False notes

[Lectron]

I have one particular tuba with very strong false notes.
That means it can be played down to fundamental with only 3 valves, but!
As the false notes acts different in regard of the horn length it seems to
cancel out the fundamental of the 5th above.

Recording playing solo it actually sound much better than it feels, but in strong
acoustics or with other players, it really seems to disappear and I'm left farting
harmonics.

I know this might be a trouble note in F & Ebs..The BBb and CCs are saved by the
longer pluming I assume as the antinode of the false note will get distanced
from the 'real' notes node compared to their smaller brothers.

Making the F & Eb longer is of course not a very bright Idea.
Has someone experimented with different throat/flares/shorter leadpipes etc.

Any way to get that little extra distance between the node/antinode?
Or to weaken the false one a tad?

[Donn]

As the false notes acts different in regard of the horn length it seems to cancel out the fundamental of the 5th above.

If you wouldn't mind elaborating, what does that mean? I could think of a couple of interpretations, but neither really makes enough sense to me. Maybe an example, with your Eb or F tuba and a specific pedal tone - say, an Ab, vs. the Eb a fifth above - now, the Eb's fundamental is weak? Which note are you playing in this example, the false Ab or the Eb?

I know my false tones seem defective in some way, harmonically speaking, but my ears aren't sharp enough to say how. I'm sure the fundamental is not strong, but I understand that to be characteristic of the tuba anyway. Anyway, I'm hoping to learn more about this.

[Lectron]

I'll do my best here.....x-squize my English, but still it's better than most' Norwegian

Looking at the tuba as an open cylinder...I know..A cylinder usually do not have an average taper of 0.1%
but just to try to keep it simple..Or at lest as simple as it can be as no basic acoustic describe these matters.

If we take a look at an Eb tuba. The open horn has a length about 4.1m (a cylinder would need ~4.4m)
For the beneficiary notes to appear, the tuba should need to be 50% longer but as it's not actually growing
on your lap it somehow uses the horn as if length was wavelength/3

So what we have appearing is on open Ab below staff played open on an Eb tuba.

That particular tone is usually not the problem thou. The one above is. The Bb flat below staff for the Eb tuba
and as the same phenomena arises for the F, it would be the C below staff. Or the 4th valve on both instruments
or whatever fingering you should prefer.

That particular tone tends to loose its 1st harmonic -> in this case the Bb and C below staff, leaving
only the over harmonics out...And they don't sound all that good alone

What seems to happen there is that a partial of a false notes high pressure (node) meets the intended notes antinode
(or the other way around)

I could of course run a model to see if that was the fact, but why not ask the gurus first

[Donn]

Ah. The notorious low C. I don't know the problem very well, it's reportedly far worse on some tubas than others and mine are evidently not so bad as some. Common complaints seem to feature rotary F instruments. Your theory about the acoustics vs. false tones is an interesting one, don't think I've heard it before; I personally would look at the location of a large length of straight valve section vs. the nodal structure of the note. I'm not sure the problem is really confined to bass tubas, it might just be more annoying there when you're trying to make a low C sound somewhat like the one that comes out of a contrabass tuba.

[Lectron]

Just a few rough calculations...And this will be the same on all the tubas (and instruments?)

I'll call the notes by the transposed names for ease (or for CC tuba)

The fundamental is..Of course a C. The false an F
Using the valves one can play down from that F to the C, but that would also give a fundamental for that
fingering for a theoretically freakin low G (1-3, 4 or whatever) and guess what the f3 (3rd partial) is for that note?

The notorious G for CC tuba, F for BBb tuba, Bb for Eb tuba and C for F tuba

It's been mentioned that German rotary Fs (and Ebs) seems worse, and that is also my experience.
It is also my experience that less effective instruments like 981 etc do not suffer from this.

On that particular old B&S Eb, the point where the nodes would meet and make the most F.up
was in the tuningslide/spitvalve area. Probably not the best place

[Donn]

Interesting, I've wondered how false tones work and this hints at an explanation - the 3rd partial of the note is `acoustically valid' for the length of tubing, and we sketch in the 1st & 2nd by force of will. Absence of the 4th probably accounts for some of the (lack of) tonal quality.

It doesn't serve as well for your theory, though, it seems to me. If a false tone F (to return to the F tuba) exerts a malign influence on the C a fifth above, wouldn't we expect the whole false tone series to have similar effects? More broadly, if the problem with C is some simple coincidence with the overtone series, why is it only C and not D, E, F?

[Lectron]

More broadly, if the problem with C is some simple coincidence with the overtone series, why is it only C and not D, E, F?

That's a good question.....Do you have more good questions?

It could mean my theory suck, but as Bloke mention. It is in fact also the tones around being affected.
How much they even resonate there is also another question as it's hard to play that particular false note as
as solo note without hitting the real thing...BUT...

If the note ain't canceled it's just hard to focus, and it might be able to lip over a larger area.
That might be an indication right there. As it's the 3rd partial there's no really reason that it
should be in tune with the 2nd (as the note you actually want to play would be)

This is not to 'defend my theory', it's more to ask, can this be one of the reasons