Does Bell size matter?

[JJJimmink]

Maybe this is an obvious question, but I could not find it (quick and dirty) in any previous posts.

Is bigger always better? Does a bigger bell means a bigger sound, more darkness?

I am looking for a big tuba for a large orchestra, what is considered as a minium requirement for the bell size?

Cheers, Joost Jim

[Rick Denney]

Is bigger always better? Does a bigger bell means a bigger sound, more darkness?

I am looking for a big tuba for a large orchestra, what is considered as a minium requirement for the bell size?

No; no; there isn't one.

Listen to the instrument. If it sounds the way you want it to sound, it has the right size bell.

There are many sousaphones with huge bells that do not make a "bigger" sound (by which I mean richer rather than louder), and the sound they do make is anything but dark. Maybe they are louder, but I've heard some pretty loud playing on rotary tubas with smallish bells.

The bell is an impedance matching device. It's job is to allow musical frequencies to project instead of being reflected back into the instrument. As such, the bell is part of a system, and it's the whole system that has to be judged together, not just one part.

Rick "who owns tubas with big bells and tubas with small bells" Denney

[Mark]

It's not the size of your bell; it's how you use it. BTW, mine is 18.5 inches.

[sloan]

Isn't it somewhat agreed upon (a "consensus", just like man-made weather change, etc.) that - given the same tuba - a wider/larger bell flare offers a more diffuse sound whereas a narrower/smaller bell flare will tend to offer a more blatant sound?

bloke "The offered observation is not disingenuous, even though the parenthetical comment is facetious."

I would question this. For one thing, it's damn hard to get "the same tuba" with a "larger bell flare".
I suspect that wider flares come with other changes. If all you do is to extend a perfectly good
"small flare" bell, it's difficult to see how the extension would have *any* effect on the sound.

Just spitballing...if there were any effect at all, I would expect it to (very) slightly increase the effective length of the bugle for very low frequency pitches - tending to make them (very) slightly flatter. PERHAPS
this might be accompanied by a slight increase in the presence of these low frequencies. Maybe that's what you mean by "diffuse"?

I further suspect that some bells are HUGE "just for show". Carving away a few inches of useless flare may have ZERO effect on the sound.

And finally...our good friends Fletcher&Rossing have some interesting diagrams that cause me to hypothesize a connection between bell flare (more a matter of profile than size - but some profiles IMPLY size) and the proper leadpipe (and mouthpiece?) Rick Denney seems to think there is an analogy to draw between bell profiles and loudspeaker design - but I'll let him jump in and explain that.

[bort]

How do a Conn 52J, 54J, and 56J compare to each other?

[sailn2ba]

The Cerveny 681 and 683 have the same dimensions except for bell diameter, and I THINK that the 683 sounds richer and that the 681 projects (cuts through, asserts itself) a little more.
Didn't the Miraphone 186 change bell size many years ago? Perhaps someone has observations on that.

Aaargh! I mean 681 and 686 . . . NOT 683. The 681 and the 686 have the same dimensions and wrap.

[sloan]

Isn't it somewhat agreed upon... a wider/larger bell flare offers a more diffuse sound whereas a narrower/smaller bell flare will tend to offer a more blatant sound?

bloke "The offered observation is not disingenuous, even though the parenthetical comment is facetious."

Maybe that's what you mean by "diffuse"?

Not, bloke nailed it on the head. Actually diffuse means that the sound is less directly projected /"centered", no I'm not talking about the player or how it's layed just it's natural tendency. It just means that the sound is naturally a little less focused, and usually a little broader.

Fine - now, do you have an explanation of how enlarging the bell flare (while keeping "the same tuba")
achieves this effect?

[Alex C]

Does a bigger bell means a bigger sound, more darkness?

More than one current orchestral player has told me that a York sized horn was needed to make 'enough racket' to keep the rest of the brass happy. A fine player was told he needed a larger horn to keep his job. Did it make a difference? Probably... but he was loud as hell to begin with.

The quality of 'dark' vs. 'bright' is not determined by bell size (except as disfussion is a part of 'dark') but by a series of factors too numerous and complicated to get into.
___

When you ask about bell size, there are two 'main' parts, the bell stack and the bell flare.

Bell Flare

To get an idea of the effect of the bell flare, the Conn 52-54-56J's offer a good perspective: 52 = 18" - 54 = 19" - 56 = 20". The bell stack on all three models is the same.

Using purely objective terms, the 52 has more projection and a more compactt sound (ooooo I hate stepping on that). The 56 has a more diffuse sound, less definition (?). Whatever your terminology, the difference in bell flare of these horns offers a significant change in the sound.

Bell Stack

The bell stack is part of the 'amplifier system' of an instrument; it is integral to the overall taper of the horn. In simple terms (the only ones I understand) a big bell stack (fast taper) offers the potential to create more sound than a slower tapered horn.

[hbcrandy]

In simple terms (the only ones I understand) a big bell stack (fast taper) offers the potential to create more sound than a slower tapered horn.

Operationally define "more sound", please. Are you talking about greater decibel output for less input of energy?

[sloan]

In simple terms (the only ones I understand) a big bell stack (fast taper) offers the potential to create more sound than a slower tapered horn.

Operationally define "more sound", please. Are you talking about greater decibel output for less input of energy?

Please fix your citation. I did not write that.

[Z-Tuba Dude]

It is clear to me, that the wider bell flare creates a more diffuse sound. I have an older 1241 with both a 22" upright bell, and a 19". The 19" bell creates a more "compact" sound.

[imperialbari]

One, quite radical, test is about playing instruments with detachable bells without their bells. I find the bell-less sound extremely efficient, but not very attractive.

