Dual B-139's - Page 2 - 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 6th November 2007, 04:26 PM   #11
diyAudio Member
 
myhrrhleine's Avatar
 
Join Date: Jan 2006
Location: Avalon Island
Personally, I'd just build 2 TLs together and parallel for 4 ohms.
I'd be a shame to lose the sound quality by adding cheap speakers in series.
__________________
Just because you can't hear it doesn't mean no one can.
  Reply With Quote
Old 7th November 2007, 09:58 AM   #12
diyAudio Member
 
Moondog55's Avatar
 
Join Date: Jun 2007
Location: Norlane; Geelong: Victoria: Australia
Cheap price does not mean cheap sound quality but I take your meaning,
How do I stack 2 folded lines in one tower??
Do I plan to port to the rear or the front??
Given that I want to use mid-range drivers that I have in store and the transmission from a medium size driver to a 4inch is smoother ( at least in my limited experience) is there a driver of similar quality and performance avaliable here in Australia
Perhas these
http://www.soundlabsgroup.com.au/p/V...+170+A+-+8+Ohm
or these
http://www.jaycar.com.au/productView...=&SUBCATID=383
__________________
QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"
  Reply With Quote
Old 7th November 2007, 03:08 PM   #13
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by Moondog55
I want to use mid-range drivers that I have in store
How low do they go?

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 8th November 2007, 06:56 AM   #14
diyAudio Member
 
Moondog55's Avatar
 
Join Date: Jun 2007
Location: Norlane; Geelong: Victoria: Australia
Default Midrange drivers

I have some Vifa M11 dedicated mid-ranges rewired to 16 Ohm as I intended to use MTM configuration and wanted the lowest distortion from my amp, in discussion with Andy Graddon ( whose opinion I respect highly) no lower than 375hz as their resonant frequency is a little high at 110 hz and probably crossed to the Vifa neo tweeter at 3000 or higher.I have heard comments that 375/400 is a little high to cross the B-139's.
I could go 4way using the KEF's below 100, I have a couple of good amps avaliable and I have a Behringer cross0over avalable to experiment with.
__________________
QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"
  Reply With Quote
Old 8th November 2007, 07:44 AM   #15
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Default Re: Midrange drivers

Quote:
Originally posted by Moondog55
.I have heard comments that 375/400 is a little high to cross the B-139's.
I could go 4way using the KEF's below 100, I have a couple of good amps avaliable and I have a Behringer cross0over avalable to experiment with.
B139s got used as high as 1kHz when mated with a T15. 350-400 Hz was more common, but IMHO anything much over 200 Hz is pushing it. The B139 have a fairly nasty breakup at 1k.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 8th November 2007, 09:18 AM   #16
diyAudio Member
 
Moondog55's Avatar
 
Join Date: Jun 2007
Location: Norlane; Geelong: Victoria: Australia
I have been unable to find any information about the speaker i remember from England.
In my head I have a memory of a B-139 with an 8inch KEF ( B200 ) before the 4inch, I cannot remember the model, I thought it was IMF but found nothing in the archive and now that site is defunct.
I was thinking of 100/120 Hz as being the limit myself, maybe I need to rethink things and look at a better mid-range match, I have always liked Vifa P13's, it's just that I have the little ones here and paid for
__________________
QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"
  Reply With Quote
Old 8th November 2007, 01:39 PM   #17
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
FYI: A design I made about 30 years ago I remember sounded good and was quite powerful.

b

1(1)
Attached Images
File Type: gif kef_2xb139_tl.gif (55.4 KB, 295 views)
  Reply With Quote
Old 9th November 2007, 09:34 AM   #18
diyAudio Member
 
Moondog55's Avatar
 
Join Date: Jun 2007
Location: Norlane; Geelong: Victoria: Australia
Impressive, do I read that right -3dB @30hz?
Did you build as a 3-way?
__________________
QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"
  Reply With Quote
Old 9th November 2007, 12:19 PM   #19
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
…Impressive, do I read that right -3dB @30hz?

With my test gear and some moderate room gain I estimated a -3dB response below 25 Hz, I recall the speaker sounded ‘bottomless’ and it was impossible to keep the gramophone in the same room as the speakers when playing at higher levels.

…Did you build as a 3-way?…

Yes at first, before I modified the speakers to better sounding 4-way’s and the above posted simulation is an reconstruction using MJK: s software of an old sketch I still have in my possession. The only question mark is how much mineral wool was put in the TLs.

The inside walls (LDF) were covered with 2 .5 cm dense Roockwool and the rest with fluffy itchy yellow mineral wool as seen in the small picture but I never estimated the weight or density or took notes of any numbers.

I remember having a hard time to make both speaker measure equal at the low crossover point and iterated the component values of the 12 dB LP-filter (no HP-filter for the B200) and the stuffing over a long time period of until I was satisfied with the result.

My notes reveal the use of a rather lossy 1.8-Ohm inductor, 6.2 mH and a 100uF capacitor.

I don’t recall the dip seen in the simulation at about 115 Hz, but that is probably because I at that time only had a homebrew of test equipments, a gated dial tone generator system including a calibrated microphone hooked up to an oscilloscope and a DIY true analogue RMS meter.

The weak point of this design was the need for a low crossover point between the B200 and any tweeter.

At the finishing end, the best-achieved results show up when using 2 Peerless 122MF midranges in parallel placed side by side with the lower B200 driver below a Decca Ribbon look-alike tweeter, the Gamma VLD12.

b
  Reply With Quote
Old 9th November 2007, 01:29 PM   #20
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
fwiw, the B139's don't like to be overdriven -- but they are very easy to repair if you fry the voice coil -- obviously I have done this several times.
  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
EAW dual 18's billybob Subwoofers 1 9th August 2008 10:07 AM
dual primary//dual secondary toroid larryg Chip Amps 22 6th September 2006 09:24 PM
Dual 18's RacerXtreme Multi-Way 36 10th April 2006 09:52 AM
looking for dual npn and dual npn smt transistors sovadk Solid State 9 25th August 2005 10:58 AM
Dual 505-4 gchrist Analogue Source 1 30th April 2004 06:51 PM


New To Site? Need Help?

All times are GMT. The time now is 12:32 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