enclosure difference ? - diyAudio
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 10th May 2010, 09:58 AM   #1
diyAudio Member
 
Join Date: Nov 2009
Location: Pune
Default enclosure difference ?

I had enclosure with volume of 26 liters which was made of particle board 18mm thick. I kept 3 bottles filled with water,each one liter to attain 23 liters of volume. and tuned ports to my need. the woofer is down firing with front firing port.

Now keeping volume 23 liters I designed another box made of MDF 12mm thick. but this time one more change I made ie I changed port to down firing ( as read down firing ports give consistent performance.) but moment when I turned it on It was completely different to sound felt there is no bass. this stuff sounds like low bass with more mid. Now i am not clear what is making this difference ? Guys pls tell me what all corrections do I need to make.I am feeling totally lost. is the difference because of change from 18mm to 12 mm or switch from particle board to MDF or change in port placement.
__________________
There is always a first time....

Last edited by Aucosticraft; 10th May 2010 at 10:01 AM. Reason: incomplete
  Reply With Quote
Old 10th May 2010, 02:46 PM   #2
diyAudio Member
 
Inductor's Avatar
 
Join Date: Feb 2006
Location: Cascais
Maybe this new box prefers Coca-Cola.

I'm more inclined for the wood (Wood Strength Chart) materials and box construction (and also effective interior measurements).

Last edited by Inductor; 10th May 2010 at 03:04 PM. Reason: Wood Strength Chart
  Reply With Quote
Old 10th May 2010, 05:20 PM   #3
diyAudio Member
 
Join Date: Nov 2009
Location: Pune
Dear Inductor..... I guess u r right... for a trial i added bracings and surprisingly it worked to some extend. this made me clear that the thickness was the culprit. I should have used at least 18mm ply of MDF. I agree that still it doesn't sound like previous one but sure find some improvement. ( Thank God... Could save coca-cola for me... )
__________________
There is always a first time....

Last edited by Aucosticraft; 10th May 2010 at 05:23 PM.
  Reply With Quote
Old 13th May 2010, 02:56 AM   #4
diyAudio Member
 
Join Date: Apr 2010
You are doing non blind listening tests in a room with no calibration of input power or input material?

You have to be careful, your brain is not a measuring instrument but has its own
distortions and feelings ;-) We all know when a new system is heard it takes time to get used to it.

is this downfiring port exactly the same as the normal one?
I think you should read some loudspeaker design books. I used to get two from the local library. One edited by weems. Check amazon.
  Reply With Quote
Old 13th May 2010, 04:37 AM   #5
diyAudio Member
 
Join Date: Nov 2009
Location: Pune
Neddludd, Thanks for reply.

I agree I am no measuring instrument also understand the the error that could result because of non calibrated environment. but I compared ( Listened) new and the previous one at the same time by listening. the difference is distinct. also the resonance was tuned using LIMP ( Trial). on graph they look much alike with difference of 2 db max. but yes one thing I noticed was that when i measured Fq response at port and driver there was a difference. the interception of the two curves ( port & driver) for older was at 50Hz where as for new its 80Hz.

Yes, the the downfiring port is exactly as the previous one except that of its placement (Previously it was frontfiring). I did some google to find if the placement of port makes any difference. but all said port can be placed any where. all you need to take care is the distance between the wall and port end must be at least equal to diameter of port.
__________________
There is always a first time....
  Reply With Quote
Old 13th May 2010, 05:00 AM   #6
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
the down-firing port is probably getting its boundaries lengthened and tuning lower killing upper bass punch - an impedance sweep of both enclosures would tell the story. 12mm might be stiff enough (?0
  Reply With Quote
Old 13th May 2010, 07:14 AM   #7
diyAudio Member
 
Join Date: Apr 2010
Yep it sounds like the close boundary is detuning the port compared to the model. I would even compare thicker mdf or sand loading.
  Reply With Quote
Old 13th May 2010, 11:37 AM   #8
diyAudio Member
 
Join Date: Nov 2009
Location: Pune
I am thinking of an experiment. Let me close the ports of both the enclosure pretending it to be sealed enclosure. Then both enclosure should sound exactly alike if its problem with port placement. Do you agree guys? Pls comment. in the mean while I will try it out and get back here.

Last edited by Aucosticraft; 13th May 2010 at 11:39 AM. Reason: Incomplete
  Reply With Quote
Old 13th May 2010, 12:17 PM   #9
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
You changed more than one variable plus we don't know the full details of each build, so not much point in us speculating.........

I don't agree, it can be due to the cab's differing construction.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 14th May 2010, 02:25 PM   #10
diyAudio Member
 
Join Date: Nov 2009
Location: Pune
Hey..... I changed the port place as you had suggested ( its front-firing now) but could not attain much of difference. still it doesn't sound like the model . Now whats different is the enclosure material and thickness. As I said the model material was particle board with 18mm thickness and now I am using MDF with 12mm thickness.
  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
Switching car audio enclosure to home enclosure wattz Subwoofers 10 18th April 2010 05:51 PM
DIY Fuzz Factory in Arion enclosure- with a difference lordofthethings Instruments and Amps 0 23rd November 2008 08:21 AM
What's the difference? squirtacious Tubes / Valves 4 23rd October 2007 04:38 AM
Convert horn enclosure to sub enclosure chipco3434 Subwoofers 5 22nd December 2004 03:54 PM


New To Site? Need Help?

All times are GMT. The time now is 01:48 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