Bass enclosure for 3 way - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 29th August 2009, 10:15 PM   #11
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
I originally wanted a TL in fact, but the ideal model turned out very long indeed with a driver with this fs. Making a much shorter one like that drawn is a problem because it'll cause impedance variations up in the high bass ranges I guess? It a definate no-no?

I could easily incorporate the reflector you suggested, my intention was that the thick foam would absorb sound immediately behind the driver and the rest would travel through enough wadding to decrease it's energy suitably. Though mabye the reflector reduces energy reflected from immediately below the foam covered area by redirecting it to the far end of the cabinet? It'll be a squeeze to fit it in with the 100mm foam on it's face as well, but I'll look into it; perhaps profiling the foam where it encroaches on the drivers rear side.

Any other suggestions welcome! I may get back with a model including the reflector to get an idea of how it sits in
  Reply With Quote
Old 19th September 2009, 01:02 PM   #12
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
Default Space my braces!

Update for you

I've had the stock for a while, all cut at shop (done a pretty good job too), been working a few days but it's only just starting to get interesting

9mm ply laminated to 18mm MDF, the back and side are done. After doing it the resonance I hear when knocking it is shorter and higher pitched than just the 18mm MDF. What you'd expect I guess. The ply is pretty nasty exterior stuff, but it's got 5 plys at only 9mm thick and is suprisingly heavy so it could be worse.

Click the image to open in full size.

So I'm now looking to start getting the braces in. I need guidance with the spacing between them! With the total height of 852mm, there are 3 braces plus a top and bottom part leaving 762mm. Divided equally the space between each part is 190.5mm. Obviously I want these distances to be non-equal and not related. What do you suggest? I have heard of the ratio 1:1.68 but don't know exactly how to use it

There will also be wooden beams on the unbraced areas and mabye corner blocks too. I may add in the reflector at the top of the cabinet, I have some board at the correct width as offcuts, just need to bevel it.
  Reply With Quote
Old 19th September 2009, 02:19 PM   #13
diyAudio Member
 
Join Date: Aug 2008
'Looks great, Dr. EM!

I agree with Tosh - I think it's a good idea to leave out the spokes as they might introduce a new resonance. Nice design though, you put a lot into it! Are you going to leave in the un-even mounted internal baffle?

JF
  Reply With Quote
Old 19th September 2009, 03:16 PM   #14
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
Thanks!

I won't be putting in the internal baffle as it'll create a sort of TL which might have a negative effect. May do the angled board behind the driver though

I figure I shouldn't put any brace at 190mm spacing as it's the same as the width at the back. I reckon I'll put that first one in at 180mm or so and figure from there.
  Reply With Quote
Old 19th September 2009, 03:27 PM   #15
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Good work Dr.EM! Nice project

If I may suggest a much better stuffing material for bass cabs (I have found) is rockwool insulation. It kills standing waves. I have found BAF to be completely ineffective for stuffing.

Also, vertical holey braces (rather than the shelf type) would provide better overall bracing and simplify construction slightly.
I too would avoid the spokes.
  Reply With Quote
Old 19th September 2009, 08:34 PM   #16
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
Thanks MJL21193!

I've got some spacings that should work. They arn't mathmatically related to each other or the dimensions of width and depth so should all resonate differently. I actually tried clamping in the braces at these positions and it seemed to be the case. First brace from bottom is at 210mm, the ones in the middle are closer spaced and a larger spacing again at the top for the driver; the reflector should aid rigidity here.

I'll look into alternative wadding! The rockwool is fibreglass housing insulation isn't it? I guess it's quite solid and inflexible? I planned a nearly complete fill either way, mabye a combination will work well.

I have my shelf braces all cut (not drilled yet) so am really stuck with them. I see what you mean though, vertical braces will leave narrow but long areas unsupported which probably do have a harder time trying to resonante. Here's what I have though, I had planned this for a while. Photo before clamping on the brace (which is drying now):

Click the image to open in full size.

12x32mm wooden battons. A knock test shows an improvement with these added already so it should be good. Spokes arn't going in.
  Reply With Quote
Old 28th September 2009, 05:31 PM   #17
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
Bit of an update and question. Installing the last brace, here it is just resting in place:

Click the image to open in full size.

Nearest to you in this picture^^

and from the other end to show overall build:

Click the image to open in full size.

Before I fit this final brace (then onto top, deflector and other side!) I wonder if it's worth rounding over the bigger holes radius, as it'll be right below the driver and could cause reflection issues? I'd rather not as it'll make a mess and add delays but if it's truly going to make an improvement I'll hold up until I can do it
  Reply With Quote
Old 29th September 2009, 01:55 AM   #18
CLS is offline CLS  Taiwan
diyAudio Member
 
Join Date: Jun 2005
Location: Taiwan
I think, other than improvement on the sound, more important is the rounded holes won't scratch your hands in the future actions.
  Reply With Quote
Old 29th September 2009, 11:42 AM   #19
Dr_EM is offline Dr_EM  United Kingdom
diyAudio Member
 
Dr_EM's Avatar
 
Join Date: Oct 2006
Location: Swindon
Ah, so that's the main reason for it? I guess if you were adjusting the acoustic materials inside and reaching through braces to get at them. I intend to apply the fill before closing the front, it won't be possible to reach the bottom through only the driver hole, in fact the middle brace may be impossible to reach through too with the biggest hole only 64mm

I guess I'll fit it in place as it is then, then to work on the deflector. I may try and do that from solid wood if I have enough
  Reply With Quote
Old 30th September 2009, 01:54 AM   #20
diyAudio Member
 
Join Date: Nov 2006
you can always make the back panel removable to get inside of the cabinet I guess I missed it what MDF you use if ultra-light you better glue some 1/4" cement board in between the ribs to stiffen the box up
  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
6x10 bass enclosure clutch004 Multi-Way 15 4th December 2009 03:49 PM
Bass in wall enclosure? cph2000 Multi-Way 4 29th November 2007 11:50 PM
Enclosure for a mid-bass speaker? neur0tic Multi-Way 3 2nd September 2007 06:06 PM
Bass reflex enclosure Opie Subwoofers 5 5th January 2002 02:36 AM


New To Site? Need Help?

All times are GMT. The time now is 05:28 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