Lehle Sunday Driver SW II Preamp, Buffer & Booster

The Lehle Sunday Driver SW II is a studio–grade preamp, buffer and booster designed for electric and acoustic guitars, basses, and orchestral stringed instruments. Its discrete Class A JFET circuit delivers 130 dB of dynamic range courtesy of a 30 V internal voltage topology, while a microcontroller–driven relay with active pop suppression ensures silent, wear–free switching via an indirect spring–loaded footswitch. Two operation modes cater to different tonal needs: 'D' mode functions as a transparent driver to preserve signal integrity through long cable runs and effects chains, while 'S' mode multiplies input impedance by five to reveal harmonic detail and deliver characteristic warmth.

Gain is adjustable up to +18 dB without introducing noise or compression. Input impedance switches between 5 MOhm in 'S' mode and 1 MOhm in 'D' mode, with the mode selector featuring gold–plated contacts for reliability. The bypass configuration offers two distinct behaviours: True Bypass (TB) links input and output via relay with zero signal modification, while True Sound (TS) keeps the buffer circuit active to maintain signal strength across complex pedalboards. A balanced output doubles as a direct injection box for studio and stage applications, extending the pedal's utility beyond straightforward gain staging.

Features

• Discrete Class A JFET preamp circuit with 30 V internal voltage
• 130 dB dynamic range with silent operation at all gain levels
• Switchable gain up to +18 dB with zero background noise
• Dual operation modes: 1 MOhm or 5 MOhm input impedance
• Microcontroller–driven relay switching with active pop suppression
• True Bypass and True Sound buffer modes via relay circuit
• Balanced output functions as DI box for direct recording
• Spring–loaded footswitch protects circuit board from mechanical stress