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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.

TECHNOLOGY AND SPECIFICATIONS

CLASS-A OPERATION AND ACTIVE SERVO BIAS

This amplifier incorporates our exclusive Active Servo Bias (patent pending), which guarantees an optimal operation since it does not require any polarization adjustment, always operating at pure Class-A to ensure a detailed sound scenario.

By continuously adjusting the polarization based on the signal, this circuit radically extends the useful life of the output tubes and allows them an ideal operation, which in addition optimizes energy consumption by avoiding overheating.

 

TRIODE / ULTRA-LINEAR OPERATION

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.

 

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.

 

ZERO NEGATIVE FEEDBACK

On the other hand, 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.

 

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.

 

NEURO-ACOUSTIC ALIGNMENT (ANA®)

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 engaging sound theory 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 precise 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.

 

 

SPECIFICATIONS

 

Power at 4 – 8 Ohms:

Triode Stereo: 25 watts per channel

Ultralinear Stereo: 50 watts per channel

Triode Mono: 55 watts

Ultralinear Mono: 100 watts

 

Frequency Response:

-3dB 20Hz – 40KHz

 

Total Harmonic Distortion (THD):

>0.08%

 

Supply voltage:

120 VAC

 

Electrical consumption (Max.):

585 Watts

 

Dimensions:

Height: 22 cm

Width: 45 cm

Depth: 35 cm

 

Weight: 30.5 kg

 

Vacuum Tubes:

4 x KT88 (6550, KT90, KT120, KT150)

4 x 12AU7

 

* Specifications are subject to change without notice.

PRESS

WARRANTY

Like all the Margules products, The U-280 SC 30th Anniversary LTD amplifier comes with a five-year limited warranty on parts and labor excluding the tubes, which are covered by a three-month warranty.

 

Terms and Conditions

 

The warranty does not cover any damage, wear or malfunctioning caused by lack of compliance with the operation specifications included with this equipment, or any of those resulting from:

 

  • Accidents, natural disasters or events that happens due to natural causes.
  • Misuse, abuse of or negligence regarding the equipment.
  • Fault in the initial set-up and installation, incorrect maintenance, and/or inadequate cleaning of the product.
  • Repairs, modifications, or renovations performed by people or companies not expressly authorized by Margules Audio.
  • Damage during shipping, transport, packaging, or manipulation of the equipment. In this case, all damage claims must be submitted to the carrier company.
  • Any other cause not attributable to a manufacturing defect of the product.

 

The warranty covers exclusively the expense corresponding to labor and the material necessary to the repair or, give the case, the substitution of the equipment (at the discretion of Margules Audio), and thus it does not extend to:

 

  • Accessories, including but not limited to: batteries, cables, mounting hardware, brackets, furniture, cleaning accessories, antennas or dismountable feeding cables.
  • Shipping costs in case the owner needs to return the unit to Margules Audio for the purpose of service or repair of a possible defect.

 

The warranty shall be void if:

 

  • The serial number of the equipment has been altered, modified, or deleted.
  • The product has been purchased from a person or company that is not an authorized distributor of Margules Audio.

 

This warranty extends to products directly purchased from Margules Audio or an authorized distributor.

 

In case of doubt regarding the scope of the warranty or if you need technical support, call the numbers you will find on our website www.margules.com.

MANUALS