Plastic speaker cabinets - improving internal bracing & damping - 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 4th December 2012, 03:46 AM   #11
diyAudio Member
 
bitSmasher's Avatar
 
Join Date: Jun 2012
Location: Sydney.Au
Bumping this as I'm interested in PR10s for my own battery powered system, did you attempt to stiffen/dampen these as discussed?
  Reply With Quote
Old 4th December 2012, 10:20 AM   #12
diyAudio Member
 
speaker dave's Avatar
 
Join Date: Nov 2009
Location: The Mountain, Framingham
Missed this thread the first time around, but I would go the Bitumin/Dynamat route. It would add both mass and damping and those are the most important things. Stiffness is probably already adequate.

The other important factor is that those little bits of dacron fluff are nothing but placebo stuffing. Absolutely no benefit re. Internal standing waves. As it is vented it needs a good lining of fiberglass and that will make a more immediately audible improvement than even wall damping.

By the way, I'm cleaning up a pair of JBL Control 5 and the polypropylene cabinets are fairly heavy and low Q. Not a bad material choice.

David

Last edited by speaker dave; 4th December 2012 at 10:23 AM.
  Reply With Quote
Old 17th December 2012, 03:19 PM   #13
diyAudio Member
 
Join Date: Feb 2004
Thanks guys for the late responses. I have the speakers pulled apart with the front baffles off and the crossovers out. Going to run 2 horizontal cross braces between the sides, this seems to be the most flexable and vibration prone part of the box. Already had a good amount of foil backed dynamat extreme which I will use to damp all internal surfaces including the baffle and horn. I will replace the back plate with 1/2" ply and fit a speakon connector. The baffle will be sealed to the main box with a non-adhesive sealant. I've already posted in another thread that I have some very thick/heavy polyester materal to use for stuffing.

Overall, I'm hoping this will result in more sensitivity in the midbass and midrange, requiring less EQ of the speakers, with overall better clairity and power handling before cabinet distortion sets in.

Will try to take pics and post them in the next few weeks as I get more time to work on the project.
  Reply With Quote
Old 7th January 2013, 11:10 PM   #14
maxo is offline maxo  United States
diyAudio Member
 
Join Date: Sep 2012
Location: A Hole in Texas
Hey Turbo, how the results came... pics pics..
and sound sound !!!
  Reply With Quote
Old 6th February 2013, 04:36 PM   #15
diyAudio Member
 
Join Date: Feb 2004
Bump. After staring at these apart for over a month, I've started with the bracing. I've run two cross braces side to side, 3/4" ply about 1" wide. Mounted with hex head #12 sheet metal screws through the ribs, and silicone. Going to need to run some braces to the top and bottom of the box because there is considerable flex there too.

Have also made some 1/2" ply back plates to re-mount the crossover and provide for speakon inputs, considerably more hefty than the thin plastic.

Also noticed that the crossover wires the tweeter in reverse polarity, as is common with 2nd order designs. To me this seems un-needed becasue the recess of the tweeter in the horn should compensate for the phase shift at the 2200hz crossover (1/2 wave = 3.1"). I am going to try the tweeter in phase for sure, I have to do lots of EQ right now to bring up a lull in the midrange. We'll see.

Still have a considerable amount of work to do, but trying to get this system gig ready by the end of Feb.

Last edited by turbodawg; 6th February 2013 at 04:40 PM.
  Reply With Quote
Old 6th February 2013, 04:52 PM   #16
maxo is offline maxo  United States
diyAudio Member
 
Join Date: Sep 2012
Location: A Hole in Texas
not to say those are a PITA to open right ? ( torx ) screw ?
  Reply With Quote
Old 7th February 2013, 05:59 PM   #17
diyAudio Member
 
Join Date: Feb 2004
Quote:
Originally Posted by maxo View Post
not to say those are a PITA to open right ? ( torx ) screw ?
Philips screws, 10 of them screwing the baffle to main box. Not too hard just time consuming, or use power tools.
  Reply With Quote
Old 8th February 2013, 12:01 AM   #18
diyAudio Member
 
mattlong8's Avatar
 
Join Date: May 2011
Location: San Francisco, California
I would swap polarity on one and listen side by side. If the difference isn't obvious try different listening content, If still not obvious the xover could use adjusting.

Be careful not to block the area directly behind the woofer with the bracing. Also, I would bet that a front to back brace would make the greatest improvement but that is probably hard to implement. Lastly, I suggest using a more rigid adhesive than silicone for braces.

Good luck,

-Matt
  Reply With Quote
Old 8th February 2013, 08:12 AM   #19
AllenB is offline AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
I agree that silicone would flex enough that if not for those screws, the brace would be ineffective. Don't neglect the panel damping, ie: the bitumen or similar. This would probably do more than the braces especially to damp that plastic sound that sometimes emanates from bad examples of these types of cabinet.

I wouldn't stress about the tweeter polarity unless you think there is an actual problem. I doubt there is anything to gain from the 'correct' polarity unless you want to measure this up and redesign the crossover.
  Reply With Quote
Old 9th February 2013, 06:05 PM   #20
diyAudio Member
 
Join Date: Feb 2004
Thanks guys, the silicone is to prevent buzzing between the braces and cab while having some give, the screws hold them in solid. Will damp the whole thing with dynamat. One brace is bit behind the the woofer vent but there is enough space and i will round it. Will compare test the tweeter wiring.
  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
bracing and damping help rx7speed Multi-Way 15 25th October 2007 08:09 AM
BLH damping & bracing tips Klimon Full Range 11 28th July 2006 11:13 AM
bracing of large cabinets and effects on internal reflections JRKO Multi-Way 7 12th April 2005 07:12 PM
Damping and bracing? jvsb Multi-Way 2 28th October 2003 03:32 PM
Damping materials for speaker cabinets? G Multi-Way 44 28th March 2003 12:21 PM


New To Site? Need Help?

All times are GMT. The time now is 03:39 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