TromboneChat

Sesquitone wrote: ↑Fri Aug 30, 2024 3:57 pm

Posaunus wrote: ↑Thu Aug 29, 2024 2:33 pm In another thread, Sesquitone (Benny) makes the case that the F-attachment tubing I.D. (and valve ports) should be the same as the slide bore.

So that’s what I have on my Conn Elkhart. . . It was a kit from Hagmann in about 2009/10.

Yes, that sounds right. René Hagmann began providing “matched-bore”

Sesquitone wrote: ↑Fri Aug 30, 2024 3:57 pm Yes, that sounds right. René Hagmann began providing “matched-bore” valve-plus-wrap kits for individuals and commercial manufacturers in the late 1990s. René and I had worked for a couple of years before that trying to discover the reason for and, if possible, to correct well-known “problems” with attachment notes. I had noticed for some time that, except for short notes in rapid passages, professional tenor trombone players using Bb/F instruments in symphony orchestras usually favoured slide-alone (SA) 6th and 7th positions for the four notes (F2, C3, E2, B2) that theoretically could have been played with the valve. When I asked some local professionals (Jim DeSano, Steve Witser, Paul Ferguson, and my colleague at The University of Akron, Ed Zadrozny) about that, I received fairly uniform “complaints” about those attachment alternates, typically: when the F attachment is tuned so that the attachment F3 matches the SA F3, with the slide closed in both cases, the second attachment harmonic, F2, tends to be flat and “stuffy” (even when the pedal is well in tune), the third harmonic (C3) tends to be very sharp and uncentered, and attack response is unreliable. Most of those players “blamed” the valves available at that time. [The Thayer valve had been invented decades earlier but was not in common use. More advanced valves such as the Willson Rotax and the Hagmann valve were just becoming available.] When I contacted Mr. Hagmann about his valve, he confirmed that he had heard similar complaints—which had been motivating factors in developing his very “open” three-internal-duct design. But even then, the problems remained. Something else was going on!

Two facts gave me an inkling as to what might be causing the “problems”. When I had spoken at length with Allen Kofsky (long-time second trombone with the Cleveland Orchestra), he pointed out a couple of unusual things about his trombone, a modified Benge 190: (i) the attachment had been literally chopped off short to put it in Gb, and (ii) he was using a dual-bore slide, on which the larger bore (14.3 mm) matched that of the attachment. Allen preferred the dual-bore slide because its sound blended well in between the first trombone and the bass. But he never experienced any of the attachment problems others complained about. In fact, he told me, he used the major-third attachment alternates a lot, and rarely used positions beyond SA 4th. The second fact was that my own Olds “Recording” model (that I already had already modified to Bb/G) did not exhibit any of the usual problems. At first, I thought that these two facts had to do with the shorter attachment tubing. Then I realized that the Olds also had a dual-bore slide (again with the larger bore very closely matching that of the attachment). I immediately contacted René and relayed my suspicions that a “matched bore” might fix some of the problems. Thus began a long collaboration trying to solve this puzzle. I was fortunate enough to be able to visit him in Geneva several times on my way to or from international technical conferences in my research field of computational fluid dynamics. René began experimenting with matched-bore Bb/F tenor prototypes of various bore sizes (using his own valves, of course); and I had some prototypes built by modifying Willson tenors in two bore sizes with Rotax valves: replacing the “oversized” F-attachment tubing with smaller matched-bore G attachments. Plus, some other combinations: an Eb/C alto and a C/A tenor (cut down from my already constant-bore Olds).

The results were stunning: all of the usual “problems” immediately evapourated in all cases. Attachment alternates were the full equivalents of their slide-alone counterparts (of the same sound-path length) in terms of intonation, tone-quality and attack response; and those with longer sound-paths were very similar. One Saturday morning, when I was visiting Mr. Hagmann’s shop in Geneva, Andrea Bandini from Orchestre de la Suisse Romande strolled in to chat. René had been demonstrating to me a combination of a Bach 42 bell with standard (14.3 mm) F attachment and one of his own valves, with a lightweight Bach 50 slide—a constant 14.3 mm throughout slide, valve and attachment. He handed it to Andrea, who proceeded to run through some beautiful orchestral excerpts, especially in the low-tenor register using the valve. Andrea was extremely impressed with the uniformity of the response over all registers (even up to the sixteenth harmonic!). Until he looked at the slide and exclaimed, “Mon Dieu, c’est un coulisse de trombone basse!” And handed it back to René like a hot potato, as if this were some kind of Frankenbone. Except for the valve, this was, of course, identical to the LT42BOF developed by Bach several years later (in coordination with Jay Friedman).

