Lehle P-Split II
Operating instructions
www.lehle.com
Lehle GmbH • Grenzstr. 153 • D-46562 Voerde • Germany • Tel +49 (0) 2855 850070
Dear Musician!
Thank you for purchasing the Lehle P-Split 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 P-Split II comprises only the very best com-
ponents. Every assembly of your Lehle P-Split II has been made
and tested in Germany.
Your Lehle P-Split 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
P-Split II!
Burkhard Georg Lehle
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Contents
Introduction ............................................................................................................................... 2
Technical data ...........................................................................................................................3
Signal line types and preconditions for passive splitting ................................................................ 4
General description ................................................................................................................... 7
Typical uses
- Lehle P-Split II as a splitter for two amps ....................................................................... 10
- Lehle P-Split II as a compact passive DI box .................................................................. 11
- Lehle P-Split II as a line isolator – the universal cure for hum loops ................................ 12
- Lehle P-Split II as a recording splitter ............................................................................ 14
- Lehle P-Split II as a re-amplification isolator.................................................................. 16
- Lehle P-Split II as a balanced/unbalanced signal converter ............................................ 17
Lehle P-Split II signal flow diagram ....................................................................................... 20
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The Lehle P-Split II combines passive splitting
with maximum signal fidelity. Its central element
is the Lehle LTHZ high-end transformer, which
electrically isolates the two outputs, eliminating the
possibility of ground loops. The Lehle LTHZ has
been specially designed for use with high-impedance signals, but also splits low-impedance signals with zero loss of sound quality. The signal can
be picked off either balanced or unbalanced from
the ISO output. A phase inverter switch featuring
gold-plated contacts permits inversion of the input
signal phase at the ISO output, preventing phase
cancellations from impairing signal reproduction.
The classical application for the Lehle P-Split II
is splitting of an input signal to the two outputs,
enabling you to connect your instrument to two
devices, such as two amplifiers, for example, or
an amp and a mixer or recording unit (PC/DAW).
Thanks to the facility for also picking off the balanced signal on the ISO output, the Lehle P-Split
II is eminently suitable for use as a high-quality
compact DI box for all types of signals. Another
useful application for the Lehle P-Split II is as an
effective suppressor for undesirable hum. Background noise, generated by ground loops, occurs
again and again when two electronic devices are
connected to each other, and the Lehle P-Split II
provides a simple but extremely effective remedy
when installed between the two units. The two devices are electrically isolated when the ISO output
is used, eliminating this background noise. And:
the Lehle P-Split II needs no power supply at all!
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Technical data
Weight: 390 g
Length: 8.8 cm (3.47”)
Width: 9.2 cm (3.62”)
Overall height: 3.9 cm (1.54”)
Max. level: 5.7 V RMS (17 dBU)
Max. Gain: +16 dBU (<1 % THD @ +16 dBU/ 40 Hz)
Total harmonic distortion: 0.003 % at 0 dBU/ 1 kHz
Frequency range: 20 Hz to 100 kHz -0.1/ +0.4 dB
(source 600Ω, load 1MΩ)
Input impedance (transformer impedance load): min. 2 MΩ at 2 kHz
4
Signal line types and preconditions for passive splitting
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 signal ground.
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).
Preconditions for passive splitting:
The Lehle P-Split II 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 occurring and
with no loss of sound.
Tip
Signal in Phase
Sleeve
Ground
Jack XLR
Ground Sleeve Pin 1
Signal in mirrored Phase Ring Pin 3
Signal in Phase Tip pin 2
5
High-impedance signal sources and inputs:
Passive magnetic pickups as generally used, in the
form of single-coil and humbucker pickups, on
electric guitars and basses, supply such 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 sensitive 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 here for the impedance, which is
the physical expression for the internal resistance
of a signal source or a signal input, and thus
defines its low/high-impedance performance.
High-impedance signals are generally transmitted unbalanced and are relatively susceptible to
interference. Long cable routings audibly attenuate
high frequencies. Electromagnetic interference
from the environment then becomes more noticeable than in the case of low-impedance 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 the more sensitive, the
higher this figure is.
Low-impedance signal sources and inputs:
Keyboards, active pickups, preamp outputs, sound
cards and mixers supply low-impedance signals.
The output impedance 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 inputs, and also in microphone inputs
and in virtually all balanced inputs. Low-impedance
inputs have input impedances of around 600 Ω to
10 kΩ.
What is possible:
The Lehle P-Split II 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
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signal to the Hi-Z input of a sound card.
It’s important to remember: a high-impedance
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 or the output 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 guitar to the splitter
and from the splitter to the amps. The total cable
lengths to the splitter and to the amps should
generally not be more than 10m. Your individual
taste will ultimately decide, however.
Splitting your high-impedance instrument signal to
a low-impedance input, such as the line input of
a mixing desk, for example, and to a high-impedance input on a tube amplifier using the Lehle
P-Split II will result in the high-impedance input
being attenuated by the low-impedance input of
the mixing desk. The signal will become significantly quieter and will totally lose presence.
