G'day all - KEF B110 SP1003

G'day all,

This is my first post on this forum and it is a plea for help.

Today one of my speakers started making a dreadful noise. I pulled off the cover and saw the problem, the mid range had a "stretch" mark close to the centre and the cone was pulled off centre.

The speaker is a KEF B110 SP1003 and was part of a Kef transmission line kit sold in Australia in the seventies.

Any chance anyone has a spare set lying around? Any tips as to where I might source a pair? Any thoughts on a suitable replacement to go with my steam-age system?

All the best

Peter
 

Bobken

Member
2002-12-23 11:22 pm
UK
Hi,

These particular KEF drivers were very popular in the UK at the time you mentioned, but, of course, they haven't been made for many years.

As a result of this widespread use by various high-end makers of speakers, there are still a lot in current use, and there are several UK companies who can re-cone these drive units to new specification. KEF, themselves, used to do re-coning of their own drivers, but I believe that they ceased this operation (especially on older models) some time ago.

If you are completely stuck and cannot buy a suitable replacement, rather than scrapping the entire speakers, it would be worthwhile investigating this.

Of course, this would be more protracted, and extra carriage costs from down under would be involved, but as a last resort, I am sure you would be happy with the results.

Incidentally, if you do ultimately adopt this route, if it was me doing this, I would have both B110 drivers reconed at the same time as (overall) carriage costs would probably be less this way. With Bextrene cones (as these drivers have) just replacing one unit with a new cone and voice-coil etc., will give rise to an 'imbalanced' sound in my experience, when compared with the remaining drive unit which will be rather 'tired' after so many years of use.

Accordingly, an odd stereo soundfield will very likely result at best, and at worst there is a distinct likelihood that the other unit will go bad on you before too long, and you will probably need to go through the same delays and extra costs all over again.

Regards,
 
many thanks

Thanks all

Toulou, Im afraid that I do not have the drawings. I would be happy to photograph the unit and give you the external dimensions.

From memory - and it was a long time ago - the cabinets have two internal baffles that run virtually from the bottom to the top of the 1m plus unit.

Bobken, since the original posting I've located a company in the UK that specialises in restoring old speakers. I've asked them to quote on 2 speakers plus postage. Some of their typical repair costs seem most reasonable. Are there any you've dealt with a particular company and could you share your experiences?

Dehieber thanks for your offer to sell. I will follow up on the repair and email you if that falls over.

I saw a couple on ebay that I just missed out on.

I know that the whole system is of the steam era (the amp is a Kenwood KA7100!) but I built the speakers at 21 and they've travelled with me across the Wide Brown Land - I'm kinda attached...

All the best

Peter
 
In my collection i have article with an Oz TL that uses B110... is this the one you built?

dave
 

Attachments

  • os-tl.gif
    os-tl.gif
    17.2 KB · Views: 636
Not that one

That wasn't the one.

It was far simpler. The box is about a meter tall and the two baffles formed a T and were attached to the top and bottom of the unit. There was a oblong cutout in each of the baffles at the top or bottom that effectively allowed passage of 3 meters between the back of the cone and the vent.

I'll attach a photo and some of the dimensions.

Peter
 

pinkmouse

diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England
Re: many thanks

bespectacled said:
Bobken, since the original posting I've located a company in the UK that specialises in restoring old speakers. I've asked them to quote on 2 speakers plus postage. Some of their typical repair costs seem most reasonable. Are there any you've dealt with a particular company and could you share your experiences?

I'm not Bob, but Wembley Loudspeakers have always been able to recone anything I've sent to them.
 

Bobken

Member
2002-12-23 11:22 pm
UK
Hi Peter,

Like Pinkmouse suggested, I had Wembley Loudspeakers in mind as an example when I suggested this, and there is at least one other company in the London area whose name doesn't come to mind presently, but I may recall whom in the next day or so.

As I said, there are several companies doing this and although the person is away from home right now, an acqaintance of mine recently had 4 x B139s rebuilt by another company (in a different part of the UK) for his monster IMF speakers. I did all of the dissembly/re-assembly work and upgraded the x'overs etc. for him, and I was very impressed with the quality of work done on the drivers.

He is in South Africa for a while and I cannot contact him, but if all else fails, I should be able to let you know who he used in a month or so.

However, if it was me, I would try 'Wembley' as they seem to do a good job, and I have seen some of their work. Don't forget that with these drivers (short of some deliberate maltreatment) nothing can go wrong with the metal baskets nor the magnets (which can be re-magnetised when being repaired if necessary, anyway) so if the cones, surrounds and voice-coils are properly replaced, the drivers should be as good as new.

Good luck, but if you are stuck on anything, I am sure that some of us can offer some more help.

