That's what people call a false tone. I'm kinda surprised that it sits on a G, since it's usually a low F (or an Eb on a BBb tuba), but different tubas play that funky harmonic a bit differently.mandrake wrote:There is a harmonic, probably on G, which I can reach with no fingering.
From there, yes, you can go down chromatically to the pedal, and it can sound good with proper practice. It'll sound different from the same notes played with "correct" valves, which is why people are recommending using them.
The best way I found to figure out bottom-octave fingerings has been to play them an octave higher. Use the fingerings that you'd use while playing low, but just play higher so that the pitch is easier to center AND you can directly compare the many-valved-fingering to the standard one. This is different, however, from the false tone harmonic that you're talking about.
The good thing about the false tone fingerings is that they have less tubing in the way, and can sound darker & more open for the same effort.