SpeakerTalk Forum Index SpeakerTalk
This forum has been set up to facilitate discussion of 1970s KEF speakers and drive units. The owner of the Forum has no connection with KEF Audio.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Dipping my toes in

 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units
View previous topic :: View next topic  
Author Message
Joddle
Junior Contributor 10+


Joined: 11 May 2010
Posts: 11
Location: Valencia - Spain

PostPosted: Wed May 12, 2010 12:16 pm    Post subject: Dipping my toes in Reply with quote

Hi - new to this forum but avidly reading all the interesting posts.

Curently I have an early pair of Linn Sara 9s - the ones with only one set of connectors on the back and for many years have enjoyed them with a variety of amplification. More recently my daughter managed to break them by turning the amp up to full and selecting the phono input which lead to huge feedback which effectivly destroyed the front B200s - however I was able to get another pair of the right type from ebay at a good price and now have the speakers working again. So far so good.

In the past my listening room was room was prety modest in a typical UK 50s semi and the Saras could easily provide the listening volumes I liked - however now we live in a larger premises and the listening room is at least four times as big as our old room and the Saras really struggle to fill the space - and I don't want to keep replacing the B200s by overdriving them again - so am thinking of a DIY project.

First a few constraints - due to my wifes love of certain furniture items the speakers will have to be mounted on the wall - (the Saras currently sit on extreemly heavy wall brackest secured to solid walls nearly two feet thick) This positioning means only front ported or IB designs will work for me

I do have the ability to extend the height and width of the speakers a little from the sara size.

What I was considering is making a speaker based on Kef drive units in a three way design using the following:

2 B139s in an isobaric chamber similar to the sara but with 30% more volume behind the inner unit.

2 B110s both forward facing as mid range in an IB sub chamber in the same box

Kef or Scanspeak tweeter undecided but a single high efficiency unit

Controlled by 2 sp1004 crossovers in parallel with one tweeter replaced by a resistor.

The final box would be a little over 25 higher then the Sara and almost 10% wider and about 5% deeper - I would have to have the connectors at the bottom so they could be almost against the wall to prevent them coming further forward into the room that the existing Saras. (another wife constraint)

May be a dreadfull idea - but seems a fun thing to try - or then again perhaps someone will suggest a more sane project!!
Back to top
View user's profile Send private message
Lee in Montreal
Senior Contributor 200+


Joined: 22 Aug 2009
Posts: 203

PostPosted: Wed May 12, 2010 4:15 pm    Post subject: Reply with quote

Have you considered building two bass units to complement your current speakers. It is usually the bass that has problem filling big rooms. Therefore, you can keep on enjoying the sound of your current speakers, while you could add energy and support from the bass units. B139 are great and compact, but I am now partial to the B300.
_________________
Kef Calinda - since 1979
Kef Cantata - since 2009
Kef 105/2 - since 2009
Evo 105/2 - in the build
Back to top
View user's profile Send private message
Joddle
Junior Contributor 10+


Joined: 11 May 2010
Posts: 11
Location: Valencia - Spain

PostPosted: Wed May 12, 2010 4:30 pm    Post subject: Reply with quote

Lee in Montreal wrote:
Have you considered building two bass units to complement your current speakers. It is usually the bass that has problem filling big rooms. Therefore, you can keep on enjoying the sound of your current speakers, while you could add energy and support from the bass units. B139 are great and compact, but I am now partial to the B300.


That is a thought BUT again the wifes furniture layout leave little room for a sub - the other way I suppose is to have independent B139s (or something else) under the Saras - but then I need a decent crossover to cope with it AND the Saras already are a difficult load to drive - heaven knows what it would be like with the B139s as well! - my idea was to keep the loading similar to the Sara hence using two crossover units. Thanks though - maybe worth more investigation - dont know much about the B300 so will try and investigate those too.
Back to top
View user's profile Send private message
SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 223

PostPosted: Mon May 17, 2010 10:34 pm    Post subject: Reply with quote

Filling the room with sound requires moving some amounts of air and the larger the woofer and longer the max excursion, the more air can be moved.

The B139 don't have the excursion limits of the B300s; the provide roughly half the excursion and 30% less piston area, while being limited by about half the power handing.

I would dare to guess that 2 B139 would provide close to the sound level of a single B300, but not in isobaric form. That would only help to reduce the total enclosure volume, which perhaps is important to you.

I would suggest you get hold of WinISD and key in the parameters for the B139 and the B300 and experiment to get a rough idea of what the Saras are doing and what can be had with different combinations of size, drivers and configuration.
Back to top
View user's profile Send private message
Joddle
Junior Contributor 10+


Joined: 11 May 2010
Posts: 11
Location: Valencia - Spain

PostPosted: Tue May 18, 2010 7:21 am    Post subject: Reply with quote

Many thanks Sa Si - BUT where can I get B300s? - B139s are easy but I have never seen a B300 advertised for sale anywhere.

Also been having thoughts on the B139s perhaps instread of isobaric I could have them arranged opposing each other to form a fast base port open at the front with the b139s vertically on either side - would seem to solve the piston area problem at least although makes cab construction a whole lot more challenging - anyway this project is still in the early thinking stage so all suggestions welcome.


Last edited by Joddle on Tue May 18, 2010 1:29 pm; edited 1 time in total
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Tue May 18, 2010 11:50 am    Post subject: Reply with quote

Make some "stands" out of a pair of these.....



http://www.tech-diy.com/Loudspeakers/Dipol-Subwoofer.pdf


the corresponding html web page is now 404 btw.
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.
Back to top
View user's profile Send private message
Joddle
Junior Contributor 10+


Joined: 11 May 2010
Posts: 11
Location: Valencia - Spain

PostPosted: Tue May 18, 2010 1:34 pm    Post subject: Reply with quote

ColinR wrote:
Make some "stands" out of a pair of these.....


Exactly - wow and thanks. That is exactly what I imagined dual b139s should look like but I would like to see if that principle can be extended and built into a single cab as a full range speaker with two b110s and a tweeter above facing forwards.
Back to top
View user's profile Send private message
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Tue May 18, 2010 8:13 pm    Post subject: Good one Reply with quote

Good one Colin. I haven't seen that one before. I can feel a diy project coming on. Very Happy
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group