SW1X LPU II SP - MM Valve Phono Pre-Amplifier

The main difference is the type of tube employed in the output stage: 6N6P Driver Triodes (LPU II SPX) vs EL84 Power Output Pentodes (LPU III).

The LPU II Special MM RIAA Phono pre-amplfier is based on a classic circuit design used to master vinyl recordings and master tapes. Similar to LPU III, 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 6N6P 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.

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 LC (inductive loading/capacitive de-coupling) Circuit Topology
• Based on 2 x EF86 Pentodes Input and inductively loaded 2 x 6N6P 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. 50-52 dB depending on the Choice of Valves
• Maximum Input Voltage: 350mV

Tube Compliment:  2 x EF86, 2 x 6N6P, 1 x 5Y3

Optional Extras:

• Fully Hardwired Tube Output Stage on the Bakelite Board
• Fine Silver wiring on the Input, Bakelite Board and Output
• SW1X Audio Design™ Custom Designed Copper wound Super HiB DC core Signal Chokes
• AN 2W non-magnetic Niobium resistors on a Hardwired Bakelite Board
• Super HiB double C-Core mains transformers for the DHT/DHD power supplies
• Silver Foil capacitors Inter-stage Signal de-coupling Capacitors
• AN 2W Silver, non-magnetic, Tantalum resistors

Specifications

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

Weight (kg): 14

Max Power Consumption (W): 22

Output Noise, Unweighted (mVrms): < 0.5

Output Impedance (Ohms): <200

Tube Compliment:  2 x EF86, 2 x 6N6P, 1 x 5Y3

Front panel options: satin Silver or matte Black