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 

History of drive units
Goto page 1, 2  Next
 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF Speakers from the 1970s
View previous topic :: View next topic  
Author Message
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Wed Apr 23, 2003 9:51 am    Post subject: History of drive units Reply with quote

It would be most interesting for me if I could acquire a history of the development of the B139, B200, B110 and T27 with details of versions and dates. Why changes were made to drive units and what effect these changes had would also be interesting. Can anyone help?
Back to top
View user's profile Send private message Send e-mail
boyzo
Intermediate Contributor 25+


Joined: 10 May 2003
Posts: 44

PostPosted: Sat May 10, 2003 6:57 am    Post subject: KEF drive unit history Reply with quote

4 main units all from the mid to late 60's
B139 13 x 9 inch oval, first unit was sand cast chassis, susequent units had a precision cast chassis and well as a nomex Hi-temp Voice coil, these are desirable the first are not.
24 Hz res. 6mm P-P excursion. a bad resonace at ~950hz.

B200 8inch steel frame
came in various versions over thew years ie the SP no
Original B200 was only for sealed box later units with lower Q and larger magnets more suited to reflex enclosures or used with passive radiator
see KEF R104AB very nice speaker.

B110 5inch the SP1003 28 hz res. 6mm P-P was the classic as used in the LS35a later the SP1057 for the REF 105 speaker arrived.
The SP1057 is better damped with the surround and should sound better in practice the SP1003 still sounds good.
Later yet another SP version arrived for the current LS35a as commissioned for the BBC.

T27 19mm mylar dome excellent tweeter with a rear chamber and very good impulse response.
First unit had a shallow horn faceplate which was later discarded to the current unit.
Dome resosnace is 1100 Hz
Still a good tweeter.

T52 Kefs first dome its large at 50mm with low 670Hz resonace and an alnico magnet (unusual) and a large rear chamber.
This is a very smooth tweeter but gets directional can be crossed over lowish ~2000 hz

B300 12inch very expensive woofer very good unit rarely used by home constructors

These the only drive units commonly for sale to home constructors.
KEF were somewhat of a leader in their time with Raymond Cooke founder EX Wharfdale, he more than anyone led the path to plastic cones away from paper, at that time.
It must be said that KEF historically were the most outstanding company in engineering terms apart from B&W.
Back to top
View user's profile Send private message Send e-mail
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Mon May 12, 2003 12:33 am    Post subject: Re: KEF drive unit history Reply with quote

boyzo wrote:
... susequent units had a precision cast chassis and well as a nomex Hi-temp Voice coil, these are desirable the first are not.


Were these always painted black whilst the earlier ones were left unpainted?
Back to top
View user's profile Send private message Send e-mail
qguy
Intermediate Contributor 75+


Joined: 08 May 2003
Posts: 85

PostPosted: Fri May 30, 2003 8:02 am    Post subject: Reply with quote

how much would these b300 cost today ? are they still available ?
Back to top
View user's profile Send private message
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Fri May 30, 2003 9:36 am    Post subject: Reply with quote

qguy wrote:
how much would these b300 cost today ? are they still available ?


I haven't seen any advertised on eBay since I started looking and so I also would be interested in obtaining this information.
Terry
Back to top
View user's profile Send private message Send e-mail
planet10
Introductory Contributor


Joined: 11 Jun 2003
Posts: 9
Location: Victoria, BC, NA, Sol III, Milky Way

PostPosted: Wed Jun 11, 2003 7:49 am    Post subject: Re: KEF drive unit history Reply with quote

boyzo wrote:
T27 19mm mylar dome excellent tweeter


The voice coil is 20mm but by the very name T27, KEF considered it a 27mm unit.

