TubeNet

These folks have some brass instrument transmission-line model simulation software:

http://www.bias.at/index_e.htm

Mark H wrote:What is it that makes some tubas play in tune better than others?

... that depends a great deal on how the tuba is being used! In the symphony, for example, the 'A' would change from orchestra to orchestra, and oboe player to oboe player. Then, I remember not only using equal temperament with piano soloists, but also, with the trombone section, we would often use a form of just-intonation or mean-tone for chords (depending on their usage in the piece). So one could easily say that the horn's (in combimation with the mouthpiece) ability to change intonation makes a horn play "better in tune"!

Mark H wrote:I think it would be really interesting if a study were to be done that provides the measurements of bore size, at each point along the way from the mouthpiece receiver to the bell, of tubas of various brands and pitch characteristics of each.

If this could be done without destructive testing, every tuba manufacturer and player would be in line!

Mark H wrote:What is it that makes some tubas play in tune better tshan others? (Aside from the obvious answers) I heard that some manufacturers change the shape of the lead pipe in order to bring the 5th partial up, etc. What makes some tubas play flat above the bass clef staff? (I am interested in the pitch tendencies of the open bugle only, not the valves)

The obvious would be, that the different makers haven’t all adhered sufficiently to the most time honoured research method within brasses: trial and error.

The 5th partial is always flat compared to the equal temperament scale even on a Pythagorean monochord.

In tubas and other brasses the problem is, that we want to play in more than the basic key of the instrument, where the flat 5th partial often works well. So we need a solution around that 5th partial.

Conn made their 2XJ tubas and 20K sousaphones in a way said to remedy the flat 5th partial. But then these instruments are said to have a flat 3rd partial, which isn’t desirable either. Actually worse for most amateurs their repertory taken into consideration.

My take on the flat 5th (and 10th) partial problem is: if the instrument sounds like I want it to, and if the tuning in other areas is manageable, then I will find my ways to handle the 5th partial and its derivate notes.

One tool may be a mouthpiece, which augments my control over intonation matters.

Another tool may be re-fingering, which preferably takes a 4 valve instrument.

The problem with the flat 5th partial isn’t made easier by its often quite sharp neighbour, the 6th partial. Some euphonium players employ a main tuning slide trigger to help out on this matter.

Mark H wrote:I am wondering if some software has been designed to test different designs on a computer WITHOUT having to build an actual tuba to hear the intonation tendencies on different partials.

The Viennese sample has been mentioned. The Technical University of Hannover has an acoustical department, where German makers can have their prototypes tested from the same points of view.

Aside from the overflow of the market with bad Chinese and Indian instruments, the general level of student instruments has improved immensely through my 45 years with brasses. That is an important fact for a brass teacher, albeit retired like I am.

Within the high end trumpet and trombone areas a few makers have started to offer modular designs, where just about every single piece of tubing can be ordered to a range of specifications.

That is very good for the few wealthy high-end players, which can go to the makers workshop and spend a few day testing a host of permutations, before they have their instrument finally assembled.

I am personally intrigued by the idea, but an instruments’ retailer/repairman friend of mine tells, that this situation is a nightmare for businesses like his. There is no way, that he can afford keeping all these various parts in stock, so that he can act as a sub-“boutiqueâ€

Manufacturers fiddle with things until they find an acceptable compromise. They also remember what they did in the past that worked in similar situations. I've found that instruments that play very well in tune and slot very securely also have a very bland and boring sound. Call me a luddite, but I just can not see any benefit to a greater understanding of the intonation of brass instruments. So far I haven't found a modern bass tuba that even comes close to my 1850's bass saxhorn for tone and versatility. Intonation is a wash. I would much rather see new instruments invented than continue pointlessly refining the ones we have. How about a playable subcontrabass tuba? How about a keyed didgeridoo?

-Eric

Every model seems to have its own intonation quirks, but here are the general tendencies that I have observed:
1. The flatnes of the fifth partial (D in the middle of the staff on a BBb tuba) seems to be related to the fatness of the instrument. Open D is usually usable on a smaller instrument such as a Fullerton Olds O-99 or a King. On the fatter tubas that I have tried, such as Martins, Cerveny Kaisers & Conn 20Js the D is usually too flat to use. Older Kings from the 1930s had the tuning slide in the leadpipe; those instruments had a D that was not flat at all, but the open F above it was way sharp.
2. A uniform taper throughout the instrument usually results in better intonation than a taper that is interrupted by cylindrical segments, i.e, tuning slides. Of course tuning slides are necessary, but having both sleeves the same bore is a mistake. Most trombone tuning slides have the smaller sleeve attached to the slide crook and the larger sleeve attached to the bugle. This produces a closer approximation to uniform taper. I find that a similar design is beneficial for tubas. (The conventional design is better for student instruments however, because it is more durable.)
3. Conical BBb tubas such as the Olds and older King models have a good "false pedal Eb", while tubas with exponential taper such as Bessons, Yamahas, and Werils do not. The conical tubas also tend to make a nice tone in the low register, where exponentially tapered tubas tend to be more harsh down there.
4. Altering just one section of a tuba (such as the leadpipe) cannot alter one partial without affecting the others. But theoretically you could do so by modifying the entire bugle.

Art Hovey wrote:3. Conical BBb tubas such as the Olds and older King models ...

