My New Dipoles - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 2nd April 2012, 08:35 PM   #11
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

I can't see the point of the narrow OB's for the mid treble unit. MJK uses
a 20" square baffle with an offset driver, and then uses the x/o to suppress
the baffle hump you get before baffle roll off. With narrow baffles the hump
is a lot higher and a lot of boost is required to get down to the bass unit.
wings on the narrow baffle will introduce cavity resonances, not good.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 2nd April 2012, 08:42 PM   #12
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
Quote:
Originally Posted by soundaatma View Post
I would hate to see you throwing out the baby with the bath, if you dismiss the wide ranger on OB atop the h-frame, so early
Ψ

Please read the OP.

Bob
  Reply With Quote
Old 2nd April 2012, 09:13 PM   #13
diyAudio Member
 
Godzilla's Avatar
 
Join Date: Nov 2005
Location: New York
>>> I can't see the point of the narrow OB's for the mid treble unit.

I can't either.

But i did enjoy BIBs (using Fostex 165k) enhanced by H-frames so i believe something other than an OB works beautifully together. The trick with H-frames is making them look good in the room. I think of them as two big subs but with the special qualities of OB. I also think of them as speaker stands.
  Reply With Quote
Old 2nd April 2012, 11:30 PM   #14
DaveCan is offline DaveCan  Canada
diyAudio Member
 
DaveCan's Avatar
 
Join Date: Nov 2005
Location: Moncton NB
Really like mine at approx 70-75hz and under, but over that not so much. I think it's an H-Frame thing by design that messes with the higher signals, the way the driver is walled/boxed in etc..Now if the leading part of the box could be flared out like a front horn then maybe things would be different ?..

Bob, if they don't work out for your project it would be interesting to see how you might like them as subs? I really enjoy them that way myself, and as Jeff stated they mate up real fine with the BiB cabs..
  Reply With Quote
Old 3rd April 2012, 12:30 AM   #15
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
So the small OB's didn't work out. I knew I was stretching things. I knew that the OB would roll off at 300 Hz. I didn't know how high I could push an H-frame. Turns out that cavity resonance ~100Hz is a killer. It takes the right music to hear it, but it's there. This causes a general smear in the mid bass. As promised, I brought out my small TL's. These little suckers will go all the way to 40Hz on their own, but not with enough SPL to be convincing.

This setup has the H-frames low-passed at 70Hz 4th order Chebechev and the TL's high-passed at 100Hz 4th order Bessell. Works great. Nice smooth transition through the cross-over helped by a serious room-mode notch. The combination gives some serious weight to the bottom, but is nice and tight -- no booming. Of course, these H-frames are not real subs. They die below ~30Hz. But there is precious little music that low.

I know that it may sound like sour grapes, but I like the TL's better than the OB's anyway. The OB's were much too forward. The TL's have a lot less pronounced baffle hump and a generally smoother sound.

This rig needs some playing with, but I feel confident about it. If you want to hear them, be in Dallas May 4th for the LSAF meet.

Bob
Attached Images
File Type: jpg H-Baffle+Tl.jpg (84.3 KB, 646 views)
  Reply With Quote
Old 3rd April 2012, 03:22 PM   #16
chrisb is online now chrisb  Canada
diyAudio Member
 
Join Date: Aug 2002
Location: victoria BC
Quote:
Originally Posted by Bob Brines View Post
So the small OB's didn't work out. I knew I was stretching things. I knew that the OB would roll off at 300 Hz. I didn't know how high I could push an H-frame. Turns out that cavity resonance ~100Hz is a killer. It takes the right music to hear it, but it's there. This causes a general smear in the mid bass. As promised, I brought out my small TL's. These little suckers will go all the way to 40Hz on their own, but not with enough SPL to be convincing.

This setup has the H-frames low-passed at 70Hz 4th order Chebechev and the TL's high-passed at 100Hz 4th order Bessell. Works great. Nice smooth transition through the cross-over helped by a serious room-mode notch. The combination gives some serious weight to the bottom, but is nice and tight -- no booming. Of course, these H-frames are not real subs. They die below ~30Hz. But there is precious little music that low.

