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After removing my second valve slide and looking down I see what looks like the knuckle not being cut or finished properly. Can any experienced people tell me what I'm looking at, how to fix it, and whether or not this problem could affect intonation?

It does appear that the tubing was not properly trimmed. Similar to misaligned valves, this can affect the tone, intonation, and "free-blowing-ness" of the horn. Take it to your friendly neighborhood brass instrument repair tech and they'll get you straightened out.

On the other hand, if your intonation is good and you aren't unhappy with the how the horn plays...consider not messing with a good thing? I'd probably get it fixed just the same.

What kind of tuba is it?

Well, I've had a hard time playing A (1 and 2) in tune. E just below the staff is pretty flat, too. I normally blame myself for things like that but perhaps once the knuckle is repaired something will change.

This is a BMB J445SP16. F tuba.

I purchased a new Bach Strad trumpet in 1995 that had a problem like that, only much worse. Local repairman fixed it in about 40 seconds. I was very disappointed in the factory's quality control. Hope things are improved now.

Ace

As far as A 1 & 2 - that is a problematic note on my horn (BMB F) as well. Needs a bit of a pull or extremely careful and focused/locked centering. The A flat and G is a little touchy too, but not really that bad. I sit on my tuner on a regular basis just to stay familiar with where pitches fall and how to center them. It's easy to lose track if you are playing on several different instruments. I assume if you play on an F you likely have a CC or BBb as well. Lots of little quirks to try to keep sorted out.

It looks like the problem inside the slide could be cleaned up relatively easily, but I do not think that is causing the intonation/centering issue on the 'A' that you mentioned or for that matter the E. That seems to be characteristic of the instrument. I have a similar little burr inside the bell of my BMB CC BAT down at the ferule where the bell attaches to the bow. Its fine on the outside, but just a little burr on the inside. I know it really should not be there.

Just for fun I have been messing with putting strips of 3 mm neoprene foam sheets in various tuning slides to see if changing resistance may have a positive effect on pitch centering on certain notes. I was surprised at how much it took to make a difference. The BMBs are by their nature very open blowing instruments. Some may not find that a useful characteristic and prefer a bit more resistance. Playing that BMB F is similar in some respects to playing a CC or BBb BAT. I find them extraordinary tubas. Used the BMB F in a large symphony orch just today and its presence was impressive and downright beautiful. Got several compliments. They are not like european F tubas which tend to have a bit more resistance.

Probably the next time you take your horn into the shop, get them to go in with a scraping tool and remove that burr.
You'll feel better.

PM

Took my BMB F to Matt Walters. Thanks, Matt! The horn is drastically improved. Now for that Dillon AGR, more water keys, and MAW valves.

Makes one wonder if everybody at the factory was asleep! Things like this need to be brought to the manufacturer (and the importer) immediately.

The quality we accept us what we will get.