Velodyne Digital DrivePLUSSeries - Manual (Page 16)

Comparison of Results
Because not everyone has a Digital Drive PLUS subwoofer, we will now compare the results from listening to music and looking at frequency
responses. This shows that with the “Crawl Test” technique, if you have a good ear for how bass sounds, you can choose the same locations
as the more advanced method of viewing frequency response curves.
We picked the same best locations for one and two subwoofers using both listening to music and viewing the frequency responses.
Location Listening Evaluation Frequency Response Evaluation
1 Crisp The curve was flat and within +/- 3 dB which is why the bass sounded crisp when
listening at this location.
2 Hot, heavy, boomy More level at 50 to 63 Hz. Hence, this curve has more energy in it than for Location 1.
This accounts for why the evaluator thought there was too much bass at this location.
3 Thin The dip in the curve at around 42 Hz to 50 Hz explains why the bass sounded thin
when listening at this location. The overall bass level was lower at this location
than at Location 1.
4 Crisp Although visually this curve is slightly less flat than the one for Location 1, it is still
within +/- 1 dB. This amount of variation isn’t perceptible to most people. This curve
also doesn’t start to roll off until 80 Hz as compared to 63 Hz in Location 1. The
evaluator couldn’t hear the differences between these two curves.
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Subwoofer Placement Recommendations Guide APPENDIX A