Whether your new speakers require time to break-in is something that is not often talked about, however we have delved into the subject to explain why their sound may improve over time.
There are two common opinions when it comes to the need to burn in or break-in new speakers; the first being that it isn't required. This school of thought basically states that our ears become accustomed to the sound of our new speakers (making them seem to sound better) and that the overall performance of a speaker doesn't change perceptively with use.
On the other hand, some say that speakers have a better sound after several hundred hours of burn-in with a white noise generator and increasing amounts of bass-driven music. This school of thought believes that speakers must be broken in sufficiently and properly in order for the performance of the speaker to be enjoyable to even the average listener.
As usual, the truth lies somewhere in the middle of these two thoughts.
With advanced materials being used in the construction of modern suspensions and surrounds, the performance of a speaker changes over time. Out of the box, a speaker will tend to sound a little stiff, particularly in the bass frequencies, and you may find that the overall response on your new drivers is a little tight or restricted. After a period of time, you'll notice the speakers open up and begin to sound more natural. This can definitely happen if you've auditioned a pair of well-played speakers at a retailer. In store, they sounded great with a lot of warmth and depth but at home, your brand-new speakers may sound cold and shallow to begin with. This is because at the store, they had dozens, if not hundreds, of hours of play through them while your new out-of-the-box speakers are factory-stiff.
According to Dr Jack Oclee-Brown, Vice President of Technology at KEF: " The suspensions see the largest change, [as] they are made from impregnated textile and at a microscopic level the textile fibres pull apart a little when they are stressed, which leads to a softening. Break-in can take from a few hours to a few days. This depends mostly on the signal used for the break-in. Louder music will break in the drivers more quickly. As typically the bass drivers break in the most. Music with more bass will speed up the process too. The same effects can apply to headphone drivers too."
The suspensions and surrounds will deform as the signal is applied to the speaker, and that deformation causes the material making up the suspensions and surrounds to soften and become more flexible. It should be noted that the cones themselves do not deform and by "deform" we simply mean "change shape" to accommodate the movement of the speaker cone and voice coil.