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In my stable of horns I have one of the older model 6-valve Jinbao F tubas...you know, the ones with the "creative" intonation. I acquired it used about a year ago to learn F tuba fingers and it was promptly borrowed by a friend until early this morning. I had about a half hour before heading off to work to familiarize myself with some of the intonation quirks and F tuba fingers and then about another half hour after work before taking the horn off to the rehearsal of a local community band, thinking that I could play along with the other tuba player there and match pitch with him. As it turned out, I was the only tuba player at tonight's rehearsal...I survived the rehearsal with my dignity intact, but only just barely at times!

The intonation of this horn is indeed very strange. Remembering that I've only spent a short amount of time with this horn, a workable Bb scale looks something like this--

Bb - 5
A - 12
G - 4
F - open
Eb - 6
D - 12
C - 4
Bb - 54

So much for the fifth and sixth valves being only useful in the low register! I also found that the D in the middle of the staff was best played with the fifth valve. The B natural below that was best played with 6. E natural below the staff had to be strongly lipped up, etc etc. It was a workout keeping it all straight in my head and lipping everything as necessary.

Personally, I attribute the bizarre intonation to a too fast taper in the main tuning slide wherein the bore of the tubing increases far too quickly; more or less doubling the diameter over the short length of the tuning slide. That just plain doesn't make acoustic sense.

After a more difficult (but possibly more educational) rehearsal than I've had in a long time, I got home exhausted and decided to put my Dennis Wick practice mute in (so as to not disturb my housemates) and try to work out some of the odd intonation tendencies that I hadn't quite managed during rehearsal. After working up and down a few scales with a tuner, I noticed something very odd-- the intonation seemed magically fixed but my horn had developed a slightly stuffy low C that everyone keeps talking about. Very strange.

Is it possible that the added resistance of the practice mute is correcting my intonation, but borking the low range? I am willing to trade a little bit of clarity in the low range for some easier range, so how can I go about adding resistance to an instrument without negatively impacting it's tone?

If you can fix the intonation, I'd like to know as well. I have the same model. I'm glad to know we're using almost identical fingerings, though. That means it can't be all operator error haha. I also have a main tuning slide kicker on mine.

I've worked up a couple of psuedo-acousticoil type things that I can insert into the horn to (hopefully) add the needed resistance...but I won't be able to try them until after "practice mute" hours. I'll let you know what I find!

If all else fails, I could always add some resistance the old fashioned way...

Interesting. With that instrument I have no experience but about resistance that changes intonation in other horns I have. Mostly a practice mute does things that we do not like. But, I have also experienced some instruments that automagically behaved much better or almost perfect when using a practice mute...

As it seems to be difficult to find a practice mute that works perfect on an instrument that in other situations work fine, maybe some maker/s are on their way to open up a new market niche with special practice instruments that are optimized and works at it's best with a practice mute inserted?!

From a maker's perspective it would be more money to earn by selling one instrument for practice and one for concert instead of just one and a cheaper mute as many of us only have the option to practice without too much noise at some times Just think of it, "OK so you want to buy this tuba. Today you would get a special deal if you buy the practice model too!"

After spending some more time with the horn, I have managed to make some small improvements in intonation. Through a combination of setting the slides differently and aggressively lipping a few notes, I can bring the Bb in the staff and below the staff in tune with the first valve instead of the fifth.

Tyler, here's my new tuning combo--

1st - as far out as it will go
2nd - pushed all the way in...possibly needs to be taken into a shop and shortened
3rd - pulled to tune Ab near the bottom of the staff when played 23
4th - pulled to tune Bb below the staff when fingered 14
5th - ???
6th - pulled to tune Eb below the staff.

With the above setup, the intonation is beginning to approach manageable. Initial experiments with cutting up bits of plastic and putting them into the big end of the main tuning slide to increase resistance have been mixed...I need more time to draw conclusions, but I have found that it *is* possible to bring the F in the staff into tune with an open fingering.

There is no law against using the 5th or 6th valve in other registers, if it slots a note in tune without slide pulling or excessive lipping. Once you get used to the new fingerings, they will become second nature. If the horn can be played in tune, who cares which buttons are being pushed?

Certainly, it is the case that the more time I spend behind the horn, the closer to center the notes are landing. Shocking that two half hour sessions aren't enough time to work out the quirks of an instrument, isn't it? I think that, perhaps, I will try a few more experiments with adding resistance on the basis that...

A. I'm certainly not hurting myself or the horn
B. Maybe I will learn something useful along the way

...but that said, it will always be true that the only silver bullet that exists in this world is practicing more. Time to go play etudes until using the 5th valve for Bb makes sense to my addled brain.

I've had my Mack 6V F for three years now and can confirm that you won't become friends with this horn within a couple of hours. I've attached a fingering chart with what I consider nonstandard fingerings marked in red. The worst note is probably E below the staff, because it is so flat with 2 and 234 results in an awkward fingering and inferior tone.

Everyone complains about the F in the staff being sharp open, but I find 23 to be equally as flat as open is sharp. Just take your pick and lip in the appropriate direction depending on your choice.

These slide settings work for me playing with a PT65.

Main - out 5/8"
1 - out 5/8"
2 - all the way in (and still too long!)
3 - out 1/4"
4 - out 3/4"
5 - out 1/2"
6 - out 1/4"