The U-280 SC 30th Anniversary is the principal tube power amplifier in the Margules universe and one of the clearest expressions of how we understand amplification.
For more than three decades, the U-280 has evolved around a single idea: preserving the harmonic structure, spatial dimension, and emotional character of music. Each generation has refined the relationship between circuit, tube, loudspeaker, and listener, bringing the ANA® philosophy to its most complete expression in amplification.
At the heart of that evolution is the Active Servo Bias system, which continuously adapts the operating conditions of the output stage to maintain pure Class A operation while allowing the use of different tube families without manual bias adjustment. Together with BEFS, zero global negative feedback, shunt-regulated power supplies, and Triode / Ultralinear operation, these technologies form a single architecture designed around perception rather than specification alone.
The U-280 can move from the intimacy and texture of Triode operation to the greater scale and authority of Ultralinear, and from stereo to monoblock configuration as the system evolves.
Thirty years of refinement have not changed its purpose. To let amplification disappear, and music remain.
Technical Specifications — Architecture
- Pure Class A Tube Power Amplifier
- Active Servo Bias
- Triode / Ultralinear Operation
- Stereo / Monoblock Configuration
- No Global Negative Feedback
- BEFS — Back Electromotive Force Sensor
- Independent Shunt-Regulated Power Supply
- Input Attenuators for Direct Source Connection
- Stereo: 25 W/ch Triode · 50 W/ch Ultralinear
- Mono: 55 W Triode · 100 W Ultralinear
- Frequency Response: 20 Hz – 40 kHz (–3 dB)
- Total Harmonic Distortion (THD): < 0.08%
- 4 × KT88
- Compatible with 6550, KT90, KT120, and KT150
- 4 × 12AU7
- ANA® (Aligned Neuro-Acoustics) at its most complete expression in amplification
- More than three decades of continuous evolution
- Handcrafted in Mexico
- 30th Anniversary Edition
