Re: Test what you think you know: Part 2
Art, Thanks for participating in the conversation. I have some comments about yours
I disagree that a 2 1/2 piece of foam is no different than a windscreen. All screens attenuate sound to some degree. There is a big difference between a 1/8 in to 1/4 windscreen and 2 1/2 inches even if the material is similar.
For the record, here is the picture that started the conversation:
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The tape is also adding a barrier to air flow.
I am having trouble with seeing where you are going with this. I would not call the surface of the bass a boundary in the same sense as a PCC because the surface of the bass is the source of the sound wave. In other words, your boundary is vibrating. In addition, usually with a PCC the source is placed so the wave is traveling and vibrating parallel to the boundary, not perpendicular. If the surface of the bass is a boundary, then the instrument in any close mic situation is a boundary. I am not sure this is any different than pointing a mic across the top of a snare drum.
I used pink noise. Everything that is in an upright bass is in the source I used. Because I used the same source for both tests, any differences should be attributed to the only change made: i.e. blocking the ports.
I am not talking about a windscreen. I am talking about a mounting method that significantly blocks the port. I also never claimed the wrap was similar to a hand. For the cup test, I used my hand, which I noted is smaller than many and only incompletely blocks the lower part of the mic. I DO think it is significant that partially blocking the ports with my hand produced the same effects that blocking them with the bubble wrap did. And for the record, I have seen bubble wrap used in the stuff the end piece technique, even if camp mattress foam is by far the most common material.
I am willing to extrapolate far more information from these tests (including several dozen traces with two other mics in addition to the ones I posted.) then you seem to be willing to. I am almost inclined to go cut up a camp mattress in the basement just to show that my model is a fair approximation of the photo that started the discussion.
Don't have to convince me there, but I am not necessarily only comparing with a mic on a stand. There are dozens of easy ways more appropriate mics can be mounted on a bass. As much of sound reinforcement has improved by people trying new things, I see no reason to stick with a 30 year old technique that was a compromise to begin with. (Unless you really need to use a 30 year old Shure Brothers Uniball mic onstage. That happened to me on a side stage at a festival in Kentucky)
Once again, I will concede the tailpiece is a slightly better position than a stand mount; however, I am convinced we can do much better. In those famous, loosely quoted words, "This is not my first rodeo". I have had the privilege to work with most of the top instrumentalists in bluegrass, and talk with them about what they are trying to do with their tone and how to achieve it. All I can say is that I can't imagine any of them arriving on a fly date to a rented instrument and being happy with the 58 in the tailpiece solution. (This assumes that they have set up their personal instrument so this would never be necessary)
