SW1X LPU III Phono Pre-Amplifier

SW1X Audio Design™ LPU III Performance Level 3 MM Valve Phono Pre-Amplifier

 

The LPU III is a further development of the great sounding LPU II.

It is characterised by a more powerful dynamic sound with natural, life like presentation- a combination that we look after in analogue playback.

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

The input stage utilises lush sounding 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.

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.

 

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SW1X Audio Design™ LPU III 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 Connected Power Pentode 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 EL84 Power Pentodes on the Output
• Active Series-Resistor-less RIAA Equalization
• AN Copper foil, mylar in Oil Signal Output de-coupling Capacitors PIO in Inter- and Output Stage
• 5U4GB Valve Rectified CLC2RC (choke filtered) B+ Power Supply
• 47K Input Impedance & < 200 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 x EL84, 1 x 5U4GB

 

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
• Black Gate VK capacitors in the B+ power supply
• 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

 

 

 

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

Specifications

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

Weight (kg): 11.5

Max Power Consumption (W): 22

Output Noise, Unweighted (mVrms): < 0.5

Output Impedance (Ohms): <200

Tube Compliment:  2 x EF86, 2 x EL84, 1 x 5U4GB

Front panel options: Silver or matte Black

 

Reviews and customer’s feedback can be found here  

 

Ordering

We do not recommend purchasing a key system component without first auditioning it carefully, which is why we have demonstration rooms and a 14 day trial period 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.

 

 

 

SW1X Audio Design Product Price List

 

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