Ultra compact ported 15" Dayton Ref HO - Page 4 - 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 4th October 2012, 12:30 AM   #31
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
To calculate triangle ports do you just calculate a square one and chop it in half?
__________________
http://www.minirig.org.au
  Reply With Quote
Old 5th October 2012, 12:18 PM   #32
diyAudio Member
 
Join Date: Feb 2004
Quote:
Originally Posted by col View Post
To calculate triangle ports do you just calculate a square one and chop it in half?
That seems to be it, but due to shape, they will actually tune lower. It seems to be the case with any non-round/square ports that they tune lower than predicted.
  Reply With Quote
Old 5th October 2012, 12:37 PM   #33
diyAudio Member
 
Join Date: Feb 2004
I sketched out some plans last night, and just wasn't able to come up with a compelling design with two triangle ports. It seemed like adding complexity for very marginal gains. If I was going to go with a harder to build port setup, I'd go 3x 4" with bends or one large square port with a rounded bend.

I can do the slot port box much more quickly and easily, and will nicely flare the in and out of the slot per some designs I've seen. I haven't built a box in several years and my woodworking skills are pretty basic. We'll see how this works out, and maybe I'll do a box with a large square flared vent at some point if the slot port box falls short at high output.
  Reply With Quote
Old 5th October 2012, 01:09 PM   #34
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
Originally Posted by turbodawg View Post
That seems to be it, but due to shape, they will actually tune lower. It seems to be the case with any non-round/square ports that they tune lower than predicted.
Hi,

They donít tune lower it seems youíve only used the wrong end correction factor(s) as the triangular ports are not 'one end open and one end 'IB' terminating at the baffle .

b
  Reply With Quote
Old 5th October 2012, 01:26 PM   #35
diyAudio Member
 
Join Date: Feb 2004
Quote:
Originally Posted by bjorno View Post
Hi,

They donít tune lower it seems youíve only used the wrong end correction factor(s) as the triangular ports are not 'one end open and one end 'IB' terminating at the baffle .

b
Everything thing that I've seen says that as you move away from a round port, you end up with a lower tune than the equivalent round port. Regardless of end correction. Probably because the sound propagation isn't quite as linear. This also explains why if you model a folded horn in hornresp, with round sections, if you then build it with rectangular sections, you get a lower response than modeled.
  Reply With Quote
Old 5th October 2012, 01:56 PM   #36
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
Originally Posted by turbodawg View Post
Everything thing that I've seen says that as you move away from a round port, you end up with a lower tune than the equivalent round port. Regardless of end correction. Probably because the sound propagation isn't quite as linear. This also explains why if you model a folded horn in hornresp, with round sections, if you then build it with rectangular sections, you get a lower response than modeled.
Youre partly right on your observation but the valid end correction factor depends on Port diam. to lenght, wavelenght to diam., sound pressure and air velocity... baffle placement..speaker placement to room boundaries...and so on.

Dont know if this picture(my notes) can be of any help:

b

PS: For PA I use the notes under 'End corrections' for a conventional simple port with aspect ratio <= 3:1 L/Diam. placed away from the corners and the sides.

Last edited by bjorno; 5th October 2012 at 02:03 PM.
  Reply With Quote
Old 5th October 2012, 06:20 PM   #37
dstmbgh is offline dstmbgh  United States
diyAudio Member
 
Join Date: Sep 2011
Quote:
Originally Posted by bjorno View Post
the valid end correction factor depends on...

Dont know if...my notes...can be of any help
Bjorno, regarding end correction factors, I'm hoping your notes and expertise might be of some help to me regarding a slot port for an enclosure not flat on the floor, but placed on a stand.

In the interest of getting some clarification from you without distracting from the topic of this thread, I have sent you a PM. Please check your PMs, and thanks in advance for any help.

David
  Reply With Quote
Old 5th October 2012, 11:46 PM   #38
diyAudio Member
 
Join Date: Feb 2004
Bought wood and misc stuff today, will start building and post some pics soon.
  Reply With Quote
Old 6th October 2012, 01:41 AM   #39
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
Perhaps the old Fane sub plan is the way to go to keep it KISS. It would give good venting without "touching the sides" making the tuning difficult to predict?

http://www.fane-acoustics.com/downlo...nch200Lres.pdf

col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 9th October 2012, 02:59 PM   #40
diyAudio Member
 
Join Date: Feb 2004
So I did get to work on this a bit over the weekend...

Got some 1/2" birch ply. This has 3 main plys and inner and outer veneer. It's just shy of 1/2" thick, more like 7/16-15/32. In a big sheet it seems pretty flexy, but it's plenty stiff in small panels. I will brace it pretty well.

I managed to get 4 sides of the box done. Cutting with a small 5-1/2" circular saw, battery powered. I've got a larger saw too, but the small one cuts well enough and is easier to handle. With a guide and carefull measuring the cuts are accurate to about 1/32". Using 90 clamps and 3 or 4 small sheetrock screws per side, pre drilled holes, titebond 3 woodglue. Next step is getting the port mounted, then the bracing, then last side, then the baffle. Will post some pics when there is something interesting to show.

Outer dims are 20x16x22, with the sub and slot port on the 20x16 side. Port should be about 15x2.5x21 actual, 23" effective length, for a tune in the mid-high 30's. Will put a 1" radius flare on one side of the exit, and there will be a proper bend on the inside.

Checked the fit in the car, with some creative moving around, I can actually fit 2 of these in the trunk. So I could run them as a car sub......lol.
  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
THAM15 - a compact 15" tapped horn martinsson Subwoofers 328 17th July 2014 12:51 PM
Compact Dayton Titanic 15" Offset Horn Design vnwhite Subwoofers 1 30th July 2012 11:25 AM
Pair of Dayton Reference HO 12" Relax Swap Meet 2 8th February 2007 03:59 AM
Compact 15" sub - BMS or Precision Devices? DIAR Subwoofers 7 4th January 2007 04:06 PM
T-Line for Dayton Ref 8" (RS225) dunderchief Multi-Way 20 7th November 2006 07:31 AM


New To Site? Need Help?

All times are GMT. The time now is 08:58 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