Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion HiFi & HT Chat Mains Cable Alternatives?

I don't think Andrew has moved the argument; he has clearly stated that the best place to filter out any spurious mains noise is in the power supply.

My position is the same:

There is noise on the mains; fridges and freezers are good (bad?) sources for this.
Mains filters work as designed.
Shielded cables work as designed.
Plugs and cables that meet the relevant standards (BS1363 etc.) work as designed.
If mains filtering and 'special' mains cables can make a difference to the measured performance of an piece of equipment (audio or other), the equipment is poorly designed and fails the EMC requirement (electromagnetic compatibility BS 61000).
Getting rid of the noise on the mains is very very easy (and cheap) once you are on the DC side, simple smoothing capacitors of the correct type and size.

A last thought, if your equipment is susceptible to mains noise, maybe it's power supply is out of specification, usually the capacitors are the culprits.

I think the discussion has become a little bit polarized. Maybe it is not so black and white? There is noise on the mains, the power supply needs to get rid of it, but maybe a power cable could reduce some noise and improve total system performance? I don’t know.

I am very sceptical about expensive mains cables. But many people say it makes a difference and if people have tried it and hear a difference I am the last to say its all BS. Maybe it does make a difference, I have never tried high end mains cables on my speakers. But I believe the rationale of the non believers more than the people that say it makes a massive difference. At the same time, respect listeners that believe they hear a difference and not request scientific proof. Especially if you haven’t tried it yourself. If people hear a difference, great for them!

What's left out in most discussions is the magnetic influence of a not schielded mains cable on the surrounding (signal)cables especially if they run symmetrical and close to each other. Changing that to shielded could make a difference in measurements and sound wise.

These discussions always do seem to become polarised, it feels like people have already decided what they believe to be true and no further investigation is necessary (as an aside, I didn't believe in high-end mains cables until I tried one).

Two quick thoughts:

* An early comment in this thread was about the skin effect at mains frequency being insignificant, yet our devices don't draw power that way. They take gulps of power when they need it, which (esp. with an amp) will mean much higher frequencies.

* Improved filtering in the PSU would make sense, but how far should they go? Build a £20k amp with the ultimate in power smoothing rather than a £4k amp? Not likely to work commercially (and that's ignoring the various patents around these things). In any case, how would you put a Shunyata Denali inside a DSP speaker? What about all those who would prefer to use an Everest? What happens if the next big improvement arrives before the next DSP speaker?

I get the scepticism, but try a decent mains cable before deciding. Your wallet may never forgive you, though

The current draw from the device comes from the DC side of the power supply (reservoir capacitors), the AC side tops this up; the frequency of the draw is independent of the 50 / 60 Hz mains frequency.

Skin effect at 50Hz is about 9mm, so only makes a difference if each conductor is 18mm in diameter, that’s a lot of current capacity.

If you draw current at a higher-than-mains frequency when (say) playing an oboe through your speakers, that current will be passed back to the mains supply.

Unlike how an incandescent lightbulb draws power at a relatively constant rate (in time with the mains frequency), the PSU doesn't sit there and think 'I'll sip the power supply to recharge and hope there isn't a drum beat anytime soon', it tries to recharge its capacitors as quickly as it can (made worse by the rectifier bridge introducing a voltage drop, which increases the spikes of current drawn).

It's the change in current drawn by the music being played (in this example) that induces the skin effect, not the mains frequency (the impact of which, I agree, is negligible).

The power dissipation in any class A amplifier is constant, whether Quiescent or at Full power. So the power draw from the mains is constant.
Class D is different. Power is drawn at the transition of the digital switching, and these is often back noise at 50-100Khz from switchmode PSU's as well.
This can get back into the mains chain and by radiation into the audio chain, if attention is not paid to the routing of the cables (mains cable at 90 degrees to signal cables). This is where a screened mains cable comes into its own, in reducing the potential noise floor. However, a proper mains filter, and, if you have smps, screened mains lead. Will make a much bigger difference than ANY expensive boutique mains cable, and is substantially cheaper. Think a quarter of the price of a Russ Andrews BS mains block.

