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For those that have built instruments (particularly in Eb), how much longer is the 5th valve tubing than the first valve? According to Dan's chart he posted years ago, the first valve is approximately 20" of tubing. So if the 5th valve is a flat whole step, about how long would that be? 22? 24? 26 inches? Obviously there will be some experimentation and tweaking when it's all together, but where should I start? Thanks!

Or if people can measure their 5th valves on Eb horns, that would give me a rough idea of where to start.

OK. Here's a description of the math so you can sort it out. You first need to know the length of the open bugle. Precisely. Then each half step is 2^(n/12), with n being the number of half steps. As the "long tone" fifth valve is usually used with 4th valve to intone a note a whole step below the 4th valve, first look at 4th valve. The 4th valve is five half-steps lower than the open bugle, making the T+4 seven half steps below the open bugle.

So, the length of the "Long tone" circuit (using B for "bugle" in the equation) is [B multiplied by 2^(7/12)] minus [B multiplied by 2^(5/12)].

Pitch is geometric, not linear. Western tonal music is based on a twelve tone per octave chromatic scale. So each half step has to get progressively higher in pitch going up to double the frequency, or progressively longer for each half step in tubing length going downwards. That is why the 1st valve loop is a tad longer than twice the 2nd valve loop, and so forth.

IMHO, it's better to err on the short side - you can pull a slide a little if it's too sharp, but you can't push it in if it's too flat.

If, in the future, you decide to make it longer, just make up longer ferrules.

Great stuff you guys, thanks!

The real question is: how long do YOU need it to be?
(and if you don’t know, why are you asking?)

windshieldbug wrote:The real question is: how long do YOU need it to be?
(and if you don’t know, why are you asking?)

The only 5th valve setup I've ever played was a long whole step (on a CC horn), so that's all I'm familiar with. Now that I'm trying my hand at building a horn, I just decided to go with what I know, but in the key of Eb. Thanks for all the help folks.

roweenie wrote:IMHO, it's better to err on the short side - you can pull a slide a little if it's too sharp, but you can't push it in if it's too flat.

If, in the future, you decide to make it longer, just make up longer ferrules.

+1

SteveP wrote:

iiipopes wrote: . . . Then each half step is 2^(n/12), with n being the number of half steps. As the "long tone" fifth valve is usually used with 4th valve to intone a note a whole step below the 4th valve, first look at 4th valve. The 4th valve is five half-steps lower than the open bugle, making the T+4 seven half steps below the open bugle.

So, the length of the "Long tone" circuit (using B for "bugle" in the equation) is [B multiplied by 2^(7/12)] minus [B multiplied by 2^(5/12)].

Great, but some of us don't have math degrees.

Knowledge is power.

I don't have a math degree. I just paid attention in high school algebra. And the calculator I use when I want to compute such items, including fret distances on a guitar, golf club lofts, etc., is a TI-30 with a manufacturing date of the 25th week of 1978. Yes, I typed 1978, purchased new for me as a gift for school.

bloke wrote:When I build circuits, the consideration (neither being whether I'm going to make it too long or two short, as I will do neither) is whether I can both shorten it enough for the shortest applications of that circuit and lengthen it enough for the longest applications of that circuit.

It seems to me that, unless I'm missing something (which is highly likely) this logic dictates that you must calculate to the shortest needed length.

PS - I seem to recall receiving this advice before.......

roweenie wrote:

bloke wrote:When I build circuits, the consideration (neither being whether I'm going to make it too long or two short, as I will do neither) is whether I can both shorten it enough for the shortest applications of that circuit and lengthen it enough for the longest applications of that circuit.

It seems to me that, unless I'm missing something (which is highly likely) this logic dictates that you must calculate to the shortest needed length.

Except that for vagaries of tuning, like some going to A=442, and for temperature extremes, and for other idiosyncratic intonation quirks, like flat fifth partials on many horns, the "shortest" the circuit should be is not just the highest pitch it will be expected to play, but that length less an amount so that if need be the slide can be shoved in, like bloke says, for any one of a number of reasons, or pulled, sometimes as much as two inches or thereabouts, like when I have the upper loop of the 1st valve circuit on a 3-valve souzy made into a slide so that it can be pulled for 1+3 F and C to be in tune.

iiipopes wrote:
the "shortest" the circuit should be is not just the highest pitch it will be expected to play, but that length less an amount so that if need be the slide can be shoved in

Good grief, I thought that was what I was saying.

FWIW, I've always approached the 5th valve circuit a sort of a "trial and error" situation. Since its primary function (IMHO) is aiding intonation, you want to lay it out so there are as few compromises as possible.

roweenie "if you don't make the slide short enough to push it in enough to be in tune, the note will be flat"

roweenie wrote: Good grief, I thought that was what I was saying.

Probably so. I was thinking of my own BBb tubas tending to play 3rd space C flat and not being able to do anything about it until I got the 1st valve circuit shortened a tad, but not so much my souzy couldn't pull for 1+3 C and low F in tune.

So, why doesn't somebody just give him a measurement in inches for the correct theoretical length? One reply would have saved all these other posts! Remember - save band width (probably six tubas)!!!

Thanks again guys for the great responses. If nothing else, this opened my eyes to the fact that it is similar in length to the 1st valve on a BBb tuba (once someone said it I was like "oh duh, that makes sense"). All I had thought about previously (as in my original post) was that it had to be "long" or "flat" and that it should therefore be something longer than the 1st valve circuit of the Eb horn itself. I appreciate the input and "back and forth" that goes on to spur discussion and generate more responses. This will be a ways down the road as I still need to purchase the 5th valve (and cobble together some tubing for the circuit) and finish de-denting the bugle (which will be more of a process than I originally thought, isn't that how it always goes though?).

I'm sure I'll be back with more questions! Thanks!

the elephant wrote:Seeing how we have such a Freak Jury here, THAT is why no one wants to cough up numbers; they cause arguments. It is much better (anyway) to physically measure it yourself

simply giving him numbers that may or may not actually apply to his horn and the parts he will use is the true waste of bandwidth

YES!

roweenie wrote: FWIW, I've always approached the 5th valve circuit a sort of a "trial and error" situation

Start too long, trim off little by little until you get the length you desire.

iiipopes wrote:I don't have a math degree. I just paid attention in high school algebra. And the calculator I use when I want to compute such items, including fret distances on a guitar, golf club lofts, etc., is a TI-30 with a manufacturing date of the 25th week of 1978. Yes, I typed 1978, purchased new for me as a gift for school.

ti-30 is still sold. I bought one for my 15yo taking calc. There are more recent models but they are only made to influence the buyer. ti-30 is still standard and quite useful.

While there are those who don't have math degrees, the OP is clearly interested in equating semitones.You guys, this is a kick a$$ thread.