Sound questions

[The Boogie Man]

Hi troops,

 

It's late, but I'm curious so I'm wondering (copyright me)

 

A sound reinforcement system of a mic a mixer, 1 amp and a speaker in a room ( not a big room ).

At a certain a volume the retuning sound signal will begin to make its way into the source (microphone) and howlaround begins.

A graphic finds the freq and it's cut. The volume goes up again and more signals are cut until eventually there is a point where the volume can no longer be raised without causing howlaround. This is now the maximum volume that can be achieved. ( I know there is a lot can be done to get more, drapes, carpets etc, but that isnt the point of this question)

Now if the max spl in the room is stuck at x would a second identical but totaly independant system set the same actually raise the spl or would anyone in the room just perceive it to be louder or more correctly fuller?

Or would having two sets of the same freq bouncing round the same room cause more howlaround that would necessitate lowering the volume thus negating the point of doubling up the system?

baz

[Rob_Beech]

The "lot that can be done to get more" should really be the first thing to do.

 

What you find with loudspeakers is as they are given a higher input their response tends to change. This is true throughout the range but more obvious closer to the speakers maximum power handling. You'll find that a speaker responds better to some frequencies than others when it is pushed hard, this alters a (hopefully) linear response to one less so.

 

By adding a second speaker you do many things, you increase the system headroom and thus the ability to reproduce a frequency at the required level, you increase the overall level (providing you DO have GBF) and you can improve coverage.

Remember, if you can point a number of speakers effectively in the directions you want, you may be able to work with a lower volume from each box thus lowering the problems of reverberant sound.

[The Boogie Man]

Hi Rob,

cheers for input. I think I must ramble too much and confuse things. It was more a question of theory than application. I was just curious if adding more drivers to a given situation raised the spl or it is just perceived to be louder.

Example: 0ne 15" driver putting out 100db spl on the left with say an old column type cab of 4 speakers on the right again outputting 100db spl. Will it be like the 100weight of coal v 100weight of feathers or will the column be perceived as louder or not?

baz

[Rob_Beech]

100dB is 100dB, so if both examples are outputting 100dB you'd get 100dB.

HOWEVER, you have to look at the overall surface area and coverage/dispersion of the box or boxes. You may not be covered by all of the drivers, but they may provide better coverage, though each area would receive a lower volume.

 

Similar in SOME ways to, you could see more of the cwt of coal at a given point than you could the cwt of feathers.

[The Boogie Man]

Cheers Rob, Makes sense.