Cone Conundrum


I’ve decided to ‘undress’ the little Proac Tablette 10 and, much to my surprise, there is not reallly any discernible cone movement - even during loud bass-heavy moments.

What’s going on?



It’s a sealed box isn’t it? My ATCs don’t have massive cone excursion as the air in the box maintains pressure and controls the driver…


Several things -

Firstly, and maybe most significantly, at normal programme levels there is not a lot of acoustic energy in music, therefore cones don’t need to move much except on the loudest peaks - so unless you are playing very loud, or with very loud bass peaks, they wouldn’t move a lot. However the further you are from the speakers the louder they need to be for a given sound level where you are, so the more the cones will need to move.

Secondly, with those speakers I think you’re not down in the region where the greatest movements happen: the amount of cone movement for a given loudness increases nominally by a factor of 4 for every halving of frequency. Similarly if their quoted frequency range is to the -6dB point which often is the case, at that frequency the cone would move only the same amount as it would for the same sound level an octave higher.

The other thing that can cause significant cone excursion is superimposed infrasonic signals, such as from warped vinyl - and often not directly audible, rather causing modulation of the sound, and potentially causing issues at high sound levels.