Cut the main?

[caa62]

I have an old (1956?) Conn 14J Eb. When I got it, the lead pipe had been smashed and repaired so many times that it was all but split. I had it replaced, and the new one had an American shank receiver instead of the small shank on the original . The horn sounds much better now, and has good low end with a Helleberg. However, it tunes to about A434 . The only mod I see is to cut the main. Two questions: 1) the main is not the same ID on both sides. Will this mess up the horn, if I shorten it here? 2) If OK to cut, does anyone have a guess as to how much per side to get to A440 and have some adjustment room? Also, I'm thinking I'd need to get that brace moved up the main loop to allow for cutting. Thanks for all useful suggestions.

14Ja.jpg

[royjohn]

If I were you, I'd figure out where I wanted to be with the slide all the way in (maybe A=444?), push in the main slide and play some open notes and find their frequency. If you are at A=434 and want to go to 444, then pull the slide until you get to 424 and measure how far you've had to pull. While the relationship isn't totally linear, cutting this small a fraction of the tubing, it will be close. You'll be cutting about the amount you pulled. Just to be safe, I'l probably cut 50% to 75% of that and test first. This should get you close and give you an idea of how much more you need to cut.

I have no experience doing this, but this is a method that strikes me as being able to work. A jeweler's saw will work better than a hacksaw and a friend of mine who modifies trumpets and cuts tubing all the time uses a flexshaft (or Dremel) with a little arbor and some cutoff disks. These do break, but you can buy a bunch at one of the home improvement stores. You may be able to find a cheap Dremel at a pawn shop. They go for $10 to $15 in my town and there are plenty of them. The arbor for the cutoff disks is a cheap attachment. If you are a DIY guy and don't have one of these, you should. I have heard a lot of people say, "I don't know how I ever did without one of these."

Remember that you'll be working off a percentage of the frequency. If you're going from 434 to 444, that's 10/434=2.3%. If you're measuring the frequency of an open C, say C2 (65.41Hz), the difference is going to be 0.023x65.41=1.5 Hz. This doesn't seem like much, but at that frequency it's about 35 cents! Actually, since your tuba is in Eb, you'll be working with an Eb open note (Eb2=77.78Hz). Hope you get the idea. Google "frequencies of sound tables" to get a table of frequencies.

Main thing is to get an estimate and then cut about half of that first to make sure you are in the right ball park. Based on a trial with my Eb, 25 cents is about 9/16" of slide pull, but that's just a guess. It's so easy to lip these pitches that it's hard to tell where the note center is, for me at least. So I'd cut a little and then try for a while. Make sure the horn is warmed up, too and bear in mind you'll need room to adjust if you're going to play outside. Looking at your picture, I think you have plenty of room (looks like about an inch or more to the brace) without having to move the brace.

Maybe one of our professionals has a better method, but this is how I'd do it . . . let's see how much egg is on my face at the end of the day . . .

[Michael Bush]

I have one tiny bit of lore on this subject.

I've never had the courage to cut on an actual horn (yet). But I have for a couple of years been trying to teach myself some skills that could eventually result in doing meaningful work on a real tuba. And one thing I've learned from cutting brass tubing in the shop is that if you've got petty good instincts with your hands, the Dremel tool will help make clean cuts, because it has a gyroscope effect.

Just make sure your cutting line is square, and line the tool up well with the cutting disk spinning. The tool will help you make a clean, square cut. For me, it's a lot easier to make a mess with a hand saw.

[MaryAnn]

Other than being below pitch, is your tuba is in tune with itself, i.e., the scale is not "stretched?"

MA

[aqualung]

Get another Eb that plays at the pitch you want. And another Eb player, one that can center a tone and hold it steady.
Have them play the same note as you. The amount they pull to match you is the amount you need to cut.
Don't be concerned about the difference of the slide I.D.s. In a perfect world, there would be no cylindrical tubing at all.
I have the same Conn model. I play it with the tuning slide all the way in, using a smallshank mouthpiece.

[caa62]

Thanks for all the replies. This weekend, I gave the thing a good flush (because I hadn't since I got it last fall), and nothing gross came out. Next I checked valve alignment, which was OK when open, but 1 and 2 go down too far when depressed. I put some temporary spacers in the valve caps, but I need to find a source for felts and cork spacers. I have an old mouthpiece with a very small shank that I had to wrap with teflon tape to get it to seat in the American shank receiver. With this piece buried all the way in the receiver, it is only a little flat, so that gives me an idea how far off I am. The scale is not stretched, the only wierd pitch is 4th space G, which is very sharp open, but OK with 1+2.

As to finding another E-Flat and player to compare with, that's a great idea, but it's not happening in this neck of the woods.

I'd really like to try this horn with a Wick 5 or something similar, so I'll keep my eyes open for one. Thanks again, and I'll update if I proceed further.