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I did some mocking up; I did some photographing. I even did some measuring.

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.

The lever would be a hinged bar across the back of the 1st slide that I can access from any position so long as I have my hand on the slide crook. It would be pulled from back to front by my left thumb.

Anyway, I think this will be fun to do, won't cost me anything out of pocket, will be pretty easy, and will add some functionality. Will that be USEFUL functionality? Who knows? I never thought I would like a 6-valved F tuba, and I was seriously wrong about that.

Also, another experiment is to make an extended slide to drop 5th to the flat major third (or 23) used on Mirafones in the old days, which I learned and sort of prefer.

That would make this tuba have 4 pistons PLUS:

• M2 5th
• M3 5th
• M2 5th, m2 6th
• no 5th or 6th

Move over, Jinbao. I'm going to get "more bang for my buck" without you.

I eagerly await another excellent build thread!

I *thought* I had everything I needed to do this.

I was sadly mistaken. However, I can get by with what I have. I need a 2nd crook for the bore size I am using, and I don't have one. I do, however, have a 1st crook, so I made do with that. Of course, this leaves me with a nearly functionless slide, with a mere one inch of pull, so I had better get this right because there will be next to zero adjustability. <sigh> I am making this so that it will be easy to pull the slide from the valve and make another using the needed crook once I get one. I may play this and decide it is not worth the expense and time. I really don't know yet.

Anyway, I managed to hack together two runners that will allow for the use of a 1st crook. I cut the four needed ferrules and then had to screw around with the two runners, nipping out length bit by bit to try and regain some for the slide legs. It took me forever. Two ferrules and the runners have been soft-soldered to the case of 6, using the crook as my alignment point. This will help me line up the very short legs, which I will cut and install tomorrow… maybe…

Si once again, this is not going to plan, but it will work just fine. In the pics, the crook and its two ferrules are just press-fit. The 5th is still in line with the 6th, so I need to take them apart from one another so that I can fiddle with the angle of the 6th.

I still have to decide how I want to attach this to the bugle. I think what I already have would be good, but the parts have to lose about half of an inch of length to work. Hmm…

I feel you on this mod. If I still owned a C instrument and was still fighting low D tuning, I would be scratching my head about a way to get this done... and sure, it dials in other things as well. With the instrument I have, that pitch is obviously now C, is rarely requested in gig sheet music, and the third-valve-alone fake version is remarkably good - which is something to which I wasn't accustomed (but which obviously pleases me).

In regards to that circuit loop, am I still considered to be a manly man if I refer to its shape as "cute"?

Once done, where will you then be storing your lunch?

Alas, I must now eat in the car on the way to work.

I finished the 6th circuit. It has a nice pull sans "ting" upon extraction, so despite being difficult to align due to its shortness — I nailed it. Horray, me. I would like to add one of those 186 one-piece braces, but being of a fatter bore, I am not sure if the radius of the crook is the same. I can always fit and install a three-piece brace, I guess.

The 5th and 6th are still on the same plane, and they need to be more than 45º off, so I have to pull them apart, clean inside/outside the joint parts so that I can press-fit them together, and rotate them to the correct angle. There is a small chance that this slide will not fit the space, but I think all my eyes are dotted and tees crossed in that regard. Maybe not.

I have one major issue that I have to ponder as I sleep. (The best time for me to solve problems is when I am not actively worrying about them,) I still do not have a plan for connecting 6th valve to the sixth branch. I have ideas, and all will work, but not as well as what I have. So I need to be getting more sleep at night so I can figure this out.

If I can get this installed to the removable rotary section (well, since that is just the valve and the slide and the two ends that splice them together, I guess it is more like removing the old slide and installing it to this pair of valves) I can make my lever, which is something I enjoy quite a bit.

Connecting that lever to the stop arm on the 6th will be less amusing, but I think I have that sorted already. (I took a nap, you see…)

Porn time…





I hope everyone is having a wonderful day of thanks.