Bore Size Poll

[iiipopes]

On piston instruments the lead pipe tends to be shorter, and I don't know of any piston instruments that are larger than about .770 for the primary bore, as to go much larger than that would make for a really long piston travel.

But for rotaries and the conventional long leadpipe, the only limitation is not diameter per se, but mass of the rotor that would cause unacceptable rotor inertia.

And all of this has to be combined with proper proportioning of leadpipe taper and bugle and bell profile to be usable.

[windshieldbug]

pistons vs rotary brings up the subject of bore profile in general.

I daresay that it's not valve bore at all, but where the valves are in the over-all profile, and the rest of the horn up to the bell throat.

Mouthpiece included.

So what is a "big" horn is not a single measurement, size, volume, height, dB, Hz, or mouthpiece.

It is what you think when you're playing it.

[TubaSailor]

I think we also have to consider context - what would be a "Large" horn (note I didn't say "Large Bore") in a BQ could be hopelessly inadequate in a large ensemble setting. The SOUND is more important than just the bore numbers. The 5/4 Rudy has a .866 bore - and it can sound huge when necessary, (but it also have a very nice pp.) I think the bore has meaning only as it relates to the weight of sound the horn can produce. Also, I think the very large bores like the Rudy's are getting close to reaching the limitations of human physiology to play. I'm learning entirely new ways of breathing / phrasing -

[peter birch]

could we have it in mm please?

[Rick Denney]

Large bore is nominally 3/4" or greater for piston tubas, .8 or greater for rotary tubas. For rotary tubas, I consider a Rudy to be large-bore, but a Miraphone 186 is not. Very few piston tubas have a bore larger than 3/4".

Medium bore is .689 for piston tubas, ~3/4" for rotary tubas. Examples: King 2341, Getzen G-50, Miraphone 186.

Small bore is .656 for piston tubas, .710-ish for rotary tubas. Examples: Conn 5J, Miraphone 184.

Note that a "large-bore" tuba is not the same thing as a "large" tuba.

Rick "thinking tuba size and bore are only loosely related" Denney

[iiipopes]

could we have it in mm please?

EDITED 6/10/08
.656 (Conn small bore) = 16.66mm
.687 (King) = 17.45mm
.689 (Besson Eb, M-W Bell and others) = 17.5mm
.708 = 18mm (A lot of F tubas, some smaller BBb)(or .709, depending on which way you round off or up)
.728 (Yammy piston & others) = 18.5
.730 (Besson BBb comp, Martin, Buescher) = 18.54
.734 (Conn souzy) = 18.64
.748 = 19mm
.750 (a lot of different makers) = 19.05mm
.768 = 19.5mm
.770 (Conn 2XJ pistons & Miraphone rotors) = 19.56mm
.772 = 19.61mm
.787 = 20mm
.795 = 20.19mm
.807 (smaller Alex bore, I believe) = 20mm
.812 = 20.62mm
.827 = 21mm
.835 = 21.21mm
.846 = 21.5 mm
.866 = 22 mm (large Rudy from above post)

[euphomate]

could we have it in mm please?

Well done iiipopes. This is a very handy reference resource. Almost every country other than the USA uses metric these days, so measurements in imperial are Greek err American to most of us.

[TubaSailor]

Thanks iiipopes for adding the Rudy --
Does anyone know the bore size on the Rudy 6/4 BBb? 23mm? - .906?

This is probably a dumb question, but I'm curious - why the fascination with bore size numbers? Is it really the most critical parameter of how an instrument will play? - Or is it the best indication of the potential sound of an instrument? I don't have experience with enough different instruments to really have a handle on what qualities of the sound / response / dynamic / etc. the bore size impacts, so maybe someone with broader experience could fill in some blanks. Aren't there so many other factors involved that the differences due to bore size get a bit lost? pm if you don't want to sidetrack the thread..... thanks.

[bttmbow]

I seem to remember my first owned tuba, a Yamaha rotary YBB 641, I think... had a .812 bore size? I may be wrong though; somebody correct me if I am incorrect.

Great horn, BTW...
CJH

[eupher61]

I agree...while having an idea of large medium small for purposes of looking for horns could be valuable, the reality of that classification is all but worthless.

Being primarily an F player for 20 years, almost anything bigger than .750 (18.64mm, I guess) is a black hole to me. Last time I tried a York copy it ate my lunch, and that's not a particularly large bore instrument.

[peter birch]

could we have it in mm please?

Well done iiipopes. This is a very handy reference resource. Almost every country other than the USA uses metric these days, so measurements in imperial are Greek err American to most of us.

I would second the thanks, it makes more sense to me now.

[Rick Denney]

could we have it in mm please?

Well done iiipopes. This is a very handy reference resource. Almost every country other than the USA uses metric these days, so measurements in imperial are Greek err American to most of us.

Sheesh. Multiply by 25.4. The burden of conversion goes both ways, especially when American tubas built to U.S. customary units are a major part of the discussion.

Rick "3 meters equals 10 feet" Denney

[Rick Denney]

This is probably a dumb question, but I'm curious - why the fascination with bore size numbers? Is it really the most critical parameter of how an instrument will play? - Or is it the best indication of the potential sound of an instrument?

I don't think it's even important, let alone critical.

The taper design is important, and that would include how the bore relates to the rest of the instrument. But the bore is just the arbitrary point in the bugle where the valves happen to reside. That point has an effect, but more in terms of its position in the taper than its diameter. The longitudinal dimension seems more important than the lateral one.

Rick "the only critical dimensions on a tuba are the dimensionless ratios" Denney

[tokuno]

According to the European manufacturers, .750"/19 mm = 4/4, 5/4, and 6/4...

...so which size tuba (4/4, 5/4, or 6/4) has a "large bore"?

