Lehle P-SPLIT STEREO User manual

OPERATING INSTRUCTIONS
LEHLE P-SPLIT STEREO

LEHLE GmbH · Germany · www.lehle.com · support@lehle.com
Dear Musician!
Thank you for purchasing your LEHLE
P-SPLIT STEREO!
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 P-SPLIT STEREO com-
prises only the very best components.
Every assembly of your LEHLE P-SPLIT
STEREO has been made and tested in
Germany.
Your LEHLE P-SPLIT STEREO is of ex-
tremely 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 P-SPLIT
STEREO

LEHLE GmbH · Germany · www.lehle.com · support@lehle.com
CONTENT
Introduction
Technical data
Signal line types
Preconditions for passive splitting
General description
Typical uses of the LEHLE P-SPLIT STEREO as
isolator in a stereo setup
three way amp split
split and DI box in the studio
passive summing box
reamplification box
Signal flow diagram
4
6
7
9
11
14
15
16
18
19
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The LEHLE P-SPLIT STEREO combines
passive intelligent splitting with the high-
est possible signal fidelity in a double
pack.
The classic solution for splitting, eliminat-
ing hum, balancing and reamplification
in recording applications, now appears in
a doubled version and this time adds the
passive summing of signals.
The possibilities are reaching far.
Tap the full potential.
Two LEHLE TRANSFORMER HZ are
working at the heart of the LEHLE P-SPLIT
STEREO, galvanically isolating the par-
ticular ISO outputs from each other, elim-
inating any possibility of ground loops
and hum.
The LEHLE TRANSFORMER HZ process
both high and low impedance with un-
compromising sound quality. At the ISO
outputs you can pick o the signal either
unbalanced or balanced – regardless of
the signal type in the rest of your rig.
Per channel there is a gold plated phase
switch and ground switch. This keeps you
flexible and your system safe.
A classic application is the isolation of
a stereo signal, enabling you to use two
amplifiers in stereo and send the stereo
signal to a mixer or the audio interface of
your DAW at the same time.
Another useful method for the LEHLE
P-SPLIT STEREO can be as an eective
hum suppressor.
If you connect two electronic devices,
background noise can appear, caused by
ground loops.
Here the LEHLE P-SPLIT STEREO provides
a simple, but highly eective solution:
whilst installed between the two units, this
problem solver isolates the input from the
output.
Thanks to its ability to pick o balanced
signals on the ISO outputs, the LEHLE
P-SPLIT STEREO is also eminently suitable
for use as a high-quality compact stereo
DI box for all types of active signals.
Thus you can run long cable distances in
the studio or on stage, of balanced signal
type and free of background noise.
According to which sockets are occupied,
the LEHLE P-SPLIT STEREO also works
as a passive summing box: your eects
pedal board can be wired in stereo, but
you output in mono if connected to only
one amplifier.
INTRODUCTION

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If, on the other hand, you connect only
one mono signal to the input, the LEHLE
P-SPLIT STEREO works as a three-way
split for up to three amplifiers.
Galvanically isolated, double hum free
and passively intelligent splitting
Speaking of passive: the LEHLE P-SPLIT
STEREO still doesn’t need a power
supply.

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LEHLE GmbH · Germany · www.lehle.com · support@lehle.com
TECHNICAL DATA
Weight
Length
Width
Overall height
Max Level
Total harmonic distortion
Frequency range
Input impedance
(transformer load impedance)
+20 dBu (THD < 1%, 50 Hz - 20 kHz)
0.003 % (0 dBu, 1 kHz)
min. 2 MΩ at 2 kHz
20 Hz – 100 kHz -0.1/ +0.4 dB
(source 600 Ω, load 1 MΩ)
614 g
88 mm
152 mm
35 mm

