Margules U-280SC 30th Anniversary

Through the years the U-280 amplifier has become an international reference in high-end audio thanks to its quality and unusual versatility.

The Margules U-280SC 30th Anniversary merges a new approach in circuitry technology presented in a Special Edition Design, resulting in an amplifier that produces engaging, realistic, and dynamic sonic presentation with elegant aesthetics.

Full Class-A

This amplifier incorporates our proprietary Active Servo Bias, which guarantees an optimal operation since it does not require any polarization adjustment, always operating the output stage at pure Class-A to ensure a detailed sound scenario.

At the same time, the Active Servo Bias allows the use of different tubes such as KT88, KT90, KT120, KT150, 6550, without the need of any adjustment.

Zero Negative Feedback

The U-280 SC 30th Anniversary LTD avoids the use of negative feedback, a common practice that results in a loss of details and sound richness.

To improve the damping factor without recurring to negative feedback, Margules Audio has developed the Back Electromotive Force Sensor system or BEFS, which changes the output impedance of the amplifier per the load requirement.

Efficient Power consumption and Long-Life tube expectancy

The U-280 SC 30th Anniversary LTD is a low power consumption pure Class-A tube amplifier.

The Active Servo Bias and the BEFS (Back Electromotive Force Sensor) by continuously adjusting the polarization based on the signal rather than the tube characteristics, extend the tubes life expectancy, optimizing power consumption, reducing distortion, preventing overheating, and improving the damping control, resulting on the output stage to always operate in a full Class-A.

Triode / Ultralinear output configuration

The output stage valves can be configured through the simple operation of a switch (triodes/pentodes), changing the transfer function, optimizing efficiency and tonal characteristics.

Can be used as a Stand Alone

This amplifier can work without additional pre-amplification thanks to its input attenuators.

Stereo / Monoblock

The U-280 SC 30th Anniversary LTD can be configured as a monoblock. This allows it to be used in conjunction with another U-280 SC 30th Anniversary LTD as double MONO increasing the power.

Low distortion without negative feedback

The U-280 SC 30th Anniversary LTD power/distortion curve is uniquely low in a non-feedback and tube circuit, thanks to its redesigned Active Servo Bias.

Shunt power supply

The low-level signal circuit is biased by a Shunt power supply that has no correction circuit. By not having a control loop circuit, avoids the induction of non-desirable harmonics, guaranteeing the integrity of the audio signal.

ANA® (Neuro-Acoustic Alignment) Circuitry

The ANA® technology (Neuro-Acoustic Alignment) is one of Margules' technological innovations developed from a fundamental principle: the human brain perceives sound by prioritizing the harmonic structure above fundamental tone; that is, it focuses on how humans perceive sound and not on how we measure it.

This technological advance originates from the seductive sound theory (engaging sound) and is based on the way in which our brain decodes the information from the sound waves through the ears: when sounds are closer, they keep us focused due to the relation between perception and sound, the distance at which we perceive them and their intelligibility, whereas distant sounds, even when intelligible, do not catch our attention and are easily ignored.

Our ANA® technology is designed to achieve a realistic sound, with a wide frequency response, low distortion, and accurate harmonic reproduction, optimizing to the utmost the relationship between the source and the receiver, so that you can enjoy your music in a way you have never experienced before.

SHUNT REGULATED POWER SUPPLY

The power supply for the small-signal stages is independent and of the SHUNT type. By not having a control loop circuit, avoids the induction of harmonics, guaranteeing the integrity of the audio signal.

Another advantage of the SHUNT power supplies lies in the carefully designed circuit to protect them from the common and uncommon defects of the tubes, which makes them practically indestructible.

BACK ELECTROMOTIVE FORCE SENSOR

In order to improve the damping factor without recurring to negative feedback, Margules Audio has developed the Back Electromotive Force Sensor system or BEFS, which changes the output impedance of the amplifier per the load requirement.

The BEFS together with the Active Servo Bias allow the amplifier to drive with excellent dynamics and controlled bass the difficult loads in low-efficiency or low-sensitivity speakers.