Quote ef37a:

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Nope.

Provided the material is never stressed near its plastic point (and I think Hugh was playing a blind here and knew it!)springs really do last "forever".

When did you last hear of a valve spring breaking in an engine? There are thousands of centuries old clocks and guns that just keep working.

Dave.

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Dave

your own point was that springs don't wear-out, they just break!

I agree that so long as the elastic limit isn't exceeded they should, in theory, last forever, but as it happens I have replaced broken valve springs, and I have replaced "set" springs which were significantly shorter than original spec. I recall a discussion with my father many years ago about a handgun that did not function properly after a significant time of being carried "cocked and locked" so that the mainspring was under tension, and this was also a significant concern for airgunners wanting to use spring piston weapons for field shooting. Dad made the comment at the time that this was due to poor design, and that commercial Diesel engines worked for years and many hundreds of millions of cycles with no expectation of spring breakage. But springs certainly do fatigue and they do break.

A.

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Andi, www.thedustbowl.net Mixing, Mastering, Audio Editing at The Dustbowl Audio

Quote Andi:

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Quote ef37a:

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Nope.

Provided the material is never stressed near its plastic point (and I think Hugh was playing a blind here and knew it!)springs really do last "forever".

When did you last hear of a valve spring breaking in an engine? There are thousands of centuries old clocks and guns that just keep working.

Dave.

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Dave

your own point was that springs don't wear-out, they just break!

I agree that so long as the elastic limit isn't exceeded they should, in theory, last forever, but as it happens I have replaced broken valve springs, and I have replaced "set" springs which were significantly shorter than original spec. I recall a discussion with my father many years ago about a handgun that did not function properly after a significant time of being carried "cocked and locked" so that the mainspring was under tension, and this was also a significant concern for airgunners wanting to use spring piston weapons for field shooting. Dad made the comment at the time that this was due to poor design, and that commercial Diesel engines worked for years and many hundreds of millions of cycles with no expectation of spring breakage. But springs certainly do fatigue and they do break.

A.

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Hi Andy,

Yes springs DO break but so,so seldom that I would suggest an original flaw?

You mention airgun springs? Now I am rather well read on this subject IMHO! I recall the famous Cardew once wrote that if you asked an enginner how long a spring would last in an airgun he would say about 3 shots! As I am sure you know the spring is mistreated mercilessly but they seem to survive decades until someone lubricates it with a low flash point oil (WD40 works well!) and the resulting detonation breaks it into two or more pieces!

For sure, leaving an airgun cocked will fork it but again, springs were never designed to be held coilbound for long periods, well not at all really.

If I could just change track to clocks. Balance wheel springs do not it would seem even change their compliance very much over the years, otherwise the clock would steadily go out of regulation (no doubt of course some poor quality ones do/have).

Running in engines is a complete blind! Bits are wearing OFF the surfaces and hopefully get flushed away with the first service oil change. Where's the sump plug on K&H monitors?

As for "natural" materials. Do wooden or wood/laminate bows lose power over the years? I doubt it. I have read a bit about making bows (and arrows) and the point was never mentioned.

And for XX 1000 quid I STILL want it right, out of the box!

Dave.

These are entirely spurious arguments. The diaphragms of speakers and headphnoe drivers ae not mounted on metal springs of any form. Neither are they mounted on Yew surrounds (the wood most commonly employed for longbows).

It is the specific spring-like properties of the particular materials actually used in constructing loudspeakers and headphone drivers that are of concern.

Discussing other materials is a waste of effort.

In any case, I think we have debated the subject about as far as lay-people can. No one here -- including me -- appears to have in-depth knowledge of the real design constraints and materials involved. It seems clear we will not arrive at a single, unanimous conclusion any time soon.

So, I suggest those who dismiss the concept of 'running in' continue to do so, while those who believe they can perceive a difference and/or benefit continue to follow their beliefs, safe in the knowledge that the only time they might be wasting is their own.

Moving on...

Hugh

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Technical Editor, Sound On Sound

A transducer element in headphones or speakers is not a pure spring in the manner of a valve spring or airgun spring , nor are those bits which are sprung made of remotely similar materials , they behave quite differently , thus I'm afraid you argument is entirely spurious Dave .

