
OPERATING INSTRUCTIONS
LEHLE PARALLEL SW II
LEHLE PARALLEL SW II#
Dear Musician!
Thank you for purchasing the LEHLE PARALLEL SW 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 PARALLEL SW II comprises only the very best components. Every assembly of your LEHLE PARALLEL SW II has been made and tested in Germany.
Your LEHLE PARALLEL SW 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 PARALLEL SW II!

General Description#
1. INPUT SOCKET
Connect your instrument or the Send output of your amplifier to this socket.
The LEHLE PARALLEL SW II has a high-impedance input and can therefore accept both low- and high-impedance signals of all types, so that you can plug in virtually any instrument you like: electrical and acoustic stringed instruments, such as electric guitars and basses, acoustic guitars and all types of stringed instruments, and also the low-impedance signals from computers, keyboards and mixers.
If you want to use your LEHLE PARALLEL SW II to inject an external effect into the serial effects loop of your amplifier, connect the Send output of the amplifier to this input socket.
2. MONO-TO-STEREO-SWITCH
Activates at the input socket the mono-to-stereo function.
If this switch is not pressed, the LEHLE PARALLEL SW II works with either mono or stereo signals. This means, all sockets should be occupied with either mono jacks (TS) or stereo jacks (TRS). By doing this you can place a mono or stereo effects pedal in the loop of the LEHLE PARALLEL SW II.
Some effects offer a stereo output, but a mono input. If the mono-to-stereo switch is pressed, the input (1) and send (3) can be occupied with mono jacks (TS), while the return (5) and output (6) transfer a stereo signal via stereo jacks (TRS). If the LEHLE PARALLEL SW II is activated the input signal will be sent in mono to the effects pedal. The output of the effect can be returned in stereo to the return (5) and sent out to the output (6) in stereo. If the LEHLE PARALLEL SW II is deactivated the mono signal will be split straight after the input and sent loss-free to the output (6).
3. SEND SOCKET
Connect the input of your effects unit or the input of your target device (e.g. mixer, computer, etc.) to this socket.
If you’re using the LEHLE PARALLEL SW II for parallel effects loops, connect the Send socket to the input of the effects unit. The intensity of the signal available on the Send socket can be controlled using the Send controller (9).
4. PHASE SWITCH
The phase of the return signal can be reversed here, if necessary.
Phase cancellations can occur if you are mixing the original signal with the return signal – this sound is usually felt to be too “thin” or “hollow“. Reversing the phase using the gold-contacted phase switch solves this problem. Simply move the switch to the position at which the sound is best – this is, of course, ultimately a question of individual taste.
5. RETURN SOCKET
Connect the output of your effects unit or the output of your second device (e.g. mixer, computer, second pickup on a guitar, etc.) to this socket.
If you’re using the LEHLE PARALLEL SW II for parallel effects loops, connect the output of your effects unit to the Return socket. The Return socket can also be used as an input for other signal sources – the output from a computer sound card, for example, or from a signal processor.
If the LEHLE PARALLEL SW II is being used to mix two pickups from one instrument, the Return socket can also be used as the input for the second pickup.
The Return socket has a 2 MOhm input impedance. This means that even very weak signals, such as those generated by piezo and magnetic pickups can be transmitted without loss of sound.
The Return input’s sensitivity can be adjusted using the controller (11). Like every other socket, the return input can be used in stereo as well. Please refer to paragraph „2. Mono-to-stereo switch“.
6. OUTPUT SOCKET
Connect your amplifier or the Return input from the serial effects loop of your amplifier to this socket.
The device connected here will mostly be an amplifier, but can also be a mixer, a stage box or a sound card. The signal mixed from the input and the return signal is available here. The mixing ratio can be controlled using the MIX controller (10).
Connect the output socket to the Return input of your amplifier if you want to use the LEHLE PARALLEL SW II to inject an external effect into your amplifier’s serial effects loop.
7. EXTERNAL POWER SUPPLY
Connect a power supply with a voltage of 9 – 15 V.
In order for the LEHLE PARALLEL SW II to 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 offering galvanically isolated outputs for the LEHLE PARALLEL SW II.
