I checked my parts boxes. I looked through my junk drawers.
I espied my horizons.
I'm going to do it, dammit.
I remembered that the 5th valve section of the 345 is fully removable SEPARATE from the piston section. Further, I realized that zero tools are needed to remove the 5th valve section and swap in a straight piece of tubing, making this a four-banger that wears a little less on my lower back and hips when I lug it around.
However, since the weight difference is not nearly as much as I had hoped I never avail myself of this "feature". (It is nice to know that one day when I have to take apart the rotor to clean it out, replace the corks, etc. I can do it VERY EASILY.
Things I have recently noted about this setup: I have the exact, same Miraphone .837" rotor sitting on my bench, brand new and sort of homeless. I ended up not needing it. The only difference is that the one on the Holton is brass with nickel silver knuckles, and the new one is all nickel silver. The only problem I have with this is my inborn OCD nature.
Further, there is room for another rotor between the 5th valve and the sixth branch of the bugle. Right now it is set up as a mini slide. The valve is attached to the bugle via a very short, snug (and greased) inner/outer slide leg. I have to come up with a suitable connection point between that branch and a rotary valve knuckle. If I can do that I have everything needed here to make a slide, a lever, and a linkage.
Joe added that 6th valve to his old 2165. It was simply a tuning loop and not a usable valve by itself, however, when not in use it was still an extra twist to the open horn. AND IT DID NOT AFFECT HOW IT PLAYED AT ALL. Since that 2165 and my Holton blow so similarly I am feeling safe to believe that another rotor in the open horn would not change anything at all in how it plays.
Boys and girls, I love the six-valve system of my Kurath so much that I am dying to try it out on a CC just to see what it allows me to do, technically. Right now, without moving any slides, the horn plays quite well in tune with a few alternates. Mostly I use 13 on that overtone series (rather than 4) and for low D I pull 1st. (Oddly, bottom line G is only a tad flat and I play it 0.) However, all notes I would use a half step down have to be played 24 as my 1st slide is too short to pull out far enough for 123 to work. And below the staff in certain keys where you have to move around a lot between 13 and 24, I have a hard time at this age. But 136 would be pretty easy. If I ever had to trill Db to D (okay: never gonna happen) 136 to 13 would be a cinch.
So why not? I can make a separate 5th/6th section from one that is just 5th, and swap them out with the straight tube so that this horn could be converted to 4, 5, or 6 valves in ten minutes using zero tools.
Use for this? Probably very little, but HOW FREAKING COOL!
So I was a good dog and did my math, took my pics, made my mockups… and it works!
So I am going to add a 6th valve (that is fully removable) to this tuba because I want to. HAHAHA!!!
It will go here. There is room for a Nerf football between the back piston caps and the 5th slide. Seriously, you could stick a brown bag lunch in there, so a shorty 6th slide will be no problem.
So the 5th unit's inner slide leg is in the way to see how this will fit, but I slapped a bit of the outer tube on the valve as a ferrule and slid it over the connection with the sixth branch of the bugle and you can clearly see that, despite being tight, there is more than enough room for the knuckles without hitting the 2nd piston bottom cap. To clear this the vale has to be installed at roughly a 45º angle whereas the 5th is flat. This does not add to the issues surrounding the linkage and where I want my lever to be, which is suboptimal, at best. But everything *will* work. The blue circles show where the ports will be when the valve is in its correct location.
Oh, no! You can't get to the back cap, so the rotor cannot be removed! REMEMBER: Not only does the whole valve section come off of this tuba, but the rotary valve section can be removed separately from the pistons using no tools.
Another angle from that perspective…
Move that over to the left about an inch and a half and you got it. The 5th will be almost exactly where it goes right now. I can install all this and only have to move the base of one brace to get it all to plug in correctly.
