[Trombone-l] Eb crook for bass bone

John Burton John.Burton at JohnBurton.org
Sat Jan 21 20:30:12 CST 2006

Thank you, Dave.

I appreciated the technical, complete, yet not condescending answer.  I
suspect what was making my head swim was how the heck you could get the
same note out of tubing of different lengths. And all it was me looking
at one of those Bb/F/E horns and wondering how that tiny stub could make
so much difference to make THAT horn play the same notes as my
Bb/F/Gb/D.  It just didn't make sense!

Thank you for the kind explanation.  I appreciate it.  



john burton
Bach 50B3
Bass Trombone, Charleston NeoPhonic Orchestra
South Charleston, West Virginia


> -----Original Message-----
> From: Dave Tall [mailto:davetall at btrb.com] 
> Sent: Saturday, January 21, 2006 7:07 PM
> To: John Burton; Trombone-l at server5.samford.edu
> Subject: Re: [Trombone-l] Eb crook for bass bone
> At 05:36 AM 1/21/2006 -0500, John Burton wrote:
> >It *LOOKS* as tho when both rotors on an *independent* system are 
> >engaged the resultant length is longer than when both rotors on a
> >*dependant* system are engaged.
> >
> >Is this true or are my eyes deceiving me?  
> If both instruments are tuned the same, say Bb/F/D for open/1 
> valve/2 valves, then your eyes are decieving you.  If the 
> total tube length must be X for the instrument to be pitched 
> in Bb, Y for F, and Z for D, then the first valve has to add 
> enough tubing to go from length X to length Y, and the second 
> valve enough to go from length Y to length Z.  It doesn't 
> matter where the tubing is placed.  It could be inline, 
> dependent, or just used to make the entire instrument longer. 
>  A valveless bass trombone in F is the same length as a Bb/F 
> trombone with the F valve engaged.
> An off-the-shelf dependent instrument, at least in the Old 
> Days, was tuned in Bb/F/E.  The tubing for the second valve 
> was a short stubby length of tubing which approximated the 
> length of the "E pull" on single valve instruments.  In this 
> case, the dependent tubing IS shorter than the independent 
> tubing on a Bb/F/D instrument. It wasn't long enough to put 
> the instrument in D. 
> My first bass trombone (and my second, come to think of it) 
> were dependents tuned this way.  You had to buy a different 
> tuning slide for the second valve to put the instrument in 
> Bb/F/D.  The D slide was wrapped back on itself with very 
> tight curves.  It might look like it's shorter than the 
> second valve tubing on an independent Bb/F/D instrument.  It's not.
> Repairmen and eventually manufacturers began making second 
> dependent valve tuning slides in D in a more open 
> configuration, generally one large loop coming out of the 
> rotor.  These, too, were the same length as the independent 
> second valve tuning on a Bb/F/D instrument.
> >
> >And if so, doesn't that mean, in theory the INDEPENDENT 
> collection of 
> >rotors has a theoretical ability to play a pedal BBb or even a touch 
> >lower? I'm guessing this since I can play the pedal Bb tone without 
> >dropping into pedal sound .. If that makes sense.
> That makes sense.  On a Bb/F/D instrument, you can play the 
> same note as pedal Bb (in first position on the open horn) as 
> a non-pedal note with both valves engaged and the slide 
> extended pretty much as far as it will go without falling 
> off.  This means that the instrument, with both valves 
> engaged and the slide maximally extended, is twice the length 
> of the open instrument.  It's the same length as Tom's BBb 
> contra is in first position.  
> Let's call first position low Bb  "Bb" , first position pedal 
> Bb "BBb", and
> the octave below that "BBBb".   On a Bb/F/D instrument, on the open
> intstrument you can play Bb in first position, on the second 
> partial.  BBb is in first position on the first partial, 
> which we call "pedal tones".
> With both valves engaged and the slide maximally extended, 
> you can play BBb on the second partial, where it is not a 
> pedal tone.  You can play BBBb on the first partial, which IS 
> a pedal tone.  So BBb is a pedal tone in open first position, 
> and is not a pedal tone with both valves engaged and the 
> slide maximally extended.
> This is true whether or not the instrument is dependent or 
> independent.  It depends entirely on the length of the tubing 
> added by the valves.
> This also gets into why the distance between 6th and 7th 
> position is longer than that between 1st and 2nd position, 
> and why there are 7 positions on the open horn, barely 6 with 
> the F valve, and barely 5 with both the F and D valves engaged.
> You have to add a specific percentage of the length of a tube 
> to make it a half step lower.  I think the percentage is 
> 8.3%, but that makes the math too hard :-)
> Let's assume you have to add 10% to the length of a tube to 
> make it a half step lower.  If our trombone is 10 units long, 
> we have to add 1 unit to go to second position. This makes 
> the instrument 11 units long. To go to third position, we 
> have to add 10% to the length of the instrument in second 
> position. Since the instrument is now 11 units long, we have 
> to add 1.1 units.  The instrument in 3rd position is 12.1 
> units long.  To go to 4th position, we add 10% of that, which 
> is 1.21 units.
> The distance between 1st and 2nd position was 1 unit.  The 
> distance between 3rd and 4th was 1.21 units.  The additional 
> tubing required to make the instrument a half step longer 
> increases as the instrument gets longer.  The hand slide is 
> long enough to supply enough units of length to make the open 
> instrument 6 half steps longer.  It's not long enough to 
> supply enough units of length to make the instrument plus the 
> F valve tubing 6 half steps longer.  It can barely manage 5 
> half steps.  For the instrument with both the F and D valve 
> tubing added, it's only long enough to add roughly 4 half steps.
> Tying this back to the original question, the amount of 
> tubing you have to add to the Bb instrument to put it in G (3 
> half steps) is just a bit longer than the amount you have to 
> add to the F instrument to make it 2 half steps longer.  So, 
> the "whole step" which was moved from dependent to 
> independent was long enough to make the F instrument two half 
> steps longer.  This turns out be nearly enough to make the Bb 
> instrument 3 half steps longer.  Since that's close to a G, 
> people called it a G valve.  When used by itself, it makes 
> the open instrument almost 3 half steps longer.  When used on 
> the F instrument, it makes that instrument 2 half steps 
> longer.  When it was dependent, it could only be added to the 
> F instrument.  When added to the F instrument, it adds a whole step.  
> So it's a "whole step" in reference to the trombone with the 
> F valve already added, which was the only way it could be 
> used in a dependent setup.  
> Dave Tall
> Bass Trombonist
> New Mexico Symphony

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