Slide lengths

[bigboymusic]

Ok, with 'modern' tuning practices tuba gurus, what would be the lengths of each tuning circuit on a Bflat horn? Do these change with the shape of the bugle???

[roweenie]

Short answer, very generally speaking, every horn is different.

Dan Schultz posted, some time ago, a chart of the theoretical lengths of valve tubing circuits for tubas in F, E flat, CC, and BB flat. Dan is an incredibly helpful guy - I'm sure once he sees this, he'll post it again.

I say theoretical, because these lengths are, well, theoretical. In my (limited) experience, I've seen two horns of the same model that require some different length valve circuits.

I've also seen theoretical lengths that were way off (3 to 4" shorter, in the case of a 4th valve loop) from the real required length.

Which BB flat tuba are you referring to (Conn 36J)? There are quite a few around; maybe a survey of (36J) owners will at least put you "in the ballpark".

[roweenie]

Actually, I'll help Dan and save him the trouble:

F
1st valve = 18"
2nd valve = 8"
3rd valve = 27"
4th valve = 48"

Eb
1st valve = 20"
2nd valve = 9 1/2"
3rd valve = 29 1/2"
4th valve = 52"

CC
1st valve = 23.7"
2nd valve = 11.257"
3rd valve = 34.957"
4th valve = 61.62"

BBb
1st valve = 26.66"
2nd valve = 12.66"
3rd valve = 39.32"
4th valve = 69.32"

Disclaimer: please note, these are theoretical, YMMV.....

[windshieldbug]

The overtone series itself is not in tune with a diatonic scale, so you are going to need some room for adjustment dependinding on which partial you're on.

[bigboymusic]

Perfect sense. I will not be doing any cutting, but all I am learning about the differences from horn to horn are making me want to retake my acoustics class....

[roweenie]

...if you decide to remove, say, 1" from the loop - that when you cut the slide legs that you are removing TWICE the amount as you measured because you are removing it from TWO sides at once.

I'm guessing that you mean "you need to remove HALF the amount as you measured from each side because you are removing it from TWO sides at once.) ...

(...or maybe I'm saying it wrong, too? )

[bigboymusic]

correct!

[Dan Schultz]

.... Dan Schultz posted, some time ago, a chart of the theoretical lengths of valve tubing circuits for tubas in F, E flat, CC, and BB flat. Dan is an incredibly helpful guy - I'm sure once he sees this, he'll post it again....

No need for me to repost. You done good. Thanks!

Another 'trick' I use to help set up a circuit if you already have the crook is to use a couple of pieces of garden hone to approximate how long everything has to be.