Regards,

P.S. Who is the company you contacted, if you don't mind saying? It might jog my mind and possibly be either of 2 companies I refer to above.
 

Bobken

Member
2002-12-23 11:22 pm
UK
planet10 said:
In my collection i have article with an Oz TL that uses B110... is this the one you built?

dave

Hi Dave,

I just looked more closely at your earlier pic and thought that it has an unusual shaped cut-out in the baffle for a KEF B110, assuming that it is the 'squared-off' baffle aperture on the left-hand side.
I know it is hard to see from this pic but with several drivers in this enclosure, I assume that the rightmost one at the top of the 'line' is probably a B139, as it seems to have the usual straight-sided oval shape of this driver. Also, is that provision for a couple of tweeters in the smaller 2 holes?

I thought I was familiar with (most of) the KEF-based transmission lines, but this is a new one for me. Do you know what it is and who designed it, by chance?

Regards,
 
Re; TL the box type/ shape. I'm willing to bet that this is the KEF kit that followed the SECOND Bailey design in "Wireless World" (around '71/72). (The earlier design of the late sixties was followed by IMF) It was a conventional box (externally) about 1mtr high and had two internal baffles. They were both on the diaganol when viewed from the top of the box. One ran from a rear corner to the 2/3rds of the way along the front panel and then the second ran from half way along the first baffle to the other rear corner. The box was therefore divided in three, the line length about 9 feet. Now, as I recall it, the odd intenral division was specifically designed to eliminate parrallel surfaces and the associated standing waves. The components were the standard KEF Concerto 3-way units and cross over.
Jonathan Bright
 
Planet 10's design is from the local Oz, ETI. It was a bit bigger than the Bailey model. It was a 4-way unit with a Celestion HF 1300 above the B110. They then suggested a T27 on top of that. That expains the 4 cutouts. (A STC/Coles 4001 may have been an alternative.) The cross over was different from the KEF Kit model as I recall. There was a more sophisticated attempt to reduce the mid freq' rise of the B110 with this c-over. I think a guy called David Tilbrook was the designer. He also did a series of mosfet amps and accompanying pre-amps in that period.
 
Hi Bespectacled, collective apologies from the "crew" we seem to have strayed from your original post.......as we do. Okay, I understand your affection for the B110 but I think you indicated you were open to alternatives. One possibilty is a Vifa from WES Components in Sydney. A 5" version of one of their polyprops or treated paper cones would work well and would be a bit more efficient allowing you to attenuate it easily.
Most people think that polypropolene was a bit less "coloured" than Bextrene; it should be an improvement. The WES people as v.reasonably priced and they handle other Scandinavian brands that will be well worth a look. BTW I think you have a Focal distributor in WA. (WAR?) A Focal mid in one of their recent synthetic cones should be excellent.
While you're at it how about an upgrade for the feed to the T27. The original was a "T" section with a couple of 5uF (or 4.7) caps awith a 0.25 mH inductor. Try and get the circuit for the Kef 104ab. This had what KEF called an "Acousitc Butterworth" mod' to the cross over, hence the "ab'. Transformed the tweeter apparently. Collums has a discussion in his book I think. I've got a copy some where. I'll send it over if you wish but it will take a week or two to find.
And welcome to the forum.....
 
Bobken said:
[an unusual shaped cut-out in the baffle for a KEF B110, assuming that it is the 'squared-off' baffle aperture on the left-hand side. ...
I thought I was familiar with (most of) the KEF-based transmission lines, but this is a new one for me. Do you know what it is and who designed it, by chance?

I did a double take on the B110 cutout too... i have the whole article, just haven't processed it.

I also have all the Bailey articles in pdf.

Here is a visualization i did of the triangulated bailey (from here http://t-linespeakers.org/design/foldings/tttl.html).

TTL-front.jpg


dave
 
Planet10, that's the one!

There's a crowd called Recone Lab that I found and another called Regnar.

I'll check out Wembley as well.

Thanks for the tips on refreshing the crossover. I'm handy with a soldering iron from tinkering with old cars but when it comes to electronics I'm a bit monkey see monkey do. But when it comes mods, well I'll give most things a crack...

No apologies required, I am somewhat surprised in the interest in TL arrangements. I've seen so many tiny units in stores and homes at a time when Australians are on average living in biger houses and figured that the big box was all but dead. I often thought my old dinosaurs were just taking up space.

All the best

Peter
 

jkeny

Banned
2007-02-06 12:43 am
Dublin
Here's a novices suggestion, (and I may be way off here) but I seem to remember reading about this sort of problem in LS3/5a speakers with the suggestion that turning the speaker around so as the stretch was no on top and gravity might pull the cone back on-center!

Worth a try as it costs nothing