Woofer Driver Needs a Home Built for it - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 24th June 2012, 03:58 AM   #1
diyAudio Member
Join Date: Sep 2010
Location: Perth, Western Australia
Default Woofer Driver Needs a Home Built for it

Hi All,
I've a somewhat random driver that seems to be begging for a home to live in. I don't seem to be able to find any specs for it at all, so it's a complete mystery as to parameters for a viable design.

I found Woofer & Subwoofer Thiele-Small Parameter Extraction but I've not absorbed it as yet; are there any other methodologies I should be aware of?

The driver is a "toa bst-126" and has a stated impedance of 8 ohm. Size of the radiating surface seems to be about 310mm (the whole unit is 15")

I figure I'll build some kind of home for it, but I'm unsure what would be the best way of going about it. Any suggestions? I'm moderately competent in woodworking and sourcing 17mm structural ply as a materiel is fairly easy. I also have a few decent sized bits of 25mm MDF about as well...

I guess the next steps are determining the parameters of the driver somehow, and then deciding on sealed/vented box or some sort of horn arrangement to build for it. I live in a fairly small house so an insanely large enclosure isn't viable, but I'm happy to hear the more outlandish suggestions for enclosure options!
Attached Images
File Type: jpg woofer speaker front.jpg (300.9 KB, 298 views)
File Type: jpg woofer speaker rear.jpg (273.9 KB, 282 views)

Last edited by aspringv; 24th June 2012 at 04:13 AM. Reason: clarity of driver size
  Reply With Quote
Old 24th June 2012, 04:14 AM   #2
diyAudio Member
Join Date: Sep 2010
Location: Perth, Western Australia
Default I'll do it this way...

Measuring Loudspeaker Driver Parameters

Geez theres a lot of good data on his site...
  Reply With Quote
Old 29th June 2012, 03:57 AM   #3
diyAudio Member
Join Date: Feb 2004
Location: Los Angeles
As a loudspeaker engineer, my pretty educated guess is that looking at the construction and the size of the magnet, the Q is probably high and it needs a large box to not sound boomy.

You could try
Customer Support
but I wonder, even if you get information, if it would be very accurate.

By the way, different methods of measuring parameters will give different and valid results. The "parameters" are an approximation, a model, and they vary according to the drive level.
  Reply With Quote
Old 29th June 2012, 09:06 AM   #4
diyAudio Member
KaffiMann's Avatar
Join Date: Sep 2009
Location: Grua, Just north of Oslo
I found the BST-142 in the TOA SLB subwoofer. If model numbers are anything to go by it would seem the BST-126 is the predecessor, maybe the sensitivity and power rating is similar, but there is no way to tell.


Also found what seems like an auction for the BST-126 here:

I would just toss together a H frame for the heck of it, might work excellent.

Last edited by KaffiMann; 29th June 2012 at 09:13 AM.
  Reply With Quote
Old 29th June 2012, 05:22 PM   #5
diyAudio Member
chris661's Avatar
Join Date: Feb 2008
Location: Sheffield

15" subwoofer is always gonna need a big box, unless you throw away a lot of efficiency and go for a small sealed cabinet with Linkwitz Transform.

Or, as suggested above, try a H-frame. I'm not keen on them myself, but its a surefire way of getting something out of an unknown driver.

  Reply With Quote
Old 30th June 2012, 02:46 AM   #6
diyAudio Member
Join Date: Sep 2010
Location: Perth, Western Australia
Default Cheers for the input everyone

I gave the process detailed in Rod Elliotts site a whirl, but (and I quote)

"First, measure the resonant frequency. Adjust the frequency until the voltage across the resistor reaches a null (minimum level). Without changing anything, carefully measure the frequency and voltage across the resistor ..."

...was a wash. I was started at a 200Hz tone and varied it about more or less randomly, and the voltage over the 10R resistor as measured by my multimeter never seemed to hit a 'low' as such; nor settle down at all really.

I take it from head_unit's comments that the parameters are pretty variable anyway, so would end up a rough approximation of the ideal values.

I guess popping it into a H frame is easy enough to just do and see how it goes. I'll get to reading and see what I come up with. Thanks for the commentary and suggestions!

Last edited by aspringv; 30th June 2012 at 02:52 AM. Reason: clarity
  Reply With Quote
Old 30th June 2012, 03:09 AM   #7
diyAudio Member
Join Date: Sep 2010
Location: Perth, Western Australia
Default considering a sonotube style construction...


I like parties.

Upon re-reading I realize that little bon-mot may need explanation - read the article and it'll make sense.

Now to find a local supplier of sonotube materiel... That said I've only an 8ft ceiling here

Last edited by aspringv; 30th June 2012 at 03:17 AM.
  Reply With Quote
Old 21st July 2012, 02:21 PM   #8
diyAudio Member
Join Date: Sep 2010
Location: Perth, Western Australia
Well I've reconsidered my approach and dug out the original planned enclosure for this woofer. It's about 90L of volume and sealed; the materiel used was 1 inch MDF. I figure as I have it I may as well test it out and then move to a H frame after if needs be.

Currently reading up on Linkwitz transform....
  Reply With Quote
Old 28th July 2012, 08:00 AM   #9
diyAudio Member
Join Date: Sep 2010
Location: Perth, Western Australia
So I've thrown it into a sealed enclosure of internal volume of (in mm) 635*335*500 and given it a bit of a test. Seems like the -3db point is about 40Hz (completely subjective hearing judgement). Lobbed a couple of pillows in as well and she seems a little better again...

So it seems the next step is a linkwitz transform circuit, some sort of unbalanced to balanced converter for a bridged amp setup. I've a SCULD2 amp I'd be happy to gut for this (Silicon Chip 200Watt LD amplifier) and have had a quick look at Linkwitz Transform Subwoofer Equaliser and Balanced Transmitter and Receiver II and these seem to be a potential path forward.

I have a couple of questions though.
1) bridging amp modules - is this necessary? I have em and I'm happy to sacrifice them to sub wooferage use, but I guess removing any kind of LF roll off may be in order...
2) crossover details. I guess I need something that has a variable freq cutoff to tune it in initially and then I can look at an active solution as a permanent solution once the freq is determined.
3) linkwitz transform circuit - where does it go? I guess in the end I'll be looking at

source -> preamp -> variable freq low pass crossover -> (A or B)
A> amp -> normal speakers
B> linkwitz transform -> bridged amp -> subwoofer driver

Sound about right?
  Reply With Quote
Old 28th July 2012, 01:35 PM   #10
diyAudio Member
Join Date: Feb 2004
Make sure you check out the mini-dsp.
  Reply With Quote


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
HTPC for my home built projector Projector Project PC Based 0 6th January 2011 04:52 AM
Home built subwoofer driver flyingtele Subwoofers 13 3rd August 2009 04:28 PM
Can't get home built amp working ackeron42 Solid State 3 13th November 2006 06:35 PM
Built-in home entertainment SuppersReady Everything Else 23 12th November 2003 09:17 AM

New To Site? Need Help?

All times are GMT. The time now is 08:36 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2