Finding the volume of a driver

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wigginjs

wigginjs

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Joined 2003
whatisrazar.com
#1
I'm designing a new sub for my HT involving a Dayton Titanic MKIII 12" woofer. I'm curious, whats the best way to find the volume of a particular driver? Does the manufacturer ever provide this information? I need to know because I'm going to add this amount, as well as the volume of the port tubes and bracing so I will know the exact dimensions of the enclosure I need to build.
 
#2
this is the answer I got when writning to Peerless asking for the volume of a 12"XLS:
" SNIP
We do not have the volumes of the drivers, I think that you mean how much
volume the drivers take in the box?

But in real life, you can count on the following:

1. The driver magnetsystem takes a lot of volume, it can be calculated very
easily as a cylinder.

2. The cone takes some volume also, but you have also cut a hole in the
baffle for the driver? The hole in the baffle makes the volume bigger and
the cone takes some of the volume back. This means if you neglect the hole
in the baffle and neglect the cone, the error you make is small.

This means, calculate the volume of the magnetsystem and neglect the cone.
SNIP
Click to expand...


I have even drawn a pic of the cone: volume :http://www.diyaudio.com/forums/showthread.php?postid=109255#post109255
 
#3
m0tion said:
I'm designing a new sub for my HT involving a Dayton Titanic MKIII 12" woofer. I'm curious, whats the best way to find the volume of a particular driver?
Click to expand...

Find a cardboard box that the driver fits in such as the one it shipped in. Calculate the volume of the box from it's dimensions.

Put a plastic bag around the driver and put the driver upsidedown in the box. Pour in rice until the box is full. Measure the volume of the rice. Subtract this from the box volume to get the driver volume. (Small error due to some of the speaker being in the baffel.)
 
#4
Re: Re: Finding the volume of a driver

moving_electron said:


Find a cardboard box that the driver fits in such as the one it shipped in. Calculate the volume of the box from it's dimensions.

Put a plastic bag around the driver and put the driver upsidedown in the box. Pour in rice until the box is full. Measure the volume of the rice. Subtract this from the box volume to get the driver volume. (Small error due to some of the speaker being in the baffel.)
Click to expand...
the error is the same as the volume of the hole in baffle in the final box.
 
#8
Well, it looks like the fastest way to get a number that is close to the actual volume is to use the suggestion in one of the posts above to calculate the volume by calculating it is a combination of cylinders.

The volume of the cylinder = pi * r * r* h where
pi = 3.14159
r = radius (not diameter!) of the circle that forms the base
h = hieght of the cylinder

Calculate the magnet portion which looks to be pretty much a cylinder.

Calculate the basket portion that will actually be in the subwoofer box when it is mounted. Calculate it as a cylinder and then take off some percent (maybe 35%?) since it really is a more of a cone with a lopped of top shape.

Add the two together and you have a pretty good estimate.
 
#9
In this thread, I did a rough estimate of the occupied volume for a Peerless 12" XLS. It came to 2.5 liters.
http://www.diyaudio.com/forums/showthread.php?threadid=9608&highlight=

So call it three liters and you can't be much off.

Unless you get to 10% or so of the entire box volume, there is virtually negligible effect on the response. That rough estimate simply cannot be off by much. In fact, a lot of people get good results just ignoring the volume of the speaker altogether.
 
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