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Mains Power supply and Hi-Fi

Audiolab 6000CDT Dedicated CD Transport


New Member
Jul 27, 2006
Mains Power supply and Hi-Fi

Optimising the power supply

What's wrong with the mains supply, can you improve it? Installing a dedicated supply. Mains, conditioning and filters. Battery supply? Will it improve the sound quality from your hi-fi setup?

With hi-fi equipment it is not only the availability of a continuous electrical supply that is important, but also the quality of that supply. Again, some people may be surprised that something like electricity can be discussed in terms of quality but there are a number of factors which affect its quality and suitability for powering hi-fi eqipoment. They are:
  • Low voltage
  • RFI (Radio Frequency Interference)
  • Voltage spikes
  • Fluctuating voltage (surges)
  • High impedance
The causes of these problems are, unfortunately, many. Here are just some of them:
  • A high demand on the supply from a power station may cause the voltage levels to drop.
  • Lightening strikes can cause extremely high voltage spikes, as can the operation of some types of electrical equipment.
  • Electricity is carried along cables, all the way from the power station (which may be many miles away) to your home. All the cabling in between can and does act as a large ariel, picking up radio signals which interfere with the supply.
  • Poor connections (especially to ground) cause clicks and bangs which can sometimes be heard coming from your loudspeakers.
To help you understand why a 'contaminated' electricity supply to your hi-fi affects the sound quality, we'll use the analogy of water. The electrical signal which is produced by the source component is tiny and needs to be amplified in order to be strong enough to drive the loudspeakers. This is achieved by adding more electricity to it (usually from the mains supply). Now if we start with a a pure signal (uncontaminated water) and add polluted electricity (dirty water) to it we will finish up with a contaminated signal. So the added electricity needs to be as clean or pure as possible. Using the water analogy, that means we need a clean supply with a constant rate of flow.

What are the solutions?

There are a number of measures that can be taken to improve the electrical supply which we feed into our hi-fi equipment. If you are serious about getting the best out of your system, you should consider installing a dedicated power supply from your consumer unit.

The amount of work (and disruption) this entails is dependent on where your listening room is in relation to your consumer unit, what kind of consumer unit you have, whether it has the capacity to add another circuit, and how easy it will be to install the new cables. I can say, from my own experience, that all the trouble and expense is worth it. Modifications to the electrical supply have made noticeable improvements to the sound of my hi-fi system. And remember, the final signal which drives your loudspeakers contains a higher proportion of added (mains) electricity than the original signal. So, no matter how good your equipment is, the sound will still be dependent on the quality of the power supply. Having a dedicated mains supply is the building platform on which you can continue to provide better power to your equipment.

A dedicated mains supply will isolate your hi-fi equipment from the rest of the electrical wiring in your home which may cause electrical interference. However, you should still make sure that the rest of the electrical system in your home is not producing any unwanted nasty effects. Make sure that the wires into each socket are secured and that the retaining screws are tightened. Check all earth wires are securely connected.

Make sure all your electrical appliances are in good working order and check that the wires in the plugs are secure and that the clamping screws are tight. Some appliances like refrigerators produce interference when the thermostat switches the cooling system on and off. This can usually be cured by fitting a contact suppressor and VDR across the contacts of the switch.

Make sure that all the mains leads on your hi-fi are in good condition and that the wires are securely held inside the plugs. It may sound daft, but it seems to improve the sound if you polish the pins of the mains plugs with a metal polish. Do the same with the fuses inside the plugs. The theory is that this makes for a better contact and lowers impedance but whatever the reason, it does seem to work. This polishing should be done about twice a year.


Aug 27, 2006
Re: Perfect Impediance.

Hi Hohan,

What should be the perfect impedence for the grounding?( Regarding above said subject).