SlyFoxx
Glossless
Re: PA for BAnd - serious discussion
@Laz...
(FOH=front of house)
In a passive FOH speaker set-up things go like this.... The mixing board will feed the FOH signal to an active crossover. The crossover would then split the FOH signal into two signals...one containing only signal from say about 150Hz and below....the other from 150Hz and above. The crossover then sends those two signals to their respective amplifiers and then of course the amps then drive the appropriate speaker(s) An active crossover works on the line level signal coming from the mixer so it does its business before the amplifier. This is a much better way to manage things.
Less desirable (but less hassle) is to run the full range FOH signal straight to an amp and then from the amp to the sub via a regular speaker cable feed and then from the sub to the mid/high range box above via a daisy chain speaker cable. In this case your dealing with a passive crossover. They are less efficient as some of your signal just gets lost as heat and since its a fixed deal inside a box there's never (at least I've never seen it) any way to change the crossover frequency. But if you're dealing with single manufacturer that has matched the sub to the top cab they should have already done the math for you and results can be acceptable.
As for power and speakers...good rule of thumb is an amp that will put out a program or RMS wattage about twice what you speaker is rated for. So for my 300watt EV's I'd be comfortable with a 500-600 watt amp. PA amps don't like to run on the ragged edge like their tube guitar amp counterparts. Leaving yourself plenty of headroom means the amp stays crystal clear. So if you start cranking things too loud you'll know that distortion is coming from a speaker that being pushed too hard and it's time to back it down a a notch or two.
@Laz...
(FOH=front of house)
In a passive FOH speaker set-up things go like this.... The mixing board will feed the FOH signal to an active crossover. The crossover would then split the FOH signal into two signals...one containing only signal from say about 150Hz and below....the other from 150Hz and above. The crossover then sends those two signals to their respective amplifiers and then of course the amps then drive the appropriate speaker(s) An active crossover works on the line level signal coming from the mixer so it does its business before the amplifier. This is a much better way to manage things.
Less desirable (but less hassle) is to run the full range FOH signal straight to an amp and then from the amp to the sub via a regular speaker cable feed and then from the sub to the mid/high range box above via a daisy chain speaker cable. In this case your dealing with a passive crossover. They are less efficient as some of your signal just gets lost as heat and since its a fixed deal inside a box there's never (at least I've never seen it) any way to change the crossover frequency. But if you're dealing with single manufacturer that has matched the sub to the top cab they should have already done the math for you and results can be acceptable.
As for power and speakers...good rule of thumb is an amp that will put out a program or RMS wattage about twice what you speaker is rated for. So for my 300watt EV's I'd be comfortable with a 500-600 watt amp. PA amps don't like to run on the ragged edge like their tube guitar amp counterparts. Leaving yourself plenty of headroom means the amp stays crystal clear. So if you start cranking things too loud you'll know that distortion is coming from a speaker that being pushed too hard and it's time to back it down a a notch or two.
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