Matrix Audio SI-1 Network Isolator

The Matrix Audio SI-1 is a dedicated Ethernet isolation device designed to provide galvanic isolation between standard network infrastructure—such as routers and switches—and network audio components. Its purpose is to eliminate unwanted electrical coupling through Ethernet cabling while preserving the integrity of the transmitted data.

Unlike passive isolation devices, the SI-1 employs active signal processing. The incoming electrical Ethernet signal is internally converted into an optical signal before being reconverted into an electrical signal. This optical-to-electrical conversion provides complete galvanic isolation between the two sides of the network, effectively preventing the transfer of common-mode noise, high-frequency interference, and ground currents. Technically, this represents an advanced form of galvanic isolation that extends well beyond the standard transformer isolation already present in conventional Ethernet interfaces.

The SI-1 operates transparently at Layer 1 and Layer 2 of the OSI model, without modifying network protocols, packet data, or transmission rates. It fully supports Gigabit Ethernet and functions as a plug-and-play device, requiring no configuration. Network latency and throughput remain fully within the specifications of standard Gigabit Ethernet connections.

Internally, the SI-1 features independent transmit and receive signal paths, dedicated precision clock generators for signal regeneration, and a linear power supply with multiple regulation stages to ensure exceptional signal stability. Additional protection against surge events and electrostatic discharge (ESD) enhances operational reliability, while the precision-machined metal enclosure provides effective electromagnetic shielding for optimum performance in demanding high-end audio environments.

Highlights

Active optical-to-electrical isolation: galvanically separates your hi-fi system from the home network and breaks ground loops
Separate optical channels for transmit and receive – no mutual crosstalk
Two femtosecond clocks for precise signal regeneration
Gigabit Ethernet: 10/100/1000 Mbps, plug & play with no configuration
Linear power supply with encapsulated toroidal transformer and multiple LDO regulators
CNC-machined aluminium unibody chassis with protection against lightning, surges and electrostatic discharge
Ideal in the network path between a router or switch such as the Matrix Audio SS-1 and streamers such as the NT-1 or MS-1

Design and Technology

Internally, the SI-1 transmits data over two physically separate optical channels – one for transmitting, one for receiving – so the two directions cannot interfere with each other. The output port also features an electrical isolation disc that breaks any conductive connection between the connected devices. Two femtosecond clocks regenerate the signal with high precision.

An encapsulated dual-winding toroidal transformer and multiple LDO regulators provide clean, low-noise power. The CNC-machined aluminium unibody chassis adds shielding, and protection circuits guard against lightning strikes, surges, electrostatic discharge and mains interference. The LEDs on the network ports can be switched off.

Connections and Network

Network ports: 2 × RJ45 – one input, one galvanically isolated output
Speed: 10/100/1000 Mbps
Standards: IEEE 802.3, 802.3u, 802.3z and 802.3ab
MAC table: 2K entries
Configuration: none – plug & play, transparent at Layer 1 and 2
Front indicators: 1 × power, 2 × link status
Rear indicators: speed, link and activity per port, can be switched off

Isolation and Clock

Isolation: active optical-to-electrical separation, output port with electrical isolation disc
Optical transmission: two separate channels for transmit and receive
Clock: 2 × femtosecond clock
Protection: lightning, surges, electrostatic discharge and mains interference
Chassis: CNC-machined aluminium unibody with shielding effect

Power Specifications

Mains voltage: AC 100–120 V or AC 220–240 V (50/60 Hz), factory-set
Power supply: linear, encapsulated dual-winding toroidal transformer, multiple LDO regulators
Power consumption: < 15 W