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UNBALANCED SIGNAL ROUTING
Unbalanced signal lines predominate
when instruments such as guitars, basses
and keyboards are used.
These signal lines have two conducting
cores.
The signal itself is present on the signal
conductor and is connected to the tip of
the jack plug.
The second core, which is connected to
the sleeve of the jack plug, screens the
signal conductor and constitutes the sig-
nal ground.
UNBALANCED SIGNAL ROUTING
Tip
Signal in phase
Sleeve
Ground
JACK JACK
Cable
Sleeve Sleeve
Ground
Tip Tip
Signal in phase

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BALANCED SIGNAL ROUTING
Balanced signal lines are used to cross
larger distances without interference.
They are generally fitted with XLR connec-
tors or TRS (Tip Ring Sleeve) jack plugs.
Here, three cores are required:
there are two signal conductors. In a bal-
anced signal line, the signal is present in
phase at the tip, as in the case of an un-
balanced signal line (XLR Pin 2).
The second signal conductor carries the
same signal, but with the opposite polar-
ity or mirror-image phase (Ring, XLR Pin
3).
The third conductor is the screening,
and again constitutes the signal ground
(Sleeve, XLR Pin 1).
BALANCED SIGNAL ROUTING
JACK XLR
Cable
Sleeve Pin 1
Ground
Ring Pin 3
Signal in mirrored phase
Tip Pin 2
Signal in phase

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PRECONDITIONS FOR PASSIVE SPLITTING
The LEHLE P-SPLIT STEREO is a passive
splitter which can be used to split high-
impedance signals to high-impedance
inputs. There are certain preconditions
which must be met to ensure that this is
accomplished without problems and no
loss of sound.
HIGH-IMPEDANCE SIGNAL SOURCES
AND INPUTS
Passive magnetic pickups as generally
used - in the form of single-coil and hum-
bucker pickups, on electric guitars and
basses - supply high-impedance signals.
High-impedance signals have an output
impedance in a range of 10 kΩ (10,000
Ω); the higher this figure, the more sensi-
tive the signal is to interference.
High-impedance inputs are found on
guitar and bass amplifiers, and on sound
cards with a “Hi-Z” input; “Z” stands for
the impedance, which is the physical ex-
pression for the internal resistance of a
signal source or a signal input, and thus
defines its low/high-impedance perfor-
mance.
High-impedance signals are generally
transmitted unbalanced and are relative-
ly susceptible to interference. Long cable
routings audibly attenuate high frequen-
cies. Electromagnetic interference from
the environment then becomes more no-
ticeable than in the case of low-imped-
ance and balanced signals. There are,
nonetheless, very many musicians who
swear by the sound of an electric guitar
or bass with passive pickups connected
directly to a tube amplifier via a good
cable.
The input impedance of high-impedance
inputs is generally 1 MΩ (1,000,000 Ω)
or more. Here, too, the input becomes
more sensitive, the higher this figure is.
LOW-IMPEDANCE SIGNAL SOURCES
AND INPUTS
Keyboards, active pickups, preamp out-
puts, sound cards and mixers supply low-
impedance signals. The output imped-
ance of such signals is typically 100 Ω to
around 600 Ω.
Low-impedance inputs predominate in
the line input of mixing desks, power
amps and sound cards with no Hi-Z in-
puts, and also in microphone inputs and
in virtually all balanced inputs. Low-im-