These IEC C14 to C5 Adaptors are available at a much better price, just add shipping (also available from RS and PartsExpress, etc.).

I don't believe this to be true and it goes against everything I've learned. A class A amp, at its simplest, is a single transistor with a base (which is the input to be amplified), a collector (which is the power supply), and an emitter (the output). The higher the current that flows from the base, the proportionately greater the number of electrons allowed to flow from the collector to the emitter. Ergo: the power draw has to be proportional to the music being played.

In a class A amp, there is always a positive bias to the base, which means there is always power being drawn (and heat generated), but not the same amount regardless of the volume or the music being played.

The current that an amplifier uses to drive loudspeakers comes from the charge held in the reservoir capacitors; the capacitors are (and can only be) charged at 2 x mains frequency (full rectification).

The DC side of a power supply is isolated from the AC by the reservoir of charge in the capacitors; when you design a power supply, you calculate the required capacitance for the voltage and current requirements, if they are inadequate, you will get intermodulation distortion.

Returning to the original point, the amplifier will draw power from its capacitors as well as the power source. The capacitors will then need replenishing, which they will do so as fast as possible from the power line. A kick from a bass drum at a high volume will likely mean more charge will be drawn from the caps.

But the energy to power the speakers has to come from somewhere. It's the frequency (and volume) of the music being played that creates a magnetic field, which in turn causes inductance, which creates the skin effect. The mains frequency is largely a red herring in this argument (unless you're talking about a purely resistive load such as an incandescent light bulb). While I studied this topic thirty years ago, I'm sure the fundamental principles haven't changed.

What you are descibling is class B or A-B.
A 50w class A will draw the same current (power) regardless of the input signal up to the clipping point, or with zero input signal the
power disapation is still 50w. This is one reason they are so "clean sounding". The power supply does the heavy lifting and there is not much surge energy taken from the mains supply itself, to top up the power supply capacitors.

Since I started this thread, I’ve replaced the factory-supplied C5 mains cable on my PrimePSU, 218, and 210 with Audioquest NRG-X3 C5 mains cables - providing a 'modest' improvement in perceived audio quality.

Recently, I purchased a pair of C15 Shunyata Theta NR mains cables for my DSP5200SEs from StudioAV. One of their dCS Rossini/Scarlatti customers had exchanged them for Shunyata Alpha-X NR mains cables. I wasn't able to audition them before purchase (neither did I audition my DSP5200SEs before purchasing them). The Alpha-X mains cables cost over twice as much as Theta mains cables. Even so, my Theta mains cables are in pristine factory condition and are well and truly run in.

I don't know of any Meridian owner who uses Theta mains cables. I didn't quite know what to expect from them, so I didn't have any expectation bias - other than on reading the positive Theta user experience on the Shunyata owners' forum. For me, the financial risk really was worth it. Subjectively, to my ears, in my 5 x 4 metre listening room, playing my preferred music genres, my DSP5200SEs' overall audio performance has been positively transformed.

I can't provide any objective evidence for my findings gained from any attached electronic measurement devices. That is, I cannot offer a technical assessment that would amply satisfy the naysayers’ inherent beliefs voiced elsewhere on this forum thread.

For me, in no particular order...

My DSP5200SEs have taken on the physical proportions of a prodigious Sumo Wrestler.
Bass delivery is much deeper, dynamic, extended, and cleaner: it resonates and expands throughout the room.
It's as though their power output has significantly increased.
I've gained an increased Tardis-like internal cabinet volume and gained another (phantom) woofer.
Such is the added near sub-sonic performance emanating from my DSP5200SEs, it’s as though a pair of DSW.2s has mysteriously infiltrated them.

I don't have any regrets about my purchase: I will not be returning them. Overall, Shunyata Theta NR mains cables are highly recommended for fellow DSP5200SE owners.