As mentioned elsewhere, I published an article in the Spring 1999 issue of the ITA Journal, “Improving Attachment Intonation, Tone Quality and Attack Response”, outlining the results of our investigations. This was met with “mixed” reviews, to say the least. Apparently, it was too far out of the accepted “conventional wisdom” to be believable to some people. [Apparently, I had “stepped on some toes”. I won’t go into some of the nasty personal attacks I received at that time.] Although René and I had only studied matched-bore tenor prototypes, we speculated that something similar would apply to bass trombones, as well. And this was later confirmed by René. In fact, he was particularly concerned about the fact that on an inline dual-valve bass, his constant-bore valves (which are rather bulky) were taking up too much room along the gooseneck, where there should be a gradual expansion. This was a motivating factor for his development of his “progressive-bore” idea, which is only possible with the three-duct design of his valves. The internal ducts are (laboriously) tapered, gradually expanding in the downstream direction, effectively recreating the taper that would otherwise be in a “non-valved” gooseneck.

Of course, people will have a range of experiences with different trombones, particularly with respect to how the attachment is tuned relative to the base Bb instrument. Tuning the attachment F3 sharp can produce a better-in-tune F2—but this places the attachment C3 (and other third-harmonic notes) even further out. And may cause the C2 to be too far beyond SA 7th position to be viable. Conversely, tuning the attachment flat—so that C3 is in tune with the slide closed—probably means that the F2 is unavailable. But now the C2 is well on the slide.

In any case, getting back to the original post, in addition to choosing one of the most “open” valves available today—depending on the external dimensions desired—my advice would be to consider trying the matched-bore principle, especially if the intention is for using attachment alternates, as opposed to filling the tenor gap down to (almost) connect to pedals. In other words: use a smaller-than-conventional bore for the valve and attachment wrap, matched to that of the slide. Making sure that the construction leaves no “gaps” inside ferrules or any other inadvertent discontinuities along the sound-path. And finally (of course), I would strongly advise using the far more facile minor-third tuning for this purpose!

conn88Hagmann wrote: ↑Fri Aug 30, 2024 3:33 am But what you have said, actually means that it doesn’t matter what size the pipes are, matching or not. It’s just how it plays. . Which is fine of course but means no scientific theory at all can be applied.

Sesquitone wrote: ↑Fri Aug 30, 2024 3:57 pm

Posaunus wrote: ↑Thu Aug 29, 2024 2:33 pm In another thread, Sesquitone (Benny) makes the case that the F-attachment tubing I.D. (and valve ports) should be the same as the slide bore.

although wrote: ↑Sun Sep 01, 2024 11:42 am I feel like other instruments don't have this fascination with finding the perfect valve... I don't haunt the tuba/trumpet/euphonium forums, so maybe I'm just not seeing it. Still, I sometimes think that we get way too wrapped up in the grail quest. Best valve is no valve.

Posaunus wrote: ↑Sun Sep 01, 2024 1:39 pm
Question for Sesquitone:
Benny:
What is the typical Reynolds number (probably rather low) through the slide / valve / attachment tubing?
How does that affect things?

BGuttman wrote: ↑Mon Sep 02, 2024 9:26 am Remember that the density of air is very small, the viscosity of air is near zero, and the exhalation flow rate of air is very small. I think if you calculate the Reynolds number for breath air flow through a tube approximately 13 mm in diameter you will find it to be 100 or less. This is below the left hand axis of your chart. In the scale of most engineering calculations of air in ducts or liquid in pipes our brass instrument flows are below any normal consideration.

Digidog wrote: ↑Thu Aug 22, 2024 10:02 am The CL2000 is a great valve [ ... ] I concur with Harrison, though, that there are some issues.
First: is it still in production, so spare parts or complete valves can be found? Or do one have to have a tech build parts from scratch if something like the rotor or a pin has to be switched? I have tried to purchase a complete valve for my Yamaha 421 through both the European and the Swedish Conn agencies (the 421's valve is worn and in need of replacing), but without any response at all from Conn. I don't see new horns from Conn equipped with the valve either, so it makes me wonder whether the valve is out of production or not.
[ ... ]
Over all, I think that the principles and the functions of the CL2000 are great. Had I been able to buy a valve from Conn for my 421, it had been my absolutely preferred choice, but now I'm planning to refit the horn with a Meinlschmidt valve. Then I have to see how the valves on my Conn 62 age, but this far everything has been fine and well, and if the build quality hasn't deteriorated catastrophically and if the valve still is in production, I'd wholeheartedly recommend it; both for a bass or a tenor horn.

jonathanharker wrote: ↑Sun Sep 08, 2024 6:18 pm

The CL2000 valve patent expired in 2018, so (in theory at least) anyone ought to be able to build one.

From the above discussion about airflow and tiny Reynolds number, might that be why the unused "appendix" in the Y-shaped rotor inlet port might not matter as much as we think it should?

hornbuilder wrote: ↑Tue Sep 10, 2024 6:49 pm BTW. Hagmann do not use decimal/inch tubing size. They use metric mm tubing. Tenor valve section tubing is 14mm, which is .551". Bass is 15mm, which is .590".

BGuttman wrote: ↑Mon Sep 02, 2024 9:26 am Remember that the density of air is very small, the viscosity of air is near zero, and the exhalation flow rate of air is very small. I think if you calculate the Reynolds number for breath air flow through a tube approximately 13 mm in diameter you will find it to be 100 or less. This is below the left hand axis of your chart. In the scale of most engineering calculations of air in ducts or liquid in pipes our brass instrument flows are below any normal consideration.