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LEHLE GmbH · Germany · www.lehle.com · support@lehle.com
pedance inputs have input impedances
of around 600 Ω to 10 kΩ.
WHAT IS POSSIBLE
The LEHLE P-SPLIT STEREO can be used
to split the signal from an electric guitar
or electric bass with passive magnetic
pickups to two amplifiers, each of which
has high-impedance inputs. Please use
the shortest, best-quality possible cables
for this purpose. You will hear the 100%
original signal on both amps.
Instead of an amplifier, you can also split
the signal to the Hi-Z input of a sound
card.
It’s important to remember: a high-im-
pedance signal can be passively split if
you connect only high-impedance inputs.
You can split a low-impedance signal,
such as the output from a preamp, e.g.
the LEHLE SUNDAY DRIVER II or the out-
put from a sound card, to a tube amp
with a high-impedance input and the low-
impedance input of a power amp. Since
the signal to be split is a low-impedance
one, you can connect low-impedance
and high-impedance inputs behind this if
you wish - there won’t be any problems!
WHAT IS NOT POSSIBLE
Audible sound losses will occur if you use
long cable routings from the passive gui-
tar to the splitter and from the splitter to
the amps. The sum of all cable lengths to
the splitter and to the amps should gener-
ally not be more than 10m.
Your individual taste will ultimately de-
cide, however.
Splitting your high-impedance instrument
signal to a low-impedance input, such as
the line input of a mixing desk, for exam-
ple, and to a high-impedance input on
a tube amplifier using the LEHLE P-SPLIT
STEREO will result in the high-impedance
input being attenuated by the low-imped-
ance input of the mixing desk. The signal
will become significantly quieter and will
lose presence.
Solution: these problems can be eec-
tively eliminated by connecting a preamp
or a buer, which will convert the high-
impedance to a low-impedance signal, in
the signal path.
The LEHLE SUNDAY DRIVER II, for exam-
ple, can be used here.
INPUT
INPUT
DIR
DIR
Hi-Z
Hi-Z
Low-Z
Hi-Z
Low-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Low-Z
Hi-Z
Low-Z
Hi-Z
Low-Z
Low-Z
Hi-Z
Hi-Z
Low-Z
Low-Z
Low-Z
Low-Z
Low-Z
Low-Z
ISO
ISO
!
!
!

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GENERAL DESCRIPTION
1. INPUT SOCKET
Connect the output of a stereo eects
unit, keyboard or DAW here.
The input signal is fed into this socket.
The LEHLE P-SPLIT STEREO operates en-
tirely passively.
The input signal remains connected to the
ISO and DIR outputs at all times, with no
semiconductors or any other active com-
ponents in the signal path.
Both balanced and unbalanced sig-
nals can be split, since the LEHLE
TRANSFORMER HZ is capable of han-
dling both types.
1
1 22 33 44 55
If the INPUT SOCKET L is not occupied,
the signal of the INPUT SOCKET R will
automatically be mirrored.
This way you can split up to three galvani-
cally isolated outputs.

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2. OUTPUT SOCKET
Connect the input of an amplifier, mixer
or eects unit to be connected directly to
the LEHLE P-SPLIT STEREO input here.
The input signal and its ground are pre-
sent directly on the DIR socket. The signal
from the DIR output is always the same
which is fed into the input (1).
If the input signal is unbalanced you will
have an unbalanced direct signal at this
socket. The same will occur with bal-
anced signals.
3. PHASE INVERTER SWITCH
The phase of the input signal from the
ISO output can be inverted if necessary.
This switch can be used to invert the
phase of the input signal from the ISO
output socket by 180°.
Splitting signals to two amps may some-
times cause phase cancellations, result-
ing, for most musicians, in a “thin” sound.
Inverting the phase eliminates this prob-
lem.
Experiment to find out which position you
prefer - as always, your individual taste is
what counts!
4. GROUND LIFT SWITCH
Connect the grounds of the DIR and ISO
output if necessary.
Pressing this switch connects the ground
conductors of the ISO and DIR outputs.
Connecting the ground conductors of the
DIR and ISO outputs can help in some
situations, depending on the units con-
nected and on their power supplies.
Use the ground lift switch to find out for
yourself the position in which noise is
minimised.
5. ISO OUTPUT
Connect your amp or the audio input of a
DAW or a mixer here.
The ISO output has an input signal
which is isolated by means of the LEHLE
TRANSFORMER HZ.
A balanced or an unbalanced signal is
possible, irrespective of the type of signal
fed from the input.
“Toggle the phase and ground switches,
until you have less noise and the best
sound.“
Joe B., Guitar player
DIR
ISO

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6. BASE AND FIXING
If required, mount the P-SPLIT STEREO to
a pedalboard using the mounting kit.
The P-SPLIT STEREO 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 Mount-
ing 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
spacers of the Mounting Kit.
Attach the cover and tighten the four
housing screws - done!
For flexible solutions we recommend us-
ing 3M Dual Lock™ instead of Velcro for
stability, which you can also find in handy
sizes at www.lehle-components.com
6 6
!
If you are using the Velcro / Dual Lock™
method, please make a note of the serial
number on the bottom of the pedal be-
fore you cover it, in case you have a sup-
port question for us later and don‘t fancy
dismantling your board!

