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LPU II Phono Pre-Amplifier

SW1X Audio Design™ LPU II

Performance Level 2
Valve Phono Pre-Amplifier


The LPU II is the fuller size & higher gain model of the LPU I.

The sound of LPU II is characterised by a lush yet lively and bold presentation that makes vinyl playback stand out above anything else.

Acoustic instruments and human voices sound completely naturally with accurate dense timbres, lacking of any mechanical signature.

The LPU II MM RIAA Phono pre-amplfier is based on a classic circuit design used to master vinyl recordings and master tapes. Similar to LPU I, it is a two gain stage, active RIAA equalization design. The input stage utilises lush sounding 2 x EF86 valves, loaded by RIAA equalization network and is amplified by the 2 x EC86 single triode tubes on the output stage.

LPU I, LPU II and LPU III family of Phono Pre-Amplifiers share similar tube input stage- a pair of EF86 pentode tubes. Due to the brilliant sound character of the EF86 those tubes were commonly used in many radios and RTR tape recorders in the early 60s. The idea of their circuit design was borrowed from the input stage of early Reel to Reel (RTR) tape recorders, which were used in the mastering studios and radio stations. Maybe that is one of the reasons as why most recording from the 60s are sounding at their best, much better than from the 70s and 80s? In a way, the EF86 input tube design closes the loop and makes all our LPU Phono Amps range a time-less classic.

LPU II Phono Pre-Amplifier to match Moving Coil MC SUT

SW1X Audio Design™ LPU II Features:

  • Specially Selected and Harmonically Matched Component & Material Quality
  • MM Phono Pre-amplifier is suitable for all moving magnet (MM) or moving coil (MC) in combination with a matching SUT
  • Classic 2 Gain Stage Pentode Input-RIAA-Triode Output Design
  • Pure Class A, Zero NFB, Single Ended, all Valve Amplification RC (resistive loading/capacitive de-coupling) Circuit Topology
  • Based on 2 x EF86 Pentodes Input and 2 x EC86 Single Triodes on the Output
  • Active Series-Resistor-less RIAA Equalization
  • PIO or Film/Foil de-coupling Capacitors in Inter- and Output Stage
  • 5Y3 Valve Rectified CLC2RC (choke filtered) B+ Power Supply
  • 47K Input Impedance & < 2K Ohm Output Impedance
  • Total Gain is approx. 50-56 dB depending on the Choice of Valves
  • Maximum Input Voltage: 350mV


Tube Compliment:  2 x EF86, 2 x EC86, 1 x 5Y3



Note: Due to SW1X Audio Design’s ongoing research and development process, specifications are subject to change without notice.

LPU II Phono Pre-Amplifier to match Moving Coil MC SUT


Dimensions: Height (mm) 140 x Width (mm) 340 x Depth (mm) 410

Weight (kg): 9.5

Max Power Consumption (W): 12

Output Noise, Unweighted (mVrms): < 0.5

Output Impedance (k Ohms): <2

Tube Compliment:  2 x EF86, 2 x EC86, 1 x 5Y3

Front panel options: Silver or matte Black


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