How your mains power supply affects your home cinema
9th Apr 2011 | 09:00
Mains power conditioning explained
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 www.asa.org.uk).
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.
"Taking a closer look at a mains supply reveals it's not a simple issue, and often not what we may expect," said Poulson. "Zooming in on an AC mains cycle reveals there is a lot going on; pollution and distortion of our energy supply is an inevitable consequence of its use, and it is everywhere.
"Electrical appliances in homes each turn some of the energy used into noise, either as radio interference or distortion of the mains itself. All are connected to, and share, the same physical conduit: the power grid.
"Most AV equipment is surprisingly vulnerable to this pollution, and limitations in the component parts commonly used means the interference is passed through to the sensitive circuits beyond, compromising performance.
"High energy spikes from switch contact arcing can cause clicks; broadband noise from rectifier diodes can create a haze veiling detail, and industrial inductive loads can cause significant local distortion of the mains waveform. These effects are often the reason why your system sounds better at night, when there is less local electrical activity."
So, what's the solution? Poulson opines: "Removing mains-borne noise can dramatically improve your system. A carefully designed filter or regenerator, isolating each individual component in your system, will provide superior, more predictable performance. The benefits are often not subtle. Other solutions such as specialist mains cables, which often provide improvements due to a limited degree of filtering, as a consequence of their physical geometry, are usually unpredictable, so tackling the source of the problem is a more powerful tool than just coping with its effects."
The PowerLine 1080 is a 2.3kg lump featuring a powder-coated steel chassis and an anodized 6mm thick CNC'd aluminum top plate designed to be non-magnetic and non-resonant. It has an IEC input connector, but you'll have to supply your own mains lead (the ISOLink shielded mains cable for instance).
Each of the four power outlets has a hinged cover designed to IEC standard IP54, protecting unused outlets from dirt, dust and little fingers. Internal wiring is silver-plated copper with PTFE insulation. One outlet has a dedicated filter to eliminate noise generated by video displays, while another has a filtered high current direct connection for amplifiers. The remaining two outlets are for source components.
It's all about the current
"It's specifically designed for plasmas, LCDs, and projectors," explains Poulson. "Basically, it's all about current. Displays don't need enormous amount of current; they don't normally need high peak current either. When that's the case, it allows us to put a far steeper curve in than I ordinarily I would for an audio component.
"The PowerLine 1080's output is very different to all of the others. It can only deliver around four or five amps maximum. It really has got a very very steep curve, plus we also built in a Notch Filter, which is designed to tackle a lot of the addition noise coming out of the plasma. The notch syncs specifically to that plasma noise, it's hyper-tailored specifically for the plasma display. The other two line sockets have moderate filtering just for source components, while the one for the amplifier is only parallel filtered because we don't want to limit current."
So how can the impact of your power conditioners be measured? "We use three things; one we look and listen, which is one of the finest arbiters. Then we have a Voltech power analyzer (more about these at www.voltech.com), plus we use new generation Picoscope (PC-based oscilloscope, from www.picotech.com) capturing devices, so we can freeze moments in time and look at them."
On our in-house reference system, our subjective impression was of a touch more clarity overall on our installed LED TV when we used the Powerline 1080. Display noise was reduced, and colours appeared a little more vibrant.
Attached to our receiver, we heard a slight reduction in noise - a subtle effect, but sound effects appeared to emerge from a quieter background. Improvements were more pronounced at home, supporting the argument that the perceived effect of a power conditioner will be dependent on the state of your mains in the first place.
So, if you want to get the best out of your system, think of what you're putting into it - even if it adds only a level of surge protection, a power conditioner can still be a wise investment.
First published in Home Cinema Choice Issue 193
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