The Caliper was Apogee's first 'small' full range 2 way ribbon speaker. However small sized did not mean easy to drive.

The impedance was an average 3ohms but was more difficult to drive than that suggests. It required a brute of an amplifier, at the time only something like a Krell KSA-50 was man enough for the job. It would be interesting to know what people used to drive them other than the Krells of the time.

Positioned incorrectly or too close to walls and it can sound bloated in the bass.