While I believe the shoe analogy to speaker break-in is quite apt, the internal-combustion engine one is not.

Shoe leather, like (I assume) speaker surrounds, ship with a material stiffness which changes due to use and never stops changing.

The cause is a gradual stretching and eventual loss of elasticity.

(plus degradation of material properties due to oxidation and other environmental exposures).

Piston rings, on the other hand, are exposed to friction (purposeful friction in the case of an unseated ring) which eventually declines as material is worn and deformed to the point of, if not equilibrium, at least a point where the rate of change decreases dramatically as the moving parts are well "mated".

It is my understanding that there should be no frictional wear in any speaker design, and thus all "break-in" would be of the type more akin to shoes than engines.

The scary thing about that is, IMHO, that if one accepts the proposal that some "good" speakers require break-in,

one is accepting that the materials used in their construction are ones which have significant changes in their elasticity over a relatively short amount of time.

Especially audiophile class gear is usually able to provide even laboratory grade voltage from even dirtiest input sources. Huge caps and toroidal transformers often physically show off these capabilities. These circuits flatten ripple of many volts without the bat of an eyelid. How is the tiny mV lowpass effect of an artistically plaited mains cable supposed to make even the slightest difference here?

But if an AC is very flaky

Quote from: greynol on 2009-09-24 21:36:29

Why not carefully record the signal coming from the output terminals of your amp and provide samples for us to evaluate?

Let's say I did, you listened, and found the samples sound different. In that case, we're back to square one - what would you do with these results?

The often cited skin-effect is a real phenomenon. It can make iron melt at just 50 Hz with an AC current, that could be 10 times higher as DC without the metal even getting warm. The higher the frequency the greater the current density at the outer surface of a conductor.

The funny thing is - and that's why I really don't know why in heaven cable manufacturers chose especially this phenomenon as a marketing vehicle - HF attenuation decreases with wire diameter.

That means the best HF filter wires are the thinnest ones and precisely not the finger thick sausages you can buy at audiophile stores. Increased diameter means larger surface for the outer HF carrying layers and lower impedance for HF content.

LessLoss tries to sell, that a resistive but conducting outer layer would cancel out high frequencies, because they would gather in the resistive layer and get eliminated. But current gathers were it finds least resistance and will just move further towards the inside of the conductor, so you could just use a smaller diameter cable for the same "effect"!

I would call the claimed filtering ability an outright lie. Any standard copper cable with an only slightly smaller diameter than LessLoss' would already be a better filter than their "solution". But many other "high end" cable manufacturers are sitting in the same boat here.

he only thing you can really do in a cable is active low pass filtering using capacitors or ICs. But that's the power converter of your amp/DAC usually doing anyway, it's far from black magic and very effective circuits are available since before I was even born.

If an overpriced piece of gear as jessenov1's sounds different with an actually filtering cable (unlike the LessLoss), something is really wrong with that gear and its makers don't understand even simplest electronics. Instead of dropping even more bucks for expensive cables, the malfunctioning unit should be exchanged for something properly working.

Well, letsee. The skin depth calculator at http://www.microwaves101.com/encyclopedia/calsdepth.cfm says that the skin depth at 60 Hz is about 1/3 of an inch. So basically, for skin effect to be relevant at 60 Hz, the wire has to be pretty large.

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That means the best HF filter wires are the thinnest ones and precisely not the finger thick sausages you can buy at audiophile stores. Increased diameter means larger surface for the outer HF carrying layers and lower impedance for HF content.

HF attenuation is what the speaker cable guys want to claim that they are minimizing, so that works for them.

Quote from: Arnold B. Krueger on 2009-09-29 01:51:29

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That means the best HF filter wires are the thinnest ones and precisely not the finger thick sausages you can buy at audiophile stores. Increased diameter means larger surface for the outer HF carrying layers and lower impedance for HF content.

HF attenuation is what the speaker cable guys want to claim that they are minimizing, so that works for them.

