Volume (size) Question

nukaidee · 4th February 2009, 12:05 AM

I am planning to use drivers that require the volume of 0.16 cu ft. (what I calculated) If i decided to put 2 of them in a box, does that mean I need 0.32 cu ft? or does it remain at 0.16?

Thanks!

Saturnus · 4th February 2009, 12:54 AM

Depends on how you mount them.

Normally you'd need twice the volume but if you for example coupled cavity mounted them, you'd only need half the volume.

nukaidee · 4th February 2009, 04:27 AM

I wont be cavity mounting. one will be pointing out towards the listener, the other will be pointing down facing the ground like a sub. the cabinet is sealed, hollow inside.

nukaidee · 4th February 2009, 10:28 PM

now u got me thinking. what do you mean by cavity? split the cabinet in half with a piece of mdf?

Saturnus · 4th February 2009, 10:57 PM

Actually I meant it as one driver with the magnet facing out and one with the magnet facing in but mounted on top of eachother in push-pull mode. A search on the internet seems that's not what everybody understands by coupled cavities however. Some seem to think it's another word for a bandpass cabinet, probably because some of the most successfull bandpass cabinets used (what I understand with) coupled cavity connected drivers inside the box.

Richard Ellis · 5th February 2009, 01:05 AM

Is it like this....an Isobaric Push-Pull?
_______________________________________________Ric k......

nukaidee · 5th February 2009, 01:21 AM

well.. what about my 90 degree angle? lol. will my woofer push out my mid's? do I need to build a barrier to stop the pressurization? its a sealed box design..

Richard Ellis · 5th February 2009, 01:41 AM

The Isobaric Push-Pull relies on a small 'chamber' of air to work correctly. The drivers in this configuration run the same way, as one goes in the other goes out.
As I illustrate here..Both drivers would have to go "out" at the same time. As a result you might very well be on to something as the drivers may cancell out some non-linearities (Shape of the cone)
Yes of course you will have to 'seal off' your mid-ranges...don't want the pressures inside to 'excite' the mid-range cone.
With this illustration you will have to double the assigned volumes.
Check your numbers again as it sounds like your numbers are WAY too small.
A 12" woofer should get at least 1,1/2 cu. Ft.
_________________________________________Rick..... ....

nukaidee · 5th February 2009, 01:59 AM

0.16 cu ft is about 4 litres.. considering my woofer is only 5 inches compared to your example of 12 i think its close? I just plugged it all into the winisd calculator...

4th February 2009, 12:05 AM	#1
nukaidee diyAudio Member Join Date: Nov 2008	Volume (size) Question I am planning to use drivers that require the volume of 0.16 cu ft. (what I calculated) If i decided to put 2 of them in a box, does that mean I need 0.32 cu ft? or does it remain at 0.16? Thanks!

4th February 2009, 12:54 AM	#2
Saturnus diyAudio Member Join Date: Jun 2005 Location: Copenhagen, Denmark	Depends on how you mount them. Normally you'd need twice the volume but if you for example coupled cavity mounted them, you'd only need half the volume. __________________ Maker of the ultimate boombox - The Boominator. http://www.diyaudio.com/forums/showt...hreadid=104402

4th February 2009, 10:57 PM	#5
Saturnus diyAudio Member Join Date: Jun 2005 Location: Copenhagen, Denmark	Actually I meant it as one driver with the magnet facing out and one with the magnet facing in but mounted on top of eachother in push-pull mode. A search on the internet seems that's not what everybody understands by coupled cavities however. Some seem to think it's another word for a bandpass cabinet, probably because some of the most successfull bandpass cabinets used (what I understand with) coupled cavity connected drivers inside the box. __________________ Maker of the ultimate boombox - The Boominator. http://www.diyaudio.com/forums/showt...hreadid=104402

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4th February 2009, 04:27 AM	#3
nukaidee diyAudio Member Join Date: Nov 2008	I wont be cavity mounting. one will be pointing out towards the listener, the other will be pointing down facing the ground like a sub. the cabinet is sealed, hollow inside.

4th February 2009, 10:28 PM	#4
nukaidee diyAudio Member Join Date: Nov 2008	now u got me thinking. what do you mean by cavity? split the cabinet in half with a piece of mdf?

5th February 2009, 01:21 AM	#7
nukaidee diyAudio Member Join Date: Nov 2008	well.. what about my 90 degree angle? lol. will my woofer push out my mid's? do I need to build a barrier to stop the pressurization? its a sealed box design..

5th February 2009, 01:59 AM	#9
nukaidee diyAudio Member Join Date: Nov 2008	0.16 cu ft is about 4 litres.. considering my woofer is only 5 inches compared to your example of 12 i think its close? I just plugged it all into the winisd calculator...

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