MARGULES U-280 SC 30 Limited Edition Anniversary Stereo Amplifier Owner’s Manual

U-280 SC 30 Limited Edition Anniversary Stereo Amplifier
Owner’s Manual

INTRODUCTION

Congratulations. As the owner of the U-280 SC 30TH Anniversary amplifier, you have acquired a product for musical reproduction that incorporates cutting- edge technology developed from the knowledge gained by Margules over more than 30 years of research.
This one-of-a-kind high-end amplifier was handcrafted with materials and components of the highest quality, observing the strictest production processes and looking after the smallest detail.
Due to its manufacturing philosophy, the U-280 SC 30TH Anniversary amplifier merges design with functionality, offering versatility, convenience and, most of all, a realistic sound with precise harmonic reproduction.
In the same way, this amplifier will allow you to enjoy a captivating, engaging and natural sound since its conceptualization and development are built on the implementation of our NeuroAcoustic
Alignment technology (ANAâ) based on the way the human brain perceives sound, prioritizing harmonic structure over the fundamental tone.
In Margules, we thank you for the granted trust by acquiring our product, it should bring you years of enjoyment and service.
The Margules U-280 SC 30thAnniversary merges a new approach in circuitry technology, resulting in an amplifier that produces engaging, realistic, and dynamic sonic presentation with elegant aesthetics

SAFETY INSTRUCTIONS

WARNING: To avoid electrical shock hazard, do not remove the amplifier’s cover. There are no user-serviceable parts inside so, in case of malfunction, we recommend only qualified personnel should service this component.

1. USER MANUAL: Before turning on the equipment, carefully read and follow all safety and operation instructions. Keep this User Manual for future reference.

2. ACCESSORIES AND SPARE PARTS: Only use accessories recommended by Margules. The use of accessories different to those recommended may cause damage to or malfunction of the equipment, or even create hazards while operating. If spare parts are needed, make sure the service technician uses spare parts specified by Margules. The use of non-authorized spare parts may create fire, electrical shock or other hazards. In order to maintain the warranty of the equipment, manipulation by personnel not authorized by Margules must be avoided.

3. PLACEMENT: Do not place this equipment on unstable surfaces, brackets, tripods or tables. The product could fall, causing personal injury or damage to the equipment. Always place the equipment according to the instructions of the manufacturer and with the recommended mounting accessories. Do not place the equipment near flammable materials or on surfaces that prevent heat dissipation such as beds, couches, carpets or racks without proper ventilation.

4. WATER AND HUMIDITY: Do not operate the equipment close to water (for instance, next to a pool, bathtub or sink) or in a humid environment (such as a basement), and do not expose it to the outdoors or rain.

5. MOUNTING ON WALLS OR CEILINGS: Only mount the equipment on a wall or ceiling in the way recommended by the manufacturer. Call the service number in case of doubt regarding the safe way to mount the equipment.

6. INSERTION OF OBJECTS AND ACCIDENTAL SPILL: Do not insert any objects through the openings of the unit since they could touch dangerous voltage points, creating the possibility of fire or electrical shock hazard.
   Avoid spilling liquids onto the unit. If a liquid is accidentally spilled onto or if any metallic object (such as paper clips, coins or staples) is inserted into the unit, unplug it immediately from the power source and contact Margules to receive instructions.

7. HEAT AND TEMPERATURE: Place the equipment far away from heat sources such as radiators, heat logs, stoves or other electronic equipment (including amplifiers) that produce heat.

8. VENTILATION: The rack, shelf or special furniture where you place the equipment must have ventilation slots or openings in order to protect the equipment from overheating. Place the equipment with at least 6 inches (16 cm) free space from the top and with a space behind it that allows a free flow of air.

9. GROUNDING OR POLARIZATION: As a safety feature, the unit is equipped with a polarized alternating current line plug, which has one blade wider than the other. This plug can be inserted in the electric outlet only one way. If you cannot insert the plug completely into the outlet, try inverting the plug. If the plug still does not fit correctly, contact a licensed electrician to update your obsolete outlet. Do not remove or damage the safety end of the polarized plug.

10. POWER SOURCES: Use the equipment only with outlets that have the power supply indicated in the label of the equipment. If you are not sure about the type of power supplied in your home, contact your local electricity supplier.

11. POWER CORD PROTECTION: Fix the power cords in such a way that there is no risk of them being crushed, caught or squeezed by other equipment or furniture. Particularly pay attention to the ends of the cords, both the end that goes into the outlet and the end that directly comes from the equipment.

12. LIGHTNING: For best protection during an electric storm or when the equipment is inactive for long periods of time, unplug the equipment from the outlet and disconnect the antenna or cable decoder. This will help protect the equipment from lightning and electrical surges.

