KEF Cadenza's need first aid please!

I have a pair of KEF Cadenza speakers of 1971 vintage. I know they are prone to the foam collar disintegrating on the Acoustic Bass speaker and this is exactly what has happened. They are my Dad's. They are in excellent condition apart from this problem.
I have read that i can buy an B139 and remove the magnet to replace this damaged unit.
Can someone kindly tell me how to do this or is it in fact feasible.
There are B139's on Ebay and i would like to get these speakers back into use.
And yep i am a Brit! and i am not very knowledgeable in these this so thanks for any advice.

The problem you'll have with removing the magnets from a pair of A6171 B139A drive units will be the lack of an Aluminium collar where the voice coil lurks.

The lighter DIY ABR with voice coil will have different TS parameters, so you'll have to increase the mass by adding Blu-Tack to the voice coil area, as the original design team did.

A simpler approach would be to obtain some BD139B SP1042 ABRs (with the same TS parameters) from sleezeBay and to fill in the gap with silicone sealant as the active drive units A6171 and SP1044 and corresponding SP1037 and SP1042 ABRs frames are different sizes.



This post or any other information supplied to this website or any other by myself is not available as sales and marketing material for sleezeBay or Audiodogging pimps and the like.