When is a liter not a liter? The shape of things to come. - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 26th June 2009, 11:23 PM   #1
diyAudio Member
 
brucegseidner's Avatar
 
Join Date: May 2009
Default When is a liter not a liter? The shape of things to come.

The double base reflex enclosure published by Fostex for the FE127e is a tall rectangular cabinet. If the volumes were the same for both the chambers, and the vents were all the same, etc., how would it change the driver's performance to use a tube cabinet of similar stature?

There are two issues that seem to interact as I think about it. One is the issue of front baffle and I know people go round and round on this. But I have not seen a discussion of the internal dynamics. Is it just an issue of volume and the spring it creates or does the shape of the first chamber and placement of the vent make for a different spring or harmonics than a cylindrical chamber with the port in the center, for instance? Will the first port remain tuned to (FB) 120Hz and the second to 53Hz?

I wanted to do something different and I like the looks of a tall floor standing cylinder in the placement I am thinking of. It would be a piece of cake to take a 6" PVC and fashion this puppy. Relatively cheap and almost no dust!

Anyone have experience with this or can anticipate the results?

Thanking all in advance.

Bruce
  Reply With Quote
Old 26th June 2009, 11:52 PM   #2
diyAudio Member
 
Join Date: Jan 2007
Hi Bruce, from what I've read, nobody has been too impressed with Fostex double-bass reflex cabs.

The gurus here will tell you that as a BR becomes tall and skinny, it transitions into a quarter-wave resonator a.k.a transmission line (TL). So it's not just a question of the Helmholz resonance (a function of the cab's volume) and it becomes a function of the height.

But PVC is a definitely cool way to go. You might find this of interest: http://www.t-linespeakers.org/projec...son/index.html
  Reply With Quote
Old 27th June 2009, 02:35 AM   #3
diyAudio Member
 
HareBrained's Avatar
 
Join Date: Mar 2009
You're essentially correct. The ports net different tunings. The gain of such a design is decreased excursion compared to a single reflex design. I have no experience with this driver but the DCR I built for the CHR70 works great, but I used 3 ports and the driver chamber is twice the volume of the second chamber.
__________________
John
  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
Fe127e (Pair) in 25 liter cabinets type Swap Meet 1 15th May 2008 04:38 PM
Fostex 126e response (10,5 liter BR) Juspur Full Range 0 2nd February 2005 07:18 PM
woofer in 11 liter (0.38 cu ft) rwagter Multi-Way 3 4th May 2004 08:12 PM
DIY speakers using 32-liter cabinets smurfette Multi-Way 17 2nd March 2004 03:11 PM
1000 liter sub jmiyake Subwoofers 12 26th April 2002 05:50 PM


New To Site? Need Help?

All times are GMT. The time now is 03:35 PM.


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