We often get asked how we can provide enough volume for live bands using only one top and one sub cabinet per side. I usually end up giving a technical answer that may or may not be understood by the person hiring me but I try to make it as clear as possible. I thought this post might help. In order to make this as simple as possible, some of the technical info will also be simplified,but the basic premise is all solid.
First things first. Watts of power or watts handling capability are not a good indicator of how loud a speaker can get. Speaker sensitivity is what determines that. You can have (2) 1000 watt speakers each being fed the exact same signal and one can be noticeably louder than the other if the speaker cabinet has a higher sensitivity. Sensitivity is actually a way to measure how efficient a speaker is, or how well it can convert the electrical signal it’s being fed into sound waves.
Lets take two speakers. Speaker A costs $500 is rated at 1000 watts and has a sensitivity rating of 96 db at 1w at 1 meter. This means that if you send one watt to that speaker it will produce 96 decibels of sound at 1 meter away.
Now speaker B costs $1200, is also rated at 1000 watts and it’s sensitivity is 105 db at 1w at 1 meter. So it produces 105 decibel at one meter also being fed 1 watt of power. A difference of 9 decibels. What does 9 decibels mean to the listener. Well, it is generally agreed that 6-10 decibels equates to twice as much volume to the listener’s ears. That’s a significant difference.
So what does this mean to the person using the two different speakers. In order to increase a speaker’s output by 10 decibels one has to give the speaker 10x the amount of power. So in order for speaker A to be as loud as speaker B when being fed 1 watt, we have to give speaker A 10 watts. If you increase both speakers output 10 db , you’ll only need to feed speaker B 10 watts, but 100 watts to speaker A. To increase both another 10 db, you need to give speaker A 1000 watts but give speaker B only 100 watts.
At this point, both speakers are the same volume but speaker A has reached it’s power handling limit of 1000 watts, but speaker B is only using 100 watts of power. If we feed speaker B 1000 watts it will be 10 db louder than speaker A or at least twice as loud.
At this point you might be thinking, well at $500 ea I’ll just buy 2 of speaker A and they will be just as loud as 1 speaker B and I’ll still have saved $200. Sorry, that will not work and here’s why:
We have already established that you need to increase your sound level about 6-10 db to have twice the volume. Let’s say for the sake of argument we only need to raise it 6 db. You would think that adding adding another of speaker A and feeding it 1000 watts and you would equal the ouput of speaker B being fed 1000 watts, but you would be wrong.
Anytime you double the amount of speakers you have you only raise your decibel output by 3 db. In order to match the output of speaker B you need to raise it at least 6 db. So doubling speaker A only gets you 3 more db. You have to DOUBLE it again to get 6 db. So you will need (4) of speaker A ( total $2000) to match the potential output of (1) speaker B at $1200.
These are not just made up examples and let me give you a real world one. For the point of this exercise it simply does not matter, at all, how many watts the amps are in the speakers, only what decibel level they are capable of producing.
For our pre-packaged system 4 we use 2 EV ETX35P powered speakers. They list for $1500 ea. One speaker has max output of 136 db. Combining the two we have that gives us max output of 139db (doubling only adds 3 db) for $3000.
Let’s take another powered speaker, the Peavey PV215. OK they cost $500 ea and have max output of 127 db. Let’s see how many PV215s we have to buy to equal our two ETX35Ps.
First we double it. 2 speakers gives us 130 db. OK, now we double it again. 4 speakers give us 133 db. Now we double it again. 8 speakers give us 136 db. OK getting closer. Let’s double it one more time. 16 speakers now gives us 139 db. We’ve now matched the output of (2) ETX35Ps.
And it cost us 16 x $500 = $8000. $5000 more. And we only need to haul 14 more cabinets to the job plus run cabling and power to all of them. Not too mention how bad it will sound having that sound come from 16 different locations all arriving at your ears at slightly different times due to not be equal distances from your ears.
I believe I have proven that cheaper speakers will cost you more money.