[url= http://homepage.mac.com/tlinespeakers/TLS/drivers/images/T27-dataS.gif]Full factory data[/url]

dave[/url]
Back to top
View user's profile Send private message Visit poster's website
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Wed Jun 11, 2003 9:06 am    Post subject: Reply with quote

Thanks for posting Dave
I think unfortuntately that there may be a problem with the URL
Back to top
View user's profile Send private message Send e-mail
planet10
Introductory Contributor


Joined: 11 Jun 2003
Posts: 9
Location: Victoria, BC, NA, Sol III, Milky Way

PostPosted: Wed Jun 11, 2003 9:14 am    Post subject: Reply with quote

Actually i suspect the URL is fine, but not my application of the URL codes (an extra space after the equals is screwing most of it up.

http://homepage.mac.com/tlinespeakers/TLS/drivers/images/T27-dataS.gif

dave
Back to top
View user's profile Send private message Visit poster's website
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Wed Jun 11, 2003 9:19 am    Post subject: Reply with quote

Yes I had a problem with the space as well just a minute ago. It works fine. Thanks
Back to top
View user's profile Send private message Send e-mail
boyzo
Intermediate Contributor 25+


Joined: 10 May 2003
Posts: 44

PostPosted: Thu Jun 12, 2003 10:56 am    Post subject: Re: KEF drive unit history Reply with quote

terry wrote:
boyzo wrote:
... susequent units had a precision cast chassis and well as a nomex Hi-temp Voice coil, these are desirable the first are not.


Were these always painted black whilst the earlier ones were left

unpainted?


Terry can't say for sure the very first B139 drive units had a chassis that was somewhat rough in appearence (SAND Cast)
the 2nd generation had a slimmer chassis and very smooth surface finish and I think painted in a neutral grey enamel ( i would need to look into my subwoofers to know for sure )
Smile))
Back to top
View user's profile Send private message Send e-mail
chrisallan
Introductory Contributor


Joined: 15 Jul 2004
Posts: 5

PostPosted: Thu Jul 15, 2004 5:29 am    Post subject: Reply with quote

I believe that Malcolm Jones of Falcon Acoustics had a lot of input into the KEF units.
One minor point is that the 1057 B110s where a long throw version and I've heard that the stiffer surround curtails the bass slightly.
I've had quite a few of these units through the years and thought I knew a bit until a guy from the far east asked me about a pair of B110s I have and if they had a green tint. I do have such a pair now and wonder why he wanted to know..........
Back to top
View user's profile Send private message
ian t
Junior Contributor 10+


Joined: 16 Jul 2004
Posts: 15
Location: Australia

PostPosted: Fri Jul 16, 2004 12:24 pm    Post subject: B300 availability Reply with quote

terry wrote:
qguy wrote:
how much would these b300 cost today ? are they still available ?


I haven't seen any advertised on eBay since I started looking and so I also would be interested in obtaining this information.
Terry

They do come up periodically at the German Ebay site.I managed to score a very nice pair of B300's in mint condition there recently.It's also a good place to find the equally rare T52 tweeters.
Back to top
View user's profile Send private message Send e-mail
terry
Senior Contributor 200+


Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Fri Jul 16, 2004 8:41 pm    Post subject: Reply with quote

Yes I have bought a few items from German eBay sellers including a pair of early KEF Codas.
Terry
Back to top
View user's profile Send private message Send e-mail
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Fri Sep 02, 2005 12:01 pm    Post subject: Re: KEF drive unit history Reply with quote

The very 1st T27 had a low f/s of 900Hz.

Size 4¼” X 1 3/8” Weight 1.6lbs HC 6W FR 3-30KHz 8Ω
£5.


It did not look like later T27s, the body was in a large plastic enclosure and the dome was ever so slightly set back in the plastic face plate...
In those days when enquiring to KEF I even once had a hand written reply from R.C. himself.
Something that I still view with incredulity when I try and get a response firms now owned by Chinese interests.


Last edited by proffski on Fri Sep 02, 2005 12:31 pm; edited 3 times in total
Back to top
View user's profile Send private message Send e-mail
proffski
Über Contributor 1000+


Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Fri Sep 02, 2005 12:12 pm    Post subject: Re: KEF drive unit history Reply with quote

Out of sheer interest I dug up one of my sales logs back from 1970.
The prices are interesting! Priced per speaker NOT pairs!

Concerto: Trade £40.95 List £58.50
Celeste: Trade £21.00 List £30.00
Chorale: Trade £19.95 List £28.50
Cresta: Trade £14.59 List £20.84
Cadenza: Trade £29.75 List £42.50

Plus Purchase Tax of course!
I think that tax was not payable on loudspeakers with three or more drive units as these were considered "Professional”!
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 -> KEF Speakers from the 1970s All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
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