EMI, RFI & OTHER NOISE

Electromagnetic Interference (EMI)

Electromagnetic Interference (EMI) is caused by undesirable radiated electromagnetic fields or conducted voltages and currents. EMI can be split into the following categories:

Microwave - 300MHz-300GHz

Radio Frequency - 300Hz-300MHz

Extremely Low Frequency - 30Hz-300Hz

Thus Radio Frequency Interference (RFI) is a special class of EMI.

Radio Frequency Interference (RFI)

The environment around us is continually full of radio waves which vary in frequency from 10kHz to 1GHz. There are a multitude of devices that emit interfering radio frequencies such as: radio and TV broadcasts, other radio transmitters (e.g., radio transmitters used by the emergency services and taxis), mobile phones and pagers, electrical appliances (e.g., fridges, washing machines, vacuum cleaners and power tools), computers and any other equipment that uses a microprocessor (e.g., CD and DVD players and recorders, VCRs, TVs and satellite receivers), fluorescent lights, dimmer switches, thermostats and now increasingly popular broadband internet which covers a very wide frequency range.

Thus Radio Frequency Interference (RFI) is when radio frequencies (as emitted from the equipment above for instance) interfere and affect the operation of other equipment such as a hi-fi system. RFI can be emitted (and consequently interfere with other equipment such as your hi-fi system) in two ways:

1.) Through radiation (typically 30MHz to 1GHz) whereby RFI is directly radiated into the environment from the equipment itself. Radiated RFI can very easily be picked up by any cable connected to a hi-fi system as most cables act like aerials thus affecting the performance of the system;

2.) Through conduction (typically 10kHz to 30MHz) whereby RFI is transferred from components and equipment through the mains cord (and directly through the ring main wiring with fluorescent lights, dimmer switches and thermostats) into the ring main of the house concerned. Thus conducted RFI can affect the performance of practically every other device which is connected to the ring main.

Furthermore, radiated RFI can be picked up from when it leaves the power station to when it reaches your house and then transferred through conduction to your hi-fi system.

RFI is exceptionally damaging to hi-fi performance: once it gets in, it affects every part of your system significantly reducing performance and degrading sound quality. Typically, RFI degrades sound quality in terms of lack in bass definition and depth, mid-range dynamics particularly vocal transparency, treble in terms of hardness and contamination, and soundstaging in terms of both depth and width. In addition, the worse the RFI the worse these effects may be.

Fortunately, the effect of RFI can be significantly minimised by addressing the two ways in which RFI can get into your system: by removing RFI before it enters your hi-fi system, by ensuring that radiated RFI is not picked by your system cabling and by ensuring that RFI is not transferred between hi-fi components. Firstly, by using a power cable such as the Silver-line™ Power Cable RFI that is actually on the cable line is eliminated by the Super Suppressor™ Ferrite Rings thus stopping RFI from being conducted into the system. In addition, the Star Shielding Technique™ with Parallel Earthing System™ ensures that airborne radiated RFI is not picked up by the power cable. Secondly, our interconnects and speaker cable also feature multiple shielding technologies with the Parallel Earthing System™ throughout our ranges, ensuring that they do not pick up harmful radiated RFI. The benefit is here is two-fold: radiated RFI cannot affect the performance of the cable per se, but also cannot be conducted by other components in the hi-fi system. Furthermore, the Super Suppressor™ Ferrite Rings which are featured on most of our cables ensures that any RFI that may be on the cable line is eliminated, again stopping RFI conduction through the entire hi-fi system.