13. ELECTRIC LINES: Do not place an external antenna system near the aerial electric lines or other electric power circuits. When installing an external antenna system, you must be very careful not to touch the electric lines or circuits since contact with them may be lethal.

14. OVERLOAD: Do not overload the wall outlets, extension cords or power strips, since this increases fire and electrical shock hazards.

15. SAFETY VERIFICATION: After any service or repair to the equipment, ask the service technician to perform safety controls to make sure the equipment is in proper working condition.

16. IMPORTANT SAFETY NOTES:
    CAUTION:
    Any modification not expressly approved by Margules will make the warranty of the equipment void and may result in hazard for the user.
    • Before connecting a new product such as the U-280 SC 30TH Anniversary amplifier to your audio or home theater system, turn off all other equipment (preferably by unplugging them from the AC power source). Many audio components have automatic start circuits that may activate during an installation; this could cause damage to the electronic components and/or speakers. This kind of damage is not covered by the warranty of this product and as such Margules specifically is released of liability for said damages.
    • The detachable power cord supplied with your equipment was specifically designed to be used with this product; however, you may use other better- quality power cords in order to take the utmost advantage of the capabilities of this equipment. Ask your Margules distributor for advice on power cords that may be used with your system.
    • For your protection, the amplifier is equipped with an AC fuse (6A-SB) located on the back of the chassis. This fuse may be replaced by the user. In case the fuse is replaced and the equipment does not turn on, contact an authorized service representative. The spare fuse must be always the one specified by the manufacturer.
    • The electric wiring that runs inside the walls must have the proper UL certification (Underwriters Laboratories) to indicate satisfactory compliance with all requirements set forth by the regulations in force, and belong to the list authorized by the UL, CSA or other regulation required by the UL, CSA, NEC or your local construction code. Questions on electric wiring must be submitted to a certified installer, licensed electrician or low voltage contractor.

17. RECORDING OF CONTENTS PROTECTED BY COPYRIGHT: Recording of copyrightprotected material for a use other than personal is against the law if done without permission by the owner of said copyright.

18. INSTALLATION OF THE CATV SYSTEM: The installer of the CATV system must follow the provisions of article 820-40 of the NEC, ANSI/NFPA 70, which sets forth the requirements for proper grounding installation and particularly specifies that the earth terminal of the grounding system must be connected to the grounding system of the building as near to the entering point of the cable as practically possible.

19. FCC INFORMATION (FEDERAL COMMUNICATIONS COMMISSION) FOR THE USER: This equipment generates and may radiate radiofrequency energy and if not installed and used according to the instructions it may cause interference to radio communications. These limits are designed to provide reasonable protection against interferences in a residential installation. However, there is no guarantee that interferences in any given installation will not be produced. If this equipment causes damaging interference to radio or television reception that may be determined by turning the equipment on and off, we recommend the user to try and correct the interference through one or more of the following actions:
    • Re-orient or relocate the receiving antenna
    • Increase the separation between the equipment and the receiver
    • Connect the equipment and the receiver to outlets in separate circuits

20. EXTERNAL ANTENNA INSTALLATION/SAFE ANTENNA AND CABLE CONNECTION: If an external antenna or cable system is connected to the equipment, make sure the antenna or cable system is grounded to provide protection against static charges and surges. Article 810 of the National Electrical Code, ANSI/NFPA 70 (in Canada, part 1 of the Canadian Electrical Code) provides information on the correct grounding of the mast and support structure, the connection of the grounding conductors to an antenna discharge unit, the size of the grounding conductors, the location of the antenna discharge unit, the connection to the grounding electrode system and the requirements for the grounding electrode system.
    The external antenna system must be placed as far away from electrical lines as possible and where it may never come in contact with these power sources in case of fall. When installing an external antenna, special attention must be paid to avoid contact with electrical lines, circuits or other sources of energy since this could prove to be lethal.
    Due to the danger involved, the antenna installation must be performed by a professional.

