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Kef 104ab

 
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wastegate
Intermediate Contributor 25+


Joined: 17 Oct 2014
Posts: 35
Location: Barcelona ( Spain )

PostPosted: Mon Oct 27, 2014 9:40 pm    Post subject: Kef 104ab Reply with quote

Hello, I found a store speakers for sale Kef 104ab, 104ab put on the front but the rear only puts 104.

Is that correct? or should put behind 104ab too?.

I was about to buy them but ultimately buy Calinda, today I passed by the store and still have them and I've been tempted to buy them

Thank you.
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speakerguru
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Joined: 18 Nov 2005
Posts: 958
Location: Green Hut, Tovil

PostPosted: Mon Oct 27, 2014 11:56 pm    Post subject: Reply with quote

The 104aB crossover and switch plate was available as an aftermarket upgrade kit (sorry for the jargon). So those could be Model 104s which have been upgraded by an previous owner.
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SaSi
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Joined: 24 Aug 2008
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PostPosted: Tue Oct 28, 2014 11:52 am    Post subject: Reply with quote

If the price is right for you, go get them.

Only thing to look closely is the condition of the B200 surrounds. For some reason, half the B200 SP1039 surrounds I've seen (pictures and real-life) seem to stretch and lose their half-circle shape. It certainly affects the performance as the deformation is not uniform around the cone and it reduces the effective excursion of the driver which - btw - is a long throw version of the B200.

If the surrounds look good in shape they will be fine. If not, you will need to replace these and I'm not sure the generic rubber surrounds available are a match to what was on these drivers initially.

The Calinda doesn't seem to suffer from the symptom.
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speakerguru
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Location: Green Hut, Tovil

PostPosted: Tue Oct 28, 2014 1:25 pm    Post subject: Reply with quote

SaSi wrote:

For some reason, half the B200 SP1039 surrounds I've seen (pictures and real-life) seem to stretch and lose their half-circle shape.

It depended on the batch of "velbex" used to vacuum form the surround: the starting thickness and the amount on plasticiser. The vacuum forming at KEF in the 70s was only semi-automatic. If the operator delayed in pulling the handle when the timer light came on, the surround would be overheated (and vice versa). The raw material was calendared (rolled) and always retained some memory of its initial flat state. This also explains why the flattening was always in one direction and not at right angle to that direction.

SaSi wrote:
It certainly affects the performance as the deformation is not uniform around the cone and it reduces the effective excursion of the driver
Not a lot. The material has mostly just flattened, not shrunk.

SaSi wrote:
which - btw - is a long throw version of the B200.

It's not. It is the only short coil - long gap B200. All other B200s were long coil in a short gap. However the underhang of the SP1039 (0.25") was identical to the overhang of most KEF B200 long coil versions.
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SaSi
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PostPosted: Tue Oct 28, 2014 3:21 pm    Post subject: Reply with quote

Speakerguru - thanks for the insight and corrections.

I have two SP1039 with this symptom. I will now consider them for a 104 conversion I was thinking of doing - narrow baffle version.
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wastegate
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Joined: 17 Oct 2014
Posts: 35
Location: Barcelona ( Spain )

PostPosted: Tue Oct 28, 2014 3:47 pm    Post subject: Reply with quote

Hi, thanks for answering, you apologize for the translation.

The price is 250 KEF104ab, and had many questions to verify that the back plate just put 104, just as You say detected in the cone B200 (SP1039) some anomalies like to have more thickness around the cone only in some areas ............ I had many doubts.

greetings and thanks
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darkmatter
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Joined: 26 Aug 2010
Posts: 10
Location: Eastern England

PostPosted: Sat Jan 03, 2015 6:29 pm    Post subject: Reply with quote

Reminds me I have 2 pairs of Ref 104 ab speakers in good condition; these I have had in storage (kept safe) for a few years.

I bought these from a local auction house a number of years ago; I must take a look and listen to them as I never got the chance, to due to a house move Sad

I actually know the designer personally, who has given me much guidance and speaker design advice over the years Smile

Simon Smile
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