The Aspara HL1 is really a direct descendant of the Impulse H2/Ta’us loudspeakers.

In the larger Impulse loudspeakers, mid-frequencies were reproduced by a horn driven by a Seas 11FM drive unit.  In many ways the mid-horn /Seas 11FM combination of the H2 works well, but it doesn’t quite have the ’grip’ of a small diaphragm pressure driver with a powerful magnet assembly, feeding a suitable horn. The 2” titanium driver in the new HL1 is specified as having a sensitivity of 108 db for 1 watt.

This doesn’t just mean miniscule amps can be used to drive it, it means that much more of the power being fed to it is being converted to useful sound output, so there is much less stored energy and the transient response is better.