Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

BR subwoofer design question?
BR subwoofer design question?
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 30th July 2001, 11:50 PM   #1
Helix is offline Helix  United Kingdom
diyAudio Member
Helix's Avatar
Join Date: Jul 2001
Location: UK
I have bought a eminence kappa 15 LF speaker and i am now currently trying to figure out a alignment using winISD.

I think i have found out the Vb that i need, however i have a question which i am sure you lot will help me with :

Do i have to subtract the volume of the port from Vb?

I the best way of making a rough estimate of the volume taken by the driver is my measuring it as a cylinder and dividing by 2?

What is the average volume taken by a 15" driver?

do i have to adjust anything to take in account wadding?
  Reply With Quote
Old 31st July 2001, 10:19 PM   #2
Ignite is offline Ignite  Canada
diyAudio Member
Join Date: Jul 2001
Location: Toronto, Ontario, Canada
Send a message via ICQ to Ignite
In my experience:
- yes, subtract the port volume.
- better estimation of speaker volume would be by measuring the speaker cone as a cone and the magnet/spider assembly as a cylender and adding the two plus a little bit extra for the frame.
- you probably don't need it measured to the millilitre as that's anal retentive and it's unlikely you'll make your box that accurately.
- 15" drivers are so different in size and shape that's not going to help you much.
- if you want to be really exact, yes, stuffing/wadding/whatever else should be taken into account.
- not to be sloppy but I find a box that's about what winISD says works pretty well usually. Extreme accuracy isn't all that neccesary. Hand-tune the port later and you'll find something you like.

  Reply With Quote
Old 1st August 2001, 02:23 PM   #3
Eric is offline Eric  United States
diyAudio Member
Eric's Avatar
Join Date: Nov 2000
Location: Central PA, USA
BR subwoofer design question?
Exclamation *ADD* port volume, don't subtract!

The volume that WinISD calculates is exactly that: necessary volume for the driver to work as designed. Say, for example, that WinISD tells you that you need 150 liters. Take this volume, then ADD (don't subtract) the volume taken up by the port and the volume taken up by the driver. This new figure is the volume you should design your box for.

Here are a few numbers:
a) WinISD says volume needs to be 150liters
b) your port takes up another 15 liters
c) your driver displaces another 5 liters

Design your box such that its internal volume (before adding anything) is 150+15+5 = 170 (gross) liters. This way, by the time you add in your port and put your driver in the box, the net volume in the box that your driver interacts with is 150 (net) liters as originally called for.

Note that the numbers above are just for example. Calculate the volume of your driver as a cylindrical pyramid (rounding to the nearest liter will probably be fine). The driver manufacturer may be able to give you an exact figure for this.

Box stuffing is another matter. For most vented designs, the walls of the enclosure are usually lined, rather than "stuffing" the box. Lining the walls may give you a 5-10% increase in working volume. In most cases, leave the figures alone and line the box with stuffing. The result is rather subtle and usually gives you just a pinch lower response (for example, if you designed Fb =24 Hz, lining the box may give you Fb=22 or 23 Hz)

Hope this helps a little.

[Edited by Eric on 08-01-2001 at 09:36 AM]
  Reply With Quote


BR subwoofer design question?Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Help in subwoofer design. pmkierst Subwoofers 25 2nd February 2009 07:50 PM
12'' Subwoofer box design marinbnm Subwoofers 4 14th November 2007 08:44 PM
Subwoofer crossover / subwoofer module design derMichi Subwoofers 4 20th April 2006 10:31 AM
Subwoofer design question PrimaLuna Subwoofers 1 7th February 2006 08:07 PM
Subwoofer design question Kepler Subwoofers 5 3rd September 2005 01:31 PM

New To Site? Need Help?

All times are GMT. The time now is 08:14 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio