#1
I have a peavey 212 combo amp.. but if im going to play shows with my band im gonna need more volume with that. its a $900 dollar amp so it doesn't suck, so i wanted to just add a cab to it but im not sure whether i can or should do that. im not necessarily an expert about amps so thats why i'm asking what i should do if i wanted to play shows. thank you
#3
Stick a mic in front of it. Problem solved. BIG AMPS aren't always the solution. If they were, why would anyone sell high end combos?

You can definitely add a cab, but I wouldn't bother.

Or, get a Marshall half-stack. They are pretty awesome too, and what's more they LOOK the part.
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#4
How many watts is it? A 2x12 pushes a lot of air ... I can play over a drummer without any problem with my 15 watt Tiny Terror and a 2x12. Before that I had a 50 watt Mesa/Boogie with a 1x12, and that was even louder. Like, never went past 4 1/2 louder.

Stacks aren't really necessary, unless you're playing a HUGE venue, or just want to look cool. And if you just want to look cool that's okay - stage presence is a big part of any live show. Just don't think that you NEED one. Actually in most bars and small clubs, you'll probably make people think you're a tool it you bring a half-stack.

As far as extension cabs go, check the back of the amp to make sure it's wired for an extension cab. It probably is - most high-end, non-tweed amps are. Then just find another 2x12 cabinet (or a 4x12 if the extension jack overrides the main speaker) with good speakers and you're ready to rock. Personally I prefer Celestion Vintage 30s because they're extremely loud and sound good with any type of music, but anything with a name brand on it should be decent. And really, if you're playing bars, I guarantee that your audience won't hear a difference live, unless your speakers are awful.
#6
You won't need anything else. a 2x12 combo is plenty sufficiant.

If I were you, I would worry about having backups for EVERYTHING. Nothing is like having a gig ruined because a piece of gear craps out/gets ruined. Just make sure that if any one piece of essential gear breaks down, you have something to take it's place in an emergency.
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#7
I am sure you have plenty of volume. If I where you, I would spend my hard earned cash on a compressor, delay, EQ, or new pickups before an extension cabinet.

If you really want a cab though, a 2x12 should do ya fine. (I personally don't even really like 4x12, gets soooo boomy sometimes)
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because that's where you'll find me..."