PW-1 Audio Grade Mains Filter

Owners Feedback forum.







Typical customer feedback.....

 Dear Mr Osborn

You are verily a saint and a bastard. I am unsure of which order.
Do you perchance have 3 more of the bloody Baby Ella things and another PW-1 ?
I tried out your last shipment. It was like someone had blown a hole in my back wall the way the soundstage enlarged. And that was straight out of the box ! 30 plus hours on and the inner detail and overall smoothness are truly extraordinary- the improvement in the bass we will not talk about for fear of incontinence or some unseemly tumescence.
Just by comparison the top of the line Cardas Golden Reference Power cable I bought the week before has now been moved on to my second system. It simply is not in the same class.

Chris Heycox

 Hi Greg,
I have to say that the Consonance PW-1 Line conditioner has blown me away. After plugging all my components into it, including the Music Labs power amp, and playing the system for an hour or so, I came to realize that it had improved just about every parameter of musical payback. The soundstage was now much deeper, and the location of performers/instruments within it was much better defined. Resolution had increased significantly, dynamics have much more attack and drive, subtle nuances buried below the noise floor are now revealed, bass notes have better definition. And this is on a system that had a sophisticated Australian filter (the Eliminator Plus) already in place which had made a significant difference previously. I am Utterly gob smacked. Needless to say, my "trial unit" will not be returning any time soon.

Best regards, Mark Kontjonis

This is an audio grade mains filter made by Opera Audio.
A true feed-through design providing clean mains at the 4 output sockets.
All metal construction and built on a very solid metal chassis.
It has 4 output sockets in total, these being the usual universal sockets (white), which could take any mains plug (UK/Euro/Australian/USA).

110 to 240V Operation
1800W at 240V
4 x Universal sockets (UK/Euro/USA plugs)
Mains filter and Line Protector.

The Opera Audio (Consonance) AudioGrade Hi-Fi mains filter is a Line Conditioner and Line Protector in a single very high quality made unit. This is a true feed-through design providing clean RFI filtered mains at the 4 output sockets with mains spike protection. The unit is beautifully made with an all metal construction on a very solid chassis just like their amplifiers. The silver end panels are made from thick aluminium and the case itself is black brushed aluminium. Everything is screened from the outside world since it is housed in a fully enclosed metal case rather than a plastic box. This prevents RFI noise radiating from the filter itself to nearby equipment. It has 4 output sockets in total, these being the usual universal sockets (white) which take any mains plug (UK/Euro/Australian/USA) giving great flexibilty and are a very tight fit. Consonance is a highly respected manufacturer across the USA and Europe. A well built and designed mains filter can really improve your system sound and protect your expensive audio and home cinema setup.

**See below for "What is a power Filter"


PW-3 Audio Grade Universal Power Board


This is an audio grade power board made by Opera Audio.

A true feed-through design at the 6 output sockets.

All metal construction and built on a very solid metal chassis.

It has 6 output sockets in total, these being the usual universal sockets (white), which take any mains plug (UK/Euro/Australian/USA).

110 to 240V Operation
2200W at 240V
6 x Universal sockets (UK/Euro/USA Australia plugs)

            The PW-3 is a shielded and high quality power board which also allows the use of quality power leads which are fitted with power plugs from anywhere in the world. Very high quality components are used and the solid metal chassis allows for magnetic and RFI shielding not available in plastic power boards. Despite the fact that they do not contain filtering or conditioning circuitry, like the PW-1, a surprising sound quality improvement can result from using this board.
TV reception is also improved if used with video sources. There was some confusion after the release of these two models, as we. and others in the World, did not realise that the PW-3 was not a filter, but had been designed to overcome the shortcomings of normal power boards, and we apologise to anyone who was mislead. Opera Audio has sent their apologies in the confusion, which resulted in the difficulty of Chinese trying to describe something in English. One of the main reasons we did not realise this was the surprising benefits that we and our customers had noticed when using this unit

Note..... Below relates to the theory behind Power Filters such as the PW-1.

P.S.:Why filter the mains ?

Audio Mains Filter Design Overview


Noise on the mains supply is now common place. It is not a clean sine wave that you would expect but has broadband noise from Khz and well into the Ghz region with transient spikes above 1000V. This is not ideal for any high quality audio or video system. Such noise can get through the power supply in any piece of equipment and end up in the 'main functioning' parts and affect its performance. High voltage spikes can also damage the unit. Computers, large domestic appliances like cookers and washers and industrial machinery all pollute the mains supply to various degrees. They generate large amounts of radio frequency interference (RFI) when running and can produce very high voltage spikes at switch-on. All this pollutes the grid and the mains entering your building.

Mains filters on the market range from about £35 up to £3000. You can expect to pay from £35 for a very simple plug in box that is placed near the noise source or next to the Hi-Fi but does not feed the equipment. These are the parallel type filters. They simply provide a low impedance path to earth for any noise on the ring which it is plugged into or act as a local voltage clamping device. The best mid priced units are normally feed-through designs that do supply the equipment with true filtered mains at an output or series of outputs. The high end units over £1000 also feed the equipment like the mid priced units but may also make use of isolation transformers on the output and use chokes and filter banks in more than a single stage.

The Truth on Audiograde Mains Cables

Many audiophiles invest in some very expensive audiograde mains cables in the hope that it will improve the sound of their audio system by removing noise. These are sometimes twisted pairs which have some RFI attenuation but not very much, or a screened cable which shields the mains conductors from RFI. In fact the use of heavy duty screened mains leads and twisted pairs is common practice in many large computer environments and industry running machinery.

