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I was looking at the dimensions of euphoniums and I've seen mentions of a dual bore and bore sizes being listed as two numbers. Can anyone explain what this is? I know what a dual bore trombone is, but not a euphonium. I know that the bore is usually taken from the inner part of the outer slide of the 2nd valve slide, but where would the second measurement taken from?

EDIT: I was not remember correctly and was therefore wrong. Below you will find the correct response.

thevillagetuba wrote:This should be the same concept as it's use with trombones: the "exit" side of the slide would be slightly larger than the "entrance" to allow for a more free-blowing horn/valve. I can't think of a reason why it would mean something different for euphoniums, but who knows? That's my guess, anyways. Hopefully someone with more knowledge on this than I do will correct me if I am wrong.

Sometimes it is a huge difference though, so I'm not sure if they are taking the measurement after the tuning slide or? I've also heard of triple bore instruments..... no clue what that means in regards to the dual bore.

aprilmary wrote:Sometimes it is a huge difference though, so I'm not sure if they are taking the measurement after the tuning slide or? I've also heard of triple bore instruments..... no clue what that means in regards to the dual bore.

EDIT: My explanation was incorrect (and now I feel like an idiot as at some point this was explained to me. Below is the correct response.

thevillagetuba wrote:For example:

The King 2280 is listed as haveing .580-.600 dual bore. No one slide will really have a difference of .020, but will more likely be something like .580-.585, .585-.590, .595-.600 (this is probably nowhere near what those actually measure, but just made to be simple math to be easy to see). The Yamaha 642II is listed with a dual bore of .591-.661. This will probably have each slide getting slightly bigger and then continuing that through the extra tubing for each slide through the compensating system so that the total difference between smallest slide on valve 1 to largest slide on valve 3 (because the 4th won't have an extra set for the compensation) being the one that is listed as the bore range.

Uh … no. The individual valve tuning slides on every one of the two dozen or so different brands/models of euphs I've play-tested over the past 10-12 years have been reversable. Can't do that if the bore of the slide legs is different. Not only that, the first and third valve slides on most could be swapped. Again, can't do that if the bore of the slides is different.

Bore measurements for euphs are the diameter at the second and fourth valve port. Historically, the measurement has been the inside diameter, although several (most?) mfgs have switched to reporting the outer diameter.

pgym wrote:

thevillagetuba wrote:Bore measurements for euphs are the diameter at the second and fourth valve port. Historically, the measurement has been the inside diameter, although several (most?) mfgs have switched to reporting the outer diameter.

This. No relation to the dual-bore trombone slides. No relation to dual-bore trumpet main slides. Simple: smaller number is the i.d. of the 2nd valve slide; larger number is the i.d. of the 4th valve slide.

pgym wrote:Bore measurements for euphs are the diameter at the second and fourth valve port. Historically, the measurement has been the inside diameter, although several (most?) mfgs have switched to reporting the outer diameter.

Thanks for setting me straight pgym and iiipopes! Somewhere down the line I must've gotten mixed up about this terminology as I have never played a euphonium listed as having a dual bore and therefore could only rely on what I had misremembered.

I also fixed the above quote to give credit where credit was due since I was not the one to shine light to this question.

pgym wrote:
Uh … no. The individual valve tuning slides on every one of the two dozen or so different brands/models of euphs I've play-tested over the past 10-12 years have been reversable. Can't do that if the bore of the slide legs is different. Not only that, the first and third valve slides on most could be swapped. Again, can't do that if the bore of the slides is different.

Bore measurements for euphs are the diameter at the second and fourth valve port. Historically, the measurement has been the inside diameter, although several (most?) mfgs have switched to reporting the outer diameter.

What if the euphonium only has three valves? Would the 2nd measurement not be reported then? Where would compensating horns be measured?

Thanks!

I havent heard about 3 valve compensating euphoniums having a dual bore. However Courtois used to make a 3 valve compensating British style baritone, which had a larger bore of the 3rd valve than of the 2 first valves.

At least my YEP-641 has conical tuning slide in its 4th valve loop. So maybe triple bore? Anyway a rather fast expansion of bore through the 4th piston, when it is not pressed.

Klaus

"Dual Bore" means whatever the marketing people decide it means, at the particular time they attach it to a product. The same as the x/4 system...

I've not heard the term 'triple bore' used before. There are a number of euphonium models that have a tapered 4th valve slide. Maybe that's what they're referring to. Besson, Sterling and Miraphone do not have a tapered 4th slide. My Yamaha 641 specs are listed as the same for the 642 (0.591-0.661"). Below is what I actually measured on my 641 with my digital calipers:

2nd valve slide:
.591

Comp Loop 3rd valve slide:
.630

4th valve slide:
.630 / .670

The main bore is the inside measurement of the 2nd valve slide:


Hope this helps.

imperialbari wrote:At least my YEP-641 has conical tuning slide in its 4th valve loop. So maybe triple bore? Anyway a rather fast expansion of bore through the 4th piston, when it is not pressed.
Klaus

Semantics. Does this mean on all of my instruments that have a graduated tuning slide anywhere that they are dual bore? Like the main tuning slide of my King American bari/euph? No. The accepted popular definition of "dual bore" is that the i.d. of the inlet side of the 2nd valve slide has a particular size, and that the inlet of the 4th valve slide (or last valve in the block) has an i.d. that is different, usually larger.

Other instruments may have expanding measurements from the inlet of the bow to the outlet of the bow, but by modern popular definition, these are not "dual bore" horns.

Again, the only exceptions to this that I know of are:
1) trumpets - the Bach Vindabona and the King Symphony "Dual Bore" horns are referring to the expanding bore of the main tuning slide. There may be others (possibly Schilke - as he "step-bored a number of his models), but not many.
2) trombones - each of the legs of the slide having a different i.d. There are several.

aprilmary wrote:What if the euphonium only has three valves? Would the 2nd measurement not be reported then? Where would compensating horns be measured?

Three valves = no second measurement reported; 4 banger compensator measured at 4th valve port; 3 banger compensator = no second measurement to report.