Instrument Design / Construction question

[Ken Herrick]

You actually have the answer to your question as your "location": one never knows!
As I believe you would find with an organ pipe - a larger bore takes a bit shorter length than a small bore to produce the same pitch.

The basic variations in design, including bore, taper, number of branches etc. seem to be largely determined, at the early stages at least, by a familiarity with a previous design which produces a result approximating what the designer is striving for.

Just as a personal example, when I first saw pictures of the current King 2341 I thought that should be a good tuba as the tapers seemed to mimic those of the old King .750in bore rotary monsters. I have never played one of the new ones and it would be different but, it seems, from what I have read that it is true.

When Ren Schilke was designing for Yamaha in late 60's early 70's he used the Besson as a template as many at that time considered them to be among "the best". I would have chosen others.

I spent a fair amount of time in Carl Geyer's shop in the second half of the 60's and up to 71. In a way, designing a brass instrument, as I picked up from that experience, is like designing an airplane. A plane that flies well "looks" like it will fly well.

It seems that the "perfectly designed" by computer Holton Phillips model tubas were not so perfect after all. Conn, many years ago, did a lot of research on the effects of placement of braces in search of the perfect tuba. Did they achieve that goal?????

Fred Marzan did a lot of experimenting with tubas built with few or no bows - LONG pipes - in search of the "perfect" bore and taper etc. funny things happened when bends had to be included to make them manageable to handle. Then there is Dr Fred Young and his experimenting. I think it was good he did it, even if some others disagree.

We now have the likes of Sam Gnagey, blending parts of different instruments to make nice ones. Lee Stofer and Matt at Dillons make some very nice instruments as do some others.

Back we go to the opening part of this. It depends what you seek and unless you have a lot of money to experiment and keep making new tooling, it is most likely that your design will be very similar to something which you feel produces results approximating what you want and make small adjustments.

What will make YOUR idea of perfection, which won't be everybody's idea of perfection?
Well, one never knows - at least not until you try and possibly find out.

[Dan Schultz]

Great answer, Ken!

[UDELBR]

Other than pitch, where do you start? Bell? Bore?

Depends on what you want, of course. I recall posts from Matt Walters. In essence they said: leadpipe largely determines response. Taper (shape of bugle) determines intonation, and bell determines dispersion into the room.

Once that is determined, how is the rate of taper calculated?

Google "exponential horn" and "Bessel horn". Of course a brass instrument isn't a straight cone, but it flares as well.

How is the overall length calculated?

Measured via midline, but "end effect" has to be taken into account as well. This page has a good, basic explanation of frequency/wavelength: http://news.bbc.co.uk/dna/place-lancash ... n/A9567723

Is a tuba with a small bore/bell shorter than a same pitched tuba of larger bore/bell?

Yes, instrument volume (i.e.: interior space) plays a role, but a minor one. Bell diameter plays a role in the "end effect" calculation.

Here's a pretty good beginner's book on musical instrument design: http://www.amazon.com/Musical-Instrumen ... 1884365086

[Matt Walters]

Why do I waste my time?

[Ken Herrick]

Why do I waste my time?

I hope Matt does not decide he is just wasting his time with his knowledgeable contributions!!!!!

Must say though, that with the way some people regularly set out to destroy worthwhile discussions here, I would not blame him for coming to the conclusion that it isn't worth the effort of trying to be helpful.

[UDELBR]

Just a curious guy who knows about acoustics, physics, and pipe organ design/construction/voicing/tuning/maintenance, and would appreciate the same amount of knowledge in how we get from blank paper to playable tuba.

THAT's where you start from. The metalworking aspect ain't rocket science, and making tubas doesn't require the same fine tolerances that trumpet-building does. The rest is motivation, a smattering of knowledge, and some trial & error (the guys at the Melton factory admitted to me that fully 3/4 of their prototypes end up as failures; either taken apart or hidden away).

[NCSUSousa]

There are tuba design notes on both Dick Barth's Blog and Oystein Baadsvick's Blog.
Oystein was involved in the development of the current Miraphone rotary Eb tubas and of the 'travel tuba' system that Miraphone can add to any of their (they only make normal sized) Eb or F rotary tuba.
You should be able to find both - let me know if you need links.

[sailn2ba]

One place to start is <http://www.phys.unsw.edu.au/jw/brassacoustics.html >