Re: Test what you think you know: Part 2
Jay,
Nice to see some measurements to test theory.
1) Using open cell foam to mount a mic in the tailpiece does not block the ports any more than a thick windscreen. Using closed cell foam for wrapping a mic sucks.
2) The change in pattern created when using the cardioid mic mounted on the surface of the bass is similar to that of a PCC (phase coherent cardioid), the surface of the bass is a boundary, the mic in close proximity to the boundary is not subjected to multiple path length reflections.
3) Neither of the two distance tests remotely resemble an upright bass sound source.
4) "Not quite the same" is an understatement, one would not consider using bubble wrap as a windscreen, and the bubble wrap (two thin pieces of plastic with a variable air pocket) is also not similar to a hand cupping a mic.
5) Yes, wrapping a mic in bubble wrap adversely affects both the pattern and frequency response.
Wrapping a mic in open cell foam and placing in the tailpiece actually works far better than a stand mounted mic for sound reinforcement of an upright bass for the following reasons:
1) The mic position remains consistent regardless of the bass movement, freeing the player to play rather than keep his instrument an exact distance from a stand mounted mic.
2) The bridge position is the loudest point of an upright bass, other than F holes, which have a hollow, boomy sound, and promote resonant feedback. Loudest source makes for more gain before feedback. It is in theory possible to keep a stand mounted mic close to the bass, but in the reality of nearly every upright bass player I have encountered, the mic distance in performance always varied by at least a 2 to 1 ratio, a six dB variation in level and drastic tonal change.
3) The boundary effect eliminates ragged response associated with the multiple surface reflections of a stand mounted mic. Smoother response means better sound quality, as well as more gain before feedback, especially critical when stage monitors are close to the bass.
For the above reasons, and years of comparing on many different jazz, rock and bluegrass shows, I find the tailpiece position to work better than any stand mount alternative.
Art
