- Sun Sep 23, 2018 8:06 pm
Well in lew of an article, Tom did provide quite a bit of info in his posts.
From what I can glean by listening to DSD recordings on YouTube, (which I did over and over, comparing woods, diameters, bowl shapes, etc. to learn as much as possible):
The flat-ledge Guinea variety increases projection, and reduces something I understand as "acoustic collision". By which I mean the sound quality of soundwaves colliding. I call it this because it's also reduced by increasing the bowl diameter.
So I believe the conical bottom of a so-called Malian, or Wossolon bowl, funnels the soundwaves together. Whereas a so-called Guinean (flat bottom), with a ledge at a right-angle, causes reflection before it can allow compression and as much collision.
Similarly, the tapered style bowl (with a flat bottom ledge) would have slightly more of this affect, than a vertically straight-sided bowl (also with a flat ledge, and of equal diameter), since it compresses the sound somewhat. But diameter also affects this quality, so it's not the only factor.
Since Malian bowls seem to have better tone, but poorer projection, I've come to prefer a balance between the two:
A bowl with sides that are basically vertical near the rim, and continue to be so for about half the length, then gradually start tapering slightly, increasingly, and form a rounded corner, like the golden ratio design, so there is a ledge, but no sharp corner.
So they look like a cross between the two.
I do prefer deeper bowls, for the fuller, rounder sound. They might not project as much, but this can be addressed by using the stepped stem-flare Tom refers to (flaring suddenly near the bottom). This can be over-done, in which case it loses some power, but I prefer it to the plain conical stems or trumpet stems, for the projection and open quality it provides. Also, making the sound hole too small may help sound project out the top, but it limits it getting out the bottom, so I prefer a balance there.
But this is very fine-tuning of sound, other factors are of course critical as well, so I'm by no means implying that these are the most important features. I'm simply offering my observations from comparing these factors.