The Model #CD-102 is specially recorded with every low frequency audio tone from 10Hz to 121Hz in 1Hz increments.  Most other test tone CDs only give a few test tones in this range or one broadband pink noise test tone.  The benefits of the CD-102 having every tone with no gaps is improved accuracy in woofer frequency response tests.  And this full range of test tones is absolutely essential when calculating room resonance frequencies and hunting down vibrating objects in the room that add noise & distortion when excited by their respective resonant frequencies.  Often times the objects & room resonance are excited at frequencies not found on other test CDs, so they go undetected.  Every object in your room has a resonant frequency and it will vibrate and possibly give audible noise when excited by it's resonant frequency when produced by the speaker system.  This becomes unwanted shakes, rattles, and buzzing during music and movie soundtrack playing.  Under normal playback the program material tends to mask the source of these unwanted noises, making them hard to track down.  And, since the object only makes noise when excited by it's resonant frequency, it doesn't buzz all the time.  Many times these noises are mistaken for equipment problems, blown speaker drivers, over-driven speaker drivers, distortion, clipping, etc. 

By having every frequency available through your CD player with a repeat track option, you can play the exciting frequency as long as needed to discover the exact room resonance for correction or hunt down noise problems and find a way to fix it with tape, gum, felt pads, etc.  The CD-102 turns your CD player into a high-resolution low-distortion digital audio generator.  Simply use your direct track entry remote control to select the exact frequency you want to play.  Now, for the small price of this CD you have the full use of an extremely expensive low-frequency audio tone generating system.  Now you can easily test those woofers & subs and track down pesky noises.

Test CD produced by Don Hoglund of Granite Audio using Hewlett-Packard Dual-Channel Digital Storage Spectrum Analyzer, HP decibel meters, Tektronix ultra-low distortion audio signal generator, Tek digital frequency counter, Tek digital decibel meters, and Tascam Pro-Studio CDRW.