 To overcome the lack of sub-bass frequencies on 1970s disco records (sub-bass frequencies below 60 Hz were removed during mastering), Long added a DBX 100 "Boom Box" subharmonic synthesizer into his system.The DBX 100 Sub Harmonic Synthesizer "recreates this lost portion of the audio spectrum by seizing information in the 50-100 Hz range, creating a signal one octave lower (25-50 Hz) and mixing this new signal back into the program.