behaved than the amplitude response therefore a desired phase angle region can be predefined in the microprocessor memory and the muffler adjusted via the stepper motor 50 until the angle is in this region a minimization algorithm may be applied to the amplitude at sensor 15 to assure that the truly optimum adjustment is achieved to minimize the intensity of the pulses exiting muffler 20 it is thus necessary to tune the muffler to meet the chamber spacing requirements the distance between wall 20 3 and surface 30 2 is to be maintained at a half wavelength while the distance between surfaces 30 3 and 34 1 is to be maintained at a quarter wavelength responsive to the threshold difference in pulses sensed by sensors 13 and 15 microprocessor 100 actuates stepper motor 50 to rotate shaft 40 a predetermined amount the rotation of shaft 40 causes a coaction with ball screw 51 via threads 40 1 and with ball screw 52 via threads 40 2 causing the movement of partitions 30 and 34 partitions 30 and 34 have slots coacting with keys 20 4 and 20 5 which prevents their rotation with shaft 40 because the pitch of threads 40 1 is two thirds that of threads 40 2 the distance between wall 20 3 and surface 30 2 is always twice the distance between surfaces 30 3 and 34 1 allowing for the stepping increments of stepper motor 50 incremented changes in discharge density temperature compressor capacity pulsations the present invention will track these conditions to maintain.