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Foreword

I've lifted this from audio.stackexchange.com where it hasn't seen a lot of discussion. It's a question that interests me though so I thought I'd post it here, verbatim, and see what comes of it.


Some speaker manufacturers claim that one must "break in" their speakers for a given period of time before they sound optimal. This sounds fishy to me. Is there any reason speakers should need a "break in" period?

Some resources on the web seem to argue both sides of this question convincingly:

For example: Paradigm recommends "several hours"


Over at audio.stackexchange it's been decided that, 'Yes, speakers do require a break-in period.'

  • I could at least think of a plausible reason that maybe some fixtures (glue, screws) will shift a tiny bit until the speaker's membrane and body can vibrate optimally? Just guesswork, so let's see if someone can help :) – Lagerbaer May 7 '11 at 4:27
  • It makes me wonder why break-in would be required - why wouldn't they do it at the factory? – Thomas O May 7 '11 at 12:57
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    @Thomas O - I wonder the same thing. I suppose it could get pretty loud in there however. – user2466 May 13 '11 at 12:39
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    @Lagerbaer: How do the screws know in what direction to shift? If they would start moving, I would think it is the beginning of the end. – user unknown Aug 12 '11 at 23:00
  • Yeah, just guessing. Therefore a comment. – Lagerbaer Aug 13 '11 at 0:27
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David Clark, an AES Fellow has this to say in a paper Precision Measurement of Loudspeaker Parameters:

5.1 Break-In

A break-in process is recommended. Drive-unit storage may cause the diaphragm suspension to drift away from its normal or in-use position. Break-in, with the drive-unit axis in the in-use orientation (usually horizontal), restores the normal diaphragm position. The recommended procedure pneumatically stretches the suspension to one excursion extreme, then the other and continues to alternate, decreasing the excursion each time until x is at zero. This process can be completed in less than 1 min."

I found a reference to this article on the AV Science forum, which goes on to say:

Mr Clark also indicated that drivers which had been stored face-up or face-down sometime need 1 minute of pink noise to restore the original center position. This could also be accomplished by a few strokes of the suspension which many manufacturers do routinely when the speaker is at the end of the assembly line. This suggests that most speakers, are in fact broken in when you get them.

The poster then goes on to cite emails he received from speaker manufacturers which recommend a much longer break-in time of 20-50 hours and remarks:

In these emails, as in the replies and positions that many companies make to this day, we have two basic thoughts - physical attributes of drivers change and folks state they hear a difference over time. What hasn't been established is whether this is simply a correlation or a causation? The two are not the same.

Surely listening adaptation has a greater effect than speaker break-in?

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It seems a reasonable claim, based on what I know of speaker construction.

For one, the voice-coil in speakers is supported by the "spider", which is made of fabric impregnated resin. As it is moved back and forth, the resin would weaken, allowing freer flexing of the fabric. (this depends a lot on the resin, though).

Also, some speakers are constructed with a fabric surround, as well as a fabric spider. I would imagine that these speakers would have a more significant "break-in" period then other speakers, which have a rubber surround, which does not break in.

Whether this change would have any effect on the audible properties of the speaker, I have my doubts. However, there is really no material that withstands repeated flexing without some change of it's physical properties.


General References:
http://en.wikipedia.org/wiki/Loudspeaker
(Looking for more)

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    This answer is not properly referenced. Please add citations to support your claims! :-) – Sklivvz May 7 '11 at 11:19
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    Unfortunately, pretty much everything I could find on the internet, aside from the two articles mentioned in the OP, is just people bickering about the subject on audiophile forums. – Fake Name May 8 '11 at 2:57
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    @ Fake Name: same. Which probably means we cannot answer the question yet. – user288 May 8 '11 at 6:56
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    Agreed, this needs references. Most high-end speaker manufacturers DO specifically recommend break-in periods for their speakers. When I bought my current Focal speakers, two different company reps told me that they'd benefit from 20+ hours of break-in time. It's commonly enough recommended by manufacturers that I'm inclined to accept the break-in-period idea, but objective independent verification is still needed. – Erik Harris Aug 12 '11 at 21:48
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    Of course, it could be the listener's ears that are being "broken in" during the 20+ hour break-in period, letting them become accustomed to the sound of the speakers. I'd rather see independent verification than manufacturer recommendations, since audio manufacturers sometimes make spectacular claims without much evidence. Here is an article that has some data about headphone break-in (there were measurable changes, though quite small). I couldn't find a similar study for speakers. – Johnny May 22 '13 at 23:37
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One additional effect that might add to the plausible effects described above is the widespread use of ferroluids in loudspeakers.

Ferrofluids are used between the voice coils and the magnets to provide better thermal conduction for the coil (allowing higher power) and also to mechanically damp vibration. It is at least plausible that the distribution and physical properties change slightly with repeated use. Also, the magnetic properties are temperature dependent so will change in use.

It is not obvious whether anyone has tried to objectively quantify the effects discussed here, but they are a lot more physically plausible that some audiophile esoteric beliefs.

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