Solution: these problems can be effectively
eliminated by connecting a preamp or a buffer,
which will convert the high-impedance to a lowimpedance signal, in the signal path. The Lehle
Sunday Driver, for example, can be used here.
Input DIR ISO
Hi-Z Passive Guitar Hi-Z Hi-Z
Low-Z Hi-Z
×
Hi-Z Low-Z
×
Low-Z Low-Z
×
Low-Z Instrument (active)
Line driver output (like
Lehle Sunday Driver)
Hi-Z Hi-Z
Low-Z Hi-Z
Hi-Z Low-Z
Low-Z Low-Z
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General description
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1. Input socket
Connect your instrument or the output from an
effect unit or DAW here.
The input signal is fed into this socket. The Lehle
P-Split II operates entirely passively. The input
signal remains connected to the ISO and DIR
outputs at all times, with no semiconductors or any
other active components in the signal path.
Both balanced and unbalanced signals can be
split, since the Lehle LTHZ transformer is capable
of handling both types.
2. Output socket for direct signal
Connect the input of an amplifier or effect unit
to be connected directly to the Lehle P-Split II
input here.
The input signal and its ground are present
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 balanced 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 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!
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 connected and on their
power supplies. Actuate 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.
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The ISO output has an input signal which is
isolated by means of the Lehle LTHZ high-end
transformer. A balanced or an unbalanced signal
is possible, irrespective of the type of signal fed
from the input.
6. Base and fixing
You can use the fixing screws supplied with the
Lehle P-Split II to fix it to a base plate (or
to a pedal board, for example).
Tip: in case you prefer a velcro solution for your
pedalboard we recommend to write down the
serial number of the pedal before covering it for
eventual support matters.
Thanks to its ready-to-go fixing system, the Lehle
P-Split II can be mounted without difficulty
on a base plate. To do this, undo the four housing
screws and detach the cover. Then fix the device
base to a base plate using the two screws, the
washers and the spacers supplied. Replace the
cover and tighten the four housing screws - done!
10
Typical uses
The Lehle P-Split II as a splitter for two amps
The Lehle P-Split II operates as a splitter for
one instrument to two amps. Use the shortest
cables possible to connect instruments with passive
pickups to the input of the Lehle P-Split II. Most
musicians find the sound of two amplifiers working
in parallel extremely powerful and simply big.
What to do:
1. Connect your instrument to the input socket of
the Lehle P-Split II.
2. Connect the first amplifier to the DIR socket (2).
3. Connect the ISO socket (5) to the input of the
second amp.
4. Use the phase inverter switch to determine
which setting you prefer.
5. Actuate the ground lift switch to find the position at which noise is minimised.
6. There you go!
Device connection
Input (1) Instrument
DIR output (2) Amp 1
ISO output (5) Amp 2
11
The Lehle P-Split II as a compact passive
DI box
The Lehle P-Split II can be used as a passive
DI box. Balanced or unbalanced signals from the
ISO output can be fed. A TRS/XLR adapter will be
needed if you want a balanced signal for an XLR
input (please also see “Balanced signal lines” on
page 4).
How to do this:
1. Connect your instrument or the output from a
preamp or buffer to the input (1) of the Lehle
P-Split II.
2. Connect your amp to the DIR output socket (2).
3. Connect the ISO socket (5) to the input of your
mixer or stage box.
4. Actuate the phase switch to find out which setting sounds better to you.
5. Use the ground lift switch to determine which
position eliminates the most background noise.
6. There you go!
Note:
The signal from a passive pickup cannot be split
to an amp or mixer without negative effects on
Device connection
Input (1) Instrument (active)
DIR output (2) Amp
ISO output (5) Input mixer, stage box
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your sound, since balanced inputs are usually low
impedance.
The Lehle P-Split II functions excellently as a
neutral splitter and as a high-quality DI box with
instruments which have active pickups, and/or
when another buffer, such as the Lehle Sunday
Driver is positioned between the instrument and
the input of the Lehle P-Split II.
The Lehle P-Split II as a line isolator – the
universal cure for hum loops
The Lehle P-Split II can be used in any scenario
to eliminate noise resulting from ground loops or
hum. Ground loops occur when units grounded
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
LTHZ transformer included in the Lehle P-Split
II electrically isolates the ground connection. The
hum loop is thus broken at this point. Both highand low-impedance signals can be fed, the
Lehle P-Split II has no problems with balanced
or unbalanced signals.
Device connection
Input (1) Signal source
DIR output (2) -
ISO output (5) Signal input
13
What to do:
1. Connect the signal source to the input (1) of the
Lehle P-Split II.
2. Do not use the DIR socket (2).
3. Connect the ISO socket (5) to the signal input.
4. Use the ground lift switch to determine which
position eliminates the most background noise.