8. LED FOR SWITCHING STATUS
If the LED shows white, the input (1) is directly connected to the output (6).
The high-intensity LED clearly indicates the current switching status – even under bright spotlights. When you use the LEHLE PARALLEL SW II as an effects loop switcher and the LED shows white, the effects are in Bypass, when blue they are in the signal path.
If you use it for switching or mixing two instruments, LED white means that the instrument at the input (1) is active, blue applies that the return (5) is active.
9. SEND CONTROLLER
You can set the level of the Send signal here.
The input signal is available 1:1 on the Send input when this controller is set to its center position. Turn the controller to the left to decrease the signal by up to 15 dB, or to the right to boost the signal by up to 15 dB.
10. MIX CONTROLLER
Here you can set the ratio for mixing the Input and Return signals.
The two signals have equal strength when this controller is in its center position. Turn the MIX controller to the left to increase the Return signal and decrease the Input signal. The Input signal is increased, and the Return signal decreased when you turn the controller to the right.
11. RETURN CONTROLLER
Set the level of the Return signal here.
The signal on the Return input is transmitted 1:1 when this controller is in its center position. Turn the controller to the left to decrease the signal by up to 15 dB, or to the right to boost the signal by up to 15 dB.
12. FOOT SWITCH
Here you can switch.
The LEHLE PARALLEL SW 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 mushroom-shaped button 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 PARALLEL SW II virtually indestructible and guaranteeing years of trouble-free switching.
According to the foot switch mode following configurations are given
- Latching Mode: The LEHLE foot switch “latches“ by a press and release.
- Momentary Mode: The LEHLE foot switch triggers a contact and disconnects once released.
- Mixed Mode: A mix between latching and momentary. A short press lets the foot switch act as latching, a longer press is momentary.
You will find out how to change the operating mode and foot switch mode in the chapters „Selecting the Foot Switch Mode“ and „Selecting the Operating Mode“.
13. BASE AND FIXING
If required, mount the LEHLE PARALLEL SW II to a pedalboard using the mounting kit.
The LEHLE PARALLEL SW 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 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.
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!
SELECTION OF THE FOOT SWITCH MODE#
You can change the behaviour of the foot switch, so it works latching, momentary or in a mixed mode.
According to the foot switch mode following configurations are given:
• Latching Mode:
The LEHLE foot switch “engages” by pressing and releasing.
•• Momentary Mode:
The LEHLE foot switch triggers a contact and disconnects once released.
••• Mixed Mode:
a mix between latching and momentary. A short press lets the foot switch act as latching, a longer press is momentary
These three modes can be operated with or without the pop suppression circuit.

Selecting the operating mode#
The operating mode can only be changed for products with serial numbers from“21.59321“.
Additionally the operating mode of the LEHLE PARALLEL SW II can be changed to give you more creative possibilities: if it works in the true-bypass-mode, the Return (5) is being activated and deactivated.
In the buffered-bypass-mode the Send (3) is being activated and deactivated. This mode works especially well for the application with delay or reverb pedals, whose “trails”, the decay of echoes or reverb, won’t be cut if the LEHLE PARALLEL SW II is being deactivated.
If the operating modes of your LEHLE PARALLEL SW II cannot be changed, please get in contact with us.
To change the operating and foot switch mode please proceed as follows:
- Disconnect the power supply.
- Press and hold the foot switch.
- Reconnect the power supply.
- The white LED now flashes in the following sequence:
• for Latching Mode in true-bypass
•• for Momentary Mode in true-bypass
••• for Mixed Mode in true-bypass - The blue LED now flashes in the following sequence:
• for Latching Mode in buffered-bypass
•• for Momentary Mode in buffered-bypass
••• for Mixed Mode in buffered-bypass - If you release the foot switch after one white flash, switch mode is selected. After the second time, button mode is selected, after the third time, mixed mode is selected, in each case true bypass.
- If you release the footswitch after one blue flash, switch mode is selected. After the second time, button mode is selected, after the third time, mixed mode is selected, in each case with buffered bypass
- The LEHLE PARALLEL SW II turns off and reboots.
The selection of operating mode and foot switch mode is saved internally even after the power connection is removed and called up again the next time the device is started.