TromboneChat

Hi, is this a normal bore gap after the valves into the tuning slide? The bach is custom with a rath valve set and hoelle tuning slide. Plays very nice, but a bit to open. I wonder if the sudden expansion of the bore is a factor??

This the one from brassark? Yeah, I wasn't the biggest fan.

I like it. Work well enough with 1,5 G. It’s indeed from the brassark. This part could be improved. I used a tuba/horn trick and inserted a plastic shim in the smaller leg of the tuning slide. More focus, and takes less air. Looking for a more permanent, or intelligent fix. And the MT vernon slide/ leadpipe is awesome.

The low range and sound were really impressive. But anything in the staff and above was very unfocused to me and Tiffany when we played the horn a few months ago. This could have something to do with it.

Ah! Did you try to add some tape to your mouthpiece shank? I did and it improved sound output and high range a lot! I figured that with such and old slide the mpc was to far in (it wobbled as well!).

That step in the bore is a feature of every Bach with the standard Bach tuning slide setup. It may be that the gooseneck used on this particular example is undersized, but even on factory examples the step is quite evident.

hornbuilder wrote: ↑Mon Jul 18, 2022 8:07 am That step in the bore is a feature of every Bach with the standard Bach tuning slide setup. It may be that the gooseneck used on this particular example is undersized, but even on factory examples the step is quite evident.

Thanks!

Hey Wilco,

There are a couple of things going on with your horn at the slide receiver area. First of all, your photo shows that the knuckle entering your Hagmann valve was not fit very well before soldering. The tubing should have been expanded slightly so that the knuckle tubing fits flush in the Bach slide receiver. That knuckle is considerably too narrow and is probably creating a ton of turbulence in the air flow. I can almost guarantee that a better fitting at the connection would improve the horn.

The second thing is the “gap” that you speak of before that connection. This is a problem in both the Bach 42 and the Bach 50 horns. There is an area that is about 5/8 to 3/4 of an inch long in which the bore is oversized by about .050 to .060 inch. For years, I have created tapered brass inserts for that area of those Bach horns to make the bore match the components around it. The inserts can be inserted by hand and fit snug, but require a crochet hook-type tool to remove (I drill a small hole in the insert so the crochet hook grips it). Some people like the clarity that the inserts create, others only use the insert when they play something in the upper register that requires more pointed articulation.

The only problem that I have noticed is that the inserts are not a “one size fits all” for the 42 or the 50. I prefer to make them custom for each instrument so the fit is perfect. Hagmann makes a similar Bach 42 insert and it is on their website. My only concern with the Hagmann insert is that it might not fit all horns.

Thanks so much for this info! I will have my tech in germany check it out. He could make the fit better when the tuning slide is shortened. It is a bit to long for me. I made insert out of plastic myself this morning. But that’s not a durable solution. Thanks again

Ok, read to quickly. Went over to the Hagmann site and see what you mean now. Will check!!

Brian,
The photo shows the tuning slide side of the valve section. Not the handslide receiver side.

That gap exists in both places, above and below the valve

hornbuilder wrote: ↑Mon Jul 18, 2022 9:01 am Brian,
The photo shows the tuning slide side of the valve section. Not the handslide receiver side.

Ah yes….thanks for that correction. It looked like a tuning-in-slide set up with slide laying beside it…..the photo obviously confused me. After a closer look, those short braces would make no sense from that perspective.

Still……. The difference between the exit of the valve knuckle and the tuning slide is not good. I would have tapered the exit of that knuckle out to be a much better match or created a shim or something. I don’t like the look of that connection at all.

The other end, looks like the shim is already there?? Looks like a smooth transition into the valve…

It would depend on whose hand slide receiver was used. The issue Doug mentioned may not be there. Unfortunately, the photo is blurred..

Even though it is a bit blurred, it appears to be much better at that connection. I don't see a shim....just a better fitting of parts. If it is the original Bach receiver, there will likely be a length of about 3/4 of an inch in which the bore is larger than the parts around it. It is a more significant issue with the Bach 42 than the Bach 50.

Some manufacturers have addressed this problem by only having enough of the tapered area to accept the male connector from the slide. However, this can potentially create another problem.....if the taper wears, the male tenon can eventually "bottom out" and create a loose slide to bell connection. I think there was a recent thread about that specific issue.

Just looked down my 2 Hagmann customs. A 42B and a 50B. Both assembled at Hagmanns in Geneva. Neither of them has a large shim like that.

Other picture; it must be some kind of shim?? I hope I can have my tech take a look at it next week.

Re the slide receiver : Hagmann does ship his conversion kits with two or three different size inserts, for the gap between the end of the slide tenon and the valve port. Those are not really tapered on the inside much, they serve to eliminate or reduce the size of the "chamber" that is created by that gap.

But from the tuning slide side, yeah that looks like quite the step. Also looks like your valve core isn't perfectly aligned with the ports.

Ideally, on a brass instrument there should be no unnecessary construction discontinuities in bore size along the sound-path. On a trombone, the discontinuity between the bores of the inner and outer slides is unavoidable. Similarly, for the oversized "chambers" caused by pulling tuning slides. [The Jupiter 1600I trumpet has available "node stabiliser" sleeves (XONS) that can be inserted to eliminate most of these.] An inadvertent gap like the one that sometimes occurs inside the slide receiver or elsewhere, such as between valve knuckles and (what should be flush) adjacent tubing--due to inattentive construction--creates a tiny Helmholtz Resonator that has its own (high) natural frequency. Depending on where the pressure and velocity nodes of the tone being played lie along the sound-path, the HR frequency may interfere with the harmonic structure of the tone, sometimes detrimentally. [Conversely, there is the so-called "mouthpiece Gap" that trumpet players have been debating the "best" size of for decades that some find quite helpful. But that is a different topic for a different forum.]

A photo of a Holton TR-180. Taken from the opening of the tuning slide receiver. Same step in the bore as found on Bach.

Yep, valve alignment looks to be off. That would make far more difference in playability than the step in bore between neckpipe and tuning slide.

Is that kind of bore gap just the consequence of not having a reversed tuning slide?

Langheck wrote: ↑Thu Jul 21, 2022 2:35 pm Is that kind of bore gap just the consequence of not having a reversed tuning slide?

Yes.

The gap/step could be removed, but the gooseneck would have to be larger/greater rate of taper. There would still be a step back down again in diameter to the smaller lower inside tube of the tuning slide, though.

Wilco wrote: ↑Mon Jul 18, 2022 11:11 am The other end, looks like the shim is already there?? Looks like a smooth transition into the valve…

Slide receivers often have a recess machined into them where the valve knuckle inserts so that there is no lip at the connection. A shim is not needed.

Update. I decided to reverse the tuning slide, in this way there is a much more smooth transition from the valve to the bell. Before the transition was wide/smaller/wide/smaller.

And yes it plays more efficient. We also left some braces of. Time will tell what the best bracing is.

Did you have the valves aligned?

No, thanks for the reminder! I just aligned them during lunch. Will play later.

Forgot how tedious alignment can be with hagmanns.

Just dawned on me that the 50A3 doesn't have an upper bell brace now that you mention the braces being different. I was going to suggest doing some kind of edge bracing for structural stability if you liked having fewer bracing on the tubing but... obviously that wouldn't work