Valve ports show solder buildup

[SiteReader]

I have been playing a Thomann CR400 cornet for a little over three weeks. Have grown accustomed to the smaller handhold than on my trumpet, and am rather liking this instrument.

However, I've noticed that the ports in the valves are not completely smooth. At least one of the ports in each valve show a buildup of metal (solder perhaps?) that would theoretically prevent a perfectly clear passage of air. I've examined the valves on my 1955 Conn Victor trumpet (my only point of comparison) and found no such metal buildup, or only the faintest hint of one.

Is this a manufacturing defect that could have an effect on the instrument's sound? (The valves seem to work quite well mechanically, and have improved over my three weeks of playing and oiling.) Should I take this up with Thomann, and perhaps ask for replacement valve pistons? Or is it a trivial point?

I paid $206 for the cornet, counting $36 shipping from Germany and $5 foreign transaction fee on the credit card. I feel like it was a good deal. But they do offer a 30-day return and three-year warranty. I'm perfectly happy with how this instrument plays, sounds, and looks, but wonder if I should address this possible problem now.

[Tpt_Guy]

Anything like this?

https://m.imgur.com/uj5hMBe
_________________
-Tom Hall-

"A good teacher protects his pupils from his own influence."
-Bruce Lee

[SiteReader]

Yes, exactly that, Tom Hall.

It appears that "die Verengung im Luftgang" is obstructing my "Luftstrom."

[Tpt_Guy]

That's normal. It comes from the ports being close together and basically "overlapping" inside the piston.

Checkout http://www.deniswedgwood.com/ovoids.html

Read the section called "Valve depression length". It explains why there are bumps in the piston ports.

As you have already observed, not all trumpets have these.
_________________
-Tom Hall-

"A good teacher protects his pupils from his own influence."
-Bruce Lee

[SiteReader]

Yes, I see what he's getting at with his "ovoids."

Though it still doesn't explain why the bumps are tiny on my Conn 22B, and much larger on this cornet. I'm suspecting it may have to do with the difference in construction techniques between the under sprung valves of the Conn, and the built-in springs of the new Thomann.

Anyway, my "bumps" appear about the size of those pictured in the German-annotated link you gave me at Imgur. So I guess they are about normal, are not a defect in this model, and I'll live with it. Whatever the obstruction it is causing, it is minor compared to my meager abilities. Perhaps as I get better, this may provide an excuse to upgrade to a more expensive horn.

Thanks for the prompt help. As usual this forum is great.

[Tpt_Guy]

You're welcome!

And don't worry. Most horns, even very high-end horns have these bumps in the ports. As Denis Wedgwood no longer makes instruments, I only know of one maker who designed a horn with pistons specifically made to aviod these bumps, and that is Best Brass, and it appears they mostly copied his design. I'm sure others on the list can correct me if I'm wrong.
_________________
-Tom Hall-

"A good teacher protects his pupils from his own influence."
-Bruce Lee

[shofarguy]

Those bumps are there because of geometry. I think there are several limiting factors involved in producing this compromise, and that is what it is.

1) Diameter of the valve casing. It makes sense to me that the average human hand is the main determining factor here. The trumpet design developed over the centuries requires the player to grasp the horn around the valve set. Thus, the diameter of the casing is proportionate to the ability of the fingers to effectively hold the valve block. This, in turn, limits the diameter of the piston tube.

2)The length and radius of the 2nd valve 1/2 tone crook and tubes. These are the shortest of the three valves. Stubs and receivers have to be soldered to the casing and crook with enough purchase to last for decades without falling apart. This limits the radius of the crook, which established the vertical distance between the entrance and exit ports of this and the other two valve pistons.

3) The radial position of the transfer ports leading into and out of each valve casing. In Besson style valve designs, these ports are close to the center line running through all three valves. Close enough to allow straight transfer tubes. In Bach style valve blocks, those tubes are curved, which allows the transfer ports to shift away from that center line. This, in turn, gives more room inside the piston for the piston port tubes to occupy. More room means less overlap, thus smaller squish areas.

4) Bore range. Because the Bb trumpet/flugelhorn/cornet family stays between .413" and .470" in modern day designs, this last dimension is what precipitates the squish areas. There simply isn't enough room inside the piston tube to fit this size of port tubing without them colliding in space.

5) Piston stroke. The last relief valve, so to speak, is the stroke of the piston. Recently, I compared a long-stroke MLP Benge, a Burbank 3X+ and a Wild Thing. The Benge design sought to reduce the squish areas by lengthening the distance between the ports in the at-rest up position and the down position. It worked, but gave the horn a valve stroke a full 1/4" longer than the Wild Thing, which has very tight 1/2 tone crooks and curved transfer tubes. Though the deformed areas of the port tubes was smaller in the Benge pistons, the difference was eventually deemed undesirable, because of the added difficulty of the long stroke. The Burbank solution was to maintain the shorter (by 1/8") stroke of the standard ML and L valve block but keep the MLP's wider crooks.

From what I remember reading concerning the Wedgwood design, their valves used a larger diameter valve casing that allowed for unrestricted passage of each port tube.
_________________
Brian A. Douglas

Flip Oakes Wild Thing Bb Trumpet in copper
Flip Oakes Wild Thing Flugelhorn in copper


There is one reason that I practice: to be ready at the downbeat when the final trumpet sounds.