SW1X LPU II Phono Pre-Amplifier

SW1X Audio Design™ LPU II Performance Level 2 MM Valve Phono Pre-Amplifier


The SW1X LPU II is characterised by powerful dynamic sound with natural, life like presentation- a combination that we look after in analogue playback.

Acoustic instruments and human voices sound completely naturally, lacking of any mechanical signature.

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

The 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 design consisting of 2 (one for each channel) pentode valves on the input stage but instead of the single double triode, LPU II employs two power pentodes (used in power amps) in triode mode on the output.

The input stage utilises lush sounding E80F/EF86 valves, which drive passive RIAA equalization network (without series resistors), which is amplified by the EL84 power pentode, triode connected on the output stage. The low output impedance EL84 power output stage is choke loaded in order to deliver supreme dynamics and punchy bass. Choke loaded anode of the EL84 valve make any conventional resistor loaded sound lame and dull in comparison.

The power supply is CLCLC, EZ81 double diode valve rectified and 2 x chokes filtered

SW1X Audio Design™ LPU II Features:

  • Specially selected and harmonically matched component & material quality
  • Classic pentode input-RIAA-pentode (triode mode) output design
  • Based on 2 x E80F/EF86 pentode valves on the input and 2 x EL84 pentode (triode connected) on the output
  • Pure class A, zero feedback, single ended, twin pentode/choke loaded triode connected pentode operation
  • Low output impedance circuit design, consisting of 4 chokes in total: 2 x in power supply and 2 x anode load for the EL84 valves
  • Paper in Oil decoupling capacitors (either AN Copper Foil or vintage Siemens PIO) between the two gain stages and output stage
  • Passive series-resistorless RIAA equalization stage
  • EZ81 valve rectified CLCLC (choke filtered) HV power supply
  • The MM phono pre-amplifier is suitable for all moving magnet (MM)  or moving coil (MC) in combination with a matching SUT with max 350mV output
  • 47K input impedance /<200 Ohm output impedance
  • Total gain is approximately 40-46 dB depending on the choice of valves
  • 110/115/230/240V AC mains transformers


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










Dimensions: Height (mm) 130 x Width (mm) 330 x Depth (mm) 400

Weight (kg): 11.5

Max Power Consumption (W): 20

Output Noise, Unweighted (mVrms): < 0.5

Output Impedance (k Ohms): <0.25

Tube Compliment:  2 x E80F/EF86, 2 x EL84, 1 x EZ81


SW1X Audio Design Product Price List



We do not recommend purchasing a key system component without first auditioning it carefully, which is why we have demonstration rooms and a flexible home loan policy.

However in certain situations it can be difficult for people to get to our showroom and for those instances we can offer our mail order service.

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