Is it an easy way to estimate the power requirement
for Bass ?
In this case in a band with two guitars both running
100 watts 2 x 12" guitar amps.
Only the bass drum has an mic.
And the PA system uses 2 x 200 watt and is only used for
voice and to add a little power to the bass drum.
Welcome to TalkBass!
One idea is that an upright bass needs to be as loud as an electric bass, for a given band. Amp requirements for loud bands are discussed extensively on the electric bass forum. And then, as
drurb suggests, the real issue is SPL, which involves both amplifier and speaker ratings.
However, not to be discouraging, but... an amplifier that is loud enough to keep up with two guitarists and a drummer, if it is like in a rock band situation, could be practically unworkable due to feedback, unless heroic measures are taken. And such an amp will also be an albatross for virtually any "normal" upright bass gigging situation.
I think it's probably worth sitting down with the band and having a frank discussion, about two issues: 1) Does the music really call for upright bass? 2) Can the band control its stage volume to accommodate a manageable bass amp setup?
To give you a point of reference, I have a 170-Watt amp driving a fairly efficient 12" speaker. This is enough to make my upright bass practically unmanageable. Yet the same amp that can obliterate my upright bass would be barely audible in a loud rock band.
