New Project Beta 12LTA Fostex FT17H in a TQWT - 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 23rd February 2004, 12:26 PM   #11
BrianGT is offline BrianGT  United States
diyAudio Moderator Emeritus
 
BrianGT's Avatar
 
Join Date: Jan 2002
Location: near Atlanta, GA
Send a message via AIM to BrianGT
Default Re: Box designed on MLTQWT worksheet

Quote:
Originally posted by MIKET
Here is what I came up with unfortunately with a 6" vent 1.5 " deep as calculated by WinISD the vent Mach would be .07 and a frequency of 37.05 Hz which is a bit high. Going to a rectangular vent of 5" X 12" rectangular 6.25" deep gives the same frquency but a vent Mach of .03" see below.
That looks like a washing machine to me... similar dimensions. I would seriously consider a different driver. There are many drivers out there that can go lower in a much smaller box, and a smoother overall response.

I couldn't imagine having to accommidate large sized enclosures like that. I know that my significant other would raise hell if I tried to build those things and put them in the living room. I built a subwoofer that was 24" x 24" x 40", and it just looked ridiculous in my living room...

--
Brian
Attached Images
File Type: jpg aac.sized.jpg (43.8 KB, 657 views)
  Reply With Quote
Old 23rd February 2004, 06:13 PM   #12
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Hey Brian,

This driver was the subject of much tweaking sometime back on the fullrange forum and different cabs were tried, but I forget what folks liked best. No one measured a driver so published specs was used in each case IIRC. They must be close though since tuning was very close on those that were measured with an SLM.

A max flat is ~9.91ft^3/36Hz and I calculated a 47.25" length with rp = 3.38", Lp = 0.75", and driver down 20.88", which yields basically the same FR as yours except for a very slight increase in box efficiency due to the larger Vb.

WRT alignments, I'm not a big fan of WP's 'Pi Align' because it gives up too much useful BW with today's higher excursion drivers, but for FR and other underhung drivers it's really the 'Hot Ticket' for best overall performance since it maximizes midbass efficiency and is well damped over a wide enough BW that EQ can be used to boost the low end within its meager power/excursion limits without resorting to a huge cab and fiddling with the vent to find an acceptable audible distortion curve:

Vb = 2.453ft^3 (alpha = 1.961)
Fb = 33.09Hz (H = 0.7353)
rp = 1"
Lp = 1.38"

Your sub looks familiar, is it the one I saw in Rob Cheng's basement during the last DIY meet? I don't mind large, my mains are somewhat larger than this, but if not in a corner then they do look out of place unless finished off to look like a complementary piece of furniture. I once did a pair of 30ft^3 cabs and the owner's wife had them finished off by a furniture maker to look like antique French Provincial cabinets. With some 'hanging gardens' style greenery perched on top, they were very impressive (and expensive).

MIKET:

If you do a sim of the 'Voigt' style horn you'll see that it won't perform any better than Brian's straight pipe down low and the high taper ratio will push the driver somewhere between 5/8-3/4 down to get an aceptable tradeoff between LF extension and upper midbass/lower mids smoothness. Unfortunately, the excessively large/long vent will make a choppy mess of them, so overall, not a good design IMO.

Again, to get superior performance with pipe designs with the least effort, MJK's worksheets will save you a lot of time/$$.

HTH,

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 25th February 2004, 11:01 AM   #13
MIKET is offline MIKET  United States
diyAudio Member
 
MIKET's Avatar
 
Join Date: Jul 2003
Location: Maine
Send a message via Yahoo to MIKET
Default Here is another option a folded pipe

Pipe length 30 feet driver placed 2/3 down the pipe.
Would this work or should I just keep puttering with the design?
Attached Images
File Type: gif pipe.gif (5.4 KB, 580 views)
  Reply With Quote
Old 25th February 2004, 12:05 PM   #14
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Quote:
That looks like a washing machine to me... similar dimensions
Can't do washing machines but will fridge-freezers do?

Click the image to open in full size.
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 26th February 2004, 02:13 AM   #15
MIKET is offline MIKET  United States
diyAudio Member
 
MIKET's Avatar
 
Join Date: Jul 2003
Location: Maine
Send a message via Yahoo to MIKET
Default Speaker Apliances

So what is it and most of all how does it sound?
  Reply With Quote
Old 26th February 2004, 03:21 AM   #16
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
That's his open baffle speaker design consisting of a polystyrene-on-plywood baffle and two drivers whose names I can't recall.
  Reply With Quote
Old 26th February 2004, 09:30 AM   #17
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Quote:
So what is it and most of all how does it sound?
It's the ugly duckling! Full story HERE .
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 26th February 2004, 11:24 PM   #18
MIKET is offline MIKET  United States
diyAudio Member
 
MIKET's Avatar
 
Join Date: Jul 2003
Location: Maine
Send a message via Yahoo to MIKET
Default Cabinets

So is the PiAlign enclosure design a good match for this driver?
I am looking to get down to 45Hz or so since the Fs of the driver is 45Hz.
Is my driver 2/3 of the way down the pipe nuts or is there a chance it might work out?
  Reply With Quote
Old 13th March 2004, 11:06 AM   #19
MIKET is offline MIKET  United States
diyAudio Member
 
MIKET's Avatar
 
Join Date: Jul 2003
Location: Maine
Send a message via Yahoo to MIKET
Default Here is the best I could come up with

Both ports are 4.5" long, -3 dB at 42 Hz, Box tuned to 38 Hz
Attached Images
File Type: gif beta12lta5cuft.gif (76.1 KB, 301 views)
  Reply With Quote
Old 13th March 2004, 03:25 PM   #20
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
If I was building this type of speaker, I would use a coaxial set-up and Eminence have several options.
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  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
Fostex FE127e. Eminence 12LTA. nodiak Swap Meet 4 4th January 2009 04:30 AM
Where to find Fostex FT17H in or near the UK? bigwill Multi-Way 12 14th June 2008 06:00 PM
Phase plug for Beta 12lta JimW Full Range 1 21st April 2005 12:07 PM
FS: Fostex FT17H Illusus Swap Meet 2 6th March 2005 10:46 PM
Eminence Beta 12lta Glenn Swiderski Multi-Way 5 9th December 2003 01:31 PM


New To Site? Need Help?

All times are GMT. The time now is 12:06 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