Isol-8 Axis 10

ISOL-8 Axis 10: 10 A DC blocker

An amplifier that hums when nothing is playing often has a transformer affected by the mains supply. A small DC component, produced by other appliances in the home, is enough to make it vibrate. This compact black steel box sits between the wall socket and a single device, blocking this component before it reaches the transformer. It handles up to 10 A and connects to an existing system in seconds.

Where mechanical hum comes from

Mains current is alternating and should be perfectly symmetrical. In practice, some household appliances draw current unevenly and add a small DC voltage to the sine wave. It is slight, but a toroidal transformer, widely used in hi-fi, reacts to it: its magnetic core partially saturates, the laminations vibrate and the enclosure emits an audible hum, both at idle and during playback. This noise comes from the device itself, not the speakers, and it can appear or disappear depending on which appliances are switched on in the home.

The Axis 10 uses the Axis circuit that ISOL-8 incorporates into its power conditioners, in a standalone enclosure. It lets alternating current through and blocks the DC component. The transformer returns to quiet operation, and the background becomes quieter during soft passages.

A single-outlet device, and what to connect to it

The Axis 10 has just one output, a Schuko socket on the European version. Connect the device that hums to it: an integrated amplifier, a preamplifier with a toroidal transformer or a power amplifier with moderate power consumption. Its 10 A limit corresponds to approximately 2,300 W at 230 V continuously, providing enough headroom for most integrated amplifiers. For a power-hungry power amplifier or a Class A amplifier, the Axis 20 goes up to 16 A.

Its function is limited to blocking the DC component. To also filter high-frequency interference and separate sources from amplifiers, ISOL-8 offers its MiniSub and SubStation power conditioners, some versions of which already incorporate the Axis circuit.

Construction and connection

The black steel chassis measures 240 × 100 × 68 mm and weighs 1.3 kg: it fits behind a cabinet or beside the amplifier. The internal wiring uses silver-plated conductors with PTFE insulation, and a fuse protects the circuit. The input is an IEC C14 inlet, the same type found on many hi-fi devices. A power cord is not supplied: a standard mains cable is suitable, and ISOL-8’s IsoLink cords are available with this termination.

Technical specifications

Identification and function

• Model: Axis 10
• Type: standalone DC blocker

Electrical specifications

• Rated current: 10 A
• Supply voltage:
  • European version: 220–240 V AC
  • 117 V version: 100–127 V AC
• Protection: fuse
• Wiring: silver-plated conductors insulated with polytetrafluoroethylene (PTFE)

Mains connections

• Input: IEC C14 inlet for C13 power cord, cord not included
• Output: 1 Schuko socket, European version

Construction, dimensions and weight

• Chassis: steel, black finish
• Dimensions excluding connectors: 240 × 100 × 68 mm
• Weight: 1.3 kg