If for example A speaker is rated as 98dB/1w /1m. What does this mean?
Why are speakers housed in cabinets? 2 reasons if possible
and Which outputs of a mixing desk would you use to send monitor mixes? If you needed 5 separate monitor mixes, how many of these outputs would you need?
thanks
larss7on
That is a great question. Sorry I didn't see it until now.
OK, that figure 98dB @ 1W/1M is called a speaker's SPL (sound pressure level). It is also called efficiency or sensitivity. And it is a great and helpful thing to understand this spec. It is not the only speaker specification you should know, but it is one of the most important. OK here's what it means.
First of all, volume is expressed in decibels. That is what dB stands for. Human speech is around 70dB. A jet engine is about 135dB. A rock band is somewhere in between.
Every 12 decibels is perceived to be a doubling of volume (twice as loud).
So 82dB would be perceived as twice as loud as 70dB.
Some speakers are said to be more efficient than others. This means they will produce more volume with the same exact power applied.
Speakers are tested with 1 watt of power applied from a 1 meter distance. Some companies place the mic at different positions than others. But generally, you can trust the figures from reputable companies.
But anyway, that is what the 1W/1M meter stands for; 1 watt at 1 meter distance.
So, a speaker rated 98dB @ 1W/1M will produce 98 decibels volume with 1 watt of power applied to it at 1 meter distance.
Now, catch this and you will see how this applies to amplifiers. Knowing this will allow you to get maximum volume with lower amplification. OK, here is a very important thing to know:
EVERYTIME YOU DOUBLE (2X) THE POWER APPLIED TO A SPEAKER YOU GET A 3 DECIBEL INCREASE IN VOLUME (3dB). Remember that!
So lets say you have a 100 Watt guitar head and you want to buy a 1 X 12 speaker cabinet. One is rated 98dB @ 1W/1M, and the other is rated 101dB @ 1W/1M.
I bet you already know which speaker is louder. But will it be enough for a loud Rock band? It is said you need about 116-120 decibels to play a small club, 120-126 decibels for a medium sized club, and maybe 126-130 decibels for a large club with big crowd or outdoor concert. Anything over 130 watts is dangerous to your hearing.
OK, look at this chart. The figure on the far left shows the watts of power applied. Notice that I double it each time. Then you will see the decibel level (volume) of these two cabinets.
Watts applied 98dB @ 1W/1M speaker 101dB @ 1W/1M
1- 98 101
2- 101 104
4- 104 107
8- 107 110
16- 110 113
32- 113 116
64- 116 119
128- 119 122
256- 122 125
512- 125 128
1024- 128 131
OK, you see everytime I doubled the watts, each speaker got a 3dB increase in volume. You have a 100 watt head. With the 1st speaker you are gonna get somewhere in between 116-119 decibels, I'd say 118dB.
Speaker #2 is gonna get you 121dB with this same power. So with speaker #2 you could probably play a medium sized club with a good crowd. Speaker #1 might not make it, but would be ok at a small club with small crowd.
There are other ways to increase volume. When you put 2 identical speakers side by side you get a 3 decibel increase in volume. So if you bought a 2 X 12 cabinet with speaker #2, you would get about 124 decibels right? Wrong. Because each speaker shares the watts. Each speaker would only get 50 watts each from your 100 watt head. But still, it is known you get a volume increase with multiple speakers simply because you are pushing more air. This is the reason for the popularity of the 4 X 12 cabinet. But I bet most people don't realize that each speaker is only getting 25 watts from a 100 Watt head.
This is enough for now, but if you want to know more I will write. Tell me if you have any questions understanding this.
Wes
If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis
Whats the difference between graphic and parametric eq units?
and Why do condensor mics have better high frequency response and transient response than dynamic mics?
thanks :) if anyone knows
The cabinet houses and protects the speaker and also more importantly improves the bass response . It also focuses the sound to where you would like it to go .
For monitors I use the auxilliary sends on my Behringer 2442 of which it has four/six (if you toggle the switch some of the signals can be sent to aux sends 5 & 6 instead of 3 & 4 ) . I only use 2 monitor mixes so the other 2 aux sends can be used for effects . For 5 monitor mixes you need 5 aux sends and five power amp channels as well . That's alot ! You would probably have to sub-mix unless you have a mixer with that many auxilliary sends . I have only a three piece band so I don't have to deal with quite that many mixes .
If I claim to be a wise man , it surely means that I don't know .
