I was reading the wikipedia article on tubas for reasons that remain mysterious, and under “Types and construction,” it says:
Now, I know perfectly well what F and E♭ mean, but what in the world is CC and BB♭?
Low C, low B♭. The big boy ought to be called a “B♭ double-bass” tuba but invariably it’s called a “BB♭ bass” pronounced “double-B-flat”. Brass and military bands typically have both an E♭ and a BB♭ bass.
Incidentally, the wikipedia article does more or less explain what it means.
Amateur tuba player here. 
Malacandra got it, but I’d like to expand with my own personal rant about the sloppiness of the notation, which the wiki article correctly describes as “a traditional distortion of a now-obsolete octave naming convention”.
I don’t much care for the “double C” or “double B-flat” nomenclature, myself, but nevertheless it is in common use. It’s an attempt to indicate the octave of the horn’s fundamental, as well as it’s pitch name. A “CC tuba” has as its open fundamental the C about an octave and a half below the bass clef staff: …draws it out… the space below the fifth ledger line, I believe. That’s the lowest note that can be played with no valves depressed. (The “open” notes go up from there in integer multiples, corresponding to: C an octave up, G, C, E, G, unusably flat Bb, C, ad infinitum, just like all brasses.)
In some pitch notation schemes, that fundamental note is written CC, and increasing octaves are notated C, c, c’(I think?), etc.
Fine. But in all notation schemes I’ve ever seen, octaves are grouped from C to the B above it. Any C and the Bb one step down are in different octaves per the convention. So if what we call a CC tuba is indeed such, the similarly-sized tuba pitched a whole step down should be called a BBB-flat tuba. And, for that matter, E-flat and F tubas should be described as EEb and FF.
But it ain’t. Hardly the only example in modern musical notation/nomenclature where the “system” fails to be consistent when you really look into it…
What the terminology does do is enshrine in the nomenclature the effective differences between what are often called “bass tubas” (F and Eb) and “contrabass tubas” (CC and BBb). These two classes of horns tend to have distinct sounds and are used for different things, although “crossover” constructions can be found. (Think higher solo work where clarity is important, versus serving the organ pedals’ role in an orchestral brass section…)
And I’ll just mention here that the fundamental tone of a tuba isn’t a very practical measure. It’s the lowest note the instrument can play, but it’s really, really hard to do so (I was the only tubist in college band who could reach it, and that only for a half-second or so), and you don’t get full coverage of the notes immediately above it.
I admit the nomenclature is confusing, but there’s a lot about brass playing and brass instruments that’s just weird sometimes. It’s like tennis scoring; once you’re in it you just accept “love-15-30-40/deuce” and don’t ask why.
Not sure if I can add anything meaningful about tunings except to say that whoever wrote the Wikipedia article is most assuredly British and in some cases not entirely accurate. There’s all sorts of references to British bands, which are not the same as American concert bands or wind ensembles; we have brass bands here but it’s not as prevalent as in the United Kingdom. I won’t get into the messy details but the tubaeuph listserve routinely wrestles with these kinds of issues and if any of you are truly interested in debating this I can send you over to Yahoo Groups, you can find it there, TubaEuphonium listserve.
FTR I choose to play Bb rather than C tuba (okay, it should be notated BBb, but what the hell). I prefer the quality of the sound, which I think has more richness than C, especially on the pedal tones (the very bottom notes); I think as you travel up the scale the sound can become more pinched. As Chronos notes, some of the pedal tones are not entirely secure are actually referred to as “false” notes because you can get to that one but not the one just above or just below it.
I also own a F tuba, it’s pitched too high for most of the playing I do these days, though it’s cool to have it. Perhaps someone will ask me to do some Berlioz or the “Bydlo” solo from Pictures At An Exhibition. and I can get it out. These days I’m playing with the Seed and Feed Marching Abominable and the Band of America and they’re happy with me on my Bb horns, tubas and euphoniums . . . but euphonium, that’s another thread altogether. 
TubaDiva
Your heavy metal specialist
What about Tuna Tubing?
Like, the folks playing them? 
You know this is General Questions, right, Cal? Where jokes at the expense of the thread are not entirely appreciated, especially when someone is looking for real information.
The tuba is sometimes considered by the unknowing and the foolish to be an object of derision and humor. This is a prime example of the kind of horse crap lower brass players routinely have to put up with in everyday life and it’s annoying and hurtful.
This is a serious thread and a real topic of discussion and it comes up rarely on this board and you’re spoiling it for the rest of us. Please be ignorant somewhere else.
Exactly.
~hawksgirl, clarinetist
You need to lighten up, TunaDiva.
Aw, you’re probably right, friedo.
Cal, I apologize. Not an excuse but a reason here: I do take my method of expression seriously, perhaps too seriously for some. And I get really frustrated when people poke at it, make light of it. It comes from other musicians too sometimes, and that is the worst of all.
Perhaps I should have listened to my mother and become an accordion player instead, now there’s an instrument that commands respect wherever you go!
Most seriously, I’m always charmed when someone has a question about something that is meaningful to me and I’m happy to share. In those times I don’t always see much room for levity. Sorry about that.
TubaDiva
Tuning up for “Lady of Spain.”
Personally, I am glad Cal chimed in, because I was gonna ask about Tuba tuning, and I’m certain I would have been a grease spot when she was done with me. 
Doug (Who has a son who played tuba, one who plays trombone, and one who plays trumpet; whoda thunk from a confirmed pianist?)
I appreciate it, TD, but you’ll notice that I wasn’t poking fun at tuba players at all – it’s wordplay. Heck, I was in Marching and Symphonic band for years. (Some of my beest friends were Tuba Players…)
Deadly serious tubas: http://static.flickr.com/72/227518659_163e9acf3e_o.jpg
Yeah, but would you let your daughter marry one?
Probably not… I think his daughter’s only 12.
Muffin, what the heck are those things? Some sort of battlefield signalling device?
Don’t forget your cousins the G keyed Contrabass Bugles
Drach 87, 88, 89 Sacramento Freelancers
http://en.wikipedia.org/wiki/Sacramento_Freelancers
Took me a few minutes to post because I had to edit this page a bit.
Drum and Bugle Corps! Woo-hoo! (Yes, big musical geek here.)
I see those huge contrabasses at the DCI shows and the sound is pretty amazing, regardless of the key, though I think most of the corps no longer work strictly in G.
There’s an excellent reason you have to be under 21 to march DCI, I think it would kill an older person. (Yes, I know about DCA and I’m tempted, I’m tempted, even at my advanced age. )
TubaDiva
(who really loved The Phantom Regiment last season)
Japanese war tubas, used in conjunction with anti-aircraft guns. The tubas were used to listen for approaching planes. (Think of an old geezer with a horn in his ear as a hearing aid, and a cane with which to swat kids.)
Ah, so the sound goes the other way! Still, I bet it’d be fun to stick a mouthpiece in the ear end and sound it.
And I never realized that the shoulder-cannon model was considered a different instrument from the tuba. I’ve seen several with swappable necks of different shapes, so they could be played either on the shoulder or in the lap.