Klaus

[sloan]

One, quite radical, test is about playing instruments with detachable bells without their bells. I find the bell-less sound extremely efficient, but not very attractive.

Klaus

This "test" is absolutely useless for trying to answer the original question.

[Wyvern]

A very good model to hear the difference in sound from bell diameter is the B&H/Besson Eb. Just compare an old Imperial with 15" bell to a modern Sovereign with 19". My observation playing both is the larger bell produces a more defused, less focused sound, while it is easier to 'overblow' the 15" Imperial. Neither is necessary better than the other - it depends on the application. For quintet I think the 15" bell is preferable, for symphony orchestra the 19" bell.

The other very important bell size to consider in the sound is the bell throat. My observation is that it is the throat which mostly determines the breath of the tone which is why BAT's have that rich wrap around tone.

[JHardisk]

Maybe this is an obvious question, but I could not find it (quick and dirty) in any previous posts.

Is bigger always better? Does a bigger bell means a bigger sound, more darkness?

I believe the obvious response hasn't been stated yet...

No matter what they say, Size does matter.
And then, It's all about how you use it...

[Alex C]

The obvious response is "bigger is not always better." However in the context of the OP's question at the top of the thread I believe I gave pretty good answers earlier.

In an orchestral environment, a larger tuba is currently preferred.

A big bell is not necessarily dark.

[Donn]

Pardon me if someone already mentioned this and I missed it, but it seems to me bell flare would have a more pronounced effect from the vantage of the player, than anyone else.

The listener who would most benefit from a large bell flare, I would guess, would be located in the path of the bell - to the front, with a front facing bell, or in the vicinity of the ceiling with an upright bell. Since it isn't common practice to seat listeners on the ceiling, that may account for why a large bell flare seems diffuse - does that observation hold for a front facing bell, the same as upright?

[sloan]

The obvious response is "bigger is not always better." However in the context of the OP's question at the top of the thread I believe I gave pretty good answers earlier.

In an orchestral environment, a larger tuba is currently preferred.

A big bell is not necessarily dark.

OP did not ask about "a larger tuba". He asked about "a larger bell".

[Alex C]

In an orchestral environment, a larger tuba is currently preferred.

OP did not ask about "a larger tuba". He asked about "a larger bell".

A tuba with a larger bell is a larger tuba.

[Rick Denney]

In an orchestral environment, a larger tuba is currently preferred.

OP did not ask about "a larger tuba". He asked about "a larger bell".

A tuba with a larger bell is a larger tuba.

I don't agree. I don't think a 56J is any bigger a tuba than a 52J, though it has a bigger bell. A Holton is a larger tuba, and it definitely has a bigger sound, but the bell is smaller with respect to width of the rest of the outer branches than any of the three Conn models.

A bell made larger by extending the rim from its current profile (as is the case with the Conn) has a larger amount of bell surface that is at shallow angles to the centerline of the instrument. That provides a larger reflector, but the reflector is not focused, and this will indeed increase dispersion, in the same way that a bi-radial horn loudspeaker is used for wide dispersion and a narrow exponential horn is used for long throw. But it isn't the size of the bell, it's the shape. The shape necessarily becomes more "bi-radial" when you add more material to the rim of an existing bell shape. But you could also make a bigger bell that has the same profile as a smaller bell, in which case I would expect them to propagate more similarly. An example would be a Rudi 5/4 versus a Rudi 4/4, which has a bigger bell but also a bigger throat to match, and the two bells have the same radius of curvature in the profile. The 5/4 makes a bigger sound. But is that the bigger bell or the bigger throat and outer branches? I submit the latter is more likely. Is the sound of a Rudi 5/4 more diffuse? If so, I'd bet the difference owes more to the ratio of overall instrument width to the mouthpiece, and the size of the throat, than to just the difference in bell size.

Changing the shape of the bell changes the tone, because the bell, acting as an impedance matching device, changes the degree to which some frequencies are reflected or projected more than others. I think it's possible that the bigger bell could ruin the mix of frequencies being projected, and make the instrument sound crappy, small, and stuffy.

An instrument with no bell provides very poor impedance matching, and some important frequencies get more fully reflected rather than being allowed to project into the uncontained and unresonant air outside the instrument. The remaining frequencies may create a more strident sound, which has greater ability to penetrate through the sound of the group. That would be perceived as louder, whether or not one would see a change in sound pressure level.

Aside: Remember that sound pressure level ("dB") does not measure loudness in a particularly useful way. Standard SPL assumes a particular profile of frequencies (the "weighting") that is more related to potential ear damage than musicality. The only way to know what's really happening is to do spectrum analysis of the sound to see the relative loudness relative to frequency. And SPL is not a measure of sound "bigness" in any case. It's a measure of intensity. An intense sound vibrates the few air molecules at the test sensor strongly. A big sound vibrates more air molecules. It's like the difference between temperature and heat. A tiny 15-watt soldering iron might make it's small tip as hot (in degrees) as a big 100-watt iron. But the 100-watt iron makes much more total heat, as measured by how big a solder pool it can melt. So, a big sound puts strong vibration all over the concert hall, rather than peeling the paint in just one part of it. I really think it's not "loud" sounds that current tuba players want, but rather "big" sounds. A big tuba, with its large bell, throat, and volume, sets more air vibrating within the instrument and then provides a greater interface between those molecules and the air molecules beyond the bell--including in a wider array of directions.

The bell is part of a system, and it is the system that has to perform, not just one part of it.

Rick "suggesting that an impedance matching device has to be tuned to the resonator to achieve its objectives" Denney