I have to disagree with this. I've had too many first hand experiences that fly right in the face of this. I'll give a few of them.Rick Denney wrote:Pitch is not about volume more than length, it's still mostly about length.
First one: I was building a 3+1 compensating monster Eb tuba. I wanted to replace the inner top bow and dog leg with one that tapered slower as the Holton one I had tapered really fast. I found one that would work, but it was quite a bit longer in length. I decided to try and see how flat it would make the horn. Now remember that it played at 440 before the change to the longer bow. Once I installed it and played it the tuba now tuned very nicely to 446. The old bow tapered very fast and got to a large size quickly while the new bow stayed very small for a long time. Because the volume of the longer bow was less it raised the pitch. I had to pretty much double the length of the main tuning slide to compensate for this.
Second one: same tuba. I had an old leadpipe from a B&H Eb that I wanted to use on it. And it played nicely at 440 with about a 3/8 inch pull on the main slide. Well when we bent it it cracked. So since I'm currently not very good at making lead pipes I decided to have Alexander make one for me. They did. Same length but it was from their 173 CC tuba. It started visually a lot larger than the old one. The old used a bass trombone shank while the new use a euro shank. With the new pipe it now plays 10 cents flat with the slide all the way in. Same length, more volume inside the pipe, lowered the pitch.
Third one: in working on this now. I started with a Holton 345 body. I wanted to make a cc tuba but I didn't want to make just another Holton chop job. I decided to use a bell from a Chinese tuba and cut the bottom of the bell to fit the bottom bow. I knew that the shorter bell would also help get the pitch higher without cutting the bows as much. So I got the bell and cut it down. It ended up being just a bit over 6 inches shorter than the original bell. Now remember from BBb to CC is 24 inches. Well after fitting the new bell I rigged it and gave it a toot. I was only 10 cents flat from B. Because cutting six inches from the bell section involved losing a lot more volume than cutting six inches from say the dogleg it made the pitch rise a lot more. Not only did I lose volume from cutting the bell but the throat of the bell was smaller which also helped to raise the pitch.
If I've learned anything from my building studies here in Germany is that any rule that you make is really only a guideline. I remember watching a fellow try some different bells on a CC tuba he was building. They all changed the sound and would move the general pitch up or down but they didn't effect the overtone series accept for one. He tested two York monster Eb bells. One sounded as you would expect but the other had this amazing sound to it. It was the clear winner, until we took the tuner to it. This horn had great intonation but with this one bell the open Gs became 40cents flat across the board. This bell was from what we could tell exactly like the other one. I can't give a good reason for it.
Troy from kanstul and I were talking once about f tubas when they were first making them. He said that over the years on BBb, CC, and Eb tubas they had learned a number of things that they could do to the taper to fix response or pitch issues and they for the most part worked across those keys. But when they started the F tubas all that went out the window. None of those things worked.
Working with and studying with some of the great builders out here has shown me that while they know a lot, there's still a ton we don't know. But the cost to experiment, to try things from scratch is so high that most can't even try. That's why so many horns are similar or based off of another horn. Hell Markus told me that a single bell mandrel for those 6/4 tubas was well over half a million.
We just don't know enough to be able to say a simple equation. If we did all tubas would be awesome and play great. But that lack of knowledge, Thats the fun part in building stuff like I do. I tend to have a good hunch on things, but a lot of times I'm just shocked at the outcome.
Build some more horns. It's fun and you'll learn a lot.
