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 9th February 2014, 08:39 AM   #1
geolang is offline geolang  Hungary
diyAudio Member
 
Join Date: Jun 2013
Default Converting ported box into sealed

Hi,

I want to build a sealed sub-woofer using a pair old 10" woofers (LO-D L2502) from a Hitachi HS 330 mk2.
Unfortunately I cannot find T/S parameters anywhere on the net. I do have the original cabinets, so I figured I can use those dimensions for the new enclosure. The original box is very a precisely built vented design, but since I want to build a closed one I'm not sure that I can use those sizes (minus the reflex port, xo, mid and tweeter volume) for a sealed box? Also using thicker mdf instead of the original chipboard panels would matter?

cheers
  Reply With Quote
Old 9th February 2014, 09:00 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
seal, fit and try.

The worst that can happen is that the hump in the frequency response is too high for your listening preferences.

If it is too high, or rolls off too slowly, you can read up on and implement a Linkwitz transform.
__________________
regards Andrew T.
  Reply With Quote
Old 9th February 2014, 09:06 AM   #3
geolang is offline geolang  Hungary
diyAudio Member
 
Join Date: Jun 2013
Thanks.

I will be using with an active xo. The original xo was somewhere around 900hz for the woofer, but obviously I will set it a lot below that.
  Reply With Quote
Old 9th February 2014, 10:30 AM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
A low pass section of a crossover has no effect on the driver loading given by the box.
__________________
regards Andrew T.
  Reply With Quote
Old 9th February 2014, 10:48 AM   #5
geolang is offline geolang  Hungary
diyAudio Member
 
Join Date: Jun 2013
Just red through quickly the Linkwitz transform. I see now what you meant. Seems to be a very cool thing, but I hope there will be no need for that.
  Reply With Quote
Old 9th February 2014, 06:11 PM   #6
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Yeah, I wish everybody wanted to do the same. Just make a slightly leaky sealed box and you'll be happy (assuming the box isn't too small or the drivers too anemic).

There're no design principles with sealed boxes (or leaky boxes) worth fussing about. That's the simple practical truth.

The art lies in having whatever little output bump-up occur in a freq range that's beneficial and it often will be (see my assumptions above).

Ben
__________________
Dennesen ESL tweets, Dayton-Wright ESL (110-3200Hz), mixed-bass Klipschorn + giant OB using 1960's Stephens woofer; Behringer DSP
HiFi aspirations since 1956
  Reply With Quote
Old 9th February 2014, 06:29 PM   #7
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
FYI:
Another educated guessing of eventual occurring bumps..or..more of pure nonsense comments?:

b
Attached Images
File Type: jpg Hitachi HS 330 mk2.JPG (341.4 KB, 127 views)
  Reply With Quote
Old 9th February 2014, 06:35 PM   #8
diyAudio Member
 
Richard Ellis's Avatar
 
Join Date: Sep 2006
Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
Since this loudspeaker is a precisely engineered vented enclosure (As most are), the EBP is suited to a vented alignment. Simply sealing up the vented enclosure will get you a severely rolled off response getting you a Qtc near to 0.5.....that said, if you put the pair of drivers in an enclosure near to the same volume as ONE enclosure, this will drive up the Qtc closer to 0.7, sealed.



______________________________________________Rick ...........
  Reply With Quote
Old 9th February 2014, 06:45 PM   #9
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,


Wall thickness makes no difference to internal dimensions.

A pragmatic approach is build it sealed, with opposed
drivers on the left and right walls, well stuffed and go
for 1.5 times the one original box internal volume.

rgds, sreten.

FWIW there is nothing precise about a vented box
you can tell by just looking. You cannot tell whether
it a proper bass alignment or a serious boom box
alignment, the latter often used as cheap BSC.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 9th February 2014 at 06:50 PM.
  Reply With Quote
Old 9th February 2014, 07:27 PM   #10
geolang is offline geolang  Hungary
diyAudio Member
 
Join Date: Jun 2013
Thanks for the inputs guys, especially to bjorno for the lovely chart. Got the guidelines, though the optimal result still gonna be a bit of question of luck. Probably I install both drivers into a slightly smaller box size than the original and try to adjust with damping if needed or worth it.
  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
Ported or Sealed box for Convertible? Rich65 Everything Else 2 14th April 2012 08:13 AM
Repurposing existing sealed box to ported? Kahooli Subwoofers 7 12th October 2011 10:29 PM
what are some sealed and ported box sizes you can suggest for this speaker ? zuki Subwoofers 17 8th March 2007 05:51 PM
what size sealed or ported box can this woofer use ? zuki Multi-Way 2 23rd November 2004 02:20 AM
opinions of T/L box V ported OR sealed busterno1 Multi-Way 13 28th November 2003 08:20 AM


New To Site? Need Help?

All times are GMT. The time now is 06:20 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