Originally Posted by chadnliz
From my experience (and sorry if I dont think "Mark"at audioholics is the all knowing poster about speakers (pretty biased and at times plain silly site) but anyway its real...disagree if it makes you cool but I and many others know what we hear.
Perhaps if you can be more specific and refute the article or parts thereof that he's credited with writing it might lend more credence to your position.
The rubber band analogy that you brought up, Coytee, is reasonable. If you take a rubber band and measure its length you'll get some value. Let's call that X. Now you stretch it for a while and remeasure the length. Let's call that X+cX where c is some fractional component. Now if you come back later, say tomorrow and remeasure the rubber band, you'll find that it's length is X again. However, it's entirely possible that one will stretch the rubber band far enough that you will in effect ruin it. Some folks to their detriment have found much the same with sub drivers.
The topic of speaker break-in has been studied rather extensively using techniques such as laser interferometry, measurements of speaker parameters, and controlled listening tests.
David Clark, an AES Fellow presented "Precision Measurement of Loudspeaker Parameters", which was published in the March, 1997. Abstracting from that paper is the following quote:
"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."
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.
Further work has been performed by Tom Nousaine who has measured speaker parameters pre and post break-in as well as having conducted controlled listening tests. He has found that the Fs of the speaker falls however that is offset by a rise in Vas. Both these parameters were related to the changes in compliance that occurred. During the playing or excercising if you will of the speaker, both the spider and the surround become more compliant (they move easier). Additional measurements on samples of identical drivers indicated that the changes that occured pre and post breakin on a single driver were smaller than the variations within a particular lot of drivers. Since there are manufacturing tolerances for drivers, this indicates that whatever the changes are that occur are smaller than those of manufacturing tolerances. This further indicates that the net effect of speaker breakin is nada, nothing, zilch, forget about it, etc.
In one experiment, Nousaine used a driver that was said to need 48 hours of break-in. Placing the driver in a 1.5 cubic foot box, he found the system resonance to be 53 Hz before break in. After 48 hours the resonance was 49 Hz. After a few minutes rest, the resonance had gone back to 51 Hz. The following morning it was back to 53 Hz. This indicates that whatever small changes that occur in a driver's characteristics during playback come back to their original state after rest.
These experiments have been performed with other drivers such as from Dynaudio with similar results. Overall this indicated that whatever changes do occur, they do not change the sound quality.
So if the sound quality does not change in any significant way, what then does occur? Well listening adaptation would then have to be looked upon as speaker break-in. Anyone who has spent time listening to audio systems or components knows their opinions with regards to the nature of the sound changes with time. In the case of speakers, when one buys them and brings them home, you become used to the sound of that particular speaker. That sound may grow upon you or you may find there's something that you don't like about it. Nonetheless, however they sound in your particular home, it'll be different from the way they sounded either in someone elses home or the stores where you heard them.
A number of years ago I've sent inquiries to various speaker manufacturers and these are some of the replies on this subject of break-in.
|We've found (as have our dealers and customers) that the most significant changes occur within the first 75-150 hours, with smaller incremental changes occurring up to a few hundred hours. After that point, you shouldn't notice much change at all, as the speakers would be broken in thoroughly. This time is the same for each model and is best accomplished by just playing music through them.
Thank you for your interest in Revel.
Sent: Tuesday, July 30, 2002 8:37 AM
To: [email protected]
Subject: speaker breakin
Thank you for your enquiry into Krix Loudspeakers. Most speakers will benefit from a 'run in' time and our speakers are no different. We suggest running speakers at moderate listening levels for between 20 - 50 hours. After this time you should hear some differences as the components of the speakers start to 'free up',
I hope this information has helped, should you have any further queries please feel free to reply to this email.
National Consumer Sales
|With all mechanical parts they do require a running in period, this ideally should be about 36 hours, what I suggest you do is listen to your speakers at a moderate level when you can over this period. Following this procedure will help prolong the life of your speakers.
Customer Specialist Support
Tel: +01236 420199
E-mail: gale.o'[email protected]
|Thanks for your recent email to Definitive Technology.
In order to break-in your BP10Bs, we recommend playing them at a moderately loud volume for about 40 hours. (After this period, the suspensions on the speaker cones loosen up a bit.) Generally, you'll hear a smoother high frequency response as well as a greater openness or transparency.)
If you need any other information, please email me at [email protected]
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.
Now if studies have indicated there is no significant change during pre and post breakin and that whatever changes that do occur come back to the original over time, one must ask the question, if the speaker companies are aware of this, and larger companies, that have access to such data as I've presented here do, what is the purpose for specifying breakin that amounts to around 40 hours, give or take? To my mind, the reasons would have to do with ensuring that the customer keeps the speakers in their home for a couple of weeks to hopefully either get used to them or to convince themselves, rightly or wrongly, that they do like the speakers. During this process of listening, the customer, as can be seen on some of the posts on this forum, is actively seeking out other users opionion, corroborations, justifications, positive/negative opinions. So myself, I would recommend that anyone purchasing speakers listen to them in their homes and if during that time, which should be well before the RETURN PERIOD, they don't like them to take them back where they bought them and rethink the choice they made. Any salesman who says you need this CD or this procedure in order to effect break-in is doing so for either a couple of reasons...they're ignorant, or they're hoping you need a little more time for the speakers to grow on you so you don't return them and he/she doesn't blow the sale and commission.
Here's a question to ponder for those who hear differences in speaker qualities over time regardless of studies that strongly suggest otherwise. If you're able to hear such things, why in heaven's name do you need an SPL meter and or software to adjust your levels?