A compact, portable and NIST traceable pressure source dynamically generates very low pressures includes at least one adjustable valves in-line with a fluid, such as air, flowing through the valve. This test architecture advantageously allows for changing scan inputs during the scan operation on a per shift basis. The compactor machine further includes a handle which is mounted on the operative unit by means of a plurality of first damping mounts which are spaced from the base plate. The shock absorber insert is either mid mounted between an upper and lower shaft or bottom mounted into a lower end of the lower shaft. One or more stacks of ultrasonic transducers arranged around the screw feeder may be employed in which the diameter of each transducer preferably is substantially the same as the pitch of the screw feeder.