How to calculate speaker box volume for boom box i.e. two speakers

[Nooneknows]

Hi all,

i was using one of the many on line speaker box calculator for a small, battery powered, boom box I’d like to make, but I couldn’t find info on how to proceed when two loudspeakers share the same box. Can anyone help?

 

[AllenB]

You could work it as two boxes side by side without a divider.

 

[Nooneknows]

Just thinking out loud: in this case each speaker will have the double volume needed, isn‘t it?
I mean if a single cone would need for example 1 liter of internal volume doing that would result in 2 speakers in 2 liters. Doesn’t sound right

 

[AllenB]

If one half of the box is up to the same pressure as the other half, then the sound will stay in that half. It is the same as having a wall.

 

[GM]

Just thinking out loud: in this case each speaker will have the double volume needed, isn‘t it?
I mean if a single cone would need for example 1 liter of internal volume doing that would result in 2 speakers in 2 liters. Doesn’t sound right

Why not? He asks rhetorically........😉 Assuming no box aspect ratio high enough to create eigenmodes (some form of TL), then the box's air mass 'spring' is presumed to have a ~uniform particle density, so double the driver's compliance (Vas), not effective piston area (Sd), requires doubling the box's air mass 'spring' to compensate.

 

[mdpaudio]

Double the volume of one speaker if you are using two of the same driver. If one wants 4 liters then 2 want 8 liters. That simple.

 

[dotneck335]

I think I would build the box twice as large to accomodate two speakers. Then build an insert panel to separate the two halves and compare the sound with and without. Then you would know for sure.

 

[JMFahey]

Just thinking out loud: in this case each speaker will have the double volume needed, isn‘t it?
I mean if a single cone would need for example 1 liter of internal volume doing that would result in 2 speakers in 2 liters. Doesn’t sound right

Another way to see it:

* One speaker 1 liter means speaker works against air springiness/stiffness.

* You think one speaker in 2 liter box works against half the stiffness .... and that would be true if speaker were alone.

* but if there is a second speaker, compressing that air, air is not "passive" any more, but "active" ... it´s being compressed also by the second speaker.

In the grand total, it works as if each speaker is working only with its own 1 liter space.