Question on sealed box volume vs. shape

[ashwin]

Hi All,

my question is this : suppose you calculate the optimum volume for a sealed box given speaker parameters and expected response, how does one decide the shape of the box ? I.e. does it make a big difference whether I make a tall and narrow box compared to a short but wide box, as long as the volume is correct?

I'm assuming that we ignore effects like baffle step and box bracing for this. What I really want to know is, is the acoustic compliance of a certain volume of air dependent on the shape of that volume?

Thanks

- Ashwin

 

[oz]

G'day ashwin.

I would take a guess and say that to some degree there would be certain criteria to the shape of the box. I would only guess that there are more efficent box enclosures than others.

I spose that as long as the speaker can breath then maybe it doesnt make much diference, but i dont realy know for sure, it may enhace certain charachteristics in a particular fequency and not so much in another.

All the best with whatever you try.

oz

 

[Coolin]

The compliance is not effected

But the sound will be different because of the way back waves will be reflected back through the drivers.

CO

 

[ashwin]

Re: The compliance is not effected

But the sound will be different because of the way back waves will be reflected back through the drivers.

CO

How will it be different? Will it affect the Fs, Q etc. of the box? If that's so, then the equations don't tell the whole story, right? How do the equations take care of the actual shape of the box? Or do the equations assume that the box dimensions are in a certain "sensible" ratio?

- Ashwin

P.S. : my apologies to you all for speaking in questions 🙂

 

[Coolin]

Re: Re: The compliance is not effected

How will it be different? Will it affect the Fs, Q etc. of the box? If that's so, then the equations don't tell the whole story, right? How do the equations take care of the actual shape of the box? Or do the equations assume that the box dimensions are in a certain "sensible" ratio?

- Ashwin

P.S. : my apologies to you all for speaking in questions 🙂

What i'm talking about isn't in the equasions.

The parameters will not change.

Half of the sound is going into the box, but that doesnt mean it wants to........

CO

 

[Vikash]

Hi Ashwin,

I.e. does it make a big difference whether I make a tall and narrow box compared to a short but wide box, as long as the volume is correct?...Or do the equations assume that the box dimensions are in a certain "sensible" ratio?

As long as there is free access to the enclosure volume, the shape doesn't matter to the equations.

Or to put it another way, the equations do not take into account the effects of standing waves, panel vibrations etc. which will change the modeled frequency response. You need to choose a "sensible" ratio to minimise these unwanted enclosure effects, but they do not affect driver performace strictly speaking.

 

[ashwin]

thanks

Guys, thanks for the replies.

Vikash, your MTM speakers are very inspiring!

- Ashwin

 

[GM]

>You need to choose a "sensible" ratio to minimise these unwanted enclosure effects, but they do not affect driver performace strictly speaking.
====
Note that standing waves can be beneficial in a sealed cab as well as in a vented one, such as designing for the 3rd harmonic to damp the hump in the response caused by a high Q driver or too small a cab Vb.

GM