Amplified tuba: It's more than a gimmick, and applies to ALL tuba players now and then....
(tubafatness: going a bit beyond your question, as people regularly ask me and I never get around to posting)
I play amplified a lot, simply so I don’t have to honk when playing with a drumset or anyone else who is amplified. I’ve played my tuba through so many different amps and sweated through many a gig and it seems my setup and scheme is always changing a bit. I always try my best to replicate or facsimile a true tuba sound.
I agree with both Art AND Bloke... and what they use is similar to what I use.
What I use depends on the role I’m playing in the ensemble...
For situations where I am the bass role, I use a small 1-12 GK (the standard acoustic bass amp everyone uses) which is great for most things - small to medium sized rooms.
However, when it is unassisted in a big room it tends to run out of gas. It sounds big a few feet in front of the amp but it has a hard time projecting and at higher volumes the EQ is different and not as effective. Overall it is rugged and the EQ deals with the tuba pretty well. It does have a built-in XLR out which sounds GREAT (much better than just going direct, more on that...) I’ve used the line out of that thing in cavernous halls / large setups, where 100% of the audience’s sound is through a massive PA and is carefully controlled and rode real-time by a quality soundperson.
For situations where I am more of a lead, and/or need heavy effects (it happens...) I pair it with a crappy old Peavy I modified into a hybrid guitar / bass amp. It’s heavy and temperamental but it can shred. I don’t use that one as much as I used to tho.
Many larger clubs will have house backline, and my fav is a good ol workhorse Ampeg or GK/Ampeg 8-10 stack. Big Hartkes can be decent too. A 4-10 + sub works too, but is best if you can control the sub through a variable crossover, or even kill the sub. It has a tendency to just be too much and have no definition or tone.
I dont like common mega power rock combos, like 1-15/16 Ampegs, Crates, etc... they are loud, but make the tuba sound like ***.
My personal fav is a hi-end 4-10 setup. Sings + power.
Keep in mind that bass amps and most pro-sound situations are EQ’d for thuddy bass which is quite a bit different from the tuba sonically and in tone. Also, the same model, but different vintage of the same amp can sound different. And a lot of it has to do with how you play too... if you are doing the second-line style sousa thing, it’s going to be a lot different than if you are doing an ambient loop thing where you want no edge at all. Your choice and order of effects will also play a big part. It also depends on the situation whether I am "playing the amp" or "playing the tuba". The other players in the ensemble have an impact too (a heavy-handed drummer can ruin your night)
The amp and it’s EQ abilites / limitations become an extension of your horn and you should be able to control the TONE in the same manner you do with your horn (but through an altogether different process). Amp placement can affect the tone a lot too. Better soundpeople can help you with placement if you are new to a room.
***About Going direct -
don’t do it if you can help it.
(unless you have a soundperson with orchestral ears and the club has a PA with LOW end and does NOT rely on a bass amp for the bottom punch) The WORST situations I’ve dealt with are direct situations. Usually, the soundperson does not even know what a tuba is, much less how to make it sound good.
...that being said, in certain situations where I am an ensemble horn, I will go direct if all the other horns are (such as in a big band or amplifed orchestral setup) then I tend not to worry about it at all.
If you are going to buy an amp, best thing to do is haul all of your electro-tuba rockstar crap

to the geetar store and mesmerize/annoy the salespeople with it. And, if it is a common amp, see if you can borrow one and try it out live and see how it stands up to the rest of the band. Record yourself live... and most of all, never let a soundperson dictate your tone.
And remember (you've been warned!), all it takes is for a classical player to do one *alternative* gig, and you get labled as "oh yeah, that jazz guy" for life.
