy
sizes at www.lehle-components.com
11. BASE AND FIXING
The LITTLE DUAL II can be mounted to a
plate such as a pedalboard using the two
holes in the bottom of the pedal.
You can find the optional LEHLE Mounting Kit V3 (order number 100981) online
at www.lehle-components.com.
To mount, undo the four housing screws
by using a 2.5 mm Allen Key and detach
the cover.
Then fix the device base to a base plate
using the two screws, the washers and the
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Tip: if you are using the Velcro / Dual
Lock™ method, please make a note of
the serial number on the bottom of the
pedal before you cover it, in case you
have a support question for us later and
don‘t fancy dismantling your board!
9
!
Page 10
SELECTING THE OPERATING MODE
The LEHLE LITTLE DUAL II can be operated in two dierent modes.
According to the operating mode the following configurations are given:
- Classic Mode:
Left switch: alternates between outputs A
and B
Right switch: adds in the other output, so
both outputs are active, press again to
remove it
- Manual Mode
Left switch: activates and deactivates output A
Right switch: activates and deactivates
output B
To change the mode please proceed as
follows:
1. Disconnect the power supply.
2. Press and hold the left foot switch.
3. Reconnect the power supply.
4. Both LEDs start flashing 1x (Classic
Mode), then 2x (Manual Mode).
5. Depending on when you release the
left foot switch, the pedal selects the requested mode, saves and reboots.
6. Finished.
When the power is disconnected, the selection of the operating mode is stored
inside and recalled when the pedal is
powered on the next time.
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SELECTING THE FOOT SWITCH MODE
It‘s possible to reprogram the LEHLESwitches (for the Manual Mode) from
latching (switch) to momentary (button)
with ease.
A switch „latches“ by a press and release,
while a button only triggers a contact
when pressed down. When released, the
contact is disconnected.
For both foot switches you can set an individual operating mode.
To change the mode for the foot switches
please proceed as follows:
1. Disconnect the power supply.
2. Press and hold the right foot switch.
3. Reconnect the power supply.
4. Both LEDs start flashing. You are in the
foot switch program mode.
5. If the LED of the respective foot switch
flashes, it works (as usual) as latching foot
switch.
6. If you are pressing a respective foot
switch, the corresponding LED turns o
and the foot switch works as a momentary button, which is deactivated by default.
7. If you are pressing the respective foot
switch again, the corresponding LED
turns on and it works again as momen-
tary button, but activated by default.
8. To save, please disconnect the power
supply, wait a second and reconnect the
power.
9. Do n e.
When the power is disconnected, the selection of the foot switch mode is stored
inside and recalled when the pedal is
powered on the next time.
Please keep in mind that the mode selection of the foot switches applies for the
Manual Mode only. In other words, if you
are using one or both foot switches in momentary or latching, they work in Manual
Mode in the selected mode. In the Classic Mode they are always latching.
!
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RESTORING FACTORY SETTING
If you decide to restore all settings back
to the factory setting, please proceed as
follows:
1. Disconnect the power supply.
2. Press and hold both foot switches.
3. Reconnect the power supply.
4. The LEDs will flash alternately.
5. The pedal turns o and starts again.
6. Done.
In factory state the Classic Mode is
selected and the foot switches work as
latching switches.
!
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TYPICAL USES
LEHLE LITTLE DUAL II AS AN AMP-SWITCHER
DEVICE CONNECTIONS
TRS
B
ABAA
B
A
LITTLE DUAL
MADE IN GERMANY
The LEHLE LITTLE DUAL II was designed
specifically to split and switch the signal
of your instrument between 2 amps which
are running at the same time. This way
you can achieve very nice blends, e.g.
with a clean and a crunchy amp sound.
Phasing issues can be corrected at the
push of a button, as mentioned previously
output A features a phase-inverter switch.
AB
B
A
Input Instrument
Output Amplifier 2
Output Amplifier 1
HOW TO DO THIS
1. Connect output A (6) to the first amplifier.
2. Connect output B (4) to the second
amplifier.
3. Input socket A (3) is not used.
4. Connect your instrument to the input
socket A/B (3) of the LEHLE LITTLE DUAL
II.
5. Activate both amps using the foot
sw itches (10 ).
6. Use the phase inverter switch (5) to find
out which setting you prefer.
7. Use the ground lift switch (7) to determine which position eliminates the most
background noise.
