Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Power cables into DSP's...not the snakeoil or fact question

I just posted a few comments in a thread re: power cords and 5200's

We've all read and played parts in "snake-oil vs worthy upgrade" debates.

The main thrust of the snake-oil view tends to be around the fact that the power has come through miles of dodgy street cabling, transformers, house ring mains etc etc.

This is undoubtedly true.

However, if you are willing to accept that what mine and Mrs L's ears are hearing with the above cable test is real, then what technically is going to contribute to that?

I'm not actually asking whether it is snake-oil or not...as I say, that has been done to death.

So, from either camp, what would cause a difference?

Hi Nick,

Excuse my ignorance, but what the hell is snake-oil and what does it mean? I am completely lost!! lol

Cheers,

Chris

Hi,

"The biggest issue for me though is how to determine what is actually better rather than just different."

This is almost the crux of the matter. What is more accurate is perhaps the question. I have not tested mains or digital leads but clearly heard a difference with analogue interconnects. I came to the conclusion that what was important was what I could not live with. It does seem at times, though, a futile quest when a recording engineer may choose microphones, interconnects to suit the recording venue and genre; and that is before it hits the mixing desk!

Regards

Chris,

I think the term harks back to the days of the wild west (USA that is) when caravan traders would roam from town to town selling "the latest thing". You know the sort...."drink this tonic and you'll be cured of x,y and z....."

I guess "snake oil" was one of those things sold to a gullible crowd.

MI....But the difference here is that with mics, interconnects, the actual sound signal (be it digital or analogue) is passing through the item. With power cables, that is not the case and power cords are perhaps the item you'd think should have least effect.

I'm after views on what the difference in power cables might be doing to the equipment to result in audible differences in sounds.

At this time I really don't want to get all 'hi-fi mag/marketing' about what those differences are though, although at some point I'm sure they'll be relevent.

Hi, Point taken, I would certainly like to know what are the variable of a power cable that affect the sound!

Regards

I like the way that you have approached the question. What are the electrical differences that could account for your results?

There are various ways of describing an electrical signal, a commonly used one is the Fourier series. You describe the signal as being composed of the summation of many periodic sine waves.

In the case of the electrical signal in the home, you can think of the signal as a sine WAV with a period of 60hz and with an amplitude of ~120v rms with lots of other smaller signals added to it. The 60hz part will not vary much at all, this is due to the fact that you are tied to a vary large utility grid that is kept in sync for the purpose of multiple power generation facilities. The frequency it regulated to such an extent that many clocks simply use the frequency of the outlet to keep time. The amplitude varies noticeably due to the power needs of your neighborhood and the power companies generation sources.

It is the small additional signals that are difficult to express mathematically for a household signal, the Fourier series is a useful concept generally, but is it used the describe a summation of signals that do not change with time. The signal varies is shape, but the components going in to the signal are the same. It is a useful model, but the small additional signals that are summed for a household signal are constantly changing as neighbors turn lights and appliances on and off randomly.

If we assume that the best sound from our system would be obtained from a pure sine wave with no added noise. And we know that the signal we get from our outlet has a pure sine wave with a summation of noise. How would the addition of a special power cord change the signal to more closely approximate the pure sine wave? The perfect power cord would need to eliminate the noise.

This idea conflicts with the sales pitch of the ultimate power cord, the ultimate power cord would be of the highest quality and would be completely transparent and not change the signal at all.

I agree with sedluk.

The only thing left for that last few feet is shielding. And it really doesn't take that much expense to shield the last 6 feet of power and their shild not be that much variation in shielding. The shield would only effect other cables that are also poorly shielded picking up the Electro-Magnetic Interference.

Now if you're running a power conditioner the argument of putting a better cable on the last 6 ft is no longer valid.

Are you running power conditioners and how did you test the difference?

Don't under estimate the power of suggestion that something is better.

Take this for example:

http://www.fda.gov/fdac/features/2000/100_heal.html

Waste of money in my opinion. I've tried out some other power cables and although they _may_ have sounded different I don't think they better.

OK...guys.....I was hoping that we don't go down the path of a thousand other threads. We know that 50% of Hikers will swear by them and 50% will think they're a waste of money

. Is that totally true ?

Assuming that the 3 cables I am testing all have some degree of shielding, some type of soldering or connection, varying thicknesses of core, purities of copper, varying levels of resistance etc etc....what is it that causes a difference in sound reproduction.

One cable has a softer bass, another has a harder voices set further back, another has more background detail.

As I mentioned before, this is repeatable and not due to buyer's expectations (my wife has no idea what I am changing from and to)

Again (and sorry to pick on your comments, George) I'm not sure which of the cables is actually better and the perceptions are not correlating to price which is what you'd also expect. That isn't the point of my question. I want to try and understand what causes them to behave differently.

The extended question I hesitate to raise is why should the PSU in an 8k be affected at all by cables?...hence why I want understand what is going on......

Sedluk,

.

I agree 100%. If I had 3 different cables all claiming to be 'ultimate' then I absolutley would expect to hear no change when swapping them about.

I do hear a change.......what causes it ????

PS... no power conditioners. Just plain old UK grid and a ring main wall outlet.

Ok, no power conditioning. Then the only difference can be shielding, you or way undersizing (which I doubt happens in any cable you tried). I have fooled myself in to thinking something sounds hugely better and then backtracked only to find out it was me.

Moving a speaker an inch will probably make more difference than the power cable. Where you sit, what humidity is, what time of day, what you ate probably makes more difference. So I can't possible see how anyone can say one cable sounds better than the other because listener varies a LOT and you have not covered how you controlled those things. Since you didn't explain how you eliminated those HUGE variables it's too subjective or should I say suggestive.

Unless you A/B it with an instant switch I don't understand how, as a human you can "memorize" what one system sounded like. Some one with a good memory can memorize 8 digits. When you play music you are thrown billions of bits of information. How can one memorize all that information and then compare it 5 minutes later with another billion bits of information.

Did you use instruments to measure the bass difference, if there is audible differences then it should be EASILY measurable. How about running MRC water falls on each and lets see if we can actually measure a difference.

The job of the power supply inside the DSP8000 is to convert from 120v AC to some DC voltage, probably a number of DC voltages (3v, 5v & 12v). A well built power transformer will produce a consistent DC voltage. The DC voltage could vary from the ideal in 2 ways, it could include sinusoidal noise and it could be higher or lower in voltage.

The voltage produced by the power supply inside the speaker will often vary by the load, it will often produce a lower voltage as current increases. I would not expect noise in the input to affect the output voltage level. The input voltage varies over the course of the day and that could have an affect on DC voltage level, you might notice that your music is a little louder in the evening. I doubt the effect could ever be heard, but it is theoretically possible.

Could the noise in the input voltage affect the noise in the DC voltage? Well, the design of a power supply is to convert AC to DC. If a power supply can smooth out those large sine waves we call AC power, then it should not have too much trouble with the tiny noise signals that are many orders of magnitude smaller in energy. I would imagine that there would be some relationship between input noise and DC output noise, it might be very small, but it would be possible. An example would be that when your neighbor runs his large air conditioner, your music does not sound as good. I have never heard of anyone experiencing this problem to the extent that it was audible, but is seems theoretically very possible.

Following this line of thought, the problem remains, how could a different power cord have an affect on line voltage noise that would have energy on the order of running a large air conditioner?