Pro Audio Asylum

RE: Division of labor in PA system-More

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Yes, room and people absorption will tend to make things sound "bass heavy", due to greater absorption at progressively higher frequencies. This is one reason why bands can get away with putting the subs on the floor but need to have the mids and uppers above the audience's heads.

Getting to the directivity issue... Bands often have a hard time getting the system to sound "right" throughout the room. At the risk of giving away one of my sound reinforcement "secrets" ;) , this is often because the mids and uppers are too directional for the venue, and so I always designed systems to have wide dispersion as high up as possible. This improves both the direct sound and the reverberant sound, and makes it much easier to tune the system, and have people coming away saying "wow, that band sounded great!". Along that line, one thing I'd avoid is a 2-way 15" design. Inevitably, the crossover has to be much higher than a 15 should be used - they get too beamy.

Regarding the JBL system you mentioned... It's fairly easy to get a lot of output from the main boxes, which is one reason why you'll often see them capable of more output than the subs. It's not that the system is mismatched, it's just harder and more expensive to get lots of output at lower frequencies (but you already know that!), and so you'll see systems which have similar mids and uppers, but increasingly more on the low end, as the price point goes up - effectively - it's boosting the low end to "catch up" with the capabilities of the mids/highs. But, remember that the waveform peaks (especially snare drum, cymbals, and other fast rise-time sounds) are created by the mid and upper harmonics, so some extra headroom there is often necessary. This is one reason why so many systems which are driven to near their max levels are sound so distorted - the peaks are clipped.



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