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 

General Meanderings Chit-Chat & KEF Loudspekers Et Al.

 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF Speakers from the 1970s
View previous topic :: View next topic  
Author Message
proffski
Über Contributor 1000+


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

PostPosted: Sat Sep 30, 2006 11:23 pm    Post subject: General Meanderings Chit-Chat & KEF Loudspekers Et Al. Reply with quote

I will get shot for going off topic here.
It was before it became a pretend university.
All the speakers I built there were based on KEF units, and all forms of loading were tried and tested.
Daline, labyrinth, TL, IB, reflex etc. As well as open baffle where I failed miserably…

The sound almost exclusively was analytical yet did not cut and shred your eardrums like some of the newly emerging ‘shoebox monitors’.

Testing almost always was done by a panel of the terrible three against live musical sources whenever possible. This included the college organ for the bass.

Some designs were copies, some from magazines etc as well as our personal projects like my half wave stretched Bailey TL with Decca Horn Ribbon tweeter.

Now one of the panel is in Spain with ATCs, the other is on some military base in the East with the latest KEFs and me with bastardised KEF, Wharfedale, Audax hybrids!

My foray into loudspeakers started circa 1968, Hi-Fi well before that as when I discovered on my parents valve radio receiver that by removing the capacitor across the primary winding of the output transformer I could get some treble from the very set even on medium wave!

Over to you.
Back to top
View user's profile Send private message Send e-mail
RGBE
Intermediate Contributor 25+


Joined: 22 Sep 2006
Posts: 46
Location: Sevilla, Spain

PostPosted: Sun Oct 01, 2006 10:43 pm    Post subject: Reply with quote

Your HI-FI story keeps some resemblance with mine.

I started in the mid sixties using the speaker of a wrecked table radio. The "enclosure" was a fruit box and I glued newspapers to block the numerous cracks and holes. The associated electronics were a Philips radio with a little turntable in the top that happened to have a handy "external speaker" output that did not cut off the internal speaker, so I used to block it by covering it with a cusshion when the "Hi-FI" speaker was in use.

Later it was the Wharfedale period with the help of that wonderfull audio man: Gilbert Briggs, that made me the honour of being his letter friend for many years untill he leaved us. He encouraged me to build two large marble enclosures and I´m sending a drawing of mine that he published in his book "About Your Hearing" taken from one of my letters.



Then came the KEF period, but that is another story...


Last edited by RGBE on Mon Oct 02, 2006 12:24 pm; edited 2 times in total
Back to top
View user's profile Send private message
RGBE
Intermediate Contributor 25+


Joined: 22 Sep 2006
Posts: 46
Location: Sevilla, Spain

PostPosted: Sun Oct 01, 2006 10:48 pm    Post subject: Reply with quote

I forgot to say that the letter drawing was in color; that is why the book reproduction looked so patchy.

Last edited by RGBE on Mon Oct 02, 2006 12:30 pm; edited 1 time in total
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


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

PostPosted: Sun Oct 01, 2006 11:20 pm    Post subject: Reply with quote

Fantastic! I love the input!

Sadly all the magnificent work done by people who worked for Goodmans, Wharfedale, KEF, QUAD, Celestion and many others now has somehow found its new roots in China. In the case of Quad it certainly has been a positive move in the quality stakes, but not in the jobs in the UK.
The latest panels are INCREDIBLE!

KEF without any doubt are or were the best known and most influential manufacturers on earth not long ago. The closest you will get to the following is the AR site. I happen to own the LST and MST versions, they sure have their strengths but are only brought out of the loft a few times a year. KEF sound is beguiling!
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 Oct 06, 2006 10:20 pm    Post subject: Solid Enclosures Reply with quote

Yes the marble/brick corner designs had a lot going for them. I only ever heard a mono version back in 1970 in a friends house.

I'd love to have the time money and resources to do the same with good quality modern transducers.

I still read and re-read regularly his publication "Loudspeakers" ' The why & how of good reproduction'.

First printed in May 1948.
Back to top
View user's profile Send private message Send e-mail
RGBE
Intermediate Contributor 25+


Joined: 22 Sep 2006
Posts: 46
Location: Sevilla, Spain

PostPosted: Fri Oct 06, 2006 11:01 pm    Post subject: Reply with quote

One of the good points of corner marble enclosures is that they are not too expensive.

In its simplest form they are made with a marble panel with a square window cut on it for the bass speaker baffle -bolted from the back- and a top triangular wood lid. Mine were a bit more elaborated and were made by a professional shop.

If you have the subbaffle window cut large enough you can easily experiment with various sizes of bass units.

But, of course, you need two good clear corners and cross your fingers... because some times a corner acoustics are not good. In fact my left corner sounded much better than the right one.

I will try to find some photos that I keep some where.
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


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

PostPosted: Fri Oct 06, 2006 11:15 pm    Post subject: Corner Enclosures. Reply with quote

Yes, the construction is straight forward, but the price of marble...

I'd love to see your pictures of the enclosures.
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: Sun Oct 08, 2006 9:37 pm    Post subject: KEF But not as I know them... Reply with quote

Can anybody shed some light on the centre 'suspension' on these.
I thought I knew most quirks in the KEF production line, but this is the very first time I have been aware of this design feature... Embarassed Shocked

http://cgi.ebay.com/Kef-102-2-103-3-104-2-107-107-2-speaker-reconing_W0QQitemZ150040500597QQihZ005QQcategoryZ47123QQrdZ1QQcmdZViewItem
Back to top
View user's profile Send private message Send e-mail
Parts
Senior Contributor 100+


Joined: 13 Jan 2006
Posts: 174
Location: Edinburgh

PostPosted: Mon Oct 09, 2006 9:31 am    Post subject: Reply with quote

Hi Proffski,

That little foam ring is what I believe replaces the dust cap in the coupled cavity designs which Kef produced.

It is what allowed the force canceling rod to be connected, while still keeping the coils free of dust and debri.

I am not sure if there was a more technical reason for it though ?

Steve
Back to top
View user's profile Send private message
speakerguru
VIP Contributor 750+


Joined: 18 Nov 2005
Posts: 958
Location: Green Hut, Tovil

PostPosted: Mon Oct 09, 2006 12:20 pm    Post subject: Reply with quote

Spot on Parts. You can't fit rods with a regular dustcap.

The only other thing to add is that without a dust cap you would get an air leak from front to back of the cone via the voice coil gap. Although there are plenty of speakers around with porous dustcaps this leakage can be very noisy due to air turbulence and is best avoided. Non porous dustcaps are usually combined with ventilated voice coils and/or polepieces to avoid the caps being blown off at high excursion.

These types of leaks are also non-linear and can have unpleasant overload characteristics and slow speaker recovery from overdrive.

Note for Trivia buffs: KM1 midrange units had vented magnet assembly top plates to reduce ferrofluid splash. The centre pole could not be vented as it was screwed to the heatsink rod.

SG
Back to top
View user's profile Send private message
proffski
Über Contributor 1000+


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

PostPosted: Mon Oct 09, 2006 4:28 pm    Post subject: Reply with quote

Cheers Guys!

It all makes sense now.
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
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