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LPU III Phono Pre-Amplifier RIAA

SW1X Audio Design™ LPU III Balanced

Performance Level 3
Signal OPTs de-coupled Phono Pre-Amplifier


The LPU III Balanced is a Signal Output Transfomer (OPT) de-coupled model of the LPU III.

Just like with all our Balanced versions, highest Quality Signal OPTs further improve transparency & dynamics.

The classic RIAA circuit is made of specially selected materials & components out of production and only available in limited quantities.

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 III Phono Pre-Amplifier RIAA

SW1X Audio Design™ LPU III Balanced Phono 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
  • Signal Output Transformer De-coupled, Zero NFB, Triode Valve Output Stage in Pure Class A, (inductive loading & de-coupling) Circuit Topology
  • SW1X Audio DesignCustom Designed Signal Output Transformers
  • Based on 2 x EF86 Pentodes Input and 2 x 6S45P Special Driver Triodes on the Output
  • Active Series-Resistor-less RIAA Equalization
  • 5U4GB Valve Rectified CLC2RC (choke filtered) B+ Power Supply
  • 47K Input Impedance & < 20 Ohm Output Impedance
  • Total Gain is approx. 46-52 dB depending on the Choice of Valves
  • Maximum Input Voltage: 350mV
  • Orient Grain, M6 EI Core, Copper flux banded, mains Transformer & Choke


Tube Compliment:  2 x EF86, 2 xEL84 (Single Ended) 2 x 6S45P /WE 437 (Balanced), 1 x 5U4GB




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

LPU III Phono Pre-Amplifier RIAA


Dimensions: Height (mm) 140 x Width (mm) 440 x Depth (mm) 410

Weight (kg): 15.5

Max Power Consumption (W): 65

Output Noise, Unweighted (mVrms): < 0.5

Output Impedance (Ohms): <20

Tube Compliment:  2 x EF86, 2 x 6S45P, 1 x 5U4GB

Front panel options: Silver or matte Black


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