All of 'em if I'm playing long tones.
Sousa marches tend to be a pretty large bore, too . . .

[iiipopes]

could we have it in mm please?

Well done iiipopes. This is a very handy reference resource. Almost every country other than the USA uses metric these days, so measurements in imperial are Greek err American to most of us.

I would second the thanks, it makes more sense to me now.

Glad to do it. As I surf, I'll add more odd bore sizes as I run across them, and I'll try to fill in some more of the manufacturer cross references as I can. Remember that I'm using the "conventional" bore definition of inside diameter of the removable second valve slide. Other measurements will vary.

Except for .687 being the only bore King uses now (at one point they did to a .750 for some tubas in the 1930's), and .734 being the only bore that Conn ever used for BBb souzys (again, with the possible exception of a few in the same era), Most manufacturers use more than one bore depending on the model, and more than one manufacturer may use the same bore. And other manufactureres may use a "stepped bore" or "conical bore" through the block, especially enlarging the 4th or (if it's after the main block) 5th valve. So this is just a take-off to get some general idea of where to start.

Notice the interesting pairs that occur throughout the chart, depending on whether the manufacturer is of English measurement origin or metric measurement origin, as 2/1000 of an inch really doesn't mean much. I'm talking about in particular .687 vs .689, .728 vs .730 and .748 vs. .750. Find me somebody who can hear the difference this makes apart from all the other variables of the horn, and I will pay homage.

And remember, leadpipe diameter and taper, bugle profile, bell taper, profile, flare and rim, and bracing have much more to do with how a tuba actually plays than bore. For example, B&S uses the .748/.750/19mm as a primary bore for many of their tubas at all pitches, and, of course, they all have completely different characteristics.

Sheesh. Multiply by 25.4. The burden of conversion goes both ways, especially when American tubas built to U.S. customary units are a major part of the discussion.

Rick "3 meters equals 10 feet" Denney

Aww, Rick, you resident genius you, don't be such a stick in the mud. Yes, anybody with a rudimentary knowledge of metric vs English and a calculator can do it. But it is still handy to have it compiled all together in one chart for ease of reference. And to just get into the geek side of things:

mm = inches X 25.4

inches = mm / 25.4

Now, instead of going on about bore measurements in millimeters verses inches, let me expound on exponential and logarithmic functions in using my TI-30 calculator from high school to get the fret coordinates on my fanned fret guitars with compound scale lengths. Or maybe not.

[Rick Denney]

Notice the interesting pairs that occur throughout the chart, depending on whether the manufacturer is of English measurement origin or metric measurement origin, as 2/1000 of an inch really doesn't mean much. I'm talking about in particular .687 vs .689, .728 vs .730 and .748 vs. .750. Find me somebody who can hear the difference this makes apart from all the other variables of the horn, and I will pay homage.

If you dig back into this, I bet you would find that it has to do with machine tools that were available in the country of origin at the time that particular tubing was made. And I think you'll find the dimensions that started out as inches are really related to fractions of an inch.

King's .687 is probably really 11/16"ID (.6875"), for example. And all .750 tubing is, of course, 3/4"ID. And .656 tubing is 21/32"ID (.65625"), or 11/16"OD tubing with a 1/64" wall thickness. And the fourth valve of my Holton is nominally 13/16".

Additionally, I think you'll find that European tubing is on an even millimeter, but often to approximate the bore of an English or American equivalent from a prior era. So, when the Europeans copy a 3/4" bore, they use 19mm, which is within 2 thousandths. And when they copy the American and British 11/16" bore, they use 17.5mm (close enough to .689).

I can't guess where .770 tubing came from, unless it was made in a machine designed around outside diameter, in which case it might be 7/8" OD (I've never taken a micrometer to the outside of Miraphone tubing, but I will tonight if I remember to). Lots of machine tools in Europe after WWII followed U.S. customary dimensions because those were the only machine tools they could buy (Germany's production of same having been destroyed). Thus, some bicycle fittings have metric diameters and English threads, for example. I don't know if that has anything to do with Miraphone's use of .770 tubing. And Cerveny uses .795"ID tubing that doesn't seem to line up to anything, but it could be something as weird as a 21mm OD tubing machine using .4mm sheet. That would also be consistent with their .835"ID tubing, which is 22mm OD and .4mm sheet.

It is surely true that we take a micrometer or calipers and measure the tubing, and the record that as the bore. That may be the dependent variable rather than the independent variable built into the machine, however. If the machine was designed to make tubing of a specific OD, and adapted to do so with thin brass, the inside diameter may have just been what it turned out to be, in which case the units used don't provide much illumination to the original nominal diameter. Many diameters, though, are metrified approximations of American dimensions they are trying to copy, and that surely explains .748/.750 and .687/.689.

(I can tell the difference, by the way, between my .750-bore Holton and my .748-bore York Master. The Holton inner tubing won't fit in the YM outer tubing.)

Rick "wondering if our resident machine tool expert has an opinion" Denney

[Dan Schultz]

I may come to some as a pleasant surprise to some folks that much of the manufacturing in Europe that was done for many years after WWII was done in English rather than metric. The reason?..... There were plenty of horizontal/vertical mills, lathes, and other machine tools with inch-leadscrews and hand cranks calibrated in 'thousanths' that remained in Europe after The War. Most of the threaded parts on Mirafone tubas are in inch sizes rather than metric.

[iiipopes]

Rick, I agree with you as to the probable origins of the various sizes. As far as the 2/1000 differences, I was referring to how they play. I also know that can make a big difference as to slide fit and finish.

The chart is now edited to include .795 and .835.

[windshieldbug]

UPDATE!
My bore is bigger than yours.

And here I thought just your *** was bigger than mine!

[eupher61]

Doc, you sayin you're a bigger bore?