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TYPICAL USES
LEHLE P-SPLIT STEREO AS ISOLATOR IN A STEREO SETUP
The LEHLE P-SPLIT STEREO can be used
in any scenario to eliminate noise result-
ing from ground loops or hum.
Ground loops occur when units ground-
ed by a protective earth conductor (“PE
conductor”) are connected to each other.
The protective earth conductor and the
ground connection of the audio signal
create a loop which will pick up external
interference generated, for example, by
coils. Such interference will impair the
signal. The LEHLE TRANSFORMER HZ
galvanically isolate the ground connec-
tion. The hum loop is thus broken at this
point.
Both high- and low-impedance signals
can be fed, the LEHLE P-SPLIT STEREO
has no problems with balanced or unbal-
anced signals.
HOW TO DO THIS
1. Connect the signal source (e.g. an
eects device or amp simulation) to the
input sockets (1) of the LEHLE P-SPLIT
STEREO.
2. Connect the output sockets R ISO and
L ISO (5) to the inputs of your mixer.
3. Use the ground lift switch (4) to deter-
mine which position eliminates the most
background noise.
4. There you go!
Output signal source right
Output signal source left
Input mixer right
Input mixer left
DEVICE CONNECTION
If you are using one section of the LEHLE
P-SPLIT STEREO only, use the left one.
Using the right section and toggling the
phase button, will cause the signal to
be muted if the left phase button isn’t
toggled, too.
R
R ISO
L ISO
L

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LEHLE P-SPLIT STEREO AS THREE WAY AMP SPLIT
What‘s better than two amps?
Right: three amps.
If the left input socket is not used, the left
section will be fed by the right inputted
signal.
This way the LEHLE P-SPLIT STEREO can
be used as three way amp split; of course
with galvanically isolated outputs and
thus hum- and noise-free.
HOW TO DO THIS
1. Connect your instrument to the right in-
put socket of the LEHLE P-SPLIT STEREO.
2. Connect the first amplifier to the R DIR
socket.
3. Connect the second amp to the R ISO
socket.
4. Use the L ISO socket to feed your third
amp.
5. Use the phase inverter switch (3) to de-
termine which setting you prefer.
6. Use the ground lift switch (4) to find the
position at which noise is minimised.
7. There you go!
DEVICE CONNECTION
Instrument
Input amp 2
Input amp 1
Input amp 3
R
R ISO
R DIR
L ISO
Avoid long cable runs and thus loss in
signal and treble.
Elsewise we recommend to use a bu-
er before the split, such as the LEHLE
SUNDAY DRIVER II.

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LEHLE P-SPLIT STEREO AS SPLIT AND DI-BOX IN THE STUDIO
In studio situations it’s often useful to re-
cord not only the amplifiers, but at the
same time a dry, unprocessed signal, too.
This signal can then be routed in the mix
either to a real amplifier, or to a digital
simulation, for editing.
Even at the recording of electric bass sig-
nals it often makes sense to add the direct
signal to the record amp signal.
At the L ISO output the signal can be
tapped balanced via TRS already.
Keep in mind, if you want to use a low
impedance and balanced input at your
audio interface, the signal needs to be
buered, as shown on page 17.
Otherwise use the Hi-Z input of your in-
terface.
HOW TO DO THIS
1. Connect your instrument to the right in-
put socket of the LEHLE P-SPLIT STEREO.
2. Connect the first amplifier to the R DIR
socket.
3. Connect the second amp to the R ISO
socket.
4. Use the L ISO socket to feed your au-
dio interface.
5. Use the phase inverter switch (3) to de-
termine which setting you prefer.
6. Use the ground lift switch (4) to find the
position at which noise is minimised.
7. There you go!
DEVICE CONNECTION
Instrument
Input amp 2
Input amp 1
Input audio interface
R
R ISO
R DIR
L ISO

