I've decided after hearing someone hear say something idk who about playing through a guitar head, and I want in realllllllly bad. I want to get one of those 2-3 channel peavey/b-52 budget tube heads, so I can foot switch between clean and searing overdrive and distortion. I've also seen a Sovtek Mig100 on the Clist. I am going for nothing less than 100 watts, tube, should I be able to gig this and be heard? I also have a 250 watt GK MB200 so I'll be running two amps most likely. I'd never at the moment do any major gigs, so would I need to mic at all?
If you plug a 100-watt tube guitar amplifier head into a good 4x10 cabinet, you should be fine. Whether you'll have to mic it depends on the music you play, what the guitarist uses and how big the venue is. Unless you're playing metal in big venues, you should be able to do without the microphone.
"Maybe this world is another planet's hell?" - Aldous Huxley
a hundred watts of tube power should do ya just fine. my acoustic b200 (running at 120 watts SS) kept up with 3 different punk drummers and my 60 watt SS guitar amp in a large venue(1000 people sized room).

I would asume you'll do okay with a 100 watt tube head. although you will have to be sure to be eq'd properly.
no sir away a papaya war is on
^ you play with 3 drummers at once or are you in three bands/ jam things
I leave all my bass gear at our practice place and play out of my Randall 150 all the time at home thru my extra 4x10. I use my external preamp and leave the Randalls tone knobs alone, and if you didn't see the Randall turned on, I highly doubt you would be able to tell.
Lets put it this way.When you would normally D.I a bass,instead you would just stick a mic on the cabinet.Use a proper bass mic if you can,if not,a kick mic blended with a guitar mic can work,at bare minimum,an sm57 does the trick.If you can,blend the mic'd signal with a D.I signal,to retain some low end.

For wattage,it's important to know that bass frequencies draw a lot more power than a normal guitar.Overdrive is great,but some headroom is nice.
I used to run a 50 watt,valve guitar head and 4x10.For small venues,it was great.Plenty of volume, and a ton of natural overdrive.That being said,I ran than that thing into the ground.I wore out my cabinet,and the tubes wore out after a year or so.I think with 100 watts you should be fine.See if you can put some KT88's in,they have more headroom,and a bit better bass response.
I run a 230 watt tube head on KT88's now,which is just amazing

As for distortion,I've found guitar amp distortion channels to be terrible for bass.
Get a fuzz, or a thick distortion pedal,and either bi-amp,or put them in a high pass filter,then you'll be set.
Goodluck,and feel free to ask me any more questions about this,I've been there and done it.
Seagulls,the chicken of the ocean.

Originally posted by Gunpowder:
Everyone just jumps on the bandwagon and gives the same advice in these situations. You know what? I'm going to be different. Call the firemen.
^ you mean the dedicated dirt channel? because Geezer used a guitar amp and he sounds great
Now that I grant you.Geezers tone is amazing.But most of that sound comes from an overdriven clean channel,and a unique picking style.
Notice how geezer finger picks on the fretboard.There's a couple bassists who do this,and I find,the percussive kind of attack it delivers really warms and drives a tube amp.
Check out some videos of Scott Reeder from Kyuss to see what I'm talking about.
Seagulls,the chicken of the ocean.

Originally posted by Gunpowder:
Everyone just jumps on the bandwagon and gives the same advice in these situations. You know what? I'm going to be different. Call the firemen.
Oh yes, and I do play that way, cause for a long time I used a P bass with a pickup cover, and hate the treble bite at the other end. I might not go far onto the fretboard but I was always right on it if not right at the dip off. But whatever I'm not trying to be Geezer. Most newer 100+ watt tube guitar amps are meant for high gain but they do have clean channels, so with a foot switch, my dirt pedals and an EQ I will be very good in the tones department, especially if I bi amp, thank you all
Micing a live amp gives you this advantage:

The sound guy can balance your sound out in the theater. On stage, you do *not* know what the mix is in the audience 30 feet or 100 feet back.

Also, the sound guy can place your amp into left-right speakers for a wider sound. With just your amp, you are limited to the sound radiating from just that one point.

A huge consideration is on-stage sound volume. If it's a small stage, don't bring too much power, you will have too much on-stage volume. A single 100-watt amp is plenty.

Quick tip: some serious pros that I've seem turn their speaker cabinets *backwards* on stage. They point them into the curtains behind them. Then they mic the cab, and the sound volume on stage is more reasonable.