That's an interesting design parameter. Where exactly does this show up? From casual examination of my own tubas, my clumsy measurements at 3 foot intervals makes all 3 of them look more or less conical. I'd have to measure more carefully to say for sure, but am I measuring the right thing? or is this mostly about the bell?

Maybe it's all because I'm measuring outside diameter, but they actually seemed to have a slightly less than conical shape, i.e., each larger diameter a bit less than predicted by the previous two. The helicon and sousaphone pulled out of it a little towards the bell, but the little Orsi Eb held it up to the bell flare.

Go read Horns, Strings and Harmony by Arthur Benade and The Physics of Musical Instruments by Fletcher and Rossing. You'll learn much.

Basically, the pitches produced are the results of three influences, the player's lips, the mouthpiece, and the instrument. Each has an impedance curve which defines the resonances. Lips have a broad impedeance curve centered (hopefully) over the pitch desired. Mouthpieces have a less broad curve with more central pitch and less noise. The tuba has a series of resonant peaks depending on the length of the bugle and the design of the taper.

A change in the impedance of any of the those three components will change the pitch. Benade concludes that a mouthpiece with a higher "popping frequency"--the pitch you get when slapping the open mouthpiece flat against your palm--tends to push the instrument sharp in the upper register. Higher popping frequences result from smaller cups and larger throats. Larger throats in mouthpiece also reduce the central tendency of a pitch, making it easier for the player to adjust the pitch by embouchure.

The resonances of a tuba are controlled by the taper design first and foremost, but there are lots of influences on intonation as evidenced by different horns of the same make and model that have different intonation characteristics. It is quite possible to design something that is nicely conical and won't make anything that sounds like music or that has a usable scale.

There is software that will analyze the taper design of an instrument to determine its intonation characteristics (Chuck linked it), but it assumes the bugle is straight and doesn't model the effect of the mouthpiece.

Most of the best players seek the pitch that provides the greatest abundance of in-tune overtones in the sound, and adjust the length of the bugle to make that good sound in tune. They either do that by tromboning a valve slide, or by using alternate fingerings. They won't be happy with a tuba that wants to play the wrong pitches, and those are definitely out there.

Good intonation is such a moving target that most manufacturers try to make an instrument (at least for better players) that is pretty close but that is also easy to manage. It's like working a six-dimension jugsaw puzzle in that moving one piece has effects that can't be seen or predicted. That favors a trial-and-error approach. The computer models make many simplifying assumptions that are not justified in practice.

Rick "who thinks there's a good reason good designs keep getting copied" Denney

Art Hovey wrote:Every model seems to have its own intonation quirks, but here are the general tendencies that I have observed:
1. The flatnes of the fifth partial (D in the middle of the staff on a BBb tuba) seems to be related to the fatness of the instrument. Open D is usually usable on a smaller instrument such as a Fullerton Olds O-99 or a King. On the fatter tubas that I have tried, such as Martins, Cerveny Kaisers & Conn 20Js the D is usually too flat to use. Older Kings from the 1930s had the tuning slide in the leadpipe; those instruments had a D that was not flat at all, but the open F above it was way sharp

But you neglect intonation quirks within the same model! On my Marzan slant-rotor CC, for instance, the fifth partial (open E on the staff) was just fine, but when using the first valve, the D below it was VERY flat (in any temperament) ...

A more continuous tapered bore WAS tried by turn-of-the-century cornet soloist E.A.Couturier, who built an entire line of continuous Conical Bore brasses. They were so continuous that they did not have valve slides at all, and the tuning slide length was kept to a minimum. These brasswinds (even the tubas) were not any more successful than any other, and the company was sold to Lyon and Healey in 1923.

I agree with the mouthpiece discussion. Last season in community band, we played a march with a dogfight that was pretty high in register, including a fourth space Gb. As you know, a Gb can be played 1st valve, but it will usually be too flat to use. With my Wick 1, which has the deeper funnel cup, of course it was too flat. But with my Wick 2, which has a rounded cup, more Bach-ish, it sharpened the note so I could use 1st valve on Gb, in an Eb minor chord, so what little bit flat it still was did not matter as it was at a good tempo. It made the fingering in a Bb minor dogfight MUCH easier!

Mark H wrote:Okay, my question regarding the above post about mouthpieces is, do the shallower cups affect the pitch of the Gb any more than any of the other notes, or does it raise the pitch of all notes to the same degree? Also, does the shallow cup raise the pitch of the high register more than it does in the low register?

When you look at the impedance curve of a mouthpiece, you see a wide, smooth hump centered on something like Ab in the staff. That hump is too wide and too smooth to by itself affect one note and not the ones around it, in my view, though it can affect a big section of the instrument's scale.

But there can be interactions between the tuba and the mouthpiece. And larger throats probably give more influence to the player's lips, making it easier to steer the pitch. Thus, a difference mouthpiece might be any better on the problem note, but it might make it easier for the player to adjust.

It isn't the depth of the cup, but rather its volume. A shallow cup with a very wide bowl (even wider than the rim, as Ellis Wean has experimented with) can have the same volume. But the shallower bowl does, in my experience, improve the ease of articulation.

At least, that's what I think I know.

Rick "thinking the mouthpiece can only have broad influence" Denney