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 

Redesign of the KEF Kit 3 enclosure

 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> DIY with KEF drive units
View previous topic :: View next topic  
Author Message
ben_wiid
Introductory Contributor


Joined: 06 Nov 2007
Posts: 2
Location: George, South Africa

PostPosted: Wed Nov 21, 2007 1:56 pm    Post subject: Redesign of the KEF Kit 3 enclosure Reply with quote

I have the following drivers: T27A - SP1032, B110, and KEF B139 - SP1044. Additional to these drivers I also have an ABR with the same dimensions as the B139. These units are still in their original packing, and I would like to put them to good use. Has anybody re-looked at the original enclosure design for a Kit3? (If this is where these units are used) Can I use the B139 with the ABR and achieve good response?
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Wed Nov 21, 2007 7:05 pm    Post subject: Re: Redesign of the KEF Kit 3 enclosure Reply with quote

Very Nice!!! Very Happy
There is plenty on this sites technical area for all the information you need to build some great loudspeakers. What is the SP number on the ABR?

As far using ABR with the driven version it is something I contemplated many years ago but never had the courage to pursue.

I'm sure that the resident experts will soon put you right...
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill
Back to top
View user's profile Send private message Send e-mail
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Wed Nov 21, 2007 8:45 pm    Post subject: Reply with quote

With those drivers you build a tallish 86 litre box 450mm wide with an internal box of ~10 litre for the B110. Stuff to taste Shocked .

The drive unit configuration is T27 next to the B110, a B139 below and a BD139 below that. The B139s are orientated longest dimension across the baffle.

It's in the book of German (never seen a UK version) KEF designs sometime after Terry's, so find a German who can give you a scanned copy.

The commercial varient is one of the Heathkit/Schlumberger offerings Cool .
_________________
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.


Last edited by ColinR on Wed Nov 21, 2007 10:42 pm; edited 3 times in total
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Wed Nov 21, 2007 9:19 pm    Post subject: Reply with quote

Colin, the tuning (fs) of the ABRs varies, is it something to worry about?
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill
Back to top
View user's profile Send private message Send e-mail
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Wed Nov 21, 2007 10:19 pm    Post subject: Reply with quote

Quote:
Colin, the tuning (fs) of the ABRs varies, is it something to worry about?


Apparently not in this case as the "86 litre box 450mm wide with an internal box of ~10 litre for the B110" is a crib of an earlier beastie, the Telson S4 which used a Celestion MF500 in a 76 litre box.
_________________
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
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Thu Nov 22, 2007 12:27 am    Post subject: Reply with quote

ColinR wrote:
Quote:
Colin, the tuning (fs) of the ABRs varies, is it something to worry about?


Apparently not in this case as the "86 litre box 450mm wide with an internal box of ~10 litre for the B110" is a crib of an earlier beastie, the Telson S4 which used a Celestion MF500 in a 76 litre box.


The mind boggles, so much for the equivalent calculations but using a port rather than the ABR.

I have heard unsupported rumours of a labyrinth being terminated with an ABR, hmm.
Shocked
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill
Back to top
View user's profile Send private message Send e-mail
ben_wiid
Introductory Contributor


Joined: 06 Nov 2007
Posts: 2
Location: George, South Africa

PostPosted: Fri Nov 23, 2007 5:01 am    Post subject: Reply with quote

I appreciate all the experts showing interest and taking time to respond. Thank you.

proffski wrote; "What is the SP number on the ABR"

I'm unsure of the ABR Model Number, the type number written on it is SP1042. I left out the B110 type number its SP1003. How can I establish if I have a B139 - SP1004 or a B139B - SP1004, is there a difference?

ColinR wrote; "With those drivers you build a tallish 86 litre box 450mm wide with an internal box of ~10 litre for the B110. Stuff to taste"

Why a 10l box for the MF unit, I have seen on the specification sheets a requirement of only 4l. What benefit is there in making the box bigger?

What is a preferred stuffing – un-spun wool, washed and bleached, un-spun cotton or fiberglas strands?

As I understand the design calculations for a enclosure with a ABR is the same as an enclosure with a ported enclosure. What resonant frequency should I use for the calculations, that of the driver or the ABR unit? For a normal ported system there is no additional weight load on the driver, how do I compensate for this in the calculation?

What is your opinion on time alignment of drivers? Is there any merit in slanting the enclosure away from the listener, with the HF unit at the top and low frequency at the bottom? Does driver unit height above the ground have any significance in the design of a system?
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Sat Nov 24, 2007 2:33 pm    Post subject: Reply with quote

Quote:
SP1004, is there a difference


No.


Quote:
10l box for the MF unit, I have seen on the specification sheets a requirement of only 4l. What benefit is there in making the box bigger


Somehow the tild ~ disappeared.

Most commercial boxes including some KEF used a midrange >4.5 litres.
They're usually made via convenient positioning of an internal divider to make a triangulated volume stuffed to taste.

The specification sheet ~4.5 mid volume used 1.25" anechoic grade foam damping which is a tad expensive these days.


Quote:
Is there any merit in slanting the enclosure away from the listener


Sloped baffle multi driver arrays usually sound smeared to me compared with a conventional vertical array or time aligned configuration.
_________________
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
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