Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

JR149 Redesign
JR149 Redesign
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 9th February 2015, 03:10 AM   #1
DDF is offline DDF  Canada
diyAudio Member
 
DDF's Avatar
 
Join Date: Sep 2004
Location: Ottawa
Default JR149 Redesign

Hi Folks,

A different thread got onto the topic of the JR149, a vintage speaker meant to compete with the LS3/5A.

I modified a pair and thought I'd share the outcome and design process here, attached. It was a tough design journey, the B110 being an enigma of sorts.

It was an interesting trip, and made me really appreciate the challenges faced by designers of yesteryear working with suspicious drivers and scant CAD at their disposal. It helped me respect their accomplishments that much more.

Thanks,

Dave
  Reply With Quote
Old 9th February 2015, 03:17 AM   #2
DDF is offline DDF  Canada
diyAudio Member
 
DDF's Avatar
 
Join Date: Sep 2004
Location: Ottawa
PDf exceeded the size limit, so I've broken into two, here's part 1 of 2
Attached Files
File Type: pdf JR149Plus_2015_part1of2.pdf (601.8 KB, 167 views)
  Reply With Quote
Old 9th February 2015, 03:18 AM   #3
DDF is offline DDF  Canada
diyAudio Member
 
DDF's Avatar
 
Join Date: Sep 2004
Location: Ottawa
And part 2 of 2
Attached Files
File Type: pdf JR149Plus_2015_part2of2.pdf (810.7 KB, 118 views)
  Reply With Quote
Old 9th February 2015, 12:15 PM   #4
PierreQuiRoule is offline PierreQuiRoule  Canada
diyAudio Member
 
PierreQuiRoule's Avatar
 
Join Date: Feb 2004
Location: Ottawa
JR149 Redesign
Wow. Nice paper. Thank you Dave for sharing your journey .
  Reply With Quote
Old 9th February 2015, 03:20 PM   #5
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
way kool ! - and a great speaker for starters - do you have some "from scratch" designs published?
  Reply With Quote
Old 10th February 2015, 12:44 AM   #6
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
Very nice PDF articles on fitting the JR 149 with Scanspeak D2905-9300 tweeter, Dave. Enjoyed reading that. Much simpler filter.

There were two 5" bextrene KEF bass drivers, the original KEF B110A SP1003 used in the LS3/5A, and later smoother B110B SP1057 used in the KEF CS1. Not quite the same.

Just my OCD nature, but a schematic would have been nice. Hey, and let's lead with a picture in this thread!

I take on board your good feeling about the 4" Tang Band W4-1720 polycone for a modern equivalent:
Tang Band W4-1720 4" Underhung Midbass Driver
Attached Images
File Type: jpg JR149 Modified.jpg (97.4 KB, 185 views)
File Type: png JR149 with Scanspeak D2905-9300.PNG (5.4 KB, 175 views)
__________________
Best Regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 10th February 2015, 02:48 AM   #7
DDF is offline DDF  Canada
diyAudio Member
 
DDF's Avatar
 
Join Date: Sep 2004
Location: Ottawa
Thanks system7. The TS params were so off spec I couldn't tell which variant these used.

There were also two different versions of the JR crossover, the first with a parallel trap on the woofer (LS3/5A used one as well), and the "V2" crossover which made well enough without the trap.

I tried a few iterations of a trap based crossover as well, none provides a sense of accuracy and ease I had hoped for.

Sorry about the (lack of) schematic, I knew I'd get called out for that.

Regarding the W4-1720, I very much like that driver. Very detailed for a cone not made from metal. I just updated my design spec for another small two-way, this one using the W4-1720, at
http://www.diyaudio.com/forums/multi...ml#post4218347

Hi freddi, I've designed allot of other stuff over the years but don't generally publish. It's a miracle to find time to publish these two designs.
  Reply With Quote
Old 10th February 2015, 03:26 AM   #8
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
I'm very equivocal about sophisticated filtering with difficult drivers. It's OK on paper, but I wonder how well it works with significant non-linearities.

Your Napoleons look fun:
Click the image to open in full size.

I notice I made a complete *** of myself in saying the Tang Band W4-1720 4" Underhung Midbass Driver was a polycone. It's paper.

Your idea is not unlike Eekels' Mini

If you don't mind a slight lack of bass, this is a nice idea. Certainly a great midrange for vocals.
__________________
Best Regards from Steve in Portsmouth, UK.

Last edited by system7; 10th February 2015 at 03:31 AM.
  Reply With Quote
Old 10th February 2015, 03:56 AM   #9
DDF is offline DDF  Canada
diyAudio Member
 
DDF's Avatar
 
Join Date: Sep 2004
Location: Ottawa
Thanks, they were fun, and the xovers were much simpler to get right than the JRs.

Mini? 4.8L, that's huuuge! Actually, they look to me to have a somewhat different application. the napoleons were made for on wall and shelf application. The Mini has that rear port and long front/back application that's not well suited for that use.

The modest bass was a design parameter, it allows me to work in the evening at decent listening levels without someone pounding the floor above me. For daytime, a flick of the subwoofer switch takes me down to 30Hz.

They also respond very well to some gentle bass boost equalization (digital or analog) to provide some decent mid bass as that woofer can take a beating and not complain.

IME (after countless hours simming, voicing, building, testing over many years) the problem with complex crossover equalization in a standard 2 or 3 way is that its very often used to equalize at one point in space (some edge reflection or diffraction, or non-ideal driver summing) and it destroys the off axis response in an audible way. Maybe works for extreme near field or a huge room, but audible IME in a regular space. Over the years I think the sonic benefits of low order (ie simple xovers) have been mistakenly ascribed to "simpler electron path" because perhaps it wasn't understood why complex sounded bad.
  Reply With Quote
Old 10th February 2015, 02:06 PM   #10
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
Location: Portsmouth UK
You might find this article interesting then. "Audibility of different crossover types". I can hear the difference between BW3 and lean LR4. 90 degree phase BW3 works much better off-axis and no power dip. Some drivers play nicely, some don't.

http://www.ctc-dr-weber.de/speaker/A...er%20types.pdf

Quote:
This might come as a shock, but we think that the overall winner was the 3rd order Butterworth filter, which was
terribly popular in the 70's and 80's.
Ooh, I love being right! Bess 2 works well on pink noise, which is something Lynn Olson uses.
Attached Images
File Type: png Visaton BW3 Crossover.PNG (7.4 KB, 153 views)
File Type: png Visaton BW3 Dispersion.PNG (30.8 KB, 152 views)
__________________
Best Regards from Steve in Portsmouth, UK.
  Reply With Quote

Reply


JR149 RedesignHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Should I refurbish a set of jr149 speakers jjl Multi-Way 14 2nd July 2015 01:41 PM
JR149 - HOW THE HELL DO YOU REMOVED THE CROSS OVER...AARRRGGHHHH.... REXTON Multi-Way 9 25th November 2013 08:05 PM
Redesign ACOUSTAT III Williams Audio Planars & Exotics 5 8th October 2011 07:58 PM
Repair or redesign? Racket Scientist Solid State 3 30th August 2010 04:44 AM
redesign amp need prorms Solid State 9 17th June 2006 08:35 AM


New To Site? Need Help?

All times are GMT. The time now is 07:53 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki