I too am struggling somewhat with this. Of course venting the palm D key is one approach, but I want to know if anyone has direct experience with fixing the underlying problem. Here are some possible approaches, I would like to know if anyone can comment on them from experience.
Lower octave vent - bigger? smaller? tube extend further into bore, or extend less distance into bore? I do notice that compared to say an alto, it seems that the bass sax vent tube is comparatively smaller in diameter.
Lower octave vent - different location? I notice that the location is same on my bassax as on my baritone and tenor, yet the bass' D is very hard to get to speak and the tenor and bari speak easily. The lower vent is between D# and E tone holes, and it's intended to vent notes from D through G#, so it's already a compromise that's heavily biased toward the D side of things (if it was exactly in the center of the range for which it is supposed to vent, I think it would be located across from the F tone hole) Has anyone direct knowledge of relocating a lower octave vent and improving the problem?
Third vent location? Where? How to design the linkage, would it open simultaneously with the current lower vent, as the Yamaha baritones do?
What mouthpiece characteristics seem to mitigate the issue (if there are any)? It seems that my dill pickle bass MP may be "less bad" on this than my large chamber bari mouthpiece. As an aside, the dill pickle MP has to go on the neck about 1" further to play in tune than the bari MP; maybe this is implicated in the problem? If I had a really huge chamber MP, might the "way on the neck" position result in cleaning up the scale dimensions and curing the middle D problem? Has anyone else with more experience seen this, or the opposite?
MRZEL, can you provide details/update on the pantyhose/splitter proposal?
For information, the horn in question is a Noblet, short wrap French style, keyed to high F. MPs tried:
- Geo. Bundy dill pickle style, true bass MP, "woolly" sound with weak projection
- Meyer 8 Bari MP with a small wedge, and chamber hogged out for a past project, not satisfied with sound and intonation esp. in palm keys not so good, no longer using
- Runyon model 88, facing lengthened to ~ 27-28 mm as recommended by Paul Coats, tone fairly bright, middle D extremely stuffy
- King "B" bari mouthpiece, long flat baffle with large chamber, facing lengthened to 27-28 mm, good tone, best intonation of the batch except maybe the true bass MP, can get middle D to speak inconsistently depending on how I voice it (coming down from above it almost always speaks well, coming up from below it's tough and usually splits up to an A).