hello i have a pair of 2 x 15 em series martin audio bass cabs and a pair of em 12 inch cabs on top ,can anyone tell me what crossover setting i should set my rack mount passsive croosover unit to,i use this rig in my band and so the drums bass guitar keyboard and vocals are running thru it,i have a 1200 watt amp on the bottom and a 1200 hundred watt amp on the top which i think is wrong ,should i turn the top amp down a bit ,cheers
It's really better to run the subs at the lowest point manageable, like 70-100hz. If you cross the subs at a higher frequency, you wind up with a big hump in the frequency response, which causes low frequency feedback and ringing, and you wind up tuning out the hump with your equalizer.
You see, crossing the subs at a higher point seems to make the system louder, but you lose the loudness when you get the feedback out with the equalizer.
And you SHOULD be using a 31 band 1/3 octave equalizer, if you do not have that, get one.
Then another problem is the highs are too loud, and the mid range is not loud enough. Turn the highs down if they are adjustable, use just enough highs to balance with the mids and the lows. The highs should be at a much lower level than the mids and the lows.
You see, this is always a problem, because the efficiency of one horn is equal to six speakers. So if you have two horns, you would need twelve speakers to balance it out. And that is why the horns are used at minimum level, the speakers are used at close to maximum level.
And then if the highs are not adjustable, separate from the mids, you are really having problems.
Now for the power, 1200 watts is not too much, not really. You see it's not power that blows speakers, it's distortion. As long as the power is clean, the speakers won't blow. As soon as the amp goes into clipping and produces distortion, then the speakers blow. That's why we use an amp with more power than we need, the amp never clips, the amp never distorts, the speakers don't blow.
So if I use a smaller amp, say 200 watts, the amp clips much sooner, then the speakers blow much easier. The extra power is called HEADROOM. The HEADROOM is the safety zone which keeps the amp from producing distortion, therefore keeping the speakers safe from distortion.
So now you can see that a 1200 watt amp is not really too much, as long as the highs are adjusted down to match the mids and lows.