Instrument tube lengths
Nov 16th, 2008,
I know, it isn't exactly earth-shattering, but I don't remember that this table is posted anywhere else on the site, so here goes for approximate lengths:
(measurement is assumed to be from receiver to the rim of the bell and passing through the open position of the instrument)
Instrument Length
Trumpet/Cornet/Flugle 52
Mellophone in F 72
Eb Alto Horn 82
Baritone/Trombone/ Bb French Hn 106
French Horn in F 148
Eb Tuba 162
BBb Tuba 222
Reply #1 - Nov 16th, 2008,
I picked this up a while ago from somewhere...
BBb Tuba 18 ft. open pipe
CC Tuba 16 ft. open pipe
F Tuba 12 ft. open pipe
Eb Tuba 13.5 ft. open pipe
Bb Euph/Tenor Trombone - 9 ft. open pipe
Reply #2 - Nov 16th, 2008,
And these are for modern Low Pitch with A=440Hz.
Reply #3 - Nov 17th, 2008,
OK, as usual the easy isn't always the best way. So, here is a more complete chart:
Pitch Low High
Eb 38 36 1/2
D 40 39
C 45 1/2 44 1/2
Bb 51 1/2 50
A 54 1/2 53
Ab 58 1/2 56 1/2
G 62 60
F 69 1/2 67 1/2
E 74 72
Eb 78 1/2 76 1/2
D 83 1/2 81
Db 88 1/2 86
C 94 91 1/2
Bb 106 1/2 103
A 113 1/2 110
Ab 120 1/2 117
G 128 1/2 124 1/2
F 145 1/2 141
E 153 1/2 149
Eb 164 159
D 174 169
C 197 191
Bb 221 1/2 215
Reply #5 - Nov 18th, 2008,
This is great. I knew that much of this info was scattered in many of Kenton's posts, but to have a full table is fabulous.
It allows for some fun analysis and comparisons, octave by octave, or other as desired. I would assume that by pure physics, the tubing length would double for each octave. This table shows approx. 106% increase in length from trumpet to trombone/euph, and approx. 109% increase from trombone to tuba. Any explanations for this?
Reply #8 - Nov 19th, 2008,
Somewhere, I snatched:
the acoustical standing waves produced while playing inside a brass instrument extend beyond the end of the bell. This effect varies with frequency and the width of the bell. For almost all common purposes, this effect can be expressed thusly:
effective tube length = actual tube length + (0.6 * bell diameter)
Reply #7 - Nov 19th, 2008,
The major problems come from the bell flair.
If we are talking about the length of the closed tube the working length changes with each partial due to the bell flair. Change the flair and change the relationship between harmonics.
Although not quite correct - Think of it as like the high (short) partials can’t hang on to the bell if the low (long) partials can.
Reply #6 - Nov 19th, 2008,
I don't know, I've never studied this, I just reported it!
But the references always say that these are approximate lengths, affected at least partially by the bore profile of the tube. So, I wonder if a purely cylindrical tube would be exact doubling at the octave?
A couple of other things that I believe can be deduced from the chart are:
1) when you press down - say your 1st valve - you just change your horn from a Bb length to an Ab length. So, subtracting the Bb length from the Ab length I believe should tell you how long the 1st valve loop should be. *
2) Using a high pitch Bb cornet as an example, moving down to A is 3 inches, to Ab is 6.5 inches and to G is 10 inches. But the combination of 1 + 2 (3in + 6.5in) does not equal 3 (10in). [which shows you if you want to play in tune, you must play a trombone!]
*Another question: Since the tubing in the valve section is predominately cylindrical, do lengths in that portion act more like the cylinders or is the critical factor the overall bore profile of the instrument?
Reply #9 - Jun 16th, 2006,
The effective length of a brass instrument is out beyond the bell due to the flare of the bell, therefore brass instruments are NOT their equivalent organ pipes. When one "hand stops” a horn, one makes the effective length of a "French" horn shorter (hence the term "hand stop"). When hornists use this technique, they must transpose to make up for this. The stop valve merely adds back the missing length. The stop valve makes the horn the right length, the valve lengths are then correct, too!