Supra MainBlock MD08-EU/SP MK3

The Supra MainBlock MD08-EU/SP MK3 represents the third generation of power distribution strips designed by the Swedish manufacturer. This eight-outlet power strip features a sophisticated filtering system and comprehensive surge protection, all housed in a fully shielded aluminum chassis designed to optimize power delivery for hi-fi and home theater systems.

An aluminum chassis with optimized magnetic properties

The MD08-EU/SP MK3 enclosure uses an extruded aluminum construction with generous dimensions of 837 mm in length, 90 mm in width, and 50 mm in height. This material choice is deliberate: aluminum exhibits significantly lower magnetic conduction properties than the steel used by many competing manufacturers. This physical characteristic enables it to create a true Faraday cage that shields the internal circuits from external electric, electromagnetic, and magnetic fields.

The conductive chassis serves a dual function. On the one hand, it prevents external interference—whether from mobile phones, DECT phones, light dimmers, or other household equipment—from entering the power circuit. On the other hand, it drains internal noise to ground, making a connection to a wall outlet equipped with a grounding pin imperative for optimal operation.

The finish of the aluminum profile, manufactured in Sweden, reflects meticulous build quality. Rubber feet and a wall-mounting kit are included, allowing flexible installation according to your listening environment. Final assembly is carried out at Supra’s Ljungskile factory, ensuring rigorous quality control for every unit produced.

The NIF filtering system: a measured approach to interference

At the heart of the MD08-EU/SP MK3 is the NIF (Non-Intrusive Filtering) filter, the result of a collaboration between Supra and Ben Duncan Research, a UK laboratory renowned for its work in professional audio electronics. This transient filtering circuit adopts a particular philosophy: rather than implementing aggressive filtering that could stifle musical dynamics, NIF applies a progressive and calibrated attenuation of radio-frequency noise.

The system achieves a reduction of radio-frequency interference by up to 40 dB, precisely targeting noise frequencies without affecting the transient current demands of connected power supplies. This approach preserves the liveliness and fast transients that are the essence of high-fidelity musical reproduction.

The filtering configuration on the MD08-EU/SP MK3 reveals a thoughtful strategy. The first two outlets are deliberately left without NIF filtering, making them ideal for power amplifiers that benefit from direct, unrestricted access to the mains. The next six outlets incorporate full filtering, with the last outlet featuring reinforced filtering for maximum attenuation. This modular architecture allows the filtering level to be tailored to the specific needs of each connected device.

Tri-directional surge protection: beyond conventional standards

The “SP” (Surge Protection) suffix in the model name indicates the presence of an especially sophisticated surge protection system. Unlike conventional protections that typically only safeguard between line and neutral, the MD08-EU/SP MK3 deploys comprehensive tri-directional protection.

This Type 3 protection acts across three distinct paths: line to neutral with a maximum continuous voltage of 2.5 kV and a protection level of 2.0 kV, line to ground with a maximum continuous voltage of 4.0 kV and a protection level of 2.05 kV, and neutral to ground with the same values as line to ground. This tri-directional configuration ensures effective protection against surges induced by nearby lightning, a phenomenon often overlooked by conventional protections.

Internal wiring and electrical capacity

The internal wiring uses oxygen-free copper conductors with a 2.5 mm² cross-section, ensuring current transmission with minimal losses. This generous cross-section allows a continuous maximum power of 3,680 watts at 230 volts with a nominal current of 16 amperes, more than sufficient to power a complete hi-fi system including power amplifiers, sources, and peripherals.

The eight output outlets follow the Schuko standard (SUPRA MCH-16/EU), allowing polarity reversal to optimize the phasing of each device. The input socket, also a SUPRA MCH-16 16A type, requires the use of a suitable power cable, which is not included with the strip. Supra naturally recommends the use of its LoRad cables to maximize the performance of the shielding and filtering system.

Improvements over previous generations

The MK3 designation reflects a continuous improvement process since the first versions of the MainBlock. This third generation incorporates higher-quality connectors, manufactured in Germany to strict standards. The filtering system has been refined for increased efficiency without compromising sonic transparency. Surge protection has also been optimized, offering improved responsiveness to transient disturbances on the power grid.

The new aluminum profile, fully manufactured in Sweden, offers superior shielding characteristics compared to earlier versions. Assembly, now carried out entirely at Supra’s Ljungskile factory, ensures consistent quality and complete traceability for every unit produced.

Technical specifications

Key features

• Noise attenuation up to 40 dB
• 2.5 mm² oxygen-free copper internal wiring
• Maximum power: 3,680 W at 230 V and 16 A
• Protection against alternating fields and surges
• Custom mains noise interference filter (NIF) by Ben Duncan Research (UK)
• Shielded aluminum chassis (protection against electric, electromagnetic, and magnetic fields)

Installation

• Wall-mount or placement on a flat, rigid surface
• Rubber feet and brackets included

Technical specifications

• Chassis: Aluminum
• Standard: European standard
• Input socket: SUPRA MCH-16, 16 A
• Output sockets: 8 SUPRA MCH-16/EU, Schuko
• Rated current/voltage: 16 A, 250 V, 3,680 W
• Maximum radio-frequency noise attenuation: 40 dB, enhanced filtering

Surge protection (Type 3)

• Line–Neutral:
  • Maximum continuous operating voltage (Uc): 2.5 kV
  • Protection level (Up): 2.0 kV
• Line/Neutral–Earth:
  • Maximum continuous operating voltage (Uc): 4.0 kV
  • Protection level (Up): 2.05 kV

Dimensions

• Width: 90 mm
• Height: 50 mm
• Length: 837 mm

Filtering

• Sockets 1–2: without mains NIF filter
• All sockets surge-protected
• Last socket: reinforced filtering with maximum attenuation