All manufacturers for example , will normally change driver assemblies as pairs in the event of a fault, especially tweeters , in order to maintain matching, (and tweeters can apparently wear faster than woofers I presume due to the higher cycle count they operate for in the same time period)

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if you don't know who i am, i aint gonna tell you.

Quote Max!:

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A transducer element in headphones or speakers is not a pure spring in the manner of a valve spring or airgun spring , nor are those bits which are sprung made of remotely similar materials , they behave quite differently , thus I'm afraid you argument is entirely spurious Dave .

All manufacturers for example , will normally change driver assemblies as pairs in the event of a fault, especially tweeters , in order to maintain matching, (and tweeters can apparently wear faster than woofers I presume due to the higher cycle count they operate for in the same time period)

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I will just say this before Hugh locks us out!
Drive units should be changed as pairs since no two are the same (paper cones are apparently a QC nightmare even for such a low tech' app as guitar cabs!) so just as there are stereo "pairs" of microphones, one can assume at the sort of high end kit we are discussing, speakers will be matched. (KEF had this all done on a database I understand for the legendary R105?)

Lastly (probably!) I do not doubt people can hear "something" I would just like some evidence and a mechanism?

Dave.

Quote Hugh Robjohns:

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No one here -- including me -- appears to have in-depth knowledge of the real design constraints and materials involved.

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Where is Phil Ward when you need him?

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http://soundcloud.com/richie-royale
http://www.mixcrate.com/richieroyale

Most of the people who have practical knowledge are presumably working for headphone manufacturers, and the manufacturers really don't seem keen on making definitive public statements about the phenomenon. I guess that's one reason why these debates go on.

Try searching a few manufacturers websites for phrases like 'burn in', 'break in', and so on...

I couldn't really find any official, on-the-record statement from any of the major manufacturers. All I've seen are a few informal forum postings from company representatives, and reports of conversations.

Not to say that such clear statements don't exist somewhere - just that they're surprisingly hard to find, considering how much discussion the issue attracts.

I didn't believe it happened myself. But then I heard it for myself as clear as day.
My new PMC's sounded horrible for the first week or two. Over a year later now, and they are sublime It's a very marked difference. Apparently it is a common trait of PMC's, and you'll find many owners report very similar findings.

It doesn't happen to all speakers & headphones. But believe it or not, it definitely happens to some of them..

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Paul

I posted a direct quote from Pete Thomas (owner and designer at PMC) on this subject a few years ago where he explained why burning in was required in some systems -- I'm sure a goggle search will find it if you perservere.

The reason PMCs reveal this characteristic so strongly is because of the unusual bass unit parameters to suit the relatively high loading they receive in the ATL cabinet -- and the fact that the design only works properly over a narrow range of drive unit parameters.

New drive units are too stiff to work with the line properly and the whole thing needs a few tens of hours to reach the optimum compliance. It's a very obvious change indeed with new PMCs.

hugh

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Technical Editor, Sound On Sound

a friend of mine is the technical development type R&D guy for Kurt Muellers , probably the primary source of speaker components for the industry...

i'll ask his opinion ....

Quote Hugh Robjohns:

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I posted a direct quote from Pete Thomas (owner and designer at PMC) on this subject a few years ago where he explained why burning in was required in some systems -- I'm sure a goggle search will find it if you perservere.

The reason PMCs reveal this characteristic so strongly is because of the unusual bass unit parameters to suit the relatively high loading they receive in the ATL cabinet -- and the fact that the design only works properly over a narrow range of drive unit parameters.

New drive units are too stiff to work with the line properly and the whole thing needs a few tens of hours to reach the optimum compliance. It's a very obvious change indeed with new PMCs.

hugh

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Indeed, this is probably the post:

http://www.soundonsound.com/forum/showthreaded.php?Cat=&Number=722700& amp;page=27&view=expanded&sb=5&o=&vc=1

Quote:

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When loudspeakers are new they will take time to reach their full potential... the characteristics of mechanical devices such as loudspeakers do alter and improve their performance significantly after a short ‘running in’ period.

...as the soft material surrounding the dome or woofer cone is flexed it will eventually reach a point where it has optimum compliancy allowing the drive unit to move more freely. This translates to greater accuracy and speed of attack in the bass region and the mid and high frequency produces a far more vivid audio picture...

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Not sure why, but for some reason I get the strangest sense of deja vu reading that old thread...