8. There you go!
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LEHLE LITTLE DUAL II AS AN AMP-SWITCHER FOR STEREO EFFECTS
AND AMPLIFIERS
DEVICE CONNECTIONS
TRS
B
ABAA
B
A
LITTLE DUAL
MADE IN GERMANY
A dual amp setup suggests the use of
stereo eects, with one amp receiving
the left stereo signal and the other amp
receiving the right stereo signal. Chorus
and delays create a very wide soundscape when played through 2 amps simultaneously.
In case you don‘t have enough space for
your second amp or it‘s simply too loud
you can easily sum down the stereo signal
to mono. If both input jacks A/B (2) and
A (3) are plugged-in, but not output jack
A (6), a passively summed signal will be
sent out of output B (4).
Please keep in mind that the stereo signal
has to be sent out of one device. If the
signals are coming from two dierent devices, an impedance mismatch can occur
and the mix won‘t sound balanced. In this
AB
A
B
A
Input
Input
Eects signal right
Eects signal left
Output Amplifier right
Output Amplifier left
case, for active summing of two dierent
signals we recommend using the LEHLE
PARALLEL SW II.
HOW TO DO THIS
1. For the left stereo signal connect the
output socket A (6) to the input of amp 1.
2. Connect the output socket B (4) to the
amp that should render the right FX signal.
3. Connect the left stereo output from
your eects unit to the input socket A (3).
4. Connect the right stereo output from
your eects unit to the input socket A/B
(2).
5. Activate both amps using the foot
sw itches (10 ).
6. Use the phase inverter switch (5) to find
out which setting you prefer.
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7. Use the ground lift switch (7) to determine which position eliminates the most
background noise.
8. There you go!
If your stereo eects unit has only TRS stereo output, use a TRS-TRS stereo cable to
make a connection to the LEHLE LITTLE
DUAL II. Use the input socket A/B (2) only
and press the TRS switch (1).
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LEHLE LITTLE DUAL II AS AN AMP SWITCHER IN A WET/DRY SYSTEM
DEVICE CONNECTIONS
TRS
B
ABAA
B
A
LITTLE DUAL
MADE IN GERMANY
When setting up two amps and eects,
it‘s not necessary to use stereo eects
only - mono eects can be used too, in
order to get a wider, but more controllable sound picture.
There is talk of a wet/dry system, where
one amp gets the dry signal (without effects) and the other amp the wet signal
(with eects). By doing this you keep the
original dry signal, but you can control
the amount of eects on the second amp.
We recommend placing dynamic eects
(volume pedal, compressor, overdrive/
distortion) between your instrument and
the LEHLE LITTLE DUAL II so both amps
benefit from them, while the modulation
and time based eects (chorus, tremolo/
vibrato, delay, reverb) are sent to one
AB
Input Instrument /
dynamc eects
B
A
Output Wet eects
Output Amplifier 1 (Dry)
amplifier only. Place them between the
LEHLE LITTLE DUAL II and the wet amp.
The order of your eects (before or after
the LEHLE LITTLE DUAL II) is up to you
too. Ultimately, your individual taste decides here.
HOW TO DO THIS
1. Connect the output socket A (6) to the
input of the dry amp.
2. Connect the output socket B (4) to wet
eects and finally the wet amp.
3. Connect your instrument or the output
of the dynamic eects to the input socket
A/B (2)
4. Activate both amps using the foot
sw itches (10 ).
5. Use the phase inverter switch (5) to find
out which setting you prefer.
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6. Use the ground lift switch (7) to determine which position eliminates the most
background noise.
7. There you go!
To get absolute control of the eect level
you can place a volume pedal like the
LEHLE MONO VOLUME between the
output B (4) and the wet eects. This way
you can control the level of the eects
with your foot.
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LEHLE LITTLE DUAL II AS AN AMP SWITCHER FOR INSTRUMENT
WITH PIEZO AND MAGNETIC PICKUPS SENT TO AMPLIFIERS
DEVICE CONNECTIONS
TRS
B
ABAA
B
A
LITTLE DUAL
MADE IN GERMANY
Some instruments are equipped with 2
dierent type of pickups, usually one
magnetic e-guitar pickup and one piezo
pickup. These signals have totally dierent characteristics and sound best when
played through their respective amptypes. Usually the instrument oers a TRS
jack for the two signals, you can use a
TRS-TRS stereo cable. In this case the TRS
switch (1) has to be pressed.
AB
B
A
Input Instrument
Output Amplifier 2
Output Amplifier 1
HOW TO DO THIS
1. Connect the amplifier for pickup signal
1 to the output socket A (6).