I know that it may sound like sour grapes, but I like the TL's better than the OB's anyway. The OB's were much too forward. The TL's have a lot less pronounced baffle hump and a generally smoother sound.

This rig needs some playing with, but I feel confident about it. If you want to hear them, be in Dallas May 4th for the LSAF meet.

Bob


while I've heard several decent to stunningly good sounding OB systems, there are definite logistic / "real estate" issues required for them to do their magic -

you might have been able to avoid the problems with the performance / integration of bass if you had space to accommodate much larger baffle and even multiple woofers, but that's exactly my point - in simple terms they ( OB) are not for everybody's real world situations - but I've yet to find a room in which a pair of sometimes pretty dinky little TLs, "BRs", or BLHs couldn't work
__________________
you don't really believe everything you think, do you?
community sites t-linespeakers.org, frugal-horn.com commercial site planet10-HiFi
  Reply With Quote
Old 3rd April 2012, 03:49 PM   #17
zman01 is offline zman01  Bangladesh
diyAudio Member
 
Join Date: Feb 2011
Location: Dhaka
Bob,

What is the distance of the H-Frames from the back wall of the room?

-Zia
  Reply With Quote
Old 3rd April 2012, 03:57 PM   #18
badman is offline badman  United States
diyAudio Member
 
badman's Avatar
 
Join Date: Sep 2003
Location: Sunny Tustin, SoCal
Quote:
Originally Posted by Godzilla View Post
>>> I can't see the point of the narrow OB's for the mid treble unit.

I can't either.

But i did enjoy BIBs (using Fostex 165k) enhanced by H-frames so i believe something other than an OB works beautifully together. The trick with H-frames is making them look good in the room. I think of them as two big subs but with the special qualities of OB. I also think of them as speaker stands.
Small OBs contribute a more consistent polar pattern, with better side cancellation, and with proper compensation and enough displacement you can get pretty incredible performance.
__________________
I write for www.enjoythemusic.com in the DIY section. You may find yourself getting a preview of a project in-progress. Be warned!
  Reply With Quote
Old 3rd April 2012, 05:56 PM   #19
hajj is offline hajj  Lebanon
diyAudio Member
 
hajj's Avatar
 
Join Date: Nov 2009
The cavity resonance at ~100hz could be due to the H frame being too deep.
I'm just paraphrasing MJK here, but the effective depth seen by the woofer is sensibly more than the actual depth (12.9" effective as opposed to 7.5" actual in Martin's Alfa 15A H-frame), and with an 18inch driver the disparity between the actual and effective could be even more pronounced.
If this is the case, then making the H frame shallower should cure the problem.
  Reply With Quote
Old 3rd April 2012, 06:06 PM   #20
diyAudio Member
 
Godzilla's Avatar
 
Join Date: Nov 2005
Location: New York
>>> They die below ~30Hz…

Yes, they do. And the Alpha 15's only into the 40s... but the bass player sounds like he's in the room with me.

>>> I like the TL's better than the OB's anyway…

I don't see what's not to like with your current setup. To be fair, the OBs you made were not sufficient. They did look great but looks and sound are often at odds.

>>> but I've yet to find a room in which a pair of sometimes pretty dinky little TLs, "BRs", or BLHs couldn't work…

Yes, those types of boxes are popular for good reason… and you can always add a sub. They do the job!

If you have the room and don’t mind large panels staring at you then large OBs (I personally think approx. 20” x 40” is about as small as you can go for ‘full range’ sound) offer a different kind of sound that’s very enjoyable. Imaging is wider and sounds seem to emanate from within their own space more realistically. The large baffle is the key IMO. I really don’t know how these guys who hang their drivers in space get a full rich sound… but I’ve never heard a properly done implementation.

Peace,
Zilla
  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
Not Your Daddy's Dipoles matevana Multi-Way 16 8th September 2010 02:39 PM
M-dipoles el`Ol Multi-Way 1 25th February 2010 09:12 AM
Dipoles ? LennyK Multi-Way 111 21st September 2006 03:12 PM
3-way or 4-way dipoles? mazeroth Multi-Way 0 25th January 2006 06:37 AM
Spicatto Dipoles Raka Multi-Way 42 6th November 2004 07:00 PM


New To Site? Need Help?

All times are GMT. The time now is 08:50 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