Brahma 15 For HT (Help with Box) - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

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
Reply
 
Thread Tools Search this Thread
Old 11th February 2005, 08:13 PM   #1
diyAudio Member
 
Join Date: Nov 2004
Location: Wisconsin
Default Brahma 15 For HT (Help with Box)

Hello all,

Before I start I just want to say that you guys rock and the info you give is very appreciated.

So here's the set up. I will be getting a Brahma 15 soon from a friend. I plan to use this sub as the main sub in my home theater. So I need to build a box. I have plenty of room to use here, so size isn't too much of an issue. I was thinking 5 cubic feet with a slot port at 20Hz (Thats what I've read to do I guess). I am not sure how to make a slot... I've only made round ports before, but I want a slot vent. Also, I have never braced a sub. So if someone could give me info on how to brace a sub in a ported box, and how to make a slot vent that would be great. Do you use insulation in a ported box? Is that necessary? What dimensions would make a box 5 cubic feet? I am totally a beginner on trying to use the correct dimensions of the driver for the box I make. In the past I've just made boxes by guessing. But with this new beast, I want to make it the best as possible. Thanks for your time to read this, and any additional information you'd like to give me would be great too. Thanks.

Jeremy
  Reply With Quote
Old 11th February 2005, 09:45 PM   #2
simon5 is offline simon5  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: Québec, Québec
A 5 cu.ft ported box with a slot port at 20 Hz will be around 24"x24"x24".

You don't need insulation in a ported box.

It will take at least a full sheet of 3/4" MDF or plywood, 4' x 8'.

To brace a box, you need to put full length panels inside the box with alot of 4" holes into them. You could look on Adire Audio, there's already a plan for a braced 5 cu.ft box, the Shiva EBS 142.5 liters, you'll need to modify it for a slot port since it's designed for a flared 4" port.
__________________
DIYaudio for President !
  Reply With Quote
Old 11th February 2005, 09:59 PM   #3
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
A slot or round port is identical in operation.
Use what you are familiar with. On a 15" Brahma, I'd go for a minimum 6" port or dual 4". There is a difference in dynamics and distortion over a small port.
  Reply With Quote
Old 11th February 2005, 10:22 PM   #4
diyAudio Member
 
Join Date: Nov 2004
Location: Wisconsin
Well, is the 5 cubic feet good? Is that what you'd do? Or should I go bigger?
  Reply With Quote
Old 13th February 2005, 10:51 PM   #5
diyAudio Member
 
BassAwdyO's Avatar
 
Join Date: Jun 2004
Location: Illinois
Send a message via AIM to BassAwdyO
If you ask me.... a bigger box would be nicer. What I typically do when designing a vented box is design for about a 6db/octave rolloff below 30-40hz. Typically this takes a larger box tuned very low, but it usually yeilds fairly flat in room response very low. I'd put that brahma in a 7 cubic ft enclosure tuned between 10hz and 16hz.

One advantage of infrasonic tuning is the fact that port chuffing will rarely occur at any power because the air in the port is typically not fully excited. Another advantage is group delay. If you look at the group delay of the brahma 15 in 5cubic feet tuned to 20hz group delay is above 10ms to 33hz. With a 7 cubic ft enclosure tuned to 10hz group delay is under 10ms above 20hz. Not to say that is plainly audible, but lower tuning yeilds group delay closer to sealed box(at least in the audible part of the frequency spectrum).

The last advantage of tuning infrasonic, is of course, infrasonic response. Its fun to play a 14hz sine and feel the house rattle. Or better yet, when guests are over make them think an earthquake is happening!!!

And of course, there is always multi tuning. Instead of having one port tuned to one frequency use 4 tuned to different frequencys. You CANNOT have four simultanious resonances, but use removable port plugs and you can change tuning easily.
__________________
The golden rule of DIY:
Build nice, or build twice!
  Reply With Quote

Reply


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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Adire Brahma 12 MK II KBK Swap Meet 5 8th March 2006 06:22 PM
Brahma 10 competition? 4real Subwoofers 10 20th October 2004 04:45 PM
Brahma vent dimensions Raoul Subwoofers 23 20th September 2004 07:52 PM
Adire Brahma MKI specs Raoul Multi-Way 5 17th May 2004 11:33 PM
Brahma as a Home Sub.. Richard Moon Subwoofers 0 1st April 2002 08:19 AM


New To Site? Need Help?

All times are GMT. The time now is 12:59 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2