5. There you go!
Note:
In the above scenario, the Lehle P-Split II is
grounded via the signal source input. In some cases, it may be a good idea to connect the ground
to the other side, in order to eliminate even more
interference. To do this, simply swap the input (1)
and the ISO output (5).
The Lehle P-Split II as a recording splitter
It can be very useful, when recording guitar or
bass, to record not only the amplified signal, but
also the dry (unprocessed) signal. This signal can
then be routed in the mix either to a real ampli-
14
fier, or to a digital emulator, for editing. It’s also
helpful to be able to hear your accustomed sound
from an amp while recording the dry signal.
In this configuration, the Lehle P-Split II again
functions as a neutral splitter.
What to do:
1. Connect your instrument to the input (1) of the
Lehle P-Split II.
2. Connect your amp to the DIR output socket (2).
3. Connect the ISO socket (5) to the Hi-Z input of
a soundcard or DAW.
4. Use the ground lift switch to determine which
position eliminates the most background noise.
5. There you go!
Note:
We recommend the use of a buffer between the
instrument and the input of the Lehle P-Split II
to convert the high-impedance instrument signal
to a low-impedance signal in cases in which your
soundcard or DAW has no high-impedance input
(Hi-Z) and you wish to record the dry signal from
your passive pickups. The Lehle Sunday Driver
is the perfect solution for this task. You can, of
course, also use a balanced input on your soundcard or DAW to record the dry signal. In this case,
it’s a good idea to take a balanced signal from
the ISO output of the Lehle P-Split II (please
also see “Balanced signal lines”, page 4).
Device connection
Input (1) Instrument (active)
DIR output (2) Amp
ISO output (5) Soundcard, DAW
(with Hi-Z input)
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P-Split II
Input (1) Lehle Sunday Driver output
DIR output (2) Amp
ISO output (5) Soundcard / DAW
(with no Hi-Z input)
Sunday Driver
Input Instrument
(with passive pickups)
Output Lehle P-Split II input (1)
Device connection:
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The Lehle P-Split II as a re-amplification
isolator
Once you’ve recorded the dry signal, it can be
fed through an amplifier during mixing; connecting the amp to the soundcard or DAW will
almost certainly generate a ground loop, causing
undesirable noise. This problem can be effectively
eliminated using the Lehle P-Split II. The built-in
Lehle LTHZ transformer electrically isolates the
ground connections, and functions perfectly with
both balanced and unbalanced signals from a
soundcard or a DAW.
What to do:
1. Connect your soundcard or DAW to the input
socket (1) of the Lehle P-Split II.
2. Do not use the DIR socket (2).
3. Connect the ISO socket (5) to the input of your
amp.
4. Use the ground lift switch to determine which
position eliminates the most background noise.
5. There you go!
Device connection
Input (1) Soundcard / DAW
DIR output (2) -
ISO output (5) Amp
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Note:
In this case, the Lehle P-Split II is grounded via
the output of the soundcard or DAW.
It may, in some cases, be a good idea to connect
the ground to the other side, to eliminate interference noise. To do this, simply swap the input (1)
and the ISO output (5).
The Lehle P-Split II as a balanced-to-unbalanced signal converter
Device connection
Input (1) Signal source (balanced
or unbalanced)
DIR output (2) -
ISO output (5) Signal input (balanced
or unbalanced)
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Some units feature only balanced inputs and outputs, whereas others have only unbalanced inputs
and outputs. A Lehle P-Split II can be used to
connect these, also enabling you to separate the
ground connection (see “Types of signal line”,
page 4).
What to do:
1. Connect the balanced or unbalanced signal
source to the input socket (1) of the Lehle P-
Split II.
2. Do not use the DIR socket (2).
3. Connect the balanced or unbalanced signal input
to the ISO socket (5).
4. Use the ground lift switch to determine the
position in which the most background noise is
eliminated.
5. There you go!
Note:
Unbalanced setups often include long cable runs
from a pedal board to an amp which, on large
stages, can be some distance away. Recording in
a mixing room via an amp located in a separate
soundproof booth will also necessitate long cable
runs. Long distances like these should be bridged
using balanced lines, in order to keep interference
as low as possible. The solution is simple: use the
Lehle Sunday Driver XLR to convert the unbalanced instrument signal to a balanced signal. Up
to 100m of cable can be connected to the XLR output socket. The Lehle P-Split II can be used at
the end of the line to convert the balanced signal
back to an unbalanced signal for input to your
amp. This system makes it possible to convey the
signal across great distances without signal losses.
19
Device connection:
Lehle Sunday Driver XLR:
Input Instrument
(with passive pickups)
XLR output Lehle P-Split II input (1)
Lehle P-Split II:
Input (1) Lehle Sunday Driver
XLR output
DIR output (2) -
ISO output (5) Amp
20
Signal flow chart for the Lehle P-Split II
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