Yeah, but what they don't tell you is that with a teensy cable the excess attenuation is very, very small, and that it could go up to .01dB (GASP!) with that firehose-sized cable.

Arny, if you're going to be at AES, drop by the first bit of Ethan's workshop. The cognative stuff we were talking about over dinner is what I'm going to present, you could consider my part of the presentation as 'why do we think the same thing sounds different'.

The real reason for my post is a test I conducted over the weekend, different aspects of which raised the qiestions in the OP.

First, I was comparing 2 power cords sighted, and thought the difference is there, but pretty insignificant, so these two weren't good candidates for blind test (which I would've most likely failed). My next thought was to compare one of the two (the one I prefer) to the stock cord, but finally, since I own several cords, I decided to pick for blind testing the one I thought sounded significantly different (worse) in sighted auditions.

Here's how test was organized:

1. Power cords were utilized on amplifier, going straight to the wall.

2. NO LEVEL MATCHING was performed - since both cords are of sufficient (and rather heavy) gauge, I don't see any need for that, and would dismiss without further discussion any notion that only loudness was affected by replacing the cords.

3. I enlisted my wife, who doesn't care for sound quality, but acknowledges visual appeal of certain components (including speakers), as helper.

4. I hanged old shower curtain, sufficiently opaque, from the ceiling using several pins so that it hid all components (but not speakers) from the sight at listening armchair. Wife was located behind the audio rack so she wasn't visible, either, and was instructed not to manifest herself in any way.

5. All of the above was performed in my listening room, which is 17'x11'x7.5' finished part of the basement, and is separated by a door from unfinished part. Some acoustic treatments present (first reflection points and couple of bass traps).

6. The procedure was as follows:

- I listened to short fragment (~15 sec.) of the same track sighted, with wife replacing cords A and B. Twice to each was enough for me to establish the differences. I determined that A is "better" and B is "worse".
- I left the room, closing the door. Wife was instructed to replace the cords in arbitrary order, making note of which one is currently plugged under sequential #. On wife's command, I returned to the room, and listened to exactly the same ~15 sec. fragment used during sighted audition. I made a note of which one, in my opinion - A or B - was used, under sequential #.
- Previous step was repeated 10 times, after which we compared notes. Intention was to continue, if results are unsatisfactory - but that turned out not to be the case, so test was stopped. It wasn't my intention to post it here, or anywhere else for that matter, otherwise it would continue.

In short, all 10 tries were successful, with me reliable identifying correct cord.

7. Relevant details of the system:

- Simaudio Supernova CD player
- Reference Line Preeminence 1B passive "preamp"
- Plinius SB-300 amplifier
- KEF Reference 3.2 speakers

8. Track used:

- Saturnus - beginning of the track "Embraced by Darkness", from "Veronica Decides to Die" album.


Now, back to my questions:

- what useful information can anyone but myself take away from that experiment?
- would anyone be willing to spend money on the same exact power cords, considering they are moderately expensive ($200-500 range used), to repeat the experiment?
- without using the same exact system - how would we know that another person's system is of equal resolution to mine, or at least of enough resolution to detect these differences?
- how would we know that another person's hearing is in good enough order?
- how would we account for possible bias NOT to hear any differences (seems pretty actual here)?


I'm all ears.

Can you prove that these power cords deliver a different electrical signal. Feed the 2 cords the exact same sine wave, and see if they make any changes to it that can be measured. then feed these cords a more realistic depiction of an AC signal (not a pure sine wave but cloe) and see if they affect the signal at all (apart from minor attenuation).
Finally, even if very slight changes in the electric supply at the end of these cords were measured, do you really believe your amplifier is so poorly manufactured it would alter its performance based on very slight fluctuations in voltage?

In other words, I don't believe for a moment there is any difference in the "sound" because of your 2 power cords. It's all in your head.
Either you have an overly active imagination, or it IS possible that one had a faulty contact with the plug point or the IEC receptacle that led to undesirable noise.