PA System amp question

[alks21]

Hi, my fraternity currently has 2 Rockville RSG-15 3 way speakers and the Rockville SBG1124 12' subwoofer (we used to have 2 of these subwoofers but one broke). We power these using a Behringer iNuke NU1000 amp. The 3 way speakers both are 8 ohms, 750 watt RMS with sensitivity of 102 db @1w/1m and the subwoofer is 4 ohms, 300 watt RMS with sensitivity of 92 db @ 1w/1m. The amp delivers 2 x 500 watts into 2 ohms and 2 x 300 watts into 4 ohms. The amp is only 2 channels so we plug the 3 way speakers into the amp and daisy chain the sub through one of the 3 way speakers.

I am still a beginner with speakers but I was trying to use the SPL calculator on the internet to understand this. For instance, with the current amp, say it is delivering 300 watts into the speakers. Then if we are listening to just the 3 way speakers from 20 feet away the db SPL at listening position is 117.1. Now, if we updated to the iNuke NU3000, which delivers 2 x 1500 watts into 2 ohms and 2 x 900 watts into 4 ohms, would we then get the effect of the full 750 the speakers are supposed to handle continuously, which at the same distance would up that number to 121.1?

In addition, how does daisy chaining affect the amount of power each speakers receive, and assuming we acquire a second sub again, should we consider a 4 channel output amp? Thanks a lot.

 

[jinjuku]

Yes on getting an amp channel per speaker. A doubling of wattage, assuming you aren't hitting x-max or thermal limits of the speaker, will net you another 3dB of output.

If you are daisy chaining a speaker, lets say several of the same type you increase the sensitivity and will gain more output up to the ability of the amp to deliver current reliably. Think of line array speakers.

When you chain multiple speakers: Series is additive impedance, parallel is a divider of impedance. Safer to run series than parallel if you are unsure of the impedance presented.