CHARACTERISTICS

The U-280 SC 30TH Anniversary is a tube amplifier that recreates realistic and dynamic scenarios thanks to the fusion between the application of cutting-edge technology and the tonal benefits of the tubes, complying with the ANA design philosophy: the formula of Casa Margules’ characteristic sound.
CLASS-A OPERATION AND REDESIGNED ACTIVE SERVO BIAS
This amplifier incorporates an improved version of our exclusive Active Servo Bias (patent pending), which guarantees an optimal operation since it does not require any bias adjustment, always operating at pure Class-A to ensure a detailed sound scenario. Also, our circuit allows the use of different kind of power tubes (KT-88, KT-90, KT-120, KT-150 and 6550) TH without any adjustments.
The active servo bias works on real time and is set by the signal and not by the tube, this circuit allows the U280 to operate in FULL CLASS A and radically extends the useful life of the output tubes and optimizes energy consumption.
TRIODE/ULTRALINEAR OUTPUT CONFIGURATION
The output stage tubes can be configured through the simple flip of a switch (triodes/pentodes), changing the transfer function, optimizing efficiency and tonal characteristics.
SHUNT REGULATED POWER SUPPLIES
The power supply for the small-signal stages is independent and of the SHUNT type.
By not having a feedback 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 tube failures.
ZERO NEGATIVE FEEDBACK
On the other hand, the U-280 SC 30 TH Anniversary amplifier 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 has developed the Back Electromotive Force Sensor system or BEFS, which changes the output impedance of the amplifier per the load requirement.
The optimal impedance of the equipment ranges between 4 and 8 Ohms, selectable through the speakers’ connectors at the back of the amplifier. Hence, the BEFS together with the Active Servo Bias allows the amplifier to drive the speakers with excellent dynamics and controlled bass.
LOW DISTORTION WITHOUT NEGATIVE FEEDBACK
The U-280 SC 30th Anniversary power/distortion curve is uniquely low in a nonfeedback and tube circuit, thanks to its redesigned Active Servo Bias.
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.

TECHNICAL SPECIFICATIONS

Power:

Maximum consumption: 585 Watts
Dimensions:| Height: 22 cm
Width: 45 cm
Depth: 38 cm
Vacuum Tubes:| 4 x KT-88 (6550, KT-90, KT-120, KT-150) 4 x 12AU7
Weight:| 32.5 kg

• Specifications are subject to change without notice.

FRONT PANEL

REAR PANEL

INSTALLATION

Carefully take the amplifier out of its box and remove the packaging material as indicated. Consider that the amplifier has a significant weight.
Once you have removed the packaging materials, place the amplifier on a solid surface, able to resist the weight of the unit and far from flammable materials.
Remove the tube protection cages by unscrewing the knobs at the top of each cage. It is important to ensure the tube protection and the plastic material covering the cupper plate is removed before you turn on the amplifier.
Make sure you remove all the protective material that covers the tubes and that they are installed properly. Verify there are no residues of the packaging or protection material before turning on the amplifier.
The U-280 SC 30 Anniversary amplifier must be installed on a solid and leveled surface that prevents vibrations and allows an optimal ventilation to dissipate the heat generated by the operation of the equipment.
Never install the amplifier outdoors. Do not expose it to rainfall or direct sunrays.
Make sure that the AC supply voltage is no more than +/- 10% of stated AC voltage.
The equipment can remain turned on continuously; however, turn it off when not in use in order to prevent premature wearing. If the amplifier is to remain turned off for long periods of time, it is recommended to unplug it from the electrical outlet.
CAUTION: There is HIGH VOLTAGE inside the TH amplifier. Never open the amplifier since you could be exposed to a potentially lethal voltage and it could void the warranty of the equipment.
CONNECTIONS AND OPERATION
Before you connect the amplifier to the AC power source, the signal sources and the speakers must be connected to the terminals on the amplifier.
The RCA line level inputs on the U-280 SC 30TH Anniversary amplifier are unbalanced and made of gold-plated copper to prevent corrosion and improve conductivity, so you should avoid forcing them.
The speakers’ connectors or binding posts are made of pure machined copper, so you should not use any tool to force them. Being a soft highly conductive metal, copper provides adequate contact when lightly tightened.
These are 5-way type connectors so they may be used with bare wire, banana plugs, spade connectors, pin connectors or ring terminals.
We recommend the use of high-quality fully shielded interconnect cables to avoid any noise that may interfere with music reproduction.
Always connect the interconnect cables of the preamplifier respecting the following order: White for left channel and Red for right channel, since inverting them prevents the generation of a realistic soundstage. In the same way, always connect the speakers respecting the corresponding channels, avoid short-circuits and, most of all, verify there are no open circuits.
Make sure the speakers’ cables make correct contact with the terminals on the amplifier and, considering the nominal impedance of your speakers, use the 4 or 8 Ohms terminals.
The main switch is located at the back of the amplifier and switching it on is necessary to operate the equipment.
When you turn on the amplifier, both the Margules logo and the bottom part of the dials will light up. The amplifier has an internal clock that delays approximately 3 minutes its powering up into operation mode. This preheating time allows the formation of an electron cloud in the (large) power tubes, which extends their useful life. You will know the equipment is in operation mode when the power tube LED indicators light up. These LED lights also work as emission indicators for the tubes, so when a tube has low emissions or does not work properly, the LED light turns out or dimer indicating that the tube must be replaced.
Verify that the Mono/Stereo selector is in the “Stereo” position (use the “Mono” position to set the unit as monoblock). When used on mono, any input and output connector can be used, we recommend to be coherent to the channel used, for example, if is going to be the left channel, use both left channels, in mono the two channels are strap in parallel.
If the U280 is use in mono, the output impedance and triode/ultralinear should be the same in both channels.
Select the Triode or Ultralinear configuration according to the desired tonal characteristic. To keep the circuit balanced, the switches for each channel must be in the same position; however, you can use different configurations on each channel in order to bi-amp your speakers.
Triode has a softer and more refined tonality but less power than ultralinear.
When used in mono, the current capability is doubled, so to have higher power use the 8 Ohms connector for 4 to 8 Ohms speakers. Since the U280 has gain control for each channel, the unit can be used without a preamplifier.
When used along with a preamplifier, it is recommended that the left and right channel gain potentiometers be fully open.

