How to Measure a Tuba??

[marzan122]

A friend of mine has an early 1900's York BBb 3-valve top action tuba. I am wondering how this model differs from modern copies. Are all the copies based on the Chicago York?

My friend's horn has a 19.5 inch bell and a .658 bore.

If you were to measure the dimensions of a tuba, how would you go about doing it? The bell diameter and bore size are easy, but what about the general taper of the instrument????

How can you measure the flare of a bell?

Thanks.

[Bob Kolada]

A friend of mine has an early 1900's York BBb 3-valve top action tuba. I am wondering how this model differs from modern copies. Are all the copies based on the Chicago York?
My friend's horn has a 19.5 inch bell and a .658 bore.

I would think your friend's horn is the smaller 33, comparable size wise to a 2341 or a 56J.

[Wyvern]

I always think the circumference around where the bell meets the bottom bow is a pretty good indicator of size as it is in effect the tuba's throat size, although the height of the bell will cause variations. It can be easily measured with a tape measure;

4/4 = 14 to 15"
5/4 = about 17"
6/4 = 19" to 20"

[Steve Marcus]

I always think the circumference around where the bell meets the bottom bow is a pretty good indicator of size as it is in effect the tuba's throat size, although the height of the bell will cause variations. It can be easily measured with a tape measure;

4/4 = 14 to 15"
5/4 = about 17"
6/4 = 19" to 20"

Jonathan, that might be the most empirical method of determining the 4/4-5/4-6/4 label that I've ever seen proposed. It could even apply to sousaphones!

Now, getting your criterion universally accepted by manufacturers, players, let alone TubeNetters, is another matter. As we know, certain manufacturers throw the entire scale off kilter with their own marketing labels (e.g. Rudolf Meinl)...

[Dan Schultz]

Fill the entire bugle including the mouthpipe (but none of the valve slides) with water. Be sure to eliminate all air bubbles. Pour out the water a liter at a time, and describe the size (volume) of the tuba in liters + the bore size of the valveset.

ie: 22 ltr. / 18mm

...etc.

--------------------------------------

No, no one uses this method, but it is (easily arguably) far more accurate than "3/4 - 4/4 - 5/4 - 6/4".

Yup. I would think the volume would be definitive. Of course... you'll have to categorize the findings into different keys of tubas. Obviously, and Eb tuba would contain much less volume that a BBb tuba.

Additionally... it would not matter what the configuration is.... whether it be an upright tuba... bell-front... top-action... front-action... sousaphone... raincatcher... helicon

[imperialbari]

One may wonder why a couple of resident scientists haven’t yet presented the application of their standard methodology on this problem:

Measure the dimensions and the air temperature of your test room.

Fill the test tuba with hot air.

Blow hot air out of the test tuba.

Measure the effect on the test room air temperature.

From there you can calculate the test tuba’s volume as a fraction of the test room volume.

Klaus

[oedipoes]

One may wonder why a couple of resident scientists haven’t yet presented the application of their standard methodology on this problem:

Measure the dimensions and the air temperature of your test room.

Fill the test tuba with hot air.

Blow hot air out of the test tuba.

Measure the effect on the test room air temperature.

From there you can calculate the test tuba’s volume as a fraction of the test room volume.

Klaus

Yip!
GO PSYCHROMETRICS ! (look it up)

Wim

[marzan122]

I must clarify. I am not interested in whether this is a 3/4, 4/4, 5/4, or a 6/4 tuba. I am interested in how to measure the taper of a tuba.

A tuba, being a conical instrument, gets bigger starting from the leadpipe all the way to the bell, with a cylindrical section for the valves.

The rate of change of the taper can itself be different (and I assume is) from one section of the tuba to another.

How does one measure these dimensions?

Thanks.

[Rick Denney]

I must clarify. I am not interested in whether this is a 3/4, 4/4, 5/4, or a 6/4 tuba. I am interested in how to measure the taper of a tuba.

A tuba, being a conical instrument, gets bigger starting from the leadpipe all the way to the bell, with a cylindrical section for the valves.

The rate of change of the taper can itself be different (and I assume is) from one section of the tuba to another.

How does one measure these dimensions?

Thanks.

At defined intervals along the taper, measure the circumference of the tubing, divide by pi, and that's the diameter. Then, subtract the thickness of the brass (which has to be assumed or measured by disassembling the instrument and measuring the edges that insert into the ferrules) to get the inner diameter. Take half that, square it, and multiply it by pi to get the area. Use that area as a sample of a length of the taper, and multiply by that length. That gives you an approximation of the volume.

What that means, though, is anybody's guess.

Bell tapers are usually modeled using cardboard templates that are trimmed until they fit the shape perfectly. It usually takes several because the bells on old tubas are usually no longer symmetrical, and then a estimate is made.

When I wrote this article, http://www.rickdenney.com/york_vs_miraphone.htm, that's how I made my measurements. Again, what does it mean? Nobody really knows for sure.

In the instruments I've seen, the taper is usually conical in sections. By conical, I mean that the taper is constant in that section. I usually see a constant taper from the main slide to the bottom bow, a bigger taper in the bells stack, and then a flare (which by definition does not have a constant taper). The leadpipe often has a constant taper, or at least it starts out that way. There may be a taper between the last valve and the main slide, maybe not. Some instruments increase the bore from one valve to the next.

It's the sum of all these tapers that determines the acoustic characteristics of the instrument, and the more one knows about the science of that, the more one will be surprised that any musical series of harmonics can be achieved.

I have two reasons for measuring something: I want to build a model of it in the hopes that the model will help me understand it, or I want to reproduce it. Many attempts at building such models have been attempted.

Rick "wondering what you hope to achieve with measurement" Denney

[iiipopes]

Measure it by how much beer it can hold, and then see how long it takes to drain it through the 4th valve: 4/4 = 1 minute; 5/4 1:15; 6/4 1:30; Rudy "Bayreuth" @ 2:00.