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If your audio interface doesn’t have a
high impedance input (Hi-Z) or if you
want to send the signal through a long
distance loss-free and balanced at the
same time, we recommend to place a
buer in between your instrument and
the LEHLE P-SPLIT STEREO. This buer
changes your high impedance signal
to low impedance, such as the LEHLE
SUNDAY DRIVER II.
In the example above, the signal line type
is balanced (TRS), too.
HOW TO DO THIS
1. Connect your instrument to the input
socket of the LEHLE SUNDAY DRIVER II.
2. Use a TRS-TRS cable to connect the
output to the input socket of the LEHLE
P-SPLIT STEREO.
3. Connect R DIR to the balanced input
of your audio interface with a TRS-TRS or
TRS-XLR cable.
4. Connect the first amp to the R ISO
socket (unbalanced TS-TS).
5. Connect the second amp to the L ISO
socket (unbalanced TS-TS).
6. Use the phase inverter switch (3) to de-
termine which setting you prefer.
7. Use the ground lift switch (4) to find the
position at which noise is minimised.
8. There you go!
DEVICE CONNECTION
LEHLE P-SPLIT STEREO
DEVICE CONNECTION
LEHLE SUNDAY DRIVER II
SUNDAY DRIVER II TRS Instrument TS
Input amplifier 1 TS
Audio interface TRS P-SPLIT STEREO TRS
Input amplifier 2 TS
R
R ISO
R DIR
L ISO

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LEHLE P-SPLIT STEREO AS PASSIVE SUMMING BOX
If you are using a complex pedal board
with stereo eects, you sometimes could
have the problem that unfortunately
there‘s only one amplifier available and
the outputted signal should be therefore
mono.
The LEHLE P-SPLIT STEREO can sum in-
putted stereo signals to mono, once only
one amplifier is being connected.
This way your pedal board stays wired but
still ready for the „small gig“.
HOW TO DO THIS
1. Connect the outputs of your last stereo
eect to the input sockets L and R (1).
2. Connect the output socket R ISO to the
amplifier.
3. Use the phase switch (3) to find out
which setting sounds better to you.
4. Use the ground lift switch (4) to deter-
mine which position eliminates the most
background noise.
5. There you go!
DEVICE CONNECTION
Eects output right
Eects output left
Input amplifier
If you are using kind of a patchbay on
your pedalboard, keep in mind that the
L ISO socket needs to be unplugged or
elsewise the passive summing won’t work.
!
R
R ISO
L

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LEHLE P-SPLIT STEREO AS REAMPLIFICATION BOX
Once you’ve recorded the dry signal, it
can be fed through an amplifier during
mixing; connecting the amp to the sound
card or DAW will almost certainly gener-
ate a ground loop, causing undesirable
noise.
This problem can be eectively eliminat-
ed using the LEHLE P-SPLIT STEREO.
The built-in LEHLE TRANSFORMER HZ
galvanically isolate the ground connec-
tions, and function perfectly with both
balanced and unbalanced signals from a
sound card or a DAW.
By means of the LEHLE P-SPLIT STEREO
it’s now possible to use two amplifiers at
the same.
HOW TO DO THIS
1. Connect the output of your audio in-
terface to the input socket R of the LEHLE
P-SPLIT STEREO.
2. Connect the R ISO socket to the input
of your first amp.
3. Connect the L ISO socket to the input
of your second amp.
4. Use the ground lift switch (4) to deter-
mine which position eliminates the most
background noise.
5. There you go!
DEVICE CONNECTION
Output audio interface
Input amplifier 2
Input amplifier 1
R
R ISO
L ISO

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LEHLE P-SPLIT STEREO
SIGNAL FLOW DIAGRAM
R ISO (5)
Phase-Shift (3)
Ground (4)
R DIR (2)
R Input (1)
L ISO (5)
Phase-Shift (3)
Ground (4)
L DIR (2)
L Input (1)
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