Need More Power

[billfitzmaurice]

I don't get this at all, Bill. If cabs can take, say 500 watts each and are both 8 ohm. And the amp puts out 900 watts at 4 ohm in bridge mode. How can those cabs get fried? The should be able to take it.

That's the problem with only talking about watts and thermal power handling. Watts alone tell you nothing, and thermal power handling doesn't tell you much.

The average 500 watt cab can only take 250 watts before reaching excursion limits. At 8 ohms that's 45 volts. Parallel wired all cabs see the same voltage, so 45 volts is the safe long term limit no matter how many cabs you run. Bridged this amp can put out 60 volts into 4 ohms. That makes it possible for it to damage a pair of 500 watt cabs. The safer route is to run each channel to its own cab.