• Power Amplifiers
  • Single-ended
    • Adagio
    • Carissa
    • Diavolo
    • Jota
    • PX-25
    • Symphony II
  • Push-pull
    • Concerto II
    • Opus Ten
    • Quartet MB
• Pre Amplifiers
  • VPL & VP1 MK II
  • Dual Mono VPS
• Phono Amplifiers
  • Vinyl One
  • Vinyl Reference
• Gill Audio Design
  • Alana Preamplifier
  • Elise DAC

PX-25 has a very similar midrange sound to the 2A3 but much more extended frequency extremes and more power. It also employs a high Mu tube, which allows the design of an amplifier to achieve a greater damping factor (better control over speaker drivers). Compared to a 300B, it possesses a lower grid-to-anode capacitance (around 8pf rather than 13pf) and a higher anode impedance (1.2k versus 800 ohms).

This allowed us to design an output transformer with extended bandwidth that transcends the capabilities of a 300B or 2A3. The result is a micro-watt amplifier capable of much more impressive performance.

The total project and combined development of this design took about 17 months, including time spent with the research of the actual tubes from Riccardo Kron.

• Zero-feedback design, high-peak current delivery
• Automatic biasing circuit
• Dual-mono design on a single chassis
• High quality mil-spec, multi-layered 2-oz. copper trace circuit boards
• Employs a tube-rectified (CV-378/GZ-37 or 274B) choke-regulated power supply preceded by a pi filter
• Capacitors are low ESR/ESL types for increased high- frequency performance
• Resistors are 1% metal oxide for low noise
• Output transformers are a novel split-core type not normally associated with single-ended designs and custom-designed by Art Audio to give a wider bandwidth than most generally available transformers
• Tube sockets are ceramic with silver-plated pins
• Standard finish with polished non-magnetic stainless steel chassis and chrome or gold accents