NAT Audio · Vacuum Tube Power Amplifiers
Transmitter Evo
Pure class A single-ended power with uncompromising direct-coupled circuitry.
The Transmitter Evo stands as a pinnacle of single-ended vacuum tube design, representing the latest refinement of a circuit philosophy that has been central to NAT Audio since the 1990s. By employing a fully direct-coupled signal path from input to output, the amplifier eliminates capacitors and inter-stage transformers, ensuring that the musical signal remains as raw and authentic as possible.
Positioned as a cornerstone of our reference amplifier collection, this model is built for the listener who demands total honesty in reproduction. It employs a high-power military-grade direct-heated triode output stage, capable of dissipating significant heat to ensure long-term reliability and linear performance, even when tasked with demanding musical transients.
Sonically, the Transmitter Evo defies the traditional characteristics of many single-ended designs by offering exceptional speed and control. It maintains harmonic richness without veering into coloration, delivering a presentation that is both rhythmically articulate and expansive. Whether in its 80-watt or 40-watt mode, it provides the authority to drive complex speaker loads while preserving the fine micro-details that define a truly live performance.
Key Features
01
Direct-coupled circuitry
Eliminates all coupling capacitors and inter-stage transformers to maintain an ultra-short, pure signal path.
02
Selectable power modes
Offers versatile 80W or 40W settings to optimise performance for high or low sensitivity loudspeakers.
03
Military-grade triodes
Utilises N.O.S. military-standard QB5/1750 output tubes for robust reliability and superior linearity.
04
Regulated power supply
Features dedicated regulation for all stages, including the output, to ensure tonal consistency regardless of line voltage fluctuations.
05
Automatic bias control
Integrated system ensures precise, drift-free operation without the need for manual adjustment.
Chapter 01
Engineering Vision
The Transmitter Evo is the result of an uncompromising design brief: to provide the musicality of single-ended triode amplification without the typical limitations of dynamic range or bandwidth. The engineering team focused on a direct-coupled architecture, which removes the 'safety nets' of traditional circuit design to allow for a faster, more transparent sound profile that remains stable under heavy electrical load.
Chapter 02
Build & Materials
Every unit is hand-assembled within a heavily braced, CNC-machined chassis that acts as a solid foundation against unwanted vibration. The construction features laboratory-grade components, including military-spec graphite resistors and custom-wound wide-bandwidth output transformers, reflecting a build philosophy that prioritises industrial longevity as much as sonic performance.
Chapter 03
Listening Notes
This amplifier exhibits a rare ability to retain the structural complexity of a recording while maintaining the liquidity of a single-ended triode. It does not soften or smooth the signal; instead, it presents transients with percussive speed and provides a stable, holographic soundstage that allows the listener to distinguish between the individual textures of an acoustic performance.
Specifications
TypeSingle-ended class A monoblock
Frequency response8 Hz to 60 kHz
Sensitivity1.0 V RMS for 80 W
ImpedanceInput: 100 kohms
Power handling80 W (high mode) or 40 W (low mode)
Dimensions (H × W × D)310 mm × 360 mm × 640 mm
Weight40 kg per unit
Finish optionsBlack or silver