Odd Euphonium Modification Question. Tuba Tinker?

[CA Transplant]

Along with my Blessing 3-valve euphonium, I also own a 3-valve Czech euphonium made in the 1920s, labeled as a New Yorker. It has a smaller bore than the .585 bore of the Blessing. I'm thinking about an experiment with that old horn. It's flat, overall, so I'm already planning to shorten the main tuning. But here's a new I idea I have been musing over:

Measuring the bore of the tubing exiting from the 3rd valve, it appears to be the same as many large-bore trombones in a section before the conical expansion begins. So...what I was thinking was maybe cannibalizing the F-rotor and tubing from an otherwise trashed trombone and adding that to the horn. Since the rotary valve I'm looking at is straight-through, it would be an easy install in that exit tubing from the 3rd valve, and the tubing on the attachment would fit neatly into the horn on the back side of the instrument. It would need a couple of braces, of course, but that wouldn't be too terribly difficult.

My reasoning is that the tubing length and tuning slide for that F-attachment should be close to correct, lengthwise, to match the euphonium and might actually not require any modification, since the overall tubing length is pretty much the same for the 'bone and the euph.

The rotor trigger would have to be modified, of course, but it should be possible to do so and let the pinkie finger of my right hand operate the valve. I can see some issues with this addition, but they look solvable in my mind's eye. Now, mind you, this isn't about to become my primary instrument, but it sounds like a cool project.

Any thoughts?

[Dan Schultz]

I once added the rotor and associated tubing from a trombone F trigger to a Trombonium and it worked out just fine. There's only one way to find out for sure... do it.

[CA Transplant]

Glad to hear that someone has tried it. I'll start looking for a junk trombone with an F-trigger. It should be interesting.

[iiipopes]

Be careful where you put the braces that you don't get them on an anti-node and damp the resonance of the note, causing the pitch to be unstable.

[CA Transplant]

Bloke: The euph in question is an old Czech instrument. The bore is smaller than today's euphoniums. From my initial measurements, it appears to match most large bore tenor trombones closely. Once I take a better measurement, I'll be able to do some research and find some good matches. I looked at a Bach large bore tenor the other day, and from an exterior measurement of the tubing on both instruments, it looks like a match for this old Czech horn. It has a crushed bell, so it's a candidate I'm considering. I can get it really cheap. I'm paying attention to the outer diameter of the tubing, because that will have a large effect on how easy it would be to splice the rotor into the tubing leaving the third valve, which is where I want to install the valve. I need to take my digital caliper over and measure the actual tubing.

The same thing couldn't be done to my Blessing, because its bore is .585. That would require a bass trombone, and I doubt that I'll find one of those in salvage condition. This is not really a serious experiment, since I'm not planning to use that old Czech horn for anything but novelty. I'd just like to see if the project is doable and if doing it would make that old horn into a 4-valver. I might play it at Tuba Christmas, though. I wouldn't spend much on the attempt, that's for sure.'

By the way, I like the wrap in your example. It would fit nicely on the back side of the euph, nestled behind the other tubing. Same thing with the Bach horn I'm looking at. Nice and compact. The real engineering will happen with the trigger paddle and linkage. I want it in a position so that I can use my right pinkie to operate the valve without altering my normal hand position. Now, that might take some doing. I won't know until I can put the stuff in position, though.

[CA Transplant]

Be careful where you put the braces that you don't get them on an anti-node and damp the resonance of the note, causing the pitch to be unstable.

Good point. The old Czech instrument is in raw brass, since the lacquer long ago disappeared. That will simplify experimentation, and I'm not that concerned about appearance, so if I have to move a brace, it wouldn't break my heart. What I'll probably do is try to use the existing brace positions, since I assume those will be properly located. I should be able to use the existing brace mounts and custom fit the length of the bracing rod.