These audio grade mains cables are useless on their own without some real filtering before them. The reason why is that you are plugging in your audio grade mains lead into a regular wall socket. Are you even considering what is behind that socket ? Your house or building is full of twin and earth gray mains cable. This is a standard, not 'high grade audio', copper cable which is buried beneath the plaster in the walls and under floor boards and pretty much covers your entire house in a loop and acts like a giant aerial. Now a few inches of plaster and wood are not going to stop noise getting onto this from various sources. Noise generated inside the building directly onto the conductors from other sources on the same ring and RFI noise again from inside and outside. This is not even taking into the consideration the many miles of mains cable in your area and in other buildings near by on the same phase of the mains before your local sub-station. So a 1m audio grade mains lead (even a silver one costing several hundred pounds) IS NOT going to remove any real amount of noise at the audio end that has accumulated in the many miles of cable before it passes into your system.

Noise must be removed by some mains filter circuit. The filter acts like a barrier between the circuit of your house and that of your hifi. Audio grade mains leads should ideally be used at the output of a mains filter and not before it if they are to serve some purpose other than look pretty and just have some 'coolness' factor.

Some Theory (Technical)

Noise is classified into 2 types depending on the conduction mode. The first type is differential noise which is conducted on the supply line and the return line in opposite directions to each other. The second type is common mode noise which is conducted on all lines in the same direction. The image below shows how these two types of noise should be suppressed.


A basic mains filter design should use a combination of methods to eliminate noise. X-Class capacitors are normally connected across live and neutral to suppress differential mode noise. Y-Class capacitors are connected between live to earth and neutral to earth to remove common mode noise. To prevent high voltage spikes from entering equipment and causing damage at least one varistor is required at the input. A varistor is a variable resistor and at its normal working voltage it has a very high resistance. However above a certain threshold voltage its resistance is low and it becomes highly conductive presenting a low impedance to the high voltage spike. It clamps the applied voltage (the spike) to a specified maximum defined by the varistor value. This is the most basic design for removing spikes and RFI from the mains supply. This type of filtering you generally find in standard trailing block computer filters and some HiFi filters.

A well designed mains filter however should employ a number of other techniques. A varistor will over time may degrade as a result of repeated spikes. Therefore more than one varistor can be used at the input, placing them in parallel. This increases their handling capability when clamping spikes and hence reduces their effective 'work load' extending the life. They should also be chosen for their clamping speed. If it is a very fast spike then the varistor sometimes cannot respond quickly enough and the spike simply passes through to the equipment. Very fast spikes are quite difficult to stop.

Chokes are common-place in valve amplifiers and pre-amplifier designs appearing in the power supply section due to their ability to reject and filter noise on the power supply lines. They are now also being introduced in power supply designs for other equipment such as CD players. Chokes should be used to form PI type networks with the X and Y-Class capacitors of the filter for proper noise rejection. Generally, however, the higher the current demand on the filter then the smaller the choke inductance. This is due to the physical size of the choke and the winding and its cost and availability from manufacturers.


Sound improvements in a HiFi or any audio system from a mains filter can be heard to various degrees depending upon the level of mains noise contamination in your area. A good mains filter will make a difference to an audio system but it will never transform a bad system into a good one. Generally the improvements are that the music sounds much cleaner and smoother, especially the top end. The more revealing your audio setup is then the bigger the difference a mains filter will make to the overall sound and the more noticeable the improvement. If you have a poorly designed and put together system then you may hear very little change by adding a mains filter. In some cases it may seem worse. If you have a dark, compressed or closed sounding system then some filters can exaggerate this. By cleaning up the sound and smoothing out any grittiness it may appear 'duller'.

Without the mains filter, the system sounds brighter and at first it seems looser but on further listening it is clear that the top end is not very clean. Most of the micro dynamics and background details are completely lost and the overall sound is very dirty and gritty. Add in a mains filter and the sound smooth's out. That gritty brightness has gone and the top end is much cleaner extending well into the mid range. It is now easier to pick out the details. Less high frequency 'mush' and a more seductive cleaner sound.

A possible explanation : Many audiophiles find that their HiFi sounds better late at night rather than during the day. Late in the evening and at night most people are no longer using large domestic appliances such as cookers and washers. Also many industry and companies have closed for the evening so there are less computers and machinery making demands on the mains supply. This amounts to less noise being generated by equipment. Many computers which use switch mode power supplies and especially heavy machinery put a lot of noise onto the mains supply. Those who live especially close to engineering works and offices can be badly affected without realising it. Industry have an obligation in that they must not 'contaminate' the mains grid and so filter techniques are generally used at the noise source for the worst offenders like heavy mains driven machinery and welding equipment for example.

Let's not forget that any decent mains filter first function is to protect the equipment from spikes for its lifetime. Then it is to remove as much RFI as possible. A good power supply in any unit, be it a CD player or amplifier, should reject all noise to prevent pops and clicks and overall sound degradation. Otherwise noise from the supply lines will appear in the 'main functioning' part of the unit and affect its performance. Any noise getting through the power supply of any unit must have an effect on its performance, the level of effect depending on the sensitivity of the circuit being driven by that supply. For example a low noise digital circuit like a CD player or a DAC is going to be more affected with mains noise than say a power amplifier running at HT on its supply rails. If mains borne noise can be filtered out further back down the chain at the mains side before the power supply in the unit then this is quite a bonus.