RECOMMENDATIONS

The amplifier may be operated with or without the tube protecting cages; however, by not leaving them installed while the amplifier is operating, you will improve heat dissipation.
Thanks to the Active Servo Bias developed by Margules, you can change the tubes without making any kind of adjustment, with the peace of mind of knowing that they will always operate in their ideal range and in Class-A.
To change the tubes, they must be removed by slowly pulling them upwards with gentle lateral movements. They should not be removed abruptly, as ceramic sockets with gold-plated connectors could be damaged.
If you change the tubes for another brand or allowed type, you may obtain different sound characteristics. Nevertheless, changing the tubes constantly is not recommended since this may damage the sockets.
When you need to change the tubes, we recommend you substitute them with matched tubes (at least per channel) and all the same brand and type.
When changing the tubes, make sure the positioning guides are oriented correctly.
Do not substitute 12AU7 tubes with a different type because this could increase distortion.
The useful life of tubes may last several years under normal use conditions (two hours per day); however, for an optimal performance of the amplifier, we suggest changing the tubes every two years.
Avoid using long interconnect cables (longer than 10m), since this may induce noise into the signal.
The quality as well as the DC offset in the AC powerline are important to avoid any mechanical noise induced by the transformers.
Placing the amplifier on vibration isolation devices (spikes) usually helps to improve the instrumental detail. The U-280 SC 30 TH Anniversary amplifier is an equipment sensitive to small adjustments, therefore we recommend the use of high-quality cables as well as firm amplifier stands.

TROUBLESHOOTING

1. The amplifier does not turn on:
   • Verify the equipment is correctly connected to the mains power or AC power source.
   • Verify that the switch on the back of the amplifier is on.
   • Check the electrical supply input fuse located at the back of the amplifier. If it is damaged, replace it by one that meets the correct specifications. If the fuse blows again, directly contact our technical support department.

2. The amplifier turns on and the LED indicators light up but it no sound is heard:
   • Verify that the preamplifier cables as well as the speakers’ cables are properly connected to the terminals on the amplifier.

3. One of the channels does not emit sound:
   • Verify that the preamplifier cables, as well as those of the speakers, are properly connected to the terminals on the amplifier.
   • Verify the volume knob is properly set.
   • Check that the LED indicators at the base of the output tubes are on.
   If the two LED indicators of a same channel do not light up, it is possible that the Active Servo Bias fuse of that channel is blown.
   In that case, unplug the amplifier from the AC power supply and wait a few minutes. Check the fuse corresponding to the channel that does not emit sound, which is located at the back of the amplifier (near the speakers’ terminal).
   In case the fuse is blown, one of the tubes of that channel has failed, so you should replace both tubes.
   Never replace these fuses by other of different characteristics.

4. The sound is distorted, or a humming sound is heard (coming from one of the channels only):
   • Check that the preamplifier cables as well as the speakers’ cables are properly connected to the terminals on the amplifier.
   • Make sure the source of the signal is operating correctly.
   • Verify the tubes are properly installed on their sockets.
   • One of the tubes may be damaged.
   In order to identify a defective tube, check that the LED indicators of each tube are lit (after the pre-heating period).
   If a LED indicator is not lit, the corresponding tube must be replaced (preferably, replace the pair of output tubes that correspond to the same channel).
   If the four LED indicators light up, the problem could come from one of the small-signal tubes (12AU7).
   To identify the damaged small-signal tube, you must first interchange between channels the two frontal tubes; if the problem persists, interchange the back row tubes.
   If the channel with the distorted sound changes or “accompanies the tube” while performing the interchange of the tubes’ position, replace the small- signal tube that is causing the distorted sound.

INSTALLATION NOTES
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References

• Margules | Tangible Musical Experience

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