SW1X Audio Design PRE III

The PRE III is a pure class A, zero negative feedback (global or local) line pre-amplifier with a signal output transformer (OPT) de-coupled valve output stage. Signal OPT of highest quality not only increases transparency (superior to any kind of capacitors) but also lowers the output impedance of the line pre-amplifier further close to 4 Ohms, capable of driving any load of power amplifier input. That virtually unlimited driving capability of PRE III (as well as the DHT version PRE IV) line pre-amplifier acts as a supercharger to a source (DAC Phono, Tape or Radio). It is a great enhancement to any tube power amplifier, driving a sources (DAC or Phono), which has a weaker small signal (high output impedance) tube based output stage. With a help of of a PRE III, any source becomes unleashed to drive subsequent power amplifiers to its full potential.

Essentially, the design of PRE III valve line pre-amplifier is akin of a power amplifier, which instead of driving high load of a speaker drives line level output. The PRE III line pre-amplifier utilises 6N6P or 5687/E182CC as a driver and a pair of triode connected EL84 is a classic power valves, which were popular in electric guitar amps and most radios in the 50s and 60s and are known for their articulate character. Altogether, the combination of powerful driver and output tubes & Signal Output Transformer (OPT) results in tonal purity, incredible transparency & the dynamic driving ability, which in turn provides an added dynamic expressiveness as the ability to dig deep into musical presentation. In combination with finest materials & component, the sound of the PRE III is transparent, characterised by scale, authority and dynamic bite.

Available with a supercharged LPU Phono stage denoted as PRE III LPX and can be ordered with our range of signal OPTs: M6 EI core (STD version), all Copper wound Double C-core Super HiB Signal OPT (Special version) or with partial Silver wound Ultra HiB (Classic version) or as all Silver wound Ultra HiB, limited production Signature version.

SW1X Audio Design™ PRE III Line Pre-amplifier Features:

• Specially Selected and Harmonically matched Component & Material Quality
• Anode follower, zero NFB, Signal Output Transformer (OPT) de-coupled Valve Output Stage
• SW1X Audio Design™ Double C-core Super (Cu/CU or Cu/Ag windings) or Ag/Ag wound Ultra HiB Signal OPT transformers
• 1 x Double triode 6N6P or 5687 driver, 2 x EL84 Triode Connected Power Pentode Valve Amplificaton Design
• 2 x SW1X Audio Design™ Mono, 24 Way, discrete resistor Stepped Attenuators made from the Finest Materials and Specially Selected Resistors
• Hybrid Point 2 Point Hardwiring Technique for the most consistent production results
• 5Y3/5U4GYB/5R4GYB Directly heated Tube rectified CLC2LC (choke filtered) B+ power supply
• For maximum transparency & dynamics, the circuit is hard wired with of a specially selected conductors (single strand or Litz)
• Internally wired exclusively with our SW1X Magnum, Genesis and Opus conductors

Tube Compliment: 2 x EL84, 1 x 6N6P or 5687, 1 x 5U4

SW1X Audio Design™ PRE III LPX Line & Phono Pre-amplifier Features:

• As the PRE III line stage above but additionally with a supercharged, fixed bias version of LPU I Phono stage to match
• 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
• Based on 2 x EF86 Pentode Valves on the Input and 6N6P/5687 Double Triode on the Output
• Pure Class A, Zero NFB, Single Ended, all Valve Amplification RC Circuit Topology
• Active Series-Resistor-less RIAA Equalization
• 5Y3 Valve Rectified CLC2RC (choke filtered) B+ Power Supply
• Maximum Input Voltage: 350mV
• 47K Input Impedance

Tube Compliment Line Section: 2 x EL84, 1 x 6N6P or 5687, 1 x 5U4
Tube Compliment Phono Section: 2 x EF86, 1 x 6N6P / 5687, 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 & Fully or Partly Silver wound Super HiB DC core Signal Output Transformers
• 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 digital and DHT/DHD power supplies
• Silver Foil capacitors Inter-stage signal de-coupling capacitors

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

 

Specifications

Dimensions: Height (mm) 150 x Width (mm) 440 x Depth (mm) 400
Weight (kg): 17 (with LPX Phono, 22kg)
Max Power Consumption (W): 180
Output Noise, Unweighted (mVrms): < 0.5
Output Impedance (Ohms): 4