TubaForum.net

Tubajug wrote: ↑Wed Apr 28, 2021 7:44 pm

UncleBeer wrote: ↑Wed Apr 28, 2021 11:32 am

Yorkboy wrote: ↑Wed Apr 28, 2021 7:35 am This particular instrument plays in tune at a length of 214.25”; with an 18.5” bell, this would mean that the acoustical length of the horn would actually be over 225 inches - (9.25” x .61) x 2 = 11.28” - could this be possible if there’s an end effect that adds almost a foot of length?

That's my understanding of all this.

I'm jumping in here trying to understand a bit of this as well.

So for simplicity's sake, let's go with the 16 foot length of a CC tuba (192 inches). If it's got a 20" bell (which the one I'd like to build actually does...), the bugle itself only needs to be about 180 inches long to account for that 12 inches of end effect?

That would actually help me a lot since I'm cutting a BBb bugle. That would mean a good deal less tubing to cut (12 inches vs. a full 24).

To make a weak attempt to answer your question (my poor grasp on this subject notwithstanding), in practical terms (which is the only experience I have), I’ve yet to encounter a situation where I’m building a horn that isn’t more than 2 to 4 inches off (usually trending closer to the larger number) of the nominal “target” length, meaning, on a BBb tuba = 216”, or on a CC tuba = 192” (for example, the before mentioned BBb tuba I’m building plays in tune at @214.25” - I’ll be building it to @212”, which is 4” off the nominal measurement of 216”).

(This takes into account you don’t want to build a horn that is perfectly in tune with the MTS pushed all the way in......there needs to be a few inches of leeway subtracted to push the slide in further to accommodate when you are playing flat, such as colder temperatures, etc., hence the @ 212” figure.)

How the end effect factors in to all of this, in light of my personal experience, still eludes me.

For a CC tuba:

C1 is 32.7Hz when A=440Hz

Speed of sound in air is ~343m/s.

Wavelength = 343/32.7 = 10.5 meters per cycle

But a CC tuba only needs half that length (closed pipe cone), so without corrections it would be 5.25 meters long or 17.2 feet.

Subtracting off that end effect correction of roughly a foot gets you to ~16 feet.

matt g wrote: ↑Thu Apr 29, 2021 3:01 am For a CC tuba:

C1 is 32.7Hz when A=440Hz

Speed of sound in air is ~343m/s.

Wavelength = 343/32.7 = 10.5 meters per cycle

But a CC tuba only needs half that length (closed pipe), so without corrections it would be 5.25 meters long or 17.2 feet.

Subtracting off that end effect correction of roughly a foot gets you to ~16 feet.

So, in essence, the “end effect” is an explanation as to why a CC tuba exists at 16 feet (or a BBb tuba at 18’, etc.), not “nuts-and-bolts” additional data that needs to be factored in when building one? That’s how it seems to me......

(Still very interesting, just the same!)

@Yorkboy, yeah, that’s the way I understand it.

I wanted to work from (kinda) first principles and establish what the length of a pipe that has a fundamental of C1 would be, and then apply the end effect correction and see if it agreed with reality.

The good news is that it does!

But to your point, yes, the 16’ length convention has that all factored in.

Just dropping this link off as well:

http://hyperphysics.phy-astr.gsu.edu/hb ... pecol.html

It will provide some of the needed calculations.

How much are wind instruments going to need to be lengthened (and Stradivarius violins sawed off) to deal with climate change?

Are these expenses classified as infrastructure?

Also, keep in mind: as was already mentioned in this thread, internal volume of an instrument has an effect on acoustic length of a brass instrument as well. That's why a euphonium is shorter than a trombone.

As if this wasn't complicated enough already.

So a holton 345 BBb has less length then a 103 3/4?

And I suppose length in the mouthpiece counts more then extra length in the last bow.

LargeTuba wrote: ↑Thu Apr 29, 2021 9:05 am So a holton 345 BBb has less length then a 103 3/4?

Yup.

As he is CONSISTENTLY very nice...
Matt Walters was extremely nice to me - several years ago - and sold me a gorgeous-condition M-W 2165 for an affordable-to-me price.

As that model mostly only significantly differs from a 6450 model on each end (bell/capillary ends) I altered that 2165 to more imitate a 6540.

In addition to a smaller mouthpipe tube, I incorporated a smaller main slide, smaller dogleg, and (having rounded one up...possibly a donation from UncaBeer...though my memory isn't 100% on whose generosity that was) I also inserted an EARLY-VINTAGE 2165 "tone ring" into the bell...which (duh) - in effect - rendered the taper of that 2165 bell SMALLER.

...and (having done all of those things) I had to make the main slide LONGER, as (yup) the pitch rose.

bloke wrote: ↑Thu Apr 29, 2021 11:44 am (having rounded one up...possibly a donation from UncaBeer...though my memory isn't 100% on whose generosity that was)

Guilty as charged. Glad to have played a small role in your creative mischief.

UncleBeer wrote: ↑Thu Apr 29, 2021 3:55 pm

bloke wrote: ↑Thu Apr 29, 2021 11:44 am (having rounded one up...possibly a donation from UncaBeer...though my memory isn't 100% on whose generosity that was)

Guilty as charged. Glad to have played a small role in your creative mischief.

Thank you again.
That tuba - sonically - was VERY “hot”.
I always had to listen, and be careful to not step on the gas.
The IRIS Orchestra used to sell tickets to dress rehearsals for roughly a third of concert ticket prices. A tuba player friend/customer would usually go.
He reported to me - during a break - that the tuba’s vibration - during our run-through of the Copland ‘Fanfare...’ “thumped him in the chest“.

bloke wrote: ↑Thu Apr 29, 2021 5:16 pm He reported to me - during a break - that the tuba’s vibration - during our run-through of the Copland ‘Fanfare...’ “thumped him in the chest“.

That was always my impression of Warren Deck's playing in Avery Fisher. Even when he was warming up softly, I could feel his sound in the floor. Never matched.

UncleBeer wrote: ↑Thu Apr 29, 2021 5:54 pm

bloke wrote: ↑Thu Apr 29, 2021 5:16 pm He reported to me - during a break - that the tuba’s vibration - during our run-through of the Copland ‘Fanfare...’ “thumped him in the chest“.

That was always my impression of Warren Deck's playing in Avery Fisher. Even when he was warming up softly, I could feel his sound in the floor. Never matched.

I’m so happy I was able to hear him live a couple of times. While the recordings are amazing, it was nothing like live.