Thread: Speaker break in: What actually happens?

I don't really know, but the composite material making up the speaker cone & support structure would be prime suspects. Composites are highly hysteretic due to interaction between the fibers and the bonding agents at the molecular level, particularly when new. Hysteresis results in energy loss which would likely be frequency sensitive and could generate both loss and harmonics. As the material is worked, many of the weaker bonds will release and much of the hysteretic behavior will go away. How much & how fast depends on the material and the conditioning.

The magnetic circuits could also be a source of error that might stabilize with use. Even with careful design, there will likely be areas of saturation in the iron pole pieces focusing the magnetic energy to the voice coils. These areas are highly sensitive to actual flux levels, temperature, mechanical strain, etc and will impact the field strength. Your audio signal current passing thru the speaker voice coils generates its own magnetic field that adds/subtracts to the permanent magnetic field of the speaker and will modulate these sensitive areas producing non-linear output.

Manufacturers probably charge the magnets to full up & ship without any further conditioning. Exposure to time and excitation currents, the speaker magnets will discharge somewhat and stabilize at that lower value. This would move the saturated areas into a less saturated condition and significantly lessen their distortion impact on what you hear.

Probably more than you wanted, but you asked... \"/.

Originally Posted by Timecop

I recently upgraded my 5.1 system, and all the new speakers basically said the same thing: "The speakers will sound great out of the box, but after XX hours they'll sound even better." Generally speaking, 40 - 60 hours was quoted.

I did leave the system running for a week, and after that time the speakers did clean up, with the sub sounding the most improved. The receiver seemed to agree, as it's suggested crossover settings were lower and more in-line with the speakers' ratings following break-in.

My question is: What actually happens to the speaker during the break-in process which allows it to play at the designed level?