New bell on Yamaha 822F

[bstevens]

Hi

I've been pondering ... I once saw a Yamaha 822F with a 15" bell ... from what I gathered, someone had put a 15" bell from a Besson horn on the Yamaha. Would that be possible?

It sounded perfect for what I'm looking for - I currently have a Yamaha 822F but I far prefer the sound of my old Yamaha YBB621 - but wanted a easier blowing high register for solo stuff. I love helicons and that agressive sound, rather than than the round "tuba-y" sound.

Any thoughts?

Thanks!

[T. J. Ricer]

I might be wrong, but I think the 822 F and 321 Eb are the same size at the bottom of the bell, so that might be an option for a bell source. I might be interested in your 822 bell if you decide you don't want it...

-T. J.

[PaulTkachenko]

I've said it in private, but I don't 'really' know...

That bell change has got to mess with the tuning, surely....

[DouglasJB]

As long as they are the same height, it should be very close, as long as the only difference is the bell flair

[UDELBR]

Bell diameter plays a part in the effective acoustic length of brass instruments (and thus tuning). Google "end effect". Quoting myself from an old thread:

Don't forget the "end effect" of the bell: effective tube length = actual tube length + (0.6 * bell diameter) The working length of the tuba actually extends past the end of the bell, and bell diameter makes a difference.

[roweenie]

Bell diameter plays a part in the effective acoustic length of brass instruments (and thus tuning). Google "end effect". Quoting myself from an old thread:

Don't forget the "end effect" of the bell: effective tube length = actual tube length + (0.6 * bell diameter) The working length of the tuba actually extends past the end of the bell, and bell diameter makes a difference.

What would the formula for this look like? It would be very useful when "prototyping" tubas...

[DouglasJB]

I didn't know that, learn something new every day

[UDELBR]

What would the formula for this look like? It would be very useful when "prototyping" tubas...

If a bell had a diameter of (say...) 50cm, you'd multiply that figure by 0.6 to find the end effect. A bell of that diameter adds 30cm to the effective length of the tuba.

[roweenie]

So, does that mean the length of a CC tuba (192", 12"×16') with a 19" bell, actually really needs to be @ 181" (192-[19×.6])?

Just trying to understand the effect in relation to intonation.....

[UDELBR]

Yep, you've got it. BUT...there are other factors at play when determining instrument length like volume. A 'fatter' instrument doesn't have to be as long. That's why euphs are shorter than trombones, even though they're in the same key.