Speaker Break-in Period - why is this needed?

[jaree]

In many speaker and amplifier reviews I have read, there is a mention of "break-in" period. For example "initially the speakers sounded harsh, but after 100 hours of break-in period, they sounded great", etc.

Questions:

From the viewpoint of the speakers, why is this break-in period needed for them to sound better? I would like to understand it from an electrical/physical charateristic and something that is measurable. For example, maybe the crossover capacitors not fully-formed, the woofer spider suspension is not sufficiently pliable, etc.

I am sure that wood for cabinets, the copper or aluminium wires for voice coils and the speaker magnets themselves should not change their properties in 100 hours to make the speakre sound better.

[Richard Greene]

The driver's spider (suspension) is stiff and breaks in upon first use.

FS and QTC typically decline up to 5-10% while VAS increases up to 5-10% permanently.

This is often done during quality control testing at the factory.

While many people claim to hear this effect over 50-100 hours,
it's funny they never seem to mention similar changes EVERY time
speakers are used and their voice coils heat up -- there are similar
changes to T/S parameters (as above) that disaappear after the voice
coils return to room temperature!

In reality most audiophiles imagine hearing break-in effects beyond the first hour or two of use simply because they expect to hear them and human aural memory is very short.

I've been building speakers since the 1960's -- most drivers have no
audible break-in effects and some have weak bass for 5-10 minutes.

Of course it could take much longer to break-in drivers playing
string quartets at 65dB -- I use loud (85dB+) bass heavy rap music to stroke new
cones 1/2 of their rated XMAX or more ... and I leave the house for 10 minutes.

RG




one's
In many speaker and amplifier reviews I have read, there is a mention of "break-in" period. For example "initially the speakers sounded harsh, but after 100 hours of break-in period, they sounded great", etc.

Questions:

From the viewpoint of the speakers, why is this break-in period needed for them to sound better? I would like to understand it from an electrical/physical charateristic and something that is measurable. For example, maybe the crossover capacitors not fully-formed, the woofer spider suspension is not sufficiently pliable, etc.

I am sure that wood for cabinets, the copper or aluminium wires for voice coils and the speaker magnets themselves should not change their properties in 100 hours to make the speakre sound better.

[PAT.P]

jaree]When you take speaker out of the box they tend to sound harsh and flat.With time they literally loosen mechanically .The elastic properties of the drivers motion achieve their intented spec and speker sound fuller,richer , more coherent and more open.The bass fills out all of which adds up more satisfying sound.

[Peter Duminy]

Certainly an area of hot debate. Whilst break-in varies considerably from Company to Company due to the driver's properties, an area of improvement is on the way. The often overlooked spider which is usually made of woven cotton/poly-cotton or aramid fibers impregnated with a phenolic resin are a major cause of some speakers requiring many hours of break-in. This will improve considerably when the new Santoprene spiders become popular. Santoprene has a greatly reduced parameter shift, is much quieter in operation, and free from sagging over extremely long periods of time. Having tried Santoprene samples here in the Lab (below photo), the need for break-in is reduced considerably.

http://img.photobucket.com/albums/v226/voicecoil/spider.jpg


The length of time for burn-in depends on the properties of the drivers used. This can depend on the supensions used for the cones, as well as their material. One can use music with good deep bass tracks at moderatle levels for 15-20 hours for most woofers, and general music for the rest of the system, although Kevlar for example can take 50+ hours to reach it's intended properties. The changes from breaking-in tend to be more subtle in sound than some have said over the years. Also, no amount of breaking-in can make a poorly designed speaker sound good. If one is in doubt, the Manufacturer can usually supply further information and their recommendations on break-in.

[jaree]

I agree with the observation that the woofer spider becomes more pliable with time and this can result in changed sound (hopefully for the better).

I do not however see how tweeters could need a break in-period, particularly in 3 way models where the x-over can be 3khz or more.