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DIY LS3/5A subwoofers

 
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andy ashworth
Junior Contributor 10+


Joined: 20 Nov 2003
Posts: 13
Location: West Sussex

PostPosted: Thu Nov 20, 2003 3:31 pm    Post subject: DIY LS3/5A subwoofers Reply with quote

Does anyone know where I can source NOS B139 and B200 drivers for a project ?

I would consider very good used drivers if available.

I know they are often available on ebay but it seems a little mercenary of the seller to buy classic speakers, then sell the drivers for profit (maybe I'm being silly/naive).

If anyone has any tips on using these drivers, that too would be appreciated.

Cheers,
Andy Ashworth.
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terry
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Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Fri Nov 28, 2003 10:10 pm    Post subject: Reply with quote

Andy

I agree, I hate to see old KEF speakers being broken up for the drive units. I suppose that is why I have a loft full of old KEF speakers.

Have you tried Falcon? The URL I have provided here takes you straight to a section where there are some on sale.

Terry
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andy ashworth
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Joined: 20 Nov 2003
Posts: 13
Location: West Sussex

PostPosted: Wed Dec 03, 2003 12:41 pm    Post subject: Reply with quote

I have spoken to Falcon and have also contacted the people selling items through their small ads section. As yet I have had no success.

The market for old KEFs appears to be dominated by a few individuals on Ebay who buy the speakers relatively cheaply, break them up and then sell the pairs of drivers seperately. Usually with a high reserve. I think a lot are trading on the coat-tails of the ls3/5a, usually advertising T27s and B110s as suitable replacements. To my knowledge, to satisfy the design parameters of this speaker, they would have to be very lucky to find a driver within the spec that had previously been fitted to a speaker other than the ls3/5a.

I love the LS3/5a, I have a pair of Kef 'Raymond Cooke' edition in my system but I do wonder how cheaply you could find any KEF drivers if it were not for these 'Little Legends' - ho hum.

Best regards,
Andy.

PS - Is there a 'best' version of the B139 and B200 ?
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terry
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Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Wed Dec 03, 2003 4:34 pm    Post subject: Reply with quote

Andy

Although the LS3/5a has a devout following, that is really only a small part of the equation. There are incredible numbers of people still using Cadenzas, Concertos and the smaller speakers from the early C Series.

I am astounded by the number of people who email me asking about replacement ABRs for Cadenzas for example.

The B110s and B139s are also used widely in diy speakers including transmission line designs not to mention KefKits and Constructor series.

Then of course we have the Linn range (Isobarik, Kan etc).

The B139s are now popular items in subwoofer designs like the 'coffin'. I have more requests for information about where to buy or repair B139s than anything else.

As much as the LS3/5a is loved by a large number of people it is only a very small part of the equation when it comes to second-hand sales of the old drive units.

Terry
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terry
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Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Wed Dec 03, 2003 4:44 pm    Post subject: Reply with quote

andy ashworth wrote:
Is there a 'best' version of the B139 and B200 ?


Certainly there are lots of different versions but especially with respect to the B200 and IMHO the difference is more a power handling issue rather than a quality issue. I would also tend to stick to the earlier 4 bolt/screw versions - pure prejudice. I favour the B200s less than the B110s - but of course they do different things and for good design reasons.

Personally I would use a B139 SP1044 or later rather than a 6171 - but from an audio spec point of view they are similar. The SP1044 is smaller and lighter. The 6171 has however got a useful function, without magnets, as a replacement for the larger ABRs used in earlier Cadenzas.
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andy ashworth
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Joined: 20 Nov 2003
Posts: 13
Location: West Sussex

PostPosted: Wed Dec 03, 2003 7:34 pm    Post subject: Reply with quote

Thanks for the info, I'll keep my eyes open for a good pair of SP1044s.

I'll post my experiences with the project 'as and when'.

Best regards,
Andy Ashworth.
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terry
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Joined: 22 Apr 2003
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Location: UK

PostPosted: Wed Dec 03, 2003 8:26 pm    Post subject: Reply with quote

Andy

B139 SP1044 on eBay. The seller is calling them ABRs but they are not ABRs. This could confuse some people and you could get a bargain.

Terry
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andy ashworth
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Joined: 20 Nov 2003
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Location: West Sussex

PostPosted: Thu Dec 04, 2003 10:55 am    Post subject: Reply with quote

Cheers, I am now watching them.

Andy.
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andy ashworth
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Joined: 20 Nov 2003
Posts: 13
Location: West Sussex

PostPosted: Mon Mar 15, 2004 5:30 pm    Post subject: DIY LS3/5a subwoofers Reply with quote

Well I finally managed to get hold of some B139s (SP6167) for a 'bargain' price (4 for 80 on ebay). All that remains is to find a suitable set of plans for the cabinets and crossovers. KEF recommend a volume of 39.8 litres for an infinite baffle enclosure and around 60-70 litres for a ported one.
I think I would prefer the former as I have always found ported boxes seem to be unpredictable in smaller rooms. Being relatively compact is of primary importance I'm afraid, otherwise I'd be building a coffin !

Has anyone got or know of any info on such a project ?

Did kef manufacture a 3-way speaker that wasn't ported ?
The reason for this is that if the low-pass section had a cutoff at around 400hz, I could build an enclosure to match the volume for which the crossover was originally designed. As for the high-pass to the LS3/5a, that's going to take a bit more headscratching.
I know of the DN12 crossover but I don't think this would be suitable because of the different characteristics of the 2 enclosure types.

Maybe I should bite the bullet and bi-amp the lot, using simple low-pass and high-pass filters between the pre-amp and power-amps. At least that would solve the impedance and phasing problems Idea !

Thanks,
Andy Ashworth.
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terry
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Joined: 22 Apr 2003
Posts: 262
Location: UK

PostPosted: Mon Mar 15, 2004 5:44 pm    Post subject: Re: DIY LS3/5a subwoofers Reply with quote

andy ashworth wrote:

Did kef manufacture a 3-way speaker that wasn't ported ?


Cantata, CS7 and CS9. See Falcon Acoustics here for crossovers.

Terry
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andy ashworth
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Joined: 20 Nov 2003
Posts: 13
Location: West Sussex

PostPosted: Tue Mar 16, 2004 12:47 pm    Post subject: Reply with quote

Thanks Terry, I must have missed that one when I looked a while back. It even looks like the low-pass section is available seperately so it could be ideal. I'll be contacting Falcon and picking their brains with regard to phase error, volumes, etc.

Regards,
Andy.
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