SW1X Phono Pre-Amplifiers

A Phono Pre-Amplifier is one of the key components in the analogue playback.

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.

 

All our LPU Phonos are 2 gain stage, MM level input designs, share the rich & lush sounding 2 x EF86 pentode tubes for the input and RIAA EQ stage in between two gain stages.

What different is a) the tube output stage topology, b) power supply and c) the components & materials employed across the LPU Phono range.

In the LPU I (entry, performance level 1, small chassis), there is a powerful 1 x 6N6P/5687 double triode as the output tube with indirectly heated 6X5 tube rectification.

In the LPU II (performance level 2) there are 2 x 6S3P/EC86/6CM4 single triodes (one per each channel) in the output stage but on a larger circuit board design, so we can use larger capacitors & resistors and also improved Directly Heated (DHD) tube rectified power supply. The sound is expressive & seductive similar to LPU I, while LPU II sounds larger and has more authority & scale.

Special version of LPU II comes in a larger chassis (DAC III Balanced chassis), same LPU II circuit board, DHD tube rectification and with inductively (choke) loaded tube output stage with 2 x 5687/E182CC/6N6P tubes. Relative to the basic LPU II, the Special version adds even more scale and authority but most importantly more dynamics to the sound.

If one wanted to take a step further, LPU III (level 3) is based on LPU II Special (larger, DAC III Balanced chassis) but uses 2 x EL84 power tubes just like on the DAC III Balanced with inductive loading. Those tubes increase power, grunt and authority & dynamics further. The Balanced version of the LPU III takes it a notch further by employing signal output transformers and one gets maximum dynamics and transparency over any LPU III/ II & LPU I.

The LPU III is currently the best possible noval tube phono pre-amplifier money can buy, especially if implemented as Special or Balanced version with signal OPTs (or Signature with silver wound OPTs, Bakelite board hardwiring).

 

Generally, all product version can be summarized according to their signal output stage topology:

While all our LPU Line of Phono Pre-Amplifiers have Musicality in their DNA, the higher performance level Phonos add more Holography, Expression and Power to the Presentation.

Besides that, there are different versions of each LPU model at each performance level: STD, Special, Balanced and Signature.

Standard (STD) versions = basic versions with active I/V, double triode tube output stage, RC (resistor loading, signal capacitor decoupling) topology

STD is a base model made of excellent sounding components & materials.  One can customise STD versions with X options package or optional extras.

Special/Balanced versions = fully charged without being too exotic versions with power tubes output stage, LC or LL (OPT, output transformer) topology

Special versions include many options already plus have higher degree of harmonic matching. Balanced are top of the line, signal OPT based, usually maxed out versions which are loaded with the specially selected or even exotic components & materials.

Signature versions =  limited production versions with no expense spared exotic materials, maxed all out Balanced versions with power tube output stage, LL topology with silver wound signal (OPT) output transformers

 

Level 1

SW1X LPU I Phono Pre-Amplifier

Level 2

SW1X LPU II Phono Pre-Amplifier

SW1X LPU II Special Phono Pre-Amplifier

Level 3

SW1X LPU III Phono Pre-Amplifier

SW1X LPU III Balanced Phono

Design Choice: Performance vs Compatiblity

 

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