2. Connect the second amplifier for pickup signal 2 to the output socket B (4).
3. Connect a TRS cable of your instrument to the input socket A/B (2).
4. Press the TRS switch (1).
5. Activate both amps using the foot
sw itches (10 ).
6. Use the phase inverter switch (5) to find
out which setting you prefer.
7. Use the ground lift switch (7) to determine which position eliminates the most
background noise.
8. There you go!
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LEHLE LITTLE DUAL II AS AMP-SWITCHER FOR ONE INSTRUMENT
WITH PIEZO AND MAGNETIC PICKUP TO ONE AMP AND A MIXER
DEVICE CONNECTIONS
TRS
B
ABAA
B
A
LITTLE DUAL
MADE IN GERMANY
In order to extend the previous setup and
to make it more flexible, you can route the
piezo signal to a mixer, stage box or DAW
instead of a regular guitar amp. This way
acoustic and electric guitar sounds can
be mixed together, either live for the FOH
mix, monitoring or recording. Having the
option to convert unbalanced signals to
balanced is extremely useful and makes
the use of additional equipment like DI
boxes redundant.
AB
B
A
Input Instrument
Output Amplifier
Output Mixer, stage box,
DAW
If your instrument has a stereo output
socket (TRS) you can use a stereo cable (TRS-TRS) to make the connection to
the LEHLE LITTLE DUAL II. Use the input
socket A/B 2) only and press the TRS
switch (1). Please take a look at „LEHLE
LITTLE DUAL II as an amp switcher for 1
instrument with piezo and magnetic pickups sent to 2 amplifiers“
HOW TO DO THIS
1. Connect the mixer, stage box or DAW
for the piezo signal to the output socket
A (6).
2. Connect the amplifier for the magnetic
pickup to the output socket B (4).
3. Connect the cable with the signal of
the piezo pickup to the input socket A (3)
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4. Connect the cable with the signal of
the magnetic pickup to the input socket
A/B (2)
5. Activate both amps using the foot
sw itches (10 ).
6. Use the phase inverter switch (5) to find
out which setting you prefer.
7. Use the ground lift switch (7) to determine which position eliminates the most
background noise.
8. There you go!
Output A can send an unbalanced signal
to guitar or bass amps, or balanced signals to mixers or DAWs.
For connections to mixers or DAWs the
signal should be buered to eliminate impedance issues/ mismatch.
Balanced signal lines are used to cross
larger distances without interference.
They are generally fitted with XLR connectors or TRS (Tip Ring Sleeve) jack plugs.
Here, three cores are required: there are
two signal conductors. In a balanced signal line, the signal is present in phase at
the tip, as in the case of an unbalanced
signal line (XLR Pin 2). The second signal
conductor carries the same signal, but
with the opposite polarity or mirror-image
phase (Ring, XLR Pin 3). The third conductor is the screening, and again constitutes
the signal ground (Sleeve, XLR Pin 1).
!
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LEHLE LITTLE DUAL II AS TUNER MUTE BOX
DEVICE CONNECTIONS
TRS
B
ABAA
B
A
LITTLE DUAL
MADE IN GERMANY
In smaller setups with only 1 guitar and 1
amplifier the LEHLE LITTLE DUAL II can
also be helpful to mute the signal for tuning in case you would like to keep it silent
for the audience or your fellow musicians.
This way the tuner is not in the direct signal path and is isolated electrically from
your amp.
AB
B
A
Input Instrument
Output Amplifier
Output Tun er
HOW TO DO THIS
1. Connect your tuner to the output socket A (6).
2. Connect the amplifier to output B (4).
3. Do not use the input socket A (3).
4. Connect your instrument to the input
socket A/B (2) of the LEHLE LITTLE DUAL
II.
5. Use the ground lift switch (7) to determine which position eliminates the most
background noise.
6. There you go!
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LEHLE LITTLE DUAL II
SIGNAL FLOW DIAGRAM
IN A/B (2)
IN A (3)
TRS (1)
B
OUT B (4)
A
PHASE-SHIFT (5)
OUT A (6)
GROUND (7)
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LEHLE GmbH · Grenzstrasse 153 · 46562 Voerde · Germany
www.lehle.com · support@lehle.com
LEHLE LITTLE DUAL II OPERATING INSTRUCTIONS EN V1.0 · 2019-08-01
Copyright 2019 by LEHLE
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