SW1X PRE III Line Pre-Amplifier

SW1X Audio Design™ PRE III Performance Level 3 Line Pre-Amplifier


EL84/EL86 is a classic power pentode, which was popular in electric guitar amps and most radios in the 50s and 60s and is known for its articulate character. Pentodes in triode mode are powerful but are still high in capacitance, therefore need a good driver to perform at its best. 5687/6N6P is a relatively powerful driver/pre-amplifier double triode, which is known for its solidity & smoothenes but it needs more power (lower output impedance without local negative feedback loop) to transfer the scale and dynamics.

In the PRE III pre-amplifier we utilise both EL86 on the output with 6N6P as a driver, a 2 gain stage, zero negative feedback (global or local) design, decoupled with signal output transformer, which lowers the output impedance further close to 10 Ohms. That makes PRE III (as well as the DHT version PRE IV) essentially a power amplifier with line stage output level and volume control, which will enable to drive subsequent power amplifiers to its full potential.

In combination with finest materials & component, the sound of the PRE III is transparent, characterised by scale, authority and dynamic bite. It is a great enhancement to any tube power amplifier, driving a sources (DAC or Phono), which has a weaker small signal, indirectly heated tube based output stage.

Available in either double C-core Super HiB transformer version or Pemalloy core version (Special version) and the limited production Signature version on request. The option of a Phono pre-amplifiaction stage will be available in the forthcoming PRE III P version.

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SW1X Audio Design™ PRE III Power line pre-amplifier Features:

  • Specially selected and harmonically matched component & material quality Performance level 3/4
  • Anode follower, zero feedback, 1 x double triode 6N6P driver, double C-core signal output transformer de-coupled 2 x EL86 power pentode (triode connected) valve output stage
  • Double C-core Super HiB transformer or 80% Nickel Pemalloy core signal ouput transformers
  • Output stage and interstage signal decoupling capacitor are Audio Note Copper Foil in Oil capacitors
  • 5R4 directly heated or GZ34 (5C4M) tube rectified CLC (choke filtered) power supply
  • Circuit is wired with of a specially selected copper (single strand or Litz)


Optional Extras:

a) Audio Note 2W copper, non- magnetic, tantalum film resistors on plates, cathodes, power supplies

b) Audio Note Silver Foil capacitors in inter-stage and ouput stage signal decoupling option

c) Circuit is normally wired with specially selected copper but can be ordered with fine silver wiring (including power inlet)

d) HiB double C-Core mains transformers and chokes in the power supplies


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




S1500005 S1480008 S1480002




Dimensions: Height (mm) 150 x Width (mm) 440 x Depth (mm) 400

Weight (kg): 15

Max Power Consumption (W): 80

Output Noise, Unweighted (mVrms): < 0.5

Output Impedance (Ohms): 10

Tube Compliment:  2 x EL84/EL86, 1 x 6N6P/6N1P, 1 x 5R4/GZ32


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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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