How your mains power supply affects your home cinema

So you think you know mains power
Power cords can emit electromagnetic interference (EMI) that affects other sensitive cables

Every component in your home cinema is a delicate electrical device. Yet people are often willing to pay for a monstrous flat panel, beefy receiver or state-of-the-art 3D Blu-ray player and connect them to the mains via a cheap, multi-plug power strip.

This will do the job, but may affect reliability or even performance, which is where we get to the controversial subject of mains power conditioning.

In the golden-eared world of hi-fi, mains conditioning is a topic of hot debate. Indeed, a long-running spat between specialist Russ Andrews Accessories and the Advertising Standards Authority (ASA) has brought the arguments into sharper focus than ever before (you can read about it at

But are the arguments for mains power conditioning equally applicable to home cinema?

Every component in a UK home cinema is designed to use a standard mains voltage of 240V at 50Hz. The problem is that your household electricity doesn't usually reflect this ideal power supply; in most cases it is 'dirty' and prone to over- and under-voltage issues.

Getting down and dirty

To fully understand what is going on, we must first look at the power foundation. Electricity is generated in a plant that's typically dozens of miles away from your home.

To get to your living room it has to navigate substations, high voltage lines, transformers and, finally, the power lines that connect to your home. Along the way, a lot could have happened to that electricity; it could have picked up radio frequency interference (RFI) or electromagnetic interference (EMI).

As more wireless devices are used, we are seeing increased issues with both. Power lines can act like aerials, picking up signals from mobile phones, radio and television broadcasts, and even wi-fi signals can have a negative effect on the quality of your power by contaminating it with noise.

But your house is the single biggest culprit of electrical contamination. Refrigerators; washer/dryers; light dimmers; hair dryers; computers and other AV components create noise by pulling power from the mains. Fridges and washer/dryers consume enormous amounts of electricity and have noisy power supplies.

This noise and power consumption affects other products on the same power line. Just about all of your AV gear is full of microprocessors and other delicate technology, and dirty electricity and over/under voltages can put stress on these sensitive components, causing them to underperform.

Measuring the existence of mains noise and voltage fluctuation is easy; proving it has a visible or audible effect on home cinema equipment is more difficult, and this is part of the ASA's beef. But it's incontrovertible that your home's electricity supply isn't perfect, so it's common sense to install a power conditioner.

There are two main types of power conditioner: traditional passive types and complete AC regenerators. The former are cheaper and use various types of electrical filters to tackle RFI and EMI. This can be pretty effective.

The more extreme method of cleaning your electricity is the AC regeneration route. This tends to be more costly, but is certainly the most effective.

Cleanliness next to Godliness

Some cinema enthusiasts have gone as far as running dedicated lines directly from their fuse box to their home cinema gear, with no other sockets attached to the lines. This is the ideal option, which should of course only be tackled by a qualified electrician.

So a power conditioner is the practical option in most cases, and there are plenty on the market from companies such as ISOL-8, IsoTek, PS Audio, and Monster Power.

We talked to ISOL-8's Nic Poulson about the philosophy of mains power conditioning and the Powerline 1080 specifically, and asked him what mains conditioners are designed to tackle.