It is not generally appreciated that with small loudspeakers such as these the amount of bass that they are able to reproduce is decided entirely by the diameter of the diaphragm. Changing the port size and the box volume will appear to change the amount of bass but all that is happening is that the cone is less well controlled and the speaker is starting to boom. Judicious use of this phenomenon can create a realistic illusion of real life but it also results in a deterioration of mid range performance, dynamic range and even dulls the treble. Hence some manufacturers choice of metal tweeters. AVI work closely with the drive unit manufacturers to ensure that the enclosure volume is chosen to minimise distortion, maximise power handling, mid range clarity and low frequency performance. The result is